INTERNATIONAL MARITIME ORGANIZATION
E
IMO
MARINE ENVIRONMENT PROTECTION
COMMITTEE
58th session
Agenda item 2
MEPC 58/2/2
20 March 2008
Original: ENGLISH
HARMFUL AQUATIC ORGANISMS IN BALLAST WATER
Application for Basic Approval of the Ecochlor® Ballast Water Treatment System
Submitted by Germany
SUMMARY
Executive summary:
This document contains the non-confidential information related to
the application for Basic Approval of the Ecochlor® Ballast Water
Treatment System in accordance with the Procedure for approval
of ballast water management systems that make use of
Active Substances (G9) adopted by resolution MEPC.126(53)
Strategic direction:
7.1
High-level action:
7.1.2
Planned output:
7.1.2.4
Action to be taken:
Paragraph 5
Related documents:
BWM/CONF/36, MEPC 53/24/Add.1 and BWM.2/Circ.12
Introduction
1
Regulation D-3.2 of the International Convention for the Control and Management of
Ships’ Ballast Water and Sediments stipulates that ballast water management systems that make
use of Active Substances to comply with the Convention shall be approved by the Organization.
2
The Procedure for approval of ballast water management systems that make use of
Active Substances (G9) stipulates the required information (MEPC 53/24/Add.1, annex 4,
paragraph 4.2.1) and provisions for risk characterization and analysis (MEPC 53/24/Add.1, annex 4,
paragraph 5.3), which, according to section 6 of Procedure (G9), should be evaluated by the
Organization.
3
The receiving competent authority in Germany has verified the application dossier
and believes it to satisfy the data requirements of Procedure (G9) adopted by
resolution MEPC.126(53).
For reasons of economy, this document is printed in a limited number. Delegates are
kindly asked to bring their copies to meetings and not to request additional copies.
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MEPC 58/2/2
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4
In accordance with BWM.2/Circ.12, Germany therefore submits the non-confidential part
of the manufacturer’s application dossier in the annex to this document. The complete dossier
will be made available to the experts of the GESAMP-BWWG with the understanding of
confidential treatment.
Action requested of the Committee
5
The Committee is invited to consider the proposal for approval and decide as appropriate.
***
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MEPC 58/2/2
ANNEX
NON-CONFIDENTIAL INFORMATION ON THE Ecochlor® BALLAST WATER
TREATMENT SYSTEM (GERMANY)
1.0
INTRODUCTION
The Ecochlor® Ballast Water Treatment System (BWTS) applies established chlorine dioxide
technology to oxidize and disinfect aquatic invasive species (AIS). Chlorine dioxide has a long
history (50+ years) of being applied safely and economically for the control of microorganisms
in industrial and municipal waters. What is unique about chlorine dioxide is its ability to be
effective against a wide range of troublesome organisms and in a broad range of water quality
conditions. A second unique feature of the chlorine dioxide generated with the Ecochlor®
BWTS compared to other oxidants (such as chlorine) is the minimization of unwanted
by-products.
Chlorine dioxide is believed to be a superior candidate for ballast water treatment for the
following reasons:
• Chlorine dioxide oxidation is well documented in drinking water applications;
• Chlorine dioxide kinetics of bacterial disinfection are fast;
• Chlorine dioxide inactivates organisms at low dosages (a favorable C x t);
• Chlorine dioxide generated with the Ecochlor® BWTS does not produce chlorinated
by-products;
• Chlorine dioxide does not significantly increase corrosion rates at the concentration used
with the Ecochlor® BWTS;
• Chorine dioxide is documented as an effective biocide against known pathogens that
demonstrate resistance (i.e. Cryptosporidium, anthrax, etc.);
• Chlorine dioxide can be safely and economically produced onboard ship;
• Chlorine dioxide is uniquely effective in preventing and neutralizing biofilm; and
• Chlorine dioxide typically decays to below detection levels in a relatively short time
period.
Ecochlor is applying for Basic Approval of the Purate® chlorine dioxide generation method
utilized with the Ecochlor® BWTS in accordance with the International Maritime Organization
(IMO) Guideline 9 (resolution MEPC.126(53)). This application was compiled using the
guidance and format provided in the Draft Methodology (MEPC 55/2/16, annex 4).
1.0.1 Technology Overview
The Ecochlor® BWTS generates chlorine-free chlorine dioxide using the Eka Chemicals Purate®
technology, a patent-protected chlorine dioxide generation method. Eka’s Purate® technology is
a chlorate-based chlorine dioxide generation process. This method differs from other
conventional chlorine dioxide generation methods that involve use of aqueous or gaseous
chlorine, making the chlorine-free Purate® method environmentally superior. Additionally,
Eka’s Purate® technology produces chlorine dioxide efficiently, thereby controlling the required
input of precursor chemicals and eliminating production of unwanted by-products.
To further explain the chemistry, chlorine dioxide can be generated using differing methods, and
a number of chlorate ion reduction processes exist to produce chlorine dioxide. Some of these
methods can also produce chlorine as a generation intermediate or by-product (e.g., Mathieson,
Solvay, R2 and R3/SVP processes). To avooid the chlorine by-product in these traditional
methods, a new process was developed where hydrogen peroxide is the reducing agent and
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1
hydrochloric acid is replaced by sulfuric acid. This newer process, utilized in the patentprotected Eka Chemicals Purate® technology employed with the Ecochlor® Ballast Water
Treatment System (BWTS), does not involve or create free available chlorine (FAC).
Additionally, it is important to note that chlorine dioxide and chlorine act very different
chemically. For instance, chlorine dioxide is an oxidant, yet it does not chlorinate. In contrast,
FAC is both an oxidant and a chlorinating agent. Because FAC is not present in any detectable
concentration, the application of chlorine-free chlorine dioxide results in oxidation without the
direct formation of organic by-products such as trihalomethanes (THM’s), and other unwanted
by-products such as haloacetic acids (HAA’s) are minimized.
To support the above statement regarding halogenated by-products, Ecochlor presents theoretical
discussion of the chlorine-free Purate® chlorine dioxide methodology as well as chemical
analysis of treated ballast water from San Francisco Bay that demonstrates that chlorine dioxide
does not directly form THM’s.
Using the preparation chemicals, the Ecochlor® BWTS generates and injects a dilute solution of
chlorine-free chlorine dioxide directly into ballast water as it is loaded onboard. Treatment of
ballast water occurs during uptake only. The chlorine dioxide solution is not stored onboard as a
concentrated chemical at any time. It is generated on demand based on the amount of ballast
water being pumped onboard. After injection into the incoming ballast water, chlorine dioxide
remains effective in the ballast water tanks for a short period (2 – 20 hours) in order to neutralize
ballast tank biofilm that can cause bacterial re-growth. Over time, the chlorine dioxide continues
to react and/or decay in the ballast tanks so that at the time of discharge the ballast water contains
an undetectable concentration of chlorine dioxide. Operational specifics of the Ecochlor® BWTS
are discussed in detail in Section 3.0.1, Manner of Application.
Since 2001, several bench scale experiments have been conducted on the use of chlorine-free
chlorine dioxide to control aquatic invasive species. The success of the bench scale studies and
the proven effectiveness of chlorine dioxide in numerous land-based water disinfection
applications indicated that the technology was ready for land-based efficacy testing. However,
because there were no land-based testing facilities available in the world, Ecochlor proceeded
directly to installing a full-scale system on the Atlantic Compass in 2004 for efficacy testing. A
second prototype system was installed on the M/V Moku Pahu in 2005. Testing of these systems
is ongoing to demonstrate and verify the efficacy of the Ecochlor® BWTS. Shipboard testing is
being conducted by scientists at the University Of Rhode Island, Graduate School of
Oceanography (URI) who are using a testing protocol approved by the United States Coast
Guard (USCG). Ballast water treated with the Ecochlor® BWTS will comply with the
performance standards in Regulation D-2 of the International Convention for the Control and
Management of Ship’s Ballast Water and Sediments, as well as standards proposed in the United
States Ballast Water Management Act of 2005 (Senate Bill S.363).
The Ecochlor® BWTS is viable for all ballast water capacity ranges, and is distinguished by the
system’s capability to treat at high ballast water flow rates. The Ecochlor® BWTS can be
installed as a retrofit on existing vessels or during a new construction, with the latter being the
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2
most straightforward and cost effective. Additionally, Ecochlor’s treatment system can be easily
incorporated into a land-based system to treat ballast water land-side.
2.0
IDENTIFICATION OF PREPARATIONS, ACTIVE SUBSTANCES AND
RELEVANT CHEMICALS (G9: 4.1)
Based on the definitions of Preparations, Active Substances and Relevant Chemicals in the G9
procedure (Resolution MEPC.126(53)), Ecochlor classifies the substances involved in the
Ecochlor® BWTS process as follows:
Preparations: There are two preparation substances used with the Ecochlor® BWTS:
1) Purate® (a proprietary formulation from Eka Chemicals containing 40% by
weight sodium chlorate (NaCl03) and 8% by weight hydrogen peroxide
(H2O2); and
2) Sulfuric acid (78% by weight).
These two preparation substances are used to generate the active substance (chlorine-free
chlorine dioxide) onboard and are not themselves active substances.
Purate® is discussed in more detail in Section 2.0.1.1 and sulfuric acid is discussed further in
Section 2.0.1.2 below.
Active Substance: Chlorine-free chlorine dioxide is the active substance that is generated
onboard and has “…specific action on or against harmful aquatic organisms and pathogens”
(Guideline 9, 2.1.1). Additional information regarding chlorine dioxide is presented in Section
2.0.2.1 below.
Relevant Chemicals: Ecochlor discusses the following two substances as Relevant Chemicals in
Section 2.0.3:
1) Sulfate ion (as sodium sulfate or sulfuric acid); and
2) Chlorite ion (as sodium chlorite).
Based on the G9 definition of relevant chemicals, both of these substances are “…transformation
or reaction products that are produced during the treatment process…” (Guideline 9, 2.1.4).
Sulfate ions are discussed as a relevant chemical because a slight excess of sulfuric acid is used
during the chlorine dioxide generation process. This is done to ensure high chlorine dioxide
production efficiency. As such, additional sulfate ions (19 mg/L) may be added to ballast water
treated with chlorine dioxide. Although the addition of sulfate ions to sea water as a result of
treatment with the Ecochlor® BWTS is inconsequential, Ecochlor presents justifications to fully
explain the chemistry associated with the treatment process. Section 2.0.3.1 of the application
provides further information regarding sulfate ions that clearly demonstrates that sulfate ions are
not added to treated ballast water at environmentally relevant concentrations.
As the primary reaction by-product in ballast water after disinfection with chlorine-free chlorine
dioxide, Ecochlor classifies chlorite ion (ClO2-), or sodium chlorite (NaClO2) as a relevant
chemical. Detailed information on chlorite ion is presented in Section 2.0.3.2 below.
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Chemical analysis and known chemical principles of disinfection using chlorine dioxide that is
generated in the chlorine-free method used with the Ecochlor® BWTS indicate that no other
reaction by-products are present at environmentally relevant concentrations. However, biocide
treatment of water can raise questions regarding the formation of THM’s and/or HAA’s.
Chemical data and justifications regarding these substances are located in Sections 1.0.1 (above)
and 2.0.3.3.
Table T2.1 below provides an overview of the chemicals involved in the Ecochlor® BWTS and
descriptions of each chemical follow the table.
Table T2.1 – Overview of Chemical Identification
Ingredient
(IUPAC Name)
Identification
Numbers
Chemical
Formula
Structural
Formula
Molecular
Weight
Percentage
(by weight)
Applied
Concentration
a. 34.01
b. 106.44
a. <8%
b. 40%
a. 0.05-2.9 M
b. 0.5-3.2 M
Preparation Chemicals
a.
®
1. Purate
a. Hydrogen
Peroxide
b. Sodium
Chlorate
a. CAS # 7722-84-1
b. CAS # 7775-09-9
a. H2O2
b. NaClO3
2. Sulfuric Acid
CAS# 7664-93-9
H2SO4
98.08
78%
0.75-4M
ClO2
67.45
--
< 5 mg/L
in ballast
water
By-product
< 20 mg/L
By-product
< 5 mg/L
b.
Active Substance in Ballast Water
Chlorine dioxide
CAS# 10049-04-4
Relevant Chemicals in Ballast Water
142.04
1. Sulfate ion
(as sodium
sulfate or
sulfuric acid)
CAS # 7757-82-6
or
CAS# 7664-93-9
2. Sodium Chlorite
(present as
chlorite ion)
CAS # 7758-19-2
Na2SO4
or
H2SO4
or
or
98.08
NaClO2
90.45
2.0.1 Preparations
In order to generate chlorine dioxide onboard Ecochlor® is utilizing a two precursor chemical
approach. The two preparation chemicals, Purate® and sulfuric acid, are mixed under controlled
conditions to generate chlorine dioxide, which is then injected into the ballast water stream. The
preparation chemicals are not added to the ballast water directly, and are not the active
substance.
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2.0.1.1 Purate®
Purate® is a proprietary formulation from Eka Chemicals containing 40% by weight sodium
chlorate (NaCl03) and 8% by weight hydrogen peroxide (H2O2). Therefore, the Ecochlor®
BWTS utilizes chlorate-based chlorine dioxide generation technology. For comparison purposes
only, the USEPA specifies that chlorate ion generators used in drinking water applications
operate at 95% efficiency. This means that at a minimum, 95% of the sodium chlorate in
Purate® is converted to chlorine dioxide. Efficiency is the amount of chlorine dioxide formed,
divided by the sum of all possible oxychlorine compounds that could form. Hydrogen peroxide
is not a part of the efficiency calculation.
% Efficiency =
[ ClO 2 ]
x 100
[ H 2 O 2] + [ ClO 2 ] + [ ClO −2 ] + [ ClO3− ]
Although the Ecochlor® BWTS is not treating drinking water, the system’s chlorine dioxide
generator is operated to achieve a minimum 95% efficiency. This high efficiency reduces the
potential for the preparation chemicals to be present as residual substances in treated ballast
water. The individual components of Purate® (hydrogen peroxide and sodium chlorate) are
discussed in more detail below to explain why they are not considered relevant residual
chemicals.
It should also be recognized that the Purate® solution acts as a precursor to the active substance
and is consumed during chlorine dioxide generation. It is not the active substance itself.
Therefore, Ecochlor is not submitting comprehensive toxicity data for the Purate® chemicals in
this application as it is not relevant to an evaluation of treated ballast water. However, data on
the individual components of Purate® (hydrogen peroxide and sodium chlorate) are provided
where pertinent to human health and/or ship safety.
Hydrogen Peroxide:
The presence of hydrogen peroxide in the Purate® solution is designed to chemically reduce
chlorate ion (+5 oxidation state) to chlorine dioxide (+4 oxidation state). Thus, it is reasonable
to presume that a slight stoichiometric excess of hydrogen peroxide may be present in the
chlorine dioxide solution. This being the case, it is important to understand what happens to any
excess hydrogen peroxide that may be present in the chlorine dioxide solution generated by the
Ecochlor® BWTS.
Chlorine dioxide reacts with hydrogen peroxide in acidic solution to slowly form chloride ion.
In basic solution, chlorine dioxide reacts rapidly (minutes time scale) with hydrogen peroxide to
form chlorite ion. Thus, any excess hydrogen peroxide that might be present in the acidic mixing
chamber (where chlorine dioxide generation occurs in the Ecochlor® BWTS) is likely to react
with chlorine dioxide and form chloride ion, which is ubiquitous in the marine environment.
Alternatively, if any excess hydrogen peroxide were to be carried over into the ballast water
which is slightly basic, it will react with chlorine dioxide to form chlorite ion. Ultimately, the
eventual fate of any residual hydrogen peroxide from Purate® is to form oxygen and water, and
its reducing effect on chlorine dioxide is to form either chloride ion or chlorite ion.
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Purate® contains 8% hydrogen peroxide. At a chlorine dioxide treatment dose of 5.0 mg/L, the
maximum initial concentration of hydrogen peroxide in the chlorine dioxide solution at 95%
reaction efficiency is 0.35 mg/L. As discussed above, this low level residual will react with
chlorine dioxide to form either chloride ion or chlorite ion and will not persist in treated ballast
water. As such, Ecochlor does not consider hydrogen peroxide a relevant chemical applicable to
an evaluation of the Ecochlor® BWTS.
Sodium Chlorate:
Although the major degradation by-product of disinfection with chlorine-free chlorine dioxide is
chlorite ion, some chlorate ion can also be produced. However, residual chlorate ion from the
chlorine dioxide generation process is expected in low concentrations due to the small excess
sulfuric acid applied to the Purate® solution during the chlorine dioxide generation process. As
mentioned above, the chlorine dioxide generator is operated at a minimum 95% efficiency to
ensure complete conversion of sodium chlorate and efficient chlorine dioxide generation.
Based on a 5.0 mg/L applied dose of chlorine dioxide, a calculated chlorate ion concentration on
the order of 0.2 to 0.49 mg/L may be present in the treated ballast water. These concentrations
of chlorate ion in treated ballast water have been confirmed by ion chromatographic analysis
(See Figures F2.1 through F2.3, Tables T2.2 through T2.4, T2.8). Again, for comparison
purposes, these concentrations of chlorate ion are well within the reported range of chlorate ion
measured in drinking water systems (United States) that use chlorine dioxide to treat water for
human consumption. Because there is no US standard for chlorate ion in drinking water and the
fact that the measured chlorate ion concentration is within the range presented in USEPA
published documents for drinking water, Ecochlor does not consider it a chemical of concern in
treated ballast water. Therefore, Ecochlor does not consider chlorate ion a relevant chemical
applicable to an evaluation of the Ecochlor® BWTS.
2.0.1.2 Sulfuric Acid
The sulfuric acid (H2S04) used to generate chlorine-free chlorine dioxide is industrial grade 78%
by weight. A slight excess of sulfuric acid is added to Purate® to increase the efficiency of the
chlorine dioxide generation reaction. Thus, a low concentration of sulfuric acid remains (as
sulfate ion) after the generation of chlorine dioxide and can be measured in treated ballast water.
As such, Ecochlor further discusses sulfuric acid below in Section 2.0.3, Relevant Chemicals.
Analytical data (sulfate ion concentration and pH) from treated ballast water is presented in
Table T2.8 of Section 2.0.3.3.
2.0.2 Active Substance
2.0.2.1 Chlorine Dioxide
The active substance generated by the reaction of the two precursor chemicals is chlorine-free
chlorine dioxide (ClO2). Chlorine dioxide is generated on demand and immediately injected into
the ballast water based on the amount of ballast water being pumped onboard. The preparation
chemicals are not added to the ballast water directly. Chlorine dioxide treatment occurs only
during uptake of ballast water. Chlorine dioxide is not stored onboard as a concentrated
chemical at any time.
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When used to treat ballast water, chlorine dioxide will rapidly react (oxidize / disinfect) with
susceptible organisms and certain chemical components over time. This continuing consumption
of chlorine dioxide is described as the chlorine dioxide demand. The concept of demand is
widely used in water purification to help determine the dose and contact time (C x t) needed for
effective disinfection of a specific water source. In practice this means that when a 5.0 mg/L
dose of chlorine dioxide is added to ballast water, there is typically a rapid decrease in the
chlorine dioxide concentration followed by a continuing reaction of the remaining chlorine
dioxide until the demand of the water is met. After meeting the demand, the chlorine dioxide
will maintain a residual concentration and continue to react with components in the ballast water.
This results in a slow decrease in concentration over time until the concentration of chlorine
dioxide falls to a level that is undetectable by available analytical methods.
In the significant number of tests Ecochlor has conducted, ballast water treated with 5.0 mg/L
chlorine dioxide has a typical decay of less than 24 hours. The chlorine dioxide demand/decay
of a specific water sample will vary depending on factors such as water temperature and amount
of organic matter present. To isolate the effect of temperature on chlorine dioxide demand,
testing was performed in a laboratory setting where temperature was controlled. A whole water
sample from Newark, New Jersey was sent to NovaChem Laboratories for testing. Figures F2.1,
F2.2, and F2.3 show the chlorine dioxide demand of the New Jersey water at 4°C, 12°C and
24°C, respectively. Data Tables T2.2, T2.3 and T2.4 correspond to these demand study curves.
Figure F2.1 – Example of Chlorine Dioxide Demand Curve, 4°C
Note: Demand testing on raw water samples performed by NovaChem Laboratories
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Table T2.2 – Ecochlor Chlorine Dioxide Demand Study, 4ºC
Ecochlor Ballast Water Chlorine Dioxide Decay Study
Source Water
ClO2 Dose
Water Temp
Time after ClO2
treatment
(minutes)
0
5
30
60
180
300
480
660
New Jersey Ballast Water
5.06 mg/L
4 ºC
Chlorine
Dioxide
ClO2 (mg/L)
5.06
3.50
2.80
1.90
1.40
1.10
0.21
0.00
Chlorite Ion
ClO2 (mg/L)
ND
0.742
0.855
1.285
1.727
--1.796
Chlorate Ion
ClO3 (mg/L)
ND
0.001
0.055
0.110
0.169
--0.282
Note: Demand testing on raw water samples performed by NovaChem Laboratories
ND = not detected, “--“ = not measured
Figure F2.2 – Example of Chlorine Dioxide Demand Curve, 12°C
Note: Demand testing on raw water samples performed by NovaChem Laboratories
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Table T2.3 – Ecochlor Chlorine Dioxide Demand Study, 12ºC
Ecochlor Ballast Water Chlorine Dioxide Decay Study
Source Water
ClO2 Dose
Water Temp
Time after ClO2
treatment
(minutes)
0
5
30
60
120
180
240
300
360
New Jersey Ballast Water
5.01 mg/L
12 ºC
Chlorine Dioxide
ClO2 (mg/L)
5.01
3.30
2.30
1.30
0.71
0.43
0.20
0.12
0.02
Chlorite Ion
ClO2 (mg/L)
ND
0.747
1.105
1.520
2.200
2.203
2.075
1.912
1.902
Chlorate Ion
ClO3 (mg/L)
ND
0.046
0.161
0.184
--0.265
-0.285
Note: Demand testing on raw water samples performed by NovaChem Laboratories
ND = not detected, “--“ = not measured
Figure F2.3 – Example of Chlorine Dioxide Demand Curve, 24°C
Note: Demand testing on raw water samples performed by NovaChem Laboratories
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Table T2.4 – Ecochlor Chlorine Dioxide Demand Study, 24ºC
Ecochlor Ballast Water Chlorine Dioxide Decay Study
Source Water
ClO2 Dose
Water Temp
Time after ClO2
treatment
(minutes)
0
5
15
30
50
60
120
150
New Jersey Ballast Water
5.05 mg/L
24 ºC
Chlorine Dioxide
ClO2 (mg/L)
5.05
-2.20
1.52
0.83
0.73
0.19
0.04
Chlorite Ion
ClO2 (mg/L)
ND
1.225
1.533
1.956
--`
2.229
2.351
2.369
Chlorate Ion
ClO3 (mg/L)
ND
0.110
0.140
0.178
0.236
0.227
0.245
0.243
Note: Demand testing on raw water samples performed by NovaChem Laboratories
ND = not detected, “--“ = not measured
As the figures depict, the chlorine dioxide demand / decay proceeds as anticipated with an initial
rapid decrease in chlorine dioxide concentration until the demand of the water is met, and then a
residual concentration decays over time. The figures also demonstrate that the chlorine dioxide
decay rate can decrease in colder water and increase in warmer water.
Because of the known decay behavior and chemical properties, it is unlikely that chlorine
dioxide will be present in treated ballast water at the time of discharge. Additionally, the
Ecochlor® BWTS employs a methodology that treats ballast water during uptake rather than
prior to discharge, which further ensures sufficient holding time to reach undetectable levels of
chlorine dioxide. Although unlikely, Ecochlor recognizes that there is potential for the discharge
of treated ballast water containing minimal amounts of chlorine dioxide. In light of this, chlorine
dioxide toxicity data is presented in this application for review. It should also be noted that one
could reasonably anticipate that any discharged chlorine dioxide would quickly react (decay)
upon introduction to the receiving water.
2.0.3
Relevant Chemicals
2.0.3.1 Sulfate Ion and Sulfuric Acid
During the generation of chlorine-free chlorine dioxide, conversion of sodium chlorate to
chlorine dioxide involves the use of sulfuric acid. To ensure high chlorine dioxide production
efficiency, an excess of acid is typically added to the Purate® solution. Thus, the applied
chlorine dioxide solution is slightly acidic and sulfate ion (SO42-), as sulfuric acid or sodium
sulfate, is produced as a by-product.
The stoichiometric equation for the chlorine dioxide generation process is:
2ClO3- + 2H2O2 + 2H2SO4 → 2ClO2 + O2 + SO4-2 + 2H2O
In water, sulfuric acid is totally miscible and readily dissociates to form hydrogen ion (H+) and
sulfate ions (SO42-). The reaction stoichiometry indicates that for every mole of chlorine dioxide
produced, 0.5 moles of sulfate ion is produced. Thus, if 5.0 mg/L ClO2 is added to the ballast
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10
water it is accompanied by less than 4.0 mg/L SO42-. Further, due to the slight excess of acid
needed for reaction efficiency, at a chlorine dioxide dose of 5.0 mg/L a maximum of 15.0 mg/L
additional sulfate ion might be added to the ballast water. Thus, a maximum total of 19.0 mg/L
of sulfate ion may be added along with a small amount of acidity. This added acidity is easily
buffered by the dissolved carbon dioxide (CO2) naturally present in seawater. Analysis of
treated ballast water shows that the effect of the excess sulfuric acid on pH is nominal. Table
T2.8 presents that control tank ballast water had a pH of 7.6, and chlorine dioxide treated ballast
water had a pH of 7.3.
Because sulfate ion is one the major ions naturally present in seawater, the addition of sulfate ion
from the BWTS is not considered environmentally relevant. Chemical analysis of treated ballast
water from the San Francisco Bay area (Richmond, CA) confirms this statement. Table T2.8
below presents analytical data in which the sulfate ion concentration in the control ballast tank
(no chlorine dioxide treatment) was 1,902 mg/L, while the chlorine dioxide treated ballast tank
had a sulfate ion concentration of 1,826 mg/L (measured 8 days after treatment). These numbers
support the theoretical conclusion that sulfate ion will not be added to treated ballast water at
environmentally relevant concentrations.
Further, at environmentally relevant concentrations, sulfuric acid is completely dissociated and
sulfate ion is at or below natural levels. Complete ionization also implies that sulfuric acid itself
will not adsorb on particulate matter and will not accumulate in living tissues1. Therefore, the
known chemical properties of sulfuric acid, along with the chemical analysis of treated ballast
water, provide justification that it will not be of concern to the aquatic environment or humans
when discharged in treated ballast water. As such, aquatic toxicity data for sulfate ions is not
presented in this application. However, data on sulfuric acid is provided where pertinent to
human health and/or ship safety.
2.0.3.2 Chlorite Ion
Based on the above discussion, the primary reaction by-product in the ballast water after
disinfection and/or decay of chlorine dioxide is chlorite ion (ClO2-), or sodium chlorite
(NaClO2). When chlorine dioxide reacts it loses an electron and forms chlorite ion, which is also
a low level biocide.
ClO2 → ClO2- + eThe concentration of chlorite ion at the time of ballast water discharge will vary depending upon
the source of the ballast water, the treatment dose, and the hold time in the ballast tanks. In
water, chlorite ion decomposes to chloride ion. Light, microorganisms, enzymes, and metals
(such as iron) in the water contribute to the decomposition of chlorite ion. Thus, in a way similar
to chlorine dioxide, chlorite ion will in many cases have an observable demand. Over time the
chlorite ion concentration decreases through continuing reactions with humic or other labile
substances in the ballast water, resulting in an increase of chloride ion (Cl-).
In addition to the chlorite ion data presented in Section 2.0.2.1 above, the chlorite ion demand of
water from Newark, New Jersey was determined and the observed curve is depicted in Figure
F2.4.
1
OECD SIDS SIAR, SIAM 11 (January 2001), UNEP Publications.
11
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Figure F2.4 – Example of Chlorite Ion Demand Curve
Newark, NJ Water
Ballast Water Chlorite Ion Demand
1.94 mg/L, 20 C
Concentration (mg/L)
2.50
2.00
1.50
1.00
0.50
0.00
0
10
20
30
40
50
60
70
80
Time (Hr)
Note: Demand testing on raw water samples performed by NovaChem Laboratories
Table T2.5 – Ecochlor Chlorite Ion Demand Study, 20ºC
Ecochlor Ballast Water Chlorite Ion Demand Study
Source Water
Chlorite Dose
Water Temp
New Jersey Ballast Water
1.94 mg/L
20 ºC
-
Time after ClO2
treatment (hour)
0
1
18
42
69
Chlorite Ion
ClO2 (mg/L)
1.94
0.88
0.30
0.36
0.19
Note: Demand testing on raw water samples performed by NovaChem Laboratories
It is important to note that the above figure and data table depicts a laboratory setting where the
water sample is static. Once the demand of the water has been met, the chlorite ion
concentration becomes stable in the closed system. However, in an actual onboard chlorine
dioxide treatment scenario the treated ballast water will be discharged. Once the ballast water is
discharged, two forces act on the remaining chlorite ion. The first is the dilution of the ballast
water with the receiving water and the second is the chlorite demand of the receiving water.
Because the chlorite ion reaction by-product may persist in chlorine dioxide treated ballast water
at the time of discharge, chlorite toxicity data is presented in this application for review.
However, Ecochlor does not believe that the low concentration of chlorite ion that may be
present in treated ballast water poses unacceptable risks. Additionally, any chlorite ion present at
the time treated ballast water is discharged into the marine environment will continue to decrease
in concentration based on the chlorite ion demand discussed above and dilution effects upon
discharge. Toxicological data verifying that treated ballast water that may contain low levels of
chlorite ion does not present unacceptable risks are presented in Sections 5.1 and 5.2.
I:\MEPC\58\2-2.doc
12
2.0.3.3 Trihalomethanes and Haloacetic Acid By-Products
The Ecochlor® BWTS generates chlorine-free chlorine dioxide using the Eka Chemicals Purate®
technology, a patent-protected chlorine dioxide generation method. Eka’s Purate® technology is
a chlorate-based chlorine dioxide generation process. This method differs from other
conventional chlorine dioxide generation methods that involve use of aqueous or gaseous
chlorine, making the chlorine-free Purate® method environmentally superior. Additionally,
Eka’s Purate® technology produces chlorine dioxide efficiently, thereby controlling the required
input of precursor chemicals and eliminating production of unwanted by-products.
To further explain the chemistry, chlorine dioxide can be generated using differing methods, and
a number of chlorate ion reduction processes exist to produce chlorine dioxide. Some of these
methods can also produce chlorine as a generation intermediate or by-product (e.g., Mathieson,
Solvay, R2 and R3/SVP processes). To avoid the chlorine by-product in these traditional
methods, a new process was developed where hydrogen peroxide is the reducing agent and
hydrochloric acid is replaced by sulfuric acid. This newer process, utilized in the patentprotected Eka Chemicals Purate® technology employed with the Ecochlor® Ballast Water
Treatment System (BWTS), does not involve or create free available chlorine (FAC).
Additionally, it is important to note that chlorine dioxide and chlorine act very different
chemically. For instance, chlorine dioxide is an oxidant, yet it does not chlorinate. In contrast,
FAC is both an oxidant and a chlorinating agent. Chlorine dioxide disinfection is the result of a
1e- transfer mechanism resulting in the formation of chlorite ion (ClO2-)
ClO2 → ClO2- + eBecause FAC is not present in any detectable concentration, the application of chlorine-free
chlorine dioxide results in oxidation without the formation of organic by-products such as
THM’s, and other unwanted by-products such as HAA’s are minimized.
Chemical analysis of ballast water treated with chlorine-free chlorine dioxide presented in Table
T2.8 confirms that THM’s are not directly formed and that HAA’s are not present at
environmentally relevant concentrations. The data show that, similar to the untreated ballast
water (control), FAC is not measurable (<0.05 m/L) (EPA Standard Method 4500-Cl F, DPD) in
treated ballast water when measured on Day 3 following treatment. Further, a chlorine dioxide
residual is not observed (Palintest Lissamine Green-B method), indicating that the entire 5.0
mg/L dose of chlorine dioxide has been reacted.
The data in Table T2.8 shows no formation of THM’s (<1 µg/L) after treatment of ballast water
with chlorine dioxide from the Ecochlor® BWTS. The table also shows the low level (12 µg/L)
presence of a single haloacetic acid (dibromoacetic acid (DBAA)). These data are consistent
with chemistry of chlorine dioxide as an oxidant. The drinking water standard in the United
States is <80 µg/L total THM’s and <60 µg/L total HAA. Both of these standard levels are
achieved in the ballast water treated with chlorine-free chlorine dioxide. Based on the chemical
analysis and the G9 definition of relevant chemicals under 2.1.4 of the Guideline, Ecochlor does
not consider THM’s or HAA’s as relevant chemicals or applicable to an evaluation of the
Ecochlor® BWTS.
I:\MEPC\58\2-2.doc
13
Table T2.8 – Analysis of Ballast Water Treated Onboard the M/V Moku Pahu,
San Francisco Bay Area (Richmond, CA)
Parameter
pH
FAC
ClO2
ClO2
ClO3
Br
BrO3
SO4
Control Ballast
Water
7.6
<0.05 mg/L
-<0.05 mg/L
<0.10 mg/L
50 mg/L
Ballast Water
Treated Onboard
+ 3 Day
13 Feb 2008
7.3
<0.05 mg/L
<0.05 mg/L
0.91 mg/L
0.49 mg/L
--
<0.02 mg/L
--
1902 mg/L
--
-2
THM’s
Bromdichloromethane
Bromoform
Chloroform
Dibromochloromethane
<1 µg/L
<1 µg/L
<1 µg/L
<1 µg/L
HAA’s
Dibromoacetic Acid
Dichloroacetic Acid
Bromoacetic Acid
Monochloroacetic Acid
Trichloroacetic Acid
<1 µg/L
<1 µg/L
<1 µg/L
<1 µg/L
<1 µg/L
Ballast Water
Treated Onboard
+ 5 Day
15 Feb 2008
7.3
-<0.05 mg/L
0.24 mg/L
0.49 mg/L
-<0.02 mg/L
(+11 Day)
1826 mg/L
(+ Day 8)
--
--
<1 µg/L
<1 µg/L
<1 µg/L
<1 µg/L
12 µg/L
<1 µg/L
<1 µg/L
<1 µg/L
<1 µg/L
Note: Demand testing on raw water samples performed by NovaChem Laboratories
“--“ = not measured
2.1
DATA ON EFFECTS ON AQUATIC PLANTS, INVERTEBRATES AND FISH,
AND OTHER BIOTA, INCLUDING SENSITIVE AND REPRESENTATIVE
ORGANISMS (G9: 4.2.1.1)
The toxicology data presented in this application varies by topic and is selective by design. To
clarify, the toxicology data set required by Guideline 9 involves several categories; 1) aquatic
toxicity, 2) mammalian toxicity and 3) environmental fate and effect. It is Ecochlor’s opinion
that these categories relate to the Ecochlor process at different phases of treatment and potential
exposure to the substances associated with the Ecochlor® BWTS is not the same for each
category. As such, each toxicological category was evaluated to determine where a potential
exposure existed and what chemicals were of potential concern throughout the treatment process.
For example, the acute and chronic aquatic toxicity data submitted is intended to provide a reallife scenario of what chemicals may be present when treated ballast water is discharged.
Because Purate® and sulfuric acid are converted into chlorine-free chlorine dioxide and are not
present at significant concentrations in treated ballast water, aquatic toxicity data is not provided
for these chemicals. However, because treated ballast water may contain chlorine dioxide (this
should not happen if the system is used as directed) and chlorite ion (the primary by-product of
disinfection with chlorine dioxide), aquatic toxicity data is provided for these chemicals.
Similarly, because Purate® and sulfuric acid are stored onboard and a potential for human
exposure (crew or technicians) exists, mammalian toxicity data is provided for these chemicals.
However, because treated ballast water is not typically handled by crew or technicians, Ecochlor
I:\MEPC\58\2-2.doc
14
did not provide mammalian toxicity data on chlorite ion as this does not seem relevant. Even in
a situation where human contact with treated ballast water could occur, (i.e. water sample
collection) the chemicals that may be present have been determined analytically to be at
concentrations that are not of concern to humans.
Toxicity testing with THM’s and HAA’s was not considered because chemical analysis of
treated ballast water indicates that these substances are not relevant to an evaluation of ballast
water disinfected with chlorine-free chlorine dioxide (see also Sections 1.0.1, 2.0.3.3 and 5.3).
Additionally, whole effluent testing of the treated ballast water includes the sum of all substances
formed in the treatment process. In Ecochlor’s opinion, aquatic toxicity testing on treated ballast
water reflects the most accurate information on the potential toxicological effects of the treated
water a ship will discharge. Toxicity testing on the precursor chemicals and/or intermediate
substances is informative, but may not reflect the most realistic toxicological evaluation of
treated ballast water.
Toxicity tests for chlorine dioxide were performed by Nautilus Environmental and end-points are
based on measured concentrations of chlorine dioxide at the start of the exposure periods. Acute
toxicity tests were static and chronic tests were static renewal with a daily renewal of test
solutions, with the exception of tests with Macrocystis pyrifera, Mytilus sp. and Skeletonema
costatum, which were static, and the 96 hr test with Clupea pallasi in which the solution was
renewed only after 48 hr of exposure. All tests were conducted according to USEPA guidelines
for conducting short term acute and chronic toxicity tests (USEPA 1995, 2002), with the
exception of the tests with Skeletonema costatum, which followed ASTM (1998) methodology,
and tests with Clupea pallasi, which were based on methodology developed by Dr. Paul Dinnel
from the Shannon Point Marine Center.
Toxicity tests for chlorite were static, with the exception of 7 day tests with Mysidposis bahia
and Atherinops affinis, which were static renewal, with daily renewal of solutions. All tests were
conducted according to USEPA guidelines for conducting short term acute and chronic toxicity
tests (USEPA 1995, 2002).
According to 3.2.1.2 of the Draft Methodology (MEPC 55/2/16, Annex 4), “In the case of whole
effluent testing, EPA, or equivalent, short term methods for estimating the acute toxicity of
substances and discharge provide acceptable alternatives.”
2.1.1 Acute Aquatic Toxicity
2.1.1.1 Chlorine Dioxide
Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean
Mysidposis bahia and the larval fish Menidia beryllina (inland silverside), as well as spore
germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were ~0.4,
>0.4 and 0.2 mg/L, respectively. Additional data are presented for survival of a second fish, the
Pacific herring (Clupea pallasi).
2.1.1.2 Chlorite Ion
Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean
Mysidopsis bahia and the larval fish Cyprinidon variegatus (sheepshead minnow), as well as
15
I:\MEPC\58\2-2.doc
spore germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were
0.58, 75.0 and >15.4 mg/L, respectively.
2.1.1.3 Treated Ballast Water
Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean
Mysidopsis bahia in ballast water treated with chlorine-free chlorine dioxide. EC50 values for
these species were 38.7% and 37.7%.
Table T2.9 – Overview of Acute Aquatic Toxicity
F
C
A
Species
Test Type
EC50
mg/L
NOEC
mg/L
1. Purate®
--
--
--
--
2. Sulfuric Acid
--
--
--
--
Test
Substance
Reference/
comments
Preparations
See Section 2.0.1.1
for justification of not
providing data
See Section 2.0.3.1
for justification of not
providing data
Active Substance
Chlorine Dioxide
F
Menidia beryllina
96 hr survival
F
C
Clupea pallasi
Mysidopsis bahia
96 hr survival
A
Macrocystis pyrifera
a
>0.4
0.4
0.35
~ 0.4
0.22
0.04
b
Nautilus Env. 2005
Nautilus Env. 2005
0.20
0.14
Nautilus Env. 2006
--
--
--
See Section 2.0.3 for
justification of not
providing data
48 hr survival
48 hr
germination
a
Nautilus Env. 2005
Relevant Chemicals
1. Sulfate Ion/
Sulfuric Acid
2. Chlorite Ion
(Sodium chlorite)
-F
Cyprinidon variegatus
96 hr survival
75.0
13.9
Env. Sci. Eng. 1994b
C
Mysidopsis bahia
96 hr survival
0.58
NR
Env. Sci. Eng. 1994a
A
Macrocystis pyrifera
48 hr germ.
>15.4
15.4
Nautilus Env. 2007
Treated Ballast Water
5.0 mg/L dose of
ClO2
C
Mysidopsis bahia
48 hr survival
38.7%
25%
Nautilus Env. 2006
C
Mysidopsis bahia
48 hr survival
37.7%
25%
Nautilus Env. 2006
F = Fish, C = Crustacean, A = Algae, NR = Not Reported
a
Calculated on the basis of data from the chronic toxicity test with this species.
b
Reported NOEC is highly conservative because the next concentration tested was 10-times higher (see discussion in Section
2.1.2.1).
2.1.2 Chronic Aquatic Toxicity
2.1.2.1 Chlorine Dioxide
Chronic toxicity data in Table T2.10 include data for a fish (survival and growth of larval
Menidia beryllina), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an
algae (germination and growth of giant [Macrocystis pyrifera] kelp spores), as well as for two
additional species (larval development for a mollusc [Mytilus sp.] and population growth for a
diatom [Skeletonema costatum]). The most sensitive test species was Mytilus sp., which
exhibited a chronic NOEC of 0.09 mg/L and an EC50 of 0.22 mg/L on the basis of a larval
development test.
I:\MEPC\58\2-2.doc
16
It should be noted that the chlorine dioxide NOEC of 0.04 mg/L reported in Table T2.10 for
Mysidopsis bahia is likely overly conservative and resulted from the ten-fold dilution series
employed in this test. A partial effect was observed at 0.4 mg/L chlorine dioxide with this
species, and no effect at the next lower concentration of 0.04 mg/L. Based on acute tests, the
bivalve larval development test using Mytilus sp. was clearly more sensitive than M. bahia and,
consequently, a definitive test was conducted using the bivalve larval development test with a
narrower (two-fold) dilution series. Thus, although the NOEC reported for Mytilus sp. of 0.09
mg/L appears to be higher than the NOEC for M. bahia, this is largely an artifact associated with
the concentrations which were tested. Consequently, it is appropriate to consider the test using
Mytilus sp. to be the most sensitive test, and therefore the most sensitive NOEC should be the
one reported for this test (0.09 mg/L).
2.1.2.2 Chlorite Ion
Table T2.10 includes chronic toxicity data for a fish (survival and growth of larval topsmelt,
Atherinops affinis), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an
alga (germination and growth of giant kelp [Macrocystis pyrifera] spores), as well as for two
additional species (larval development for a mollusc, Crassostria virginica and an echinoderm,
Strongylocentrotus purpuratus). The most sensitive test species was Mysidopsis bahia, which
exhibited a chronic NOEC of 0.18 mg/L and an EC50 of 0.25 mg/L on the basis of a 7-day
survival and growth test.
2.1.2.3 Chlorine Dioxide
Chronic toxicity testing on the mollusk Mytilus sp. was performed on ballast water disinfected
with chlorine-free chlorine dioxide. An EC50 of >81% and 84% was exhibited. Chronic NOEC
values of 11.7% and 12% for the crustacean Mysidopsis bahia were calculated based on the acute
toxicity results.
Table T2.10 – Overview of Chronic Aquatic Toxicity
Test
Substance
F
C
A
M
Species
Test Type
EC50
mg/L
NOEC
mg/L
Reference/
comments
1. Purate®
--
--
--
--
2. Sulfuric Acid
--
--
--
--
>0.4
0.4
Nautilus Env. 2005
>0.33
0.33
Nautilus Env. 2005
~ 0.4
0.04
Nautilus Env. 2005
0.20
0.14
Nautilus Env. 2006
3.09
2.09
Nautilus Env. 2006
0.22
0.09
Nautilus Env. 2005
Preparations
See Section 2.0.1.1 for
justification of not
providing data
See Section 2.0.3.1 for
justification of not
providing data
Active Substance
Chlorine Dioxide
I:\MEPC\58\2-2.doc
F
Menidia beryllina
F
Clupea pallasi
C
Mysidopsis bahia
A
Macrocystis pyrifera
D
Skeletonema costatum
M
Mytilus edulis
7 day
surv/growth
18 day embryo
devpt
7 day
surv/growth
48 hr
germination
96 hr growth
48 hr
development
a
17
F
C
A
M
Relevant Chemicals
Test
Substance
Species
Test Type
EC50
mg/L
NOEC
mg/L
Reference/
comments
--
--
--
--
See Section 2.0.3.1 for
justification of not
providing data
>13.8
6.9
Nautilus Env. 2007
0.25
0.18
Nautilus Env. 2007
>15.4
15.4
Nautilus Env. 2007
1. Sulfate Ion/
Sulfuric Acid
2. Chlorite Ion
(Sodium chlorite)
F
Atherinops affinis
C
Mysidopsis bahia
A
Macrocystis pyrifera
Strongylocentrotus
purpuratus
Crassostrea virginica
E
M
7 day
surv/growth
7 day
surv/growth
48 hr germ.
Development
10.4
5.0
Nautilus Env. 2007
Development
21.4
14.3
Env. Sci. Eng. 1994c
Treated Ballast Water
5.0 mg/L dose of
ClO2
M
Mytilus sp.
Development
>81%
81%
Nautilus Env. 2006
M
Mytilus sp.
Development
>84%
84%
Nautilus Env. 2006
C
Mysidopsis bahia
48 hr survival
--
12%b
Nautilus Env. 2006
48 hr survival
-11.7%b
Nautilus Env. 2006
C Mysidopsis bahia
F = Fish, C = Crustacean, A = Algae, D = Diatom, M = Mollusk, E = Echinoderm
a
Reported NOEC is highly conservative because the next concentration (NOEC) tested was 10-times higher.
b
Chronic NOEC calculated using acute-to-chronic ratio of 3.22
2.1.3 Endocrine Disruption
There is no evidence to suggest that Purate® or sulfuric acid would result in endocrine disruption.
There is no evidence to suggest that chlorine dioxide or chlorite would result in endocrine
disruption2.
2.1.4 Sediment Toxicity
2.1.4.1 Preparations
The sodium chlorate and hydrogen peroxide components of Purate® are both non-organic and
soluble in water. The chemical properties of both components indicate that they would not be
expected to accumulate in sediments.
2.1.4.2 Active Substance
Chlorine dioxide is not persistent as a result of its rapid degradation pathway to chlorite, and is
not expected to bioaccumulate since it is non-organic and does not have hydrophobic or
lipophilic properties. This chemical would not be expected to accumulate in sediments2.
2.1.4.3 Relevant Chemicals
In water, sulfuric acid is totally miscible and readily dissociates to form hydrogen ion (H+) and
sulfate ions (SO42-). At environmentally relevant concentrations, sulfuric acid is completely
dissociated and sulfate ion is at or below natural concentrations. Complete ionization also
implies that sulfuric acid itself will not adsorb on particulate matter and will not accumulate in
living tissues1.
Chlorite ion is not persistent as a result of its degradation pathway to chloride ion in both water
and soils, and is not expected to bioaccumulate since it is non-organic and does not have
2
Review of the Environmental Fate and Effects of Chlorine Dioxide and Chlorite, Nautilus Environmental, 2007.
18
I:\MEPC\58\2-2.doc
hydrophobic or lipophilic properties2. Therefore, chlorite would not be expected to accumulate
in sediments.
2.1.4.4 Treated Ballast Water
The potential substances present in treated ballast water at the time of discharge are chlorine
dioxide and chlorite ion. The capability of these constituents to accumulate in sediments is
discussed above.
2.1.5
Bioavailability/Biomagnification/Bioconcentration and Food Web/Population
Effects
The active substance and relevant chemical (chlorine dioxide and chlorite, respectively) are the
only constituents potentially present in treated ballast water that will be discharged to the
environment. Both substances are highly water soluble and are not organic in nature. Neither of
these chemicals would be expected to exhibit biomagnification or bioconcentration, and
consequently, would not be expected to persist in the food web2.
2.2
DATA ON MAMMALIAN TOXICITY (G9: 4.2.1.2)
Test reports used in this application were from a variety of sources, including, but not limited to,
OECD SIDS, Eka Chemicals (performed by independent laboratories), independent research,
USEPA, and the National Toxicology Program. The reports were evaluated to ensure that the
data presented was generated by accredited laboratories using accepted standard methodologies
and laboratory practices. Additional discussion on data quality is presented in Section 6.5.2.
The studies and documents referenced are attached to this application.
Potential for human exposure to Ecochlor® BWTS chemicals are limited to Purate®, sulfuric acid
and chlorine dioxide. Chlorite ion is a low-level degradation by-product that will only be present
in treated ballast water. Because treated ballast water is not handled by technicians or ship’s
crew, no potential for exposure exists. Therefore, mammalian toxicity data is presented for
Purate®, sulfuric acid and chlorine dioxide in this section. Section 2.1 provides additional
justification for the selection of toxicity data presented.
The toxicity data presented in this section has been gathered through literature review of
available data. The various forms in which the chemicals have been evaluated (gas, liquid, or
solid phases at differing concentrations) do not necessarily reflect the actual form of the
substance utilized in the Ecochlor® BWTS or the potential route of exposure. Mammalian
toxicity data is presented for informational purposes using data previously established by others.
The quality of the data used is presented in Section 6.5, Assessment Report of this application.
I:\MEPC\58\2-2.doc
19
2.2.1
Acute Mammalian Toxicity
Table T2.11 – Acute Mammalian Toxicity Data
Exposure
Route
Test Substance
Species
Value range
Reference/
comments
Preparations
Purate
®
Sodium Chlorate
Hydrogen Peroxide (10%)
Sulfuric Acid
a. Acute Oral LD50
b. Inhalation LC50
a. Acute Oral LD50
b. Inhalation LC50
a. Rat
b. Rat
a. Rat
b. Rat
a. >5000 mg/kg
b. 5.6 mg/L/4hr
a.1500 - >5000 mg/kg
b. 122 mg/L/4hr
a. Acute Oral LD50
b. Inhalation LC50
a. Rat
b. Rat
a. 2140 mg/kg
b. 0.375 mg/L/4hr
a. Rat
a. 292 mg/kg (males)
340 mg/kg (females)
®
Purate MSDS,
Eka Chemicals
®
Purate MSDS,
Eka Chemicals
OECD SIDS
SIAR, SIAM 11
(January 2001),
UNEP
Publications1
Active Substance
a. Acute Oral LD50
(EPA OPPTS
Method
870.1100)
Chlorine Dioxide
b. Inhalation (nose)
LC50
2.2.2
b. Rat
b. 32 mg/L (90
mg/m3)/4hr
a. USEPA RED
for Chlorine
Dioxide and
Sodium chlorite3
b. Schorsch
(1995) cited in
IPCS Chlorine
Dioxide (Gas)
2002) CICADS
37.4
Effects on Skin and Eye
Table T2.12 – Skin, Eye and Dermal Effects
Test Substance
Skin
Eye
Sensitization
Reference/
comments
Preparations
Purate
®
Not sensitizing to
guinea pigs.
Not sensitizing to
guinea pigs at 6%
concentration
Severely irritating to
contaminated tissue
Severe irritant
Not known to be a
sensitizer
Sulfuric acid
MSDS, Basic
Chemical
Solutions
Irritant
Strong irritant
Not located
Chlorine Dioxide
MSDS,
Eka Chemicals
Not irritating to rabbits
Hydrogen Peroxide
At concentrations
<35%, not a skin
irritant
Sulfuric Acid
®
Mildly irritating to
rabbits
Highly corrosive/
irritating at
concentrations>10%
Sodium Chlorate
Purate MSDS,
Eka Chemicals
®
Purate MSDS,
Eka Chemicals
Active Substance
Chlorine Dioxide
3
4
USEPA Reregistration Eligibility Decision (RED) for Chlorine Dioxide and Sodium Chlorite (Case 4023), August 2006.
Concise International Chemical Assessment Document (CICADS) 37, Chlorine Dioxide (Gas), 2002.
I:\MEPC\58\2-2.doc
20
2.2.3
Repeated-dose Toxicity
Table T2.13 – Repeated-Dose Toxicity
Test Substance
Exposure
Route
Species
Value range
Reference/
comments
Preparations
Purate
®
a. Oral, 90-day
subchronic
a. Rodent
a. NOAEL 100
mg/kg/day
b. Oral, 90-day
subchronic
b. Dog
b. NOAEL 360
mg/kg/day
a. Oral, 90-day
subchronic
a. Rodent
EKA Study 863112 EPA
Guideline 82-1
(1987)5
Sodium Chlorate
Hydrogen Peroxide (10%)
b. Oral, 90-day
subchronic
Sulfuric Acid
28 day, inhalation
(nose only)
b. Other
mammal
Rat
a. NOEL 30-56.2
mg/kg
b. Not located
NOEL/NOAEL not
indentified
EKA Study 863114 EPA
Guideline 82-1
(1987)6
Ito et al. 1976
and Kawasaki et
al., 1969, cited
by SCCP7
OECD SIDS
SIAR, SIAM 11
(January 2001),
UNEP
Publications1
Active Substance
Chlorine Dioxide
a. Inhalation, 60-day
a. Rat
a. LOAEL – 1 mg/L
(2.8 mg/m3)
b. Oral, 90-day
subchronic
b. Rat
b. 2-15 mg/kg in
drinking water. No
treatment related
deaths, clinical signs
or effects on
hematology, clinical
chemistry or organ
weights. Dose-related
decrease in water
consumption and food
consumption in high
dose only. Nasal
cavity was identified as
the target tissue with
hyperplasia,
squamous metaplasia
and inflammatory
responses
USEPA Tox.
Review of
Chlorine Dioxide
and Chlorite,
20008
Daniel, 1990,
cited in IPCS
Chlorine Dioxide
(Gas) 2002)
CICADS 374
5
Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study of Sodium Chlorate in the Rat via Gavage.
Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study in the Dog via Gavage Administration with Sodium Chlorate.
Scientific Committee on Consumer Products (SCCP), Opinion on Hydrogen Peroxide in Tooth Whitening Products, 2005
(SCCP/0844/04).
8
USEPA Toxicological Review of Chlorine Dioxide and Chlorite, September 2000
6
7
I:\MEPC\58\2-2.doc
21
2.2.4
Chronic Toxicity
Table T2.14 – Chronic Mammalian Toxicity
Test Substance
Exposure
Route
Species
Value range
Reference/
comments
Preparations
Purate
®
a. Rodent
a. Oral, 2 year
Sodium Chlorate
b. -a. minimum 12
month study
Hydrogen Peroxide (10%)
b. minimum 12
month study
Sulfuric Acid
--
b. Other
mammal
a. Rodent
b. Other
mammal
--
a. NOAEL < ~5
mg/kg/day for 2 years.
Thyroid hyperplasia
was observed in all
groups of males in an
NTP 2-year cancer
bioassay. Survival,
water consumption,
and body weights were
similar to controls. No
clinical findings were
attributed to sodium
chlorate exposure.
National
Toxicology
Program (2005)
Technical
Report on the
Toxicology and
Carcinogenesis
Studies of
Sodium
Chlorate.9
b. Not located
a. None located
b. None located
SEE
PARAGRAPH
BELOW TABLE
Long term studies
have focused on portal
of entry effects as
systemic effects are
considered unlikely.
OECD SIDS
SIAR, SIAM 11
(January 2001),
UNEP
Publications1
USEPA Tox.
Review of
Chlorine Dioxide
and Chlorite,
20008
Active Substance
a. Oral, 2-year
chronic
a. Rat
a. NOAEL: 10 mg/L
b. minimum 12
month study
b.Other
mammal
b. Not located
Chlorine Dioxide
Although not general toxicology studies, hydrogen peroxide has been extensively evaluated as an
aid to oral hygiene in humans. “Daily use of a … or a 1.5% hydrogen peroxide-containing
mouth rinse for 18 months or 2 years resulted in no reported adverse effects on oral health.”7
2.2.5 Developmental and Reproductive Toxicity
The sodium chlorate component of Purate® was not teratogenic to rats at doses up to 1,000
mg/kg-day during 6-15 days of gestation. Sufficient data is not available for the hydrogen
peroxide component of Purate® (See Purate® MSDS in GESAMP submission).
Hydrogen peroxide was not deemed to cause any concern for reproductive effects by the
European Chemicals Bureau10. Sulfuric acid is not reported to cause teratogenic or reproductive
toxicity effects in humans (See sulfuric acid MSDS in GESAMP submission). Additionally,
from the OECD SIDS Initial Assessment Report1:
9
NTP Technical Report on the Toxicology and Carcinogenesis Studies of Sodium Chlorate in F344/N Rats and B6C3F1 Mice
(Drinking Water Studies), 2005. NTP TR 517, NIH Publication No. 06-4457.
10
European Chemicals Bureau (2003) Hydrogen Peroxide Summary Risk Assessment Report. Special Publication I.03.148.
22
I:\MEPC\58\2-2.doc
“…due to irritant/corrosive effects of H2SO4, oral and dermal routes are not appropriate for testing toxicity
to reproduction. In addition, H2SO4 is a direct-acting toxicant. The acid as such, is not expected to be
absorbed or distributed throughout the body. Therefore, it is not likely that it will reach male and female
reproductive organs following exposures by any route.”
In a study by Carlton et al. (1991), an NOAEL of 10 mg/kg-day for reproductive effects in rats
receiving gavage doses (0, 2.5, 5, or 10 mg/kg chlorine dioxide in deionized water) was
identified8.
2.2.6 Carcinogenicity
The sodium chlorate and hydrogen peroxide components of Purate® are not considered
carcinogenic. Additionally, IARC, OSHA and ACGIH do not list hydrogen peroxide as a
carcinogen and animal experiments did not show clear carcinogenic evidence in different
species. (See Purate® MSDS in GESAMP submission).
Sulfuric acid is not considered to be, nor suspected to be, a cancer-causing agent. (See sulfuric
acid MSDS in GESAMP submission).
Chlorine dioxide has not been assessed for carcinogenic potential. The available dermal
carcinogenicity studies do not definitively characterize the carcinogenicity of chlorine dioxide3.
2.2.7 Mutagenicity/Genotoxicity
Sodium chlorate is not considered mutagenic. In vitro studies indicate that without metabolic
activation, hydrogen peroxide is mutagenic and generally not mutagenic with metabolic
activation. No mutagenic effects were observed with in vivo studies after oral administration.
(See Purate® MSDS in GESAMP submission).
Sulfuric acid is not reported to produce mutagenic effects in humans (sulfuric acid MSDS in
GESAMP submission).
From the USEPA Toxicological Review of Chlorine Dioxide and Chlorite8:
“Both positive and negative results have been found in genotoxicity studies of chlorine dioxide. Exposure
to chlorine dioxide did not induce chromosomal aberrations in vitro, but it did increase occurrence of
reverse mutations (Ishidate et al., 1984). In vivo assays did not find increases in micronucleus induction,
chromosomal aberrations, or sperm-head abnormalities following oral exposure (Meier et al., 1985), but
they did find increases in micronuclei induction after intraperitoneal injection (Hayashi et al., 1988).”
2.2.8 Toxicokinetics
When sodium chlorate was administered on a carrier by capsule in steers, the apparent
radiochlorine absorption was approximately 65%. Urine was the primary route of elimination
where 65-100% of the radiolabeled material was the parent chlorate. Chloride was the only
radiochlorine labeled metabolite detected11.
11
Smith, D.J., Anderson, R. C., Ellig, E.A., and Larsen, G.L. (2005) Tissue Distribution, Elimination, and Metabolism of Dietary
Sodium [36Cl} Chlorate in Beef Cattle.
23
I:\MEPC\58\2-2.doc
From the European Chemicals Bureau Summary Risk Assessment Report10 on hydrogen
peroxide:
“The toxicokinetic evaluation of H2O2 suggests that only under conditions of very high exposure rates the
substance might enter the systemic circulation. When accidental swallowing is excluded, it is unlikely that
such high exposures could be reached in any realistic scenario of occupational or consumer exposure. It is
especially unlikely that the substance deposited on the skin is systemically absorbed to a meaningful
degree. Results from animal studies also suggest that local toxicity at the point of contact and no systemic
effect as the primary mode of action.”
Sulfuric acid is not expected to be absorbed or distributed throughout the body1.
Seventy two hours after administration of chlorine dioxide in water to rats12, 75% of the
recovered dose had been in urine and 25% feces. Chloride ion was the major metabolite
accounting for approximately 84% of the administered dose.
From the USEPA Toxicological Review of Chlorine Dioxide and Chlorite8:
“Chlorine dioxide and chlorite are rapidly absorbed from the gastrointestinal tract and slowly cleared from
the blood. Chlorine dioxide and chlorite, primarily in the form of chloride, are widely distributed
throughout the body and predominantly excreted in the urine. Chloride is the major urinary “metabolite”
for both chlorine dioxide and chlorite.”
2.3
DATA ON ENVIRONMENTAL FATE AND EFFECT UNDER AEROBIC AND
ANAEROBIC CONDITIONS (G9: 4.2.1.3)
The active substance and relevant chemical (chlorine dioxide and chlorite, respectively) are the only
constituents potentially present at environmentally relevant concentrations in treated ballast water
that may be discharged to the environment. Therefore, environmental fate is evaluated for these
substances only.
2.3.1 Modes of Degradation (Biotic, Abiotic)
Degradation of chlorine dioxide occurs by abiotic mechanisms and results from oxidative
reactions with target organisms and some organic constituents. Degradation also occurs from
thermal decomposition, disproportionation, and is enhanced by ultra-violet (UV) light2. Chlorine
does not hydrolyze to an appreciable extent but remains in solution as a dissolved gas13.
Chlorite is more stable in aqueous solution than chlorine dioxide; however, in a similar manner
to chlorine dioxide, chlorite also degrades in aqueous solution as a result of oxidative reactions.
In treated ballast water that is discharged, residual chlorite will decrease through reactions with
organic matter to form chloride, which is non-toxic at the concentrations of interest. Chlorite is
not persistent as a result of its degradation pathway to chloride2.
2.3.2 Bioaccumulation, Partition Coefficient, Octanol/Water Partition Coefficient
The water solubility of chlorine dioxide and sodium chlorite is 3.0 g/L and 390 g/L, respectively.
These physical properties indicate that bioaccumulation is not likely. Additionally, the Kow
12
Abdel-Rahman, M.S., Couri, D., and Bull, R.J. (1982) Metabolism and Pharmacokinetics of Alternate Drinking Water
Disinfectants. Environmental Health Perspectives, v46, pp19-23.
13
EPA Guidance Manual, Alternative Disinfectants and Oxidants, Chlorine Dioxide, 1999.
24
I:\MEPC\58\2-2.doc
values of chlorine dioxide and chlorite are -3.22 and -7.173, respectively. Also see Sections 2.1.5
and 5.1.4.
2.3.3 Reaction with Organic Matter
Chlorine dioxide is an oxidizing agent. Chlorine dioxide does not chlorinate organic matter, thus
its use does not promote the formation of trihalomethanes (THMs), which are a concern with
respect to toxicity and carcinogenicity2.
In addition, data collected for the drinking water industry shows that the use of chlorine dioxide
results in a reduction of the observed concentration of organic contaminant species (e.g., THMs,
haloacetic acids (HAAs), haloaldehydes, haloketones, halocarboxylic acids and other potentially
harmful organic residues). Similarly, the reaction of chlorite ion with organic matter does not
produce harmful organic chemical species and typically results in a chemical reduction of
chlorite ion to chloride ion, which is ubiquitous in the marine environment. Therefore, the
production of harmful organic by-products is not anticipated.
2.3.4 Potential Physical Effects on Wildlife and Benthic Habitats
The chemical and physical properties of the preparation chemicals, active substance, and relevant
chemicals (Table T2-15) indicate that physical effects on wildlife and benthic habitats as
described and rated in GESAMP Reports and Studies No. 64 would not be expected to occur.
Also see Section 2.1.4.
2.3.5 Potential Residues in Seafood
No potential for residues in seafood are known or anticipated.
2.3.6 Any Known Interactive Effects
No other known or expected interactive effects.
2.4
PHYSICAL AND CHEMICAL PROPERTIES FOR THE PREPARATIONS,
ACTIVE SUBSTANCE, AND TREATED BALLAST WATER (G9: 4.2.1.4)
Table T2.15 – Physical and Chemical Properties
Preparations
Physical/Chemical
Property
(with units & reference)
®
1. Purate
2. Sulfuric Acid
(78% by weight)
Melting point (ºC)
1. -29
2. -11.3
Boiling point (ºC)
1. 111
2. 193
a
Flammability
1. Non flammable
(flash point for liquids; ºC) 2. Non flammable
Density (20ºC; kg/m3)
1. 1370 ca.
2. 1708
Vapor pressure
Vapor density (air=1)
I:\MEPC\58\2-2.doc
1. 6700 Pa (40ºC, 40%
sodium chlorate sol’n)
2. <133.32 Pa (37.8ºC)
b
1. Similar to water
2. 3.4 @ boiling
Active Substance
Chlorine Dioxide
(solution)
Same as water
(0 ºC)
Same as water
(100 ºC)
Not applicable
Relevant Chemical
Treated Ballast
Water
Sodium Chlorite
1000 - 1035 ca (for
dilute sol’n in sea
water)
399.9 Pa (30 ºC)
2.3
25
Preparations
Physical/Chemical
Property
(with units & reference)
®
1. Purate
2. Sulfuric Acid
(78% by weight)
point
Water solubility
(temp; effect of pH; mg/L)
pH in solution
Dissociation constant
(pKa)
Oxidation-reduction
potential
Corrosivity to material or
equipment
Reactivity to container
material
Autoignition temperature
(ºC)
Surface tension
Viscosity (20ºC)
Chlorine Dioxide
(solution)
Sodium Chlorite
3.0 g/L @ 25ºC and
34 mmHg
39 g/100 ml at 17°C
(from solid form)
i
1. Strong Oxidizer
2. Strong Oxidizer
c
1. See note
2. Corrosive
d
1. Yes
e
2. Yes
1. Not applicable
2. No Data
Available
Treated Ballast
Water
ca 6.7 - 7.6
1.72
0.95 V @ pH 4-7
Produced in situ and
delivered to ballast
tanks with materials
designed for ClO2.
Produced in situ, not
stored
i
1.72
ca 100 – 700
k
mV
Similar to
Similar to untreated
untreated ballast
ballast water (see
water (see
Section 6.1.2)
Section 6.1.2)
Not applicable
f
1. Strong oxidizer
g
2. Strong oxidizer
h
1. See note
2. Not Available
1. 1.8 mPa.s
2. 26.7 mPa.s
Thermal stability and
identity of breakdown
products
Other physical or
chemical properties
Relevant Chemical
1. 2 ca
2. <1 (1% aq.sol’n)
Explosive properties
Oxidizing properties
Active Substance
Stable as an
j
aqueous sol’n
Intended for use as
disinfectant/oxidizer
Similar to intake
water
Same as treated
sea water
The low
concentration will
not affect typical
sea water viscosity
1060 cP (20ºC)
(same as sea
water)
--
--
Avoid elevated
temps to
avoid/reduce
evolution of ClO2
gas.
1. Liquid slight blue color
w/ slightly pungent odor.
2. Dense, viscous,
colorless, odorless liquid
Salinity
TOC/DOC,
% Particulate Matter
Pale green/yellow
solution with an odor
similar to chlorine.
23.8 – 24.7 ppt
3271 µg/l (TOC)
3073 µg/l (DOC)
l
6.05%
Shaded cells = data not required
a
b
Contact with organic materials e.g. textiles, wood or leather may cause fire, if allowed to dry. Contamination from various metals
or organic materials may cause rapid decomposition, resulting in oxygen gas release and pressure build-up if not properly vented.
Purate® is a solution of sodium chlorate and hydrogen peroxide containing 52% water. The only relevant vapor present is water
vapor.
c
Purate® is corrosive to carbon steel, copper, and brass. Stainless steel 316 and 316L are suitable. Non-metal materials such as
CPVC, PVDF, PTFE, ECTFE, and vinyl ester resins offer excellent performance. Polyethylene and polypropylene offer good
performance, typically for storage tanks.
d
Materials to Avoid: Incompatible materials and chemicals such as organic materials, alkaline substances, strong acids,
phosphorus, sulphur, sulphides, sulphites, and metal/ammonium salts. Contaminated organic materials ignite readily if allowed to
dry. Decomposes in contact with certain metals and alkalis, which generates oxygen gas. Risk of explosion.
e
Do not store near bases, halides, sulfides, picrates, nitrates, chlorates, carbides, fulminates, cyanides, and reducing agents. Do
I:\MEPC\58\2-2.doc
26
not allow water to enter containers. Sulfuric acid may be safely stored in properly designed bulk storage tanks.
f
Contamination from various metals or organic materials may cause rapid decomposition, resulting in oxygen gas release. Assists
combustion. Contaminated clothing will become highly combustible if allowed to dry, and may be ignited by friction or heat.
g
Sulfuric acid is not flammable or combustible. However, it is highly reactive. Concentrated sulfuric acid is a strong oxidizer
capable of igniting combustible materials on contact.
h
No test data is available. Expect it to be similar to a water solution of ionic salts, like sodium chloride.
i
The pKa for chlorous acid (HClO2) is 1.72.
j
HClO2 ↔ ClO2- + H+
BWTS chlorine dioxide solution (5 mg/L) is >99.5+% water and is generally water-like. Highly concentrated solutions (>8000 mg/L)
can be explosive.
k
At higher end of range immediately after chlorine dioxide treatment, then decreases to values similar to untreated ballast water.
l
% Particulate matter calculated as follows: 100*(TOC-DOC)/TOC
2.5
ANALYTICAL METHODS AT ENVIRONMENTALLY RELEVANT
CONCENTRATIONS (G9: 4.2.1.5)
Chemistries that have been tested and verified by the USEPA are used to analyze the chlorine
dioxide treated ballast water produced by the Ecochlor® BWTS. Chlorine dioxide residuals are
measured using the lissamine green B (LGB) chemistry (USEPA Method 327). Chlorite ion
residuals are measured by ion chromatography (IC) (USEPA method 300.1).
Chlorine dioxide measurements are performed using the Palintest 1000 Chlordiox-Duo
Photometer with prepackaged reagent kits to measure chlorine dioxide in the 0.1 to 20 mg/L
concentration range. The LGB detection chemistry is highly selective for chlorine dioxide in the
presence of chlorite ion. The prepared reagents establish the proper pH to minimize any
potential reaction with chlorite ion. The reagent kit also includes a chemical mask to react with
chlorine if it is present in the sample. Under the measurement conditions, studies indicate that
the seawater matrix does not create interference issues that might lead to inaccurate
measurements. The recommended operating range is 0 – 40ºC, and the test reagents are
calibrated for use at 15 - 25ºC. For lower or higher sample temperatures equilibration of a
particular sample to ambient temperature is recommended.
The sensitivity of the Palintest LGB analytical method provides field verification of the expected
decay of chlorine dioxide in treated ballast water at levels below environmentally relevant
concentrations.
Chlorite ion is measured using USEPA Method 300.1. This method uses a sodium carbonate eluent
to separate and measure common anions (F-, Cl, NO2-, Br-, NO3-, HPO42- and SO42-) as well as
chlorite, chlorate and bromate ions. Typically, the sample (25 to 1,000 µL) is injected into the
eluent at 1.0 mL/min. The sample passes through a metal free column to remove dissolved metals
and a guard column before separation on the analytical column. An anion suppressor is used with a
weak acid regenerant solution (newer IC systems might use electrochemical suppression which is
equally effective). Detection is by conductivity.
Method 300.1 may be used to routinely measure chlorite and chlorate ions from 5.0 µg/L to
concentrations in excess of 5.0 mg/L. Measurement at lower concentrations can be made by
increasing the sample loop volume. Higher concentrations require a dilution to bring the sample
concentration to a level inside the calibration range of concentrations.
The sensitivity of USEPA Method 300.1 provides verification of the chlorite ion concentration in
chlorine dioxide treated ballast water at levels below environmentally relevant concentrations.
I:\MEPC\58\2-2.doc
27
2.6
QUALITY CONTROL/QUALITY ASSURANCE (G9: 4.2.4)
2.6.1 Chemical Quality Control
Purate® is a proprietary chemical formulation manufactured by Eka Chemicals. An outline of
the procedure Eka follows to ensure quality of their product is included in GESAMP submission.
Sulfuric acid is obtained from different suppliers depending on the location where chemical resupply may occur. Each sulfuric acid supplier provides batch control or certificate of analysis
documentation. Examples of these documents are included in GESAMP submission.
Chlorine dioxide is generated on demand and quality is assured through preparation chemical
quality. Additionally, the operational parameters of the system that are controlled automatically
(discussed in Section 3.0) ensure efficiency of chlorine dioxide production. Routine BWTS
maintenance also ensures system efficiency and quality of the active substance.
2.6.2 Test Data Quality Control
Nautilus Environmental has performed toxicity tests for evaluation of the Ecochlor® BWTS.
Quality assurance documentation is included in GESAMP submission.
NovaChem Laboratories, Inc. has performed chemical analysis for Ecochlor. Quality assurance
documentation is included in GESAMP submission.
Data quality is also discussed in Section 6.5.2.
3.0
USE OF THE ACTIVE SUBSTANCE
3.0.1 Manner of Application (G9: 4.2.6)
As described in Section 1.0, Ecochlor is utilizing a two precursor chemical approach to generate
chlorine-free chlorine dioxide onboard. The two precursor chemicals are Purate® and sulfuric
acid. Purate®, a proprietary chemical from Eka Chemicals, is a mixture containing 40% by
weight (NaCl03) sodium chlorate and 8% by weight (H2O2) hydrogen peroxide. The sulfuric
acid is industrial grade 78% by weight (H2S04) acid solution.
The Ecochlor® BWTS generates and injects a dilute solution of chlorine-free chlorine dioxide
(5.0 mg/L final concentration) into ballast water as it is loaded onboard. Chlorine dioxide is
generated on demand based on the volume of ballast water being brought onboard and is injected
immediately. Chlorine dioxide is not stored onboard as a concentrated substance at any time.
The mechanism of action of chlorine dioxide on organisms is not entirely deciphered. However,
a study by Aieta and Berg (1986) reported that permeability of the outer membrane is disrupted
by chlorine dioxide13. Additional studies supported the findings that outer membrane proteins
and lipids were altered by chlorine dioxide13.
During Ecochlor’s early investigations with chlorine-free chlorine dioxide the target dosage
found to be effective on the widest array of organisms in various water samples was 5.0 mg/L.
This target dosage was established by examining the efficacy of chlorine dioxide treated water
I:\MEPC\58\2-2.doc
28
(20°C) at 1.0, 5.0, 10 and 20 mg/L dosages in a laboratory setting. In developing the target dose,
the desired concentration had to be high enough to meet the initial chlorine dioxide demand of a
water sample (demand is discussed in Section 2.0.2), and then a residual concentration of
chlorine dioxide had to remain in the water sample long enough to be effective on biofilms
and/or AIS in ballast tank sediments. These trials indicated that at a treatment of 1.0 mg/L
chlorine dioxide, the chlorine dioxide was quickly consumed and therefore, a residual
concentration was not available for disinfection. While chlorine dioxide dosages of 10 and 20
mg/L were effective biocidal treatment, the residual concentration persisted longer than
necessary and was considered an excessive use of chlorine dioxide.
Therefore, the study demonstrated that chlorine dioxide applied at a dose of 5.0 mg/L is safe,
effective, and economical. Treatment at 5.0 mg/L neutralizes all forms of AIS and then remains
effective to neutralize any biofilm or AIS that might be present in the ballast system and ballast
tanks.
In the significant number of tests that Ecochlor has conducted on treated ballast water, the typical
time required for chlorine dioxide to decay to a non-detectable concentration is less than 24
hours. In waters that are colder or warmer, or have lower or higher levels of organic matter,
decay rates may decrease or increase. The 5.0 mg/L target dosage and subsequent residual
concentration time (i.e. holding time) ensures effective removal of AIS and a zero concentration
of chlorine dioxide in treated ballast water at the time of discharge.
3.0.2 Operational Overview & Process Description
The Ecochlor® BWTS consists of two self-contained chemical storage modules, two separate
precursor chemical pumps, a chlorine dioxide generation module (housing for the reactor
column), a booster pump, a programmable logic controller (PLC), an operator interface terminal
(OIT), a system status/start-up panel, and piping to inject chlorine dioxide solution into the
ballast water line. Ancillary equipment includes pipelines for chemical vents and re-supply, and
in-line sampling valves. For demonstration, an engineered drawing of a full scale Ecochlor®
BWTS is included in GESAMP submission. Figure F3.1 provides a photograph of the
Ecochlor® BWTS and F3.2 outlines the Ecochlor® BWTS process.
I:\MEPC\58\2-2.doc
29
Figure F3.1 – Photo of Full Scale Ecochlor® BWTS
Figure F3.2 – Ecochlor® BWTS Process Flow Diagram
Motive Water
To Ballast Tanks
Venturi Eductor
FT = Flow Transmitter, PT = Pressure Transmitter, PLC = Programmable Logic Controller
With Eka’s SVP-Pure® chlorine dioxide generator, individual chemical pumps transfer the
Purate® and sulfuric acid to the reactor column within the chlorine dioxide generation module.
The reactor column is under vacuum and is continuously monitored using a pressure transmitter
to ensure the generation of chlorine dioxide is under sub-atmospheric conditions. Loss of
vacuum for any reason (loss of water flow, power, etc.) will automatically shut down the system
and stop chlorine dioxide production. Inside the reactor column, the chemicals react to form
I:\MEPC\58\2-2.doc
30
chlorine dioxide, oxygen, sodium sulfate and water.
discussion of the chemistry.)
(Refer to Section 2.0 for a detailed
At no time during the production or injection of chlorine dioxide are any chemicals open to the
atmosphere. All chemicals are completely contained in appropriate storage vessels or pipelines
during the entire treatment process. All aspects of the treatment process take place under
conditions that are highly controlled and monitored automatically at all times. Chlorine dioxide
is generated on demand based on the volume of ballast water being brought onboard and is
injected immediately. Chlorine dioxide is not stored onboard at any time.
3.0.3 System Monitoring & Control, Crew Interaction
The Ecochlor® BWTS is designed to provide a safe, economical and completely effective
solution to the problem of AIS in ballast water. It is also designed to minimize impacts to
existing cargo and ballasting operations, crew activities, and demands of the vessel (power,
water, etc.). The Ecochlor® BWTS is fully automated and, depending on how automated the
ships’ ballast water system is, typically requires no additional actions by the crew or alteration of
current ballasting procedures. However, more “manual” ballast water systems that do not have
electronic monitoring capabilities may require slight alterations in current ballasting procedures
to avoid conditions that the Ecochlor® BWTS could falsely recognize as unacceptable. Minor
modifications to ballasting procedures, if any, are ship specific and carefully considered during
system engineering and installation.
If at any time during the ballasting operation the parameters required for safe operation are not
met, the BWTS automatically stops production of chlorine dioxide. An alarm is given and the
condition resulting in the alarm is displayed on the OIT. A list of system alarms and the
appropriate response for each are provided during Ecochlor’s training of ship’s crew and are kept
with the system. Should an alarm condition occur, reactivating the system requires that the
condition be recognized. Once addressed, the alarm is reset on the OIT. Once reset, the PLC
will again perform the series of run permissives and resume chlorine dioxide production. Further
discussion on the BWTS alarms and safety capabilities can be found in Section 3.0.7. The
reliability of Eka’s chlorine dioxide generators is discussed in Section 3.0.5.
3.0.4 System Requirements
Power Requirements: The power requirements for the Ecochlor® BWTS are quite small. These
are: 480 VAC, 3-phase, 60 Hz, rated at 16 FLA. The PLC panel requires 1-phase, 60Hz, 220
VAC rated at 2 FLA.
Water Requirements: As discussed above, a small amount of motive water flow (approximately
53 L/min) is required for a system treating 2,500 m3/hour of ballast water. The water can be
fresh or sea water, and is utilized to create a vacuum in the reactor column. This vacuum draws
the chlorine dioxide into solution for delivery to the ballast water system.
Space Requirements: The Ecochlor® BWTS can be completely enclosed within the dimensions
of a standard shipping container, or a custom design can be developed to accommodate a specific
vessel’s requirements. One of the two systems currently installed is fully enclosed in a container
with dimensions of 5.03 m x 1.98 m x 2.34 m. The other system was designed to meet the
I:\MEPC\58\2-2.doc
31
requirements of the space and is not fully enclosed, with a small footprint measuring
approximately 7.5 m2.
Personnel Requirements: The Ecochlor® BWTS was designed to require minimal input from
technicians and/or crew members. In most installations, the system is kept in an “enabled” or
idle state until the PLC detects a ballasting operation. The crew member performs the ballasting
procedure as normal (gravity, pump, etc,) and the Ecochlor® BWTS automatically treats
incoming ballast water. The BWTS also determines when ballasting has stopped and conducts a
pre-determined shut-down procedure to flush residual chlorine dioxide from the reactor column
and injection piping. The BWTS returns to an idle state until the next ballasting operation is
detected by the PLC.
For installations on ships with a more manual ballasting system that is not capable of electronic
signals, a crew member may be required to push a ‘start’ button or switch on a control panel after
the ballasting operation has been initiated. The BWTS will then operate and control chlorine
dioxide production automatically as described above. No further crew member action is required
to stop chlorine dioxide production as the PLC will recognize when the ballasting operation has
terminated, perform the shut-down procedure and return to the idle status.
Maintenance Requirements: The chlorine dioxide generator requires approximately 6 hours of
preventative maintenance per year. Ecochlor technicians will conduct this service during routine
technical service visits. The scheduled maintenance can easily be accomplished during a typical
port call and will be conducted when the BWTS is not needed for treatment of ballast water.
Maintenance that involves chemical inventory or re-supply will always be handled by Ecochlor
technicians, and never ships’ crew.
3.0.5 System Locations, Considerations and Limitations
Locations and Considerations: The most important factor in the safe operation of the Ecochlor®
BWTS is to first determine a suitable location. Some of the factors that must be considered for
placement of the Ecochlor® BWTS are:
•
•
•
•
•
•
General space limitations – what engineering will be required to fit the system in the
desired location?
Is there a location available that does not interfere with normal cargo operations or
required crew activities?
Can motive water and electricity be provided in a safe and practical manner?
Can chlorine dioxide solution piping be routed to the injection point in a safe and
practical manner?
Can the precursor chemicals be re-supplied easily or can the chemical storage units be
easily removed and re-supplied land based?
Is the area’s cleanliness acceptable? The area around the Ecochlor® system should be
clean and free of debris.
The Ecochlor® BWTS can be located in any suitable and convenient location dependant on the
ship’s design. Ecochlor’s naval architects look for placement opportunities close to the main
ballast water pumps to minimize the length of piping needed for any given installation.
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Limitations: Incoming or Raw water
Chlorine dioxide was selected for treatment of ballast water because of its ability to work
effectively under extremely varied water quality conditions. Ecochlor is confident that the
various water conditions found around the world are well within the operational parameters of
the BWTS and chlorine dioxide effectiveness. For example, chlorine dioxide is effective in brine
water (deep oil well applications), high solids applications (paper mill thick stock, 5 % by
weight) and high color / high organic loading applications (paper mill, drinking water pretreatment)14.
The Ecochlor® BWTS requires no pretreatment of the ballast water to be effective. This means
that high solids or color need not be filtered or removed for the chlorine dioxide to be effective
against potential AIS. Also, the Ecochlor® BWTS can easily handle the temperature variations
likely encountered in ballast water at different ports world wide, which are mild compared to
many other applications where chlorine dioxide technology is successful.
3.0.6 BWTS Operational Safety Features and Alarms
Safety Valve Isolation of the BWTS from the Ship’s Ballast System: The Ecochlor® BWTS and
the ships ballasting system are interconnected only by the delivery line/injection quill for
injecting the chlorine dioxide solution into the ballast water and, in the case where the ballast
water is used as motive water, the incoming water line from the ballast system to the Ecochlor®
BWTS. These lines are fitted with safety valves that separate the BWTS from the ship’s systems
in case of an emergency. These safety valves, together with the failsafe measures in the PLC that
shut down the BWTS in the event that all run-permissive criteria are not met, protects the ship’s
integrity and assures safe operating conditions. These safety valves have the appropriate
approvals by the ship’s classification society and are constructed of materials appropriate for the
application. Additional discussion regarding safety is included in Section 6.2.
System Parameter Alarms: The single most important driving factor in all of Ecochlor’s design,
manufacturing, and installation decisions of any Ecochlor® BWTS is safety. In light of this, the
Ecochlor® BWTS requires multiple and redundant system parameters to be met prior to the
activation of the system and subsequent production of chlorine dioxide. Should any of the
parameters not be met, the system will not function and chlorine dioxide will not be generated.
The Ecochlor® BWTS will provide alarms and indicate which parameter is not to specification.
Technicians and/or the ships’ crew can be alerted to an alarm condition in a variety of ways
depending upon the specific needs of each crew and vessel. For instance, the alarm can be sent
to a lighted control panel in the engine room, displayed on an OIT, or an audible signal can be
sent to the crew radio communication system. Corrective action may be taken by shipboard
personnel if it falls within the guidelines established by Ecochlor, or Ecochlor will service the
installation on-site should it be necessary.
3.0.7 Precursor Chemical Storage, Handling and Delivery
Ecochlor’s team has accumulated over 100 years of industrial and municipal experience in
storing, feeding and re-supplying these and many other chemicals. This experience is utilized in
the design, fabrication and installation of the Ecochlor® BWTS. Ecochlor also utilizes a team of
14
Simpson, G.D., Miller, R.F., Laxton, G.D., Clements, W.R., A Focus on Chlorine Dioxide: The “Ideal” Biocide.
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Naval Architects and Marine Engineers from Seaworthy Systems, Inc. to assist with the specifics
of shipboard installation and environments.
3.0.8.1 Chemical Storage
The two precursor chemicals (Purate® and sulfuric acid) are stored onboard in tanks designed
specifically for this service. Exact tank specifications such as size and location are determined
according to conditions specific to each ship. The amount of the preparation chemicals kept on
board will depend on the ballast water capacity of the vessel. Ecochlor designs the system and
performs calculations so that enough chemicals are kept onboard to ensure effective ballast water
treatment and achieve a re-supply schedule of two to three times per year. For the two Ecochlor
systems currently installed, the tanks are designed to hold a maximum of approximately 1.14 m3
of each preparation chemical. Future systems may have higher or lower chemical volumes
depending on the nature of the specific ballast water requirements and refill capabilities.
The Purate® is stored in a stainless steel tank designed for this application. Purate® can be safely
stored in a vented stainless steel tank for extended periods of time. Tanks for Purate® storage are
constructed of 316L stainless steel that is passivated prior to the introduction of Purate®.
The sulfuric acid is stored in a steel tank lined with Halar (ECTFE) to a minimum thickness of
1.5 mm. This coating is recommended for this application by the coatings manufacturer15. It is
important to note that sulfuric acid is the world’s most commonly utilized commodity chemical.
Sulfuric acid is often referred to as the “king of chemicals”, and is produced in greater amounts
than any other chemical besides water16. Many applications have utilized this material safely for
many years, often delivering the acid via ocean freight.
The chemical storage tanks are designed with secondary containment that has a capacity of 130%
of the tanks volume, assuming a 30 degree vessel list, and are approved by each ship’s
classification society (Lloyd’s & ABS). Each Ecochlor® BWTS will be equipped with the
appropriate spill containment supplies in the unlikely event of a chemical release.
Chlorine dioxide is generated on demand, is never transported to the ship, and is never stored
onboard.
3.0.8.2 Chemical Handling
Re-supply of the precursor chemicals will be the only time these chemicals are ever “handled”
during the use of the Ecochlor® BWTS. The logistical details involved will vary based on a
variety of factors for each specific ship such as the type of vessel, the geographic location where
re-supply will occur, and where the fill station is installed on the vessel. Ecochlor is capable of
conducting chemical re-supply operations at port facilities world wide. ONLY Ecochlor
technical representatives or highly qualified contractors trained by Ecochlor will perform resupply operations. Ships’ crew, longshoremen, stevedores, and any other port facility workers
will never be required to handle the precursor chemicals at any time.
15
16
Mosser, Mark L., Sermatech International Inc., September 15, 2005
The Sulphur Institute Online, Glossary of Terms, (http://www.sulphurinstitute.org/webarticles/anmviewer.asp?a=109&z=30)
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The Ecochlor system does not give off fumes or gases during normal operation. However, a
small amount of fumes may be displaced when the chemical storage tanks are refilled, and
sufficient ventilation is necessary during these operations. For this reason, the chemical tanks
are equipped with vent lines. Each Ecochlor® BWTS installation considers proper chemical
storage tank ventilation, preferably to atmospheric conditions such as the weather deck or
overboard. The locations of the chemical tank vent lines are placed to ensure that technicians,
ship or port crews are not at risk of inhalation dangers during chemical re-supply operations.
For an installation where venting the chemical tanks to the atmosphere is not possible, placement
of the Ecochlor® BWTS in a suitable location where proper ventilation can be achieved is
necessary. To be more specific, proper ventilation would ensure that the occupational exposure
limits for Purate® and sulfuric acid in air are not exceeded (MSDS sheets in GESAMP
submission) include exposure limits for each chemical). The flow rate to ensure these limits are
not exceeded is dependent upon the engineering specifics the installation (size of the space where
the tanks are located, volume of chemical vapors displaced, etc.). Therefore, it is not practical to
provide an exact air flow rate that may be required for a particular installation. However, the
ventilation rate would ensure the occupational limits are not exceeded.
Most important for an installation where venting the chemical tanks to the atmosphere is not
possible, is selection of a suitable location on the ship where existing ventilation mechanisms are
in place. An example is a Ro-Ro deck. The cargo operations that take place normally on Ro-Ro
decks can produce harmful vapors. As such, the existing ventilation equipment is in place to
comply with the occupational exposure limits of a large volume of potentially harmful vapors.
The rate of air exchange required for such cargo operations will exceed the necessary air
exchange rate for the small amount of chemical vapors that might be displaced during a chemical
refill operation.
To summarize, Ecochlor’s preferred method for chemical tank ventilation is to the atmosphere,
in a location that will not create inhalation dangers for technicians, ship or port crews. Should
ventilation to the atmosphere not be possible, placement of the system where existing ventilation
methods are already in place will ensure the occupational exposure limits are not exceeded. It is
also important to note that vapor displacement from the chemical tanks is not continual. Vapors
will only be displaced from the chemical tanks during refill operations, which are anticipated to
occur at a frequency of two - three times per year.
The unloading of foreign materials into the Ecochlor® BWTS chemical storage tanks could cause
a dangerous event.
The chemical fill lines are placed away from other lines for
loading/unloading, are clearly labeled, and secured (locked) to minimize the chance for misdelivery of material. Additionally, the chemical fill line fittings for Purate® are unique and
different from those of the sulfuric acid fill line fittings.
The unloading practices and safeguards are outlined by the manufacturer’s MSDS of the two
precursor chemicals. The Purate® and sulfuric acid MSDS sheets, as well at the Purate®
Technical Bulletin provided by Eka Chemicals / Akzo Nobel, are included in GESAMP
submission.
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Only highly trained Ecochlor technicians or representatives will conduct re-supply of precursor
chemicals. This will ensure the proper procedures are followed at all times. No crew assistance
is needed in the chemical handling procedures, but proper notification and scheduling is
mandatory.
For general safety, awareness training of the ship’s crew is required and performed by Ecochlor
or its trained representatives. Additional health and safety discussion is included in Section 6.2.
3.0.8.3 Chemical Delivery
The piping used for delivery of the sulfuric acid to the chlorine dioxide generation module is
Hastelloy™ (C22 and C276), while the pipe for delivering the Purate® to the generation module
is 316 stainless steel. The pipe used to carry the motive water to the Ecochlor® BWTS is
typically a 2” BondstrandTM pipe. This is the same type of pipe used to carry the chlorine
dioxide solution to the injection point. Bondstrand™ pipe has been approved for this service by
both ABS and Lloyds.
3.0.8 Various Procedures and Management Measures
3.0.8.1 Fire
As with any fire, human exposure to fire, smoke, fumes or combustion products will be
prevented by utilization of proper personal protective equipment (PPE). Also, non-essential
personnel will be required to evacuate the fire area.
Purate® is non-flammable in solution; however, organic materials (e.g. textiles, wood, or leather)
saturated with Purate® may increase the potential for fire if allowed to dry, and a heat or ignition
source is applied. A fire involving Purate® is to be extinguished with water or a water spray.
The use of dry foam, powder or carbon dioxide type extinguishers is to be avoided. Purate® will
sustain combustion due to release of oxygen upon thermal decomposition. Refer to the Purate®
Material Safety Data Sheet (MSDS) that is included in GESAMP submission for complete fire
procedures.
Sulfuric acid is not flammable or combustible and is not sensitive to static discharge or
mechanical impact. However, it is highly reactive and concentrated sulfuric acid is a strong
oxidizer capable of igniting combustible materials. A fire involving sulfuric acid is to be
extinguished with dry chemical, carbon dioxide or foam extinguishing agents. A fire area may
be flooded with water, or fire-exposed containers may be kept cool with a water spray, but water
shall not be allowed to enter containers of sulfuric acid. Decomposition of sulfuric acid under
fire conditions will produce sulfur oxides. Refer to the sulfuric acid MSDS that is included in
GESAMP submission for complete fire procedures.
3.0.8.2 Accidental Release Measures
Ecochlor technicians and ship’s crew will be sufficiently trained to respond to a chemical spill
situation. Training will include, but may not be limited to, familiarization of the chemical
properties and reactivity, exposure hazards, and correct donning of PPE. Proper PPE will
include respiratory protection equipment, eye and face protection (goggles and/or face shield),
chemical resistant gloves and boots (or boot covers), and chemical resistant clothing.
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Any accidental chemical release requires isolation of the spill area and evacuation of nonessential personnel. Proper PPE is to be worn, good industrial hygiene practices will be
maintained and adequate ventilation will be used in any area of accidental release.
For both Purate® and sulfuric acid, suitable dry, inert materials that are not combustible (sand,
earth) or sorbents that are designed for use with these chemicals will be used to absorb spills.
Chemical spill containment kits and PPE are kept near the BWTS in the event of a chemical
release. Used absorbent materials will be placed in appropriate chemical waste containers for
proper disposal.
3.0.8.3 Marine Environment Release
The preparations, although they should not be allowed to freely enter the marine environment,
will not create surface impacts such as oil slicks or thick sludges because both substances are
ionizable in water. Should a marine environment release occur the proper agencies/authorities
will be notified.
If contained, a Purate® spill can be handled and disposed of as a chemical waste. If released into
the marine environment, the Purate® will readily dissipate as the solution is totally miscible in
water. No practical methods of decontamination in a marine water body are available.
Neutralization of sulfuric acid can be achieved with sodium bicarbonate, crushed limestone or
agricultural lime. This product does not contain any components which are designated by the US
Department of Transportation to be Marine Pollutants (49 CFR 172.101).
3.0.8.4 Active Substance Waste Management, Reuse, Recycling, Neutralization
Because the active substance is generated on demand and applied in situ, no active substance
waste stream is created during the treatment process.
3.0.8.5 Conditions for Controlled Discharge
Because the active substance is generated on demand and not stored on board, a situation where
unwanted chlorine dioxide needs to be discharged is not anticipated.
In the very unlikely event that the precursor (preparation) chemicals need to be removed from
the vessel, the necessary chemical transfer pumps, discharge piping and vessel-specific protocols
will be onboard the vessel.
3.0.10 Evaluation of Management Measures
Preventing exposures and emergency situations begins with proper engineering and construction
of systems that are designed for use onboard ships. The measures utilized in managing the
chemicals associated with the Ecochlor® BWTS consider system placement, proper training, and
substance handling that will avoid uncontrolled or emergency situations. The management
measures discussed in Section 3.0.9 above are considered adequate to properly manage the
Ecochlor® BWTS chemicals in a safe manner.
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4.0
HAZARD CLASSIFICATION & MATERIAL SAFETY DATA SHEETS (G9:
4.2.7)
The hazard classifications presented in this section reflect hazards only and do not consider
actual potential for exposure.
4.0.1 Purate®
The hazard classification presented below for Purate® is according to the European Union
directive on classification of hazardous preparations (1999/45/EC). Complete information is
included on the Purate® MSDS provided in GESAMP submission.
R-phrases: R9, R22, R36, R51/53
S-phrases: S3/4, S36/37/39, S46, S61
4.0.2 Sulfuric Acid
The hazard classification presented below for sulfuric acid data from International Chemical
Safety Cards (ICSC #0362). Additional information is provided on the sulfuric acid MSDS
provided in GESAMP submission.
R-phrases: R35
S-phrases: S1/2, S26, S30, S45
4.0.3 Chlorine Dioxide
The hazard classification presented below for chlorine dioxide solution generated with the SVPPure® technology is according to the European Union directive on classification of hazardous
preparations (2001/59/EC). Additional information is included on the chlorine dioxide MSDS
provided in GESAMP submission.
R-phrases: R20, R36/37/38
S-phrases: S24/25, S26, S36/37/39
4.0.4 Sodium Chlorite
Utilizing a typical MSDS sheet for sodium chlorite solution for hazard classification does not
accurately represent the potential hazards at the low concentration of chlorite ion that may be
present in treated ballast water. Thus, hazard classification is not provided for chlorite ion, but
toxicology data is presented in this application.
5.0
RISK CHARACTERIZATION
5.1
SCREENING FOR PERSISTENCE, BIOACCUMULATION, & TOXICITY (G9:
5.1)
Biocide treatment of water can raise questions regarding the formation of THM’s and/or HAA’s.
Chemical analysis and known chemical principles of disinfection using chlorine dioxide that is
generated in the chlorine-free method used with the Ecochlor® BWTS indicate that these reaction
by-products are not present at environmentally relevant concentrations. As such, THM’s and
HAA’s are not evaluated in regards to persistence, bioaccumulation and toxicity in this
application. Chemical data and justifications regarding these substances are located in Sections
1.0.1 and 2.0.3.3.
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5.1.1 Persistence (G9: 5.1.1.1)
Chlorine dioxide and chlorite ion demand/decay data presented in Section 2.0 demonstrate that
these constituents do not persist for extended periods of time in water. These findings are
supported by the physical and chemical properties (i.e. high solubility, non-organic) associated
with these substances as well as studies conducted by others.
For chlorine dioxide, Cooper et al. (2007) demonstrated that chlorine dioxide degradation is
photochemically-enhanced2. Fisher and Burton (1993) reported that at 25°C, 60% of chlorine
dioxide decays to chlorite within 15 minutes, and decayed completely within four hours2.
Chlorite is more stable in aqueous solution than chlorine dioxide; however, in a similar manner
to chlorine dioxide, chlorite also degrades in aqueous solution as a result of oxidative reactions.
Residual chlorite ion in treated ballast water will decrease through reactions with organic matter
to form chloride, which is non-toxic at the concentrations of interest. Chlorite is not persistent as
a result of its degradation pathway to chloride2.
5.1.2 Bioaccumulation (G9: 5.1.1.2)
The estimated log Kow of chlorine dioxide is -3.22 and for sodium chlorite is -7.173. These
values along with the chemical properties (i.e. high solubility, non-organic) of chlorine dioxide
and chlorite indicate that bioaccumulation is not expected.
5.1.3
Toxicity (G9: 5.1.2.3)
5.1.4
PBT Criteria - Active Substance (G9: Table 1)
Table T5.1 – PBT Criteria for Chlorine Dioxide & Chlorite Ion
Substance
Chlorine dioxide
Chlorite Ion
Persistence (P)
Bioaccumulation (B)
Toxicity (T)
Half-life:
>60 days in marine water, or
>40 days in freshwater, or
>180 days in marine
sediment
>120 days in freshwater
sediment
BCF >2,000 or Log Kow
≥3
Chronic NOEC
<0.01mg/L
3.9 minutes, clear freshwater
2
at 5 meters
Criteria fulfilled - No
-3.22
Criteria fulfilled - No
<1 hour in saltwater
(See Figure F2.4)
Criteria Fulfilled – No
-7.17
(as sodium chlorite)
Criteria fulfilled - No
3
3
Lowest chronic
NOEC = 0.09 mg/L
(see Table T2.5)
Criteria fulfilled - No
Lowest chronic
NOEC = 0.18 mg/L
(See Table T2.5)
Criteria Fulfilled - No
It is important to note that the half-life of chlorite ion reported is based on laboratory analysis
with a raw sea water sample. The decay rate in another water sample may be shorter or longer,
depending on the organic matter present and water temperature. However, this analysis is
consistent with the well-documented decay behavior of chlorite ion indicating that persistence
>60 days in sea water would not be expected.
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The estimated log Kow values for chlorine dioxide and chlorite, the physical and chemical
characteristics (i.e. highly soluble, non-organic), along with well-documented degradation
behavior, indicate that chlorine dioxide and chlorite ion will not bioaccumulate. Additionally,
neither chemical meets the criteria to be classified as PBT substances.
5.2
EVALUATION OF THE TREATED BALLAST WATER
5.2.1 Determination of Holding Time
5.2.1.1 Toxicity and Dilution of Treated Ballast Water
Nautilus Environmental performed toxicity testing on treated ballast water2 (See Tables T2.9 and
T2.10). Mytilus sp. bivalve larval development and Mysidopsis bahia acute toxicity tests were
selected because these species were identified as being the most sensitive to chlorine dioxide and
chlorite, respectively. An acute toxicity test was selected for M. bahia due to the small
difference in the acute test EC50 (0.58 mg/L) and the chronic test NOEC for chlorite (0.18
mg/L). Thus, the acute-to-chronic ratio (acute LC50 divided by chronic NOEC) for M. bahia for
chlorite was 3.222.
Results of toxicity tests with treated ballast water using Mytilus sp. (chronic) and Mysidopsis
bahia (acute) are presented on the basis of percent by volume (% v/v) of treated water.
No chronic toxicity was observed with the Mytilus edulis larval development test for treated
ballast water; the EC50 was greater than the highest test concentration in each of two tests
(>81% and >84% v/v).
Acute toxicity with M. bahia resulted in EC50 values of 38.7% and 37.7% (v/v) and the NOEC
for both tests was 25% sample. Thus, a three-fold dilution was necessary to reach a
concentration less than the EC50 and a four-fold dilution was necessary to result in no acute
toxicity with M. bahia. Because M. bahia was the most sensitive species to chlorite by a
significant margin, these data can be considered appropriate to evaluate safe concentrations for
aquatic organisms.
Although chronic toxicity tests were not conducted with treated ballast water using M. bahia,
evaluation of the dilution necessary to result in a chronic toxicity NOEC was calculated. Based
on acute EC50 values (38.7% and 37.7%) and an acute-to-chronic ratio of 3.22, the NOEC for
chronic effects is calculated to be 12% and 11.7% (EC50 value divided by 3.22 ratio). Thus, a
dilution to approximately 12% (v/v) would achieve no chronic toxicity to M. bahia, which has
been demonstrated to be the most sensitive species by a significant margin in the tests
performed2. Further, the next most sensitive species (A. affinis, chronic NOEC 13.8 mg/L) was
almost two orders of magnitude less sensitive to chlorite. Consequently, application of a 10-fold
safety margin is likely highly conservative2 and protective of aquatic organisms.
5.2.1.2 Factors Influencing Holding Time
As presented in Section 3.0.1, the 5.0 mg/L target dosage and subsequent residual concentration
time (i.e. holding time) ensures effective removal of AIS and an undetectable concentration of
chlorine dioxide in treated ballast water at the time of discharge. This target dose of chlorine
dioxide treatment was developed to use the smallest concentration possible for safe and
economical treatment of ballast water.
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Shipboard testing of chlorine dioxide demand has included seasonal changes in North America
(North East, Pacific North West, Gulf Coast), Central America (Pacific), Sweden, and North
Africa. The conclusion is that temperature is the most critical factor in determining the length of
time for the chlorine dioxide residual to decay to undetectable concentrations in ballast water
tanks. However, through extensive shipboard testing and laboratory analysis, chlorine dioxide
decay is predictable.
In the significant number of tests that Ecochlor has conducted on treated ballast water, the typical
time required for chlorine dioxide to decay to a non-detectable concentration is less than 24
hours. In waters that are colder or warmer, or have lower or higher levels of organic matter,
decay rates may decrease or increase. Decay rates (i.e. demand) of chlorine dioxide in various
waters at differing temperatures are presented in Section 2.0.2. Ecochlor has found that lower
temperatures can lengthen the time required to reach an undetectable level of chlorine dioxide,
while higher temperatures typically increase the decay rate. Ecochlor takes this into account in
developing and applying the treatment methodology.
One significant advantage of chlorine dioxide treatment is its ability to remain effective in a
broad range of pH values. The lack of any significant reaction of chlorine dioxide with water is
partly responsible for retention of biocidal effectiveness over a wide pH range14. The typical pH
ranges found in various natural waters will not affect the anticipated decay rates or the holding
time for effective chlorine dioxide treatment.
Based on laboratory and shipboard tests, salinity does not interfere with chlorine dioxide’s
oxidative properties or alter the effectiveness of chlorine dioxide treatment. Ecochlor has found
that the decay rate of chlorine dioxide in fresh water can be slower that that of salt water.
However, the chlorine dioxide demand of a particular water sample is more related to the amount
of organic matter and/or AIS present in the water rather than salinity.
Another advantage to chlorine dioxide treatment is its ability to disinfect without a need for
filtration. Sediment loading does not alter the effectiveness of chlorine dioxide treatment of
ballast water. However, sediment loading may have an effect on the chlorine dioxide demand of
a particular water sample.
Although the chlorine dioxide demand of various waters may change, the overall effectiveness
and holding time required for chlorine dioxide treatment of ballast water remain stable. Ecochlor
is confident in the holding time (less than 24 hours) that has been developed for effective
treatment of AIS in ballast water.
5.3
RISK CHARACTERIZATION & ANALYSIS
5.3.1 Reaction with Organic Matter (G9: 4.2.1.3)
Chlorine dioxide is an oxidizing agent. Chlorine dioxide does not chlorinate organic matter, thus
its use does not promote the formation of trihalomethanes (THMs), which are a concern with
respect to toxicity and carcinogenicity2.
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In addition, data collected for the drinking water industry shows that the use of chlorine dioxide
results in a reduction of the observed concentration of organic contaminant species (e.g., THMs,
haloacetic acids (HAAs), haloaldehydes, haloketones, halocarboxylic acids and other potentially
harmful organic residues).
Similarly, the reaction of chlorite ion with organic matter does not produce harmful organic
chemical species and typically results in a chemical reduction of chlorite ion to chloride ion,
which is ubiquitous in the marine environment. Therefore, the production of harmful organic byproducts is not anticipated.
5.3.2 Characterization of Degradation Route & Rate (G9: 5.3.5)
Chlorine dioxide degrades rapidly in marine and fresh waters, predominantly forming chlorite
ion as a degradation by-product2. Degradation is by abiotic mechanisms and is typically a result
of oxidative reactions with target organisms and some organic constituents. Section 2.0.2.1 has
figures that demonstrate the decay rate of chlorine dioxide at different temperatures. Based on
these laboratory studies, in a static water sample at 24°C treated with 5.05 mg/L of chlorine
dioxide had an undetectable concentration within approximately 150 minutes (2.5 hours).
Chlorite ion also degrades in aqueous solution as a result of oxidative reactions. The rate at
which chlorite ion degrades depends on the demand of the water. Figures in Section 2.0.3.2
depict laboratory studies on the decay rate of chlorite ion. In a static water sample at 20°C dosed
with 1.94 mg/L of chlorite solution, the concentration of chlorite decayed to 0.19 mg/L in 69
hours. It is important to note that in a laboratory setting where the water sample is in a closed
system the chlorite ion concentration becomes stable once demand of the water has been met.
5.3.3 Prediction of Discharge & Environmental Concentrations (G9: 5.3.8)
When the Ecochlor® BWTS is utilized as directed by Ecochlor, the concentration of chlorine
dioxide is expected to be at undetectable levels when treated ballast water is discharged. Thus,
the predicted environmental concentration (PEC) for chlorine dioxide is 0 mg/L.
Figures F2.1 through F2.3 clearly depict the laboratory-derived concentrations of the active
substance and relevant chemicals over time with approximately 5.0 mg/L treatment of chlorine
dioxide at three different temperatures. Repeated testing of this type indicates that the curves are
predictable. Additionally, ion chromatographic analyses of ballast water treated with 5.0 mg/L
of chlorine dioxide have measured chlorite ion concentrations ranging from <0.1 g/L to 2.37
mg/L (see Tables T2.2, T2.3, T2.4, T2.5, T2.6 and T2.7). Therefore, the PEC for chlorite ion is
<0.1 mg/L to 2.37 mg/L. This range is a result of the varied chlorite ion demand of different
waters and factors such as organic load, pH and temperature that affect the decay rate. Section
2.0.3.2 discusses chlorite ion demand /decay in greater detail.
The data in Table T2.8 shows no formation of THM’s (<1 µg/L) after treatment of ballast water
with chlorine-free chlorine dioxide from the Ecochlor® BWTS. The table also shows <1 µg/L of
HAA’s with the exception of a single haloacetic acid (dibromoacetic acid (DBAA), which was
present at a low level (12 µg/L). These data are consistent with the chemistry of chlorine-free
chlorine dioxide as an oxidant. The drinking water standard in the United States is <80 µg/L
total THM’s and <60 µg/L total HAA. Therefore, the analysis of treated ballast water
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demonstrates that THM’s and HAA’s are present at levels well below US drinking water
standards, with a PEC’s of <1 µg/L and <1 µg/L to 12 µg/L, respectively. Based on chemical
analysis and the G9 definition of relevant chemicals under 2.1.4 of the Guideline, Ecochlor does
not consider THM’s or HAA’s as relevant chemicals applicable to an evaluation of the
Ecochlor® BWTS.
5.3.4 Assessment of Potential for Bioaccumulation (G9: 5.3.7)
Because the substances utilized with the Ecochlor® BWTS do not have characteristics that would
indicate a potential for bioaccumulation, no bioaccumulation effects are anticipated.
5.3.5 Effects Assessment
Acute and chronic toxicity test data for chlorine dioxide and chlorite are presented in Tables T2.9
and T2.10, respectively.
5.3.5.1 Chlorine Dioxide
From the Review of the Environmental Fate and Effects of Chlorine Dioxide and Chlorite2:
“It should be noted that because of the rapid dissipation rate of chlorine dioxide, it is somewhat difficult to
interpret the results of toxicity tests with this chemical since, unless the system is continually dosed in a
flow-through manner, the test organisms will typically be exposed to a concentration of chlorine dioxide
which is diminishing over time, and a concentration of chlorite which is initially increasing (as a breakdown product of chlorine dioxide) and then itself decreasing. Thus, any exposure to chlorine dioxide is
actually an exposure to both chlorine dioxide and its breakdown product, chlorite, and the extent to which
each of these toxicants is the cause for any observed effect is somewhat difficult to determine. However,
such would be the case in an environment in which a non-continuous discharge containing chlorine dioxide
occurs and, consequently, data from static and static renewal tests with chlorine dioxide appear to be
appropriate for this evaluation.”
With respect to risk, toxicity to aquatic organisms appears to be the most significant potential
exposure for chlorine dioxide because it is not persistent in the environment and is not expected
to bioaccumulate or adsorb to sediments2. An effects assessment of secondary poisoning is not
relevant. Therefore, the acute and chronic aquatic toxicity results presented in Section 2.1 for
chlorine dioxide provide the most appropriate evaluation of the potential for adverse effects to
aquatic organisms.
Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean
Mysidposis bahia and the larval fish Menidia beryllina (inland silverside), as well as spore
germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were ~0.4,
>0.4 and 0.2 mg/L, respectively. Additional data are presented for survival of a second fish, the
Pacific herring (Clupea pallasi).
Chronic toxicity data in Table T2.10 include data for a fish (survival and growth of larval
Menidia beryllina), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an
algae (germination and growth of giant [Macrocystis pyrifera] kelp spores), as well as for two
additional species (larval development for a mollusc [Mytilus sp.] and population growth for a
diatom [Skeletonema costatum]). The most sensitive test species was Mytilus sp., which
exhibited a chronic NOEC of 0.09 mg/L and an EC50 of 0.22 mg/L on the basis of a larval
development test.
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5.3.5.2 Chlorite Ion
With respect to risk, toxicity to aquatic organisms appears to be the most significant potential
exposure for chlorite because it is not persistent in the environment and is not expected to
bioaccumulate or adsorb to sediments2. An effects assessment of secondary poisoning is not
relevant. Therefore, the acute and chronic aquatic toxicity results presented in Section 2.1 for
chlorite provide the most appropriate evaluation of the potential for adverse effects to aquatic
organisms.
Acute toxicity data (LC50 or EC50) are presented in Table T2.9 for survival of the crustacean
Mysidopsis bahia and the larval fish Cyprinidon variegatus (sheepshead minnow), as well as
spore germination of the giant kelp (Macrocystis pyrifera). EC50 values for these species were
0.58, 75.0 and >15.4 mg/L, respectively.
Table T2.10 includes chronic toxicity data for a fish (survival and growth of larval topsmelt,
Atherinops affinis), an invertebrate (survival and growth of a mysid, Mysidopsis bahia) and an
algae (germination and growth of giant kelp [Macrocystis pyrifera] spores), as well as for two
additional species (larval development for a mollusc, Crassostria virginica and an echinoderm,
Strongylocentrotus purpuratus). The most sensitive test species was Mysidopsis bahia, which
exhibited a chronic NOEC of 0.18 mg/L and an EC50 of 0.25 mg/L on the basis of a 7-day
survival and growth test.
5.3.6 Effects on Aquatic Organisms
When the Ecochlor® BWTS is utilized as directed by Ecochlor, the concentration of chlorine
dioxide is expected to be at undetectable levels when treated ballast water is discharged.
However, a Probable No Effect Concentration (PNEC) for chlorine dioxide is presented. As
defined by the International Maritime Organization (IMO), the PNEC is established at ten times
lower than the lowest NOEC in cases where sufficient data are available. The data provided
meet the requirements outlined by the IMO for use of a 10-fold assessment factor and,
consequently, the PNEC for chlorine dioxide is established at 0.009 mg/L2 (lowest chronic
NOEC for Mytilus sp., 0.09 mg/L divided by 10).
The long-term PNEC for chlorite, as defined by the IMO, is established at ten times lower than
the lowest NOEC, in cases where sufficient data are available. The data provided meet the
requirements outlined by the IMO for use of a 10-fold assessment factor and, consequently, the
PNEC for chlorite is established on this basis at 0.018 mg/L (lowest chronic NOEC for M. bahia,
0.18 mg/L divided by 10). It should be noted that this PNEC is conservative, since a PNEC for
chlorite has been reported on the basis of a species sensitivity distribution to be 0.135 mg/L by
Fisher et al. (2003) on the basis of freshwater acute toxicity data2.
5.3.7 Effects on Sediment
Because the substances utilized with the Ecochlor® BWTS do not have characteristics that would
indicate adsorption to sediment particles, no effects on sediments are anticipated.
5.3.8 Comparison of Effect Assessment with Discharge Toxicity
The relevant chemicals (chlorine dioxide and chlorite ion) potentially present in treated ballast
water were evaluated in regards to discharge toxicity. No chronic toxicity was observed with the
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Mytilus edulis larval development test for treated ballast water (see Section 5.2.1.1). Therefore,
discharge toxicity testing indicates that observed toxicity in treated ballast water can be
attributed to the presence of chlorite.
Samples of ballast water from two separate onboard treatments with 5.0 mg/L of chlorine
dioxide were tested for toxicity. Chlorite ion was measured in these samples and was 2.35 mg/L
and 0.41 mg/L, which represents both the high and low ends of the overall range of chlorite ion
measured in treated ballast water. On the basis of measured chlorite ion and the EC50 values of
38.7% and 37.7% by volume, the LC50 for the treated ballast water samples was 0.91 mg/L
(2.35 mg/L chlorite multiplied by 38.7%) and 0.15 mg/L (0.41 mg/L chlorite multiplied by
37.7%), respectively. Although these LC50 values are somewhat variable, their average (0.53
mg/L) compares well with the reported LC50 for chlorite using Mysidopsis bahia of 0.58 mg/L
(Table T2.9). The variability between these two numbers may have resulted from differences in
sensitivity of different batches of test organisms, or variability in subsampling or analytical
procedures2.
Thus, the results are generally consistent with the conclusion that the toxicity to M. bahia
observed in treated ballast water was caused by residual chlorite and not by chlorine dioxide or
additional contaminants. This conclusion is further supported by the fact that toxicity was
observed using an acute test with M. bahia in both samples, and no toxicity was observed with a
chronic test using Mytilus sp.. In general, a chronic toxicity test with Mytilus sp. would be
expected to be more sensitive than an acute test with M. bahia in the vast majority of cases, with
chlorite being unusual in this regard2.
6.0
RISK ASSESSMENT
The risks presented by having the Ecochlor® BWTS onboard are discussed in Section 6.1, while
risks to technicians and/or ships crew are discussed in Section 6.2.
6.1
RISK TO SAFETY OF SHIP
6.1.1 Ship Integrity and the BWTS
The Ecochlor® BWTS and the ship’s ballasting system are interconnected only by the delivery
line/injection quill for delivering the chlorine dioxide solution into the ballast water and, in the
case where ballast water is used as motive water, the incoming water line from the ballast system
to the Ecochlor® BWTS. These lines are fitted with safety valves that separate the BWTS from
the ship’s systems in case of an emergency. These safety valves, together with the failsafe
measures in the PLC that shut down the BWTS in the event that all run-permissive criteria are
not met, protects the ship’s integrity and assures safe operating conditions. The safety valves
have the appropriate approvals by the ship’s classification society and are constructed of
materials appropriate for the application.
Further, the Ecochlor® BWTS does not become an integral part of the existing ballast system
upon installation. The ship’s ballast system will run unaffected if the BWTS is enabled/disabled,
has power/no power, etc. and the only impact from shutting off the BWTS would be that
incoming ballast water would not be treated.
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6.1.2 Corrosion
Corrosion in natural waters, to include seawater and brackish harbor waters, is caused by the
presence of dissolved oxygen, marine growth, and salts in the water. Most of the fundamental
research on corrosion in natural waters was done in the early part of the 20th Century and is
summarized in the 1948 Corrosion Handbook, edited by Professor H. H. Uhlig of MIT17.
Extreme water pH values (below 4 or above 10) can also affect corrosion rates.
Figure F6.1 shows the relationship between the salt content of water and corrosion rate. As the
salt content increases to approximately 3% by weight, the rate of corrosion begins to decrease.
This behavior was explained years ago, and is based on the principles of electrical conductivity.
As the salt content increases, so does the electrical conductivity. Although increased
conductivity increases corrosion rates, the increased conductivity is countered by a decrease in
the solubility of other substances (such as oxygen) in the water. Because dissolved oxygen is the
most common chemical to be reduced by the oxidation of iron17, increased salinity reduces the
dissolved oxygen in the water, and therefore, reduces the corrosion rate.
Figure F6.1 – Salt Content and Water Corrosivity17
Relative Corrosion Rate
Effect of Salt Content on Corrosivity of
Water
Concentration of NaCl, % wt.
1
Note: Redrawn from Uhlig Corrosion Handbook, page 131
Since the installation of the first full-scale Ecochlor® BWTS aboard the M/V Atlantic Compass
in 2004, testing relating to corrosion has been conducted. Specifically, the pH and dissolved
oxygen (DO) in dockside water as well as chlorine dioxide treated and untreated ballast water
has been measured, and corrosion test coupons have been analyzed by an independent
laboratory. The data presented in this section will demonstrate that the active substance
(chlorine dioxide) being utilized by the Ecochlor® BWTS does not increase the rate of corrosion
above that encountered under typical environmental conditions.
Additionally, installation of the Ecochlor® BWTS results in no dissimilar metals being in contact
with the existing ballast system or any other part of the ship. All parts in contact with the ship
are mild steel. If necessary, Ecochlor can match a particular ship’s alloy piping or identify
17
Heidersbach, Bob; Dr. Rust, Inc.; Ballast Water Corrosion Rates Using the Ecochlor Ballast Water Treatment System, May 2007
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another appropriate material to ensure there is no elevated risk of corrosion due to use of
dissimilar metals.
6.1.2.1 Effect of pH and Elevated Dissolved Oxygen Concentration on Corrosion
During a July 2005 investigation aboard the Atlantic Compass, DO and pH measurements were
recorded. The background DO level was measured from a sample of Newark, NJ dockside water
(FAPS Terminal) and found to be approximately 4.71 mg/L. After the ship completed a
ballasting operation, the DO was measured in a control tank (not treated with chlorine dioxide)
after the tank was filled (time, T=0). The measured DO concentration was 5.86 mg/L; a 1.15
mg/L increase in DO compared to the dockside water. At the end of the test period of 96 hours,
the DO concentration had dropped to 5.17 mg/L, possibly due to the presence of viable respiring
organisms.
In the same study, the DO level in a ballast tank that received 5.0 mg/L chlorine dioxide
treatment was also measured after being filled (time, T=0). The measured DO concentration was
6.57 mg/L; a 1.86 mg/L increase in DO compared to the dockside water. Compared to the
control tank, this represents an increase in measured DO of approximately 12%. Over the test
period of 96 hours, the DO concentration remained relatively stable and dropped to 6.47 mg/L,
possibly due to the lack of respiring organisms. The results of this study are depicted in Figure
F6.2.
Figure F6.2 – Dissolved Oxygen and pH
Dissolved O2 and pH
Incoming water
FAPS terninal
8
7
-1
O2 (mg L ) and pH
6
5
Incoming water
FAPS terninal
4
3
O2- C
2
pH- C
O2- T
pH- T
1
O2- F
pH- F
0
0
20
40
60
80
100
Time (h)
Source: University of Rhode Island, Graduate School of Oceanography, 2005
O2 = Dissolved oxygen, C= control (untreated ballast water), T= treatment (treated ballast water)
F= Water sample location ID (FAPS Terminal)
Clearly, turbulence that occurs during loading of ballast water, either through a centrifugal pump
or gravity, and the turbulent entry into an empty and vented ballast tank contributes to an
increased DO level in the incoming ballast water. For a chlorine dioxide treated tank, some of
the increase observed may also be due to the liberation of oxygen during the chlorine dioxide
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47
generation reaction (refer to the chemical equation in Section 2.0.3.1). Based on stoichiometry,
when the hydrogen peroxide component of Purate® reacts with sulfuric acid (at a chlorine
dioxide treatment dose of 5.0 mg/L) roughly 1.2 mg/L of oxygen is generated. This theoretical
increase in DO is comparable with that observed during the study. Further, increased DO at
these concentrations is not significantly greater than the increase observed during normal
ballasting operations, and is not anticipated to create increased or unacceptable corrosion risk for
the ship.
The pH of dockside water (FAPS Terminal) as well as untreated and chlorine dioxide treated
ballast water was concurrently measured during the DO investigation. During this study, the pH
of the chlorine dioxide treated tank ranged from 6.61 to 6.82. As Figure F6.2 above
demonstrates, the pH of the treated ballast water was not significantly decreased as a result of
chlorine dioxide treatment, and remained stable over the duration of the test period. Further,
corrosion rates of iron and steel are fairly uniform between pH’s of approximately 4 and 10.
Any change of pH of the ballast tank water between the pH’s of 5 and 9 will not affect corrosion
rates17.
6.1.2.2 Corrosion Coupon Testing
Corrosion tests have been conducted in ballast tanks treated by the Ecochlor® BWTS to verify
the effect of chlorine dioxide treatment on ballast tank corrosion rates. Tests were conducted
with C1010 mild steel corrosion test coupons and sent to Metal Samples Company, Inc. for
analysis18.
In July/August of 2005, corrosion test coupons were placed in one control (untreated) tank and
one chlorine dioxide-treated tank that received ballast water from Newark, NJ. The treatment
tank received a 5.0 mg/L dose of chlorine dioxide. Two test coupons were placed in each tank;
one high (approximately 1.35 m from the bottom of a 1.8 m tank) and one low (approximately
0.9 m from the bottom of a 1.8 m tank), and hung by nylon strings. Both sets of coupons
remained in the respective tanks for 672 hours (28 days).
In October/November of 2006 a similar test took place in a tank treated with approximately 4.0
mg/L of chlorine dioxide. Two test coupons were placed in the tank; one high (approximately
1.35 m from the bottom of a 1.8 m tank) and one low (approximately 0.9 m from the bottom of a
1.8 m tank), and hung by nylon strings. Both coupons remained in the tank for 768 hours (32
days).
The results of this initial testing are presented in Table T6.1 below, and indicate no adverse
effect on corrosion rates from chlorine dioxide treatment. Actually, when the July/Aug 2005
study corrosion rates of test coupons from untreated and treated tanks are compared, a slight
decrease in the corrosion rate was observed for test coupons in the treated tanks.
18
Corrosion Analysis Data Report, Metal Samples, Co., 2005.
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Table T6.1 – Comparison of Corrosion Rates
Sample
Date
ClO2 Dosage (mg/l) Exposure time (Hrs) Corrosion Rate (mpy)
Corrosion by chlorine dioxide
Untreated tank (high)
Jul/Aug 2005
0
672
9.8389
Untreated tank (low)
Jul/Aug 2005
0
672
10.9133
Treated (high)
Jul/Aug 2005
5
672
6.0879
Treated (low)
Jul/Aug 2005
5
672
7.87
Treated (high)
Oct/Nov 2006
4
768
5.0977
Ecochlor’s statement that chlorine dioxide treatment will not adversely affect corrosion rates is
supported by this data. Additional verification of these results with continued coupon corrosion
studies is planned. Additionally, visual inspections of piping close to the chlorine dioxide
injection point will be conducted as necessary during shipyard visits to ensure that there is no
sign of excessive wastage.
6.1.3 Fire and Explosion
The fire and explosion risks associated with the Ecochlor® BWTS relate to the precursor
chemicals stored onboard or electrical components that are part of the system.
6.1.3.1 Preparation Chemicals
As a solution, Purate® is non-flammable and does not have explosive properties19. Organic
materials (i.e. wood, leather) that become contaminated with Purate® can ignite by a heat or
friction source if they are allowed to dry. If evaporation of Purate® solution is allowed, solid
sodium chlorate crystals could form. Solid sodium chlorate does not burn, but if exposed to fire
it decomposes to give off oxygen, which can feed a fire. Decomposition of Purate® (in contact
with certain metals or alkalis, or upon thermal decomposition) generates oxygen gas, and has the
potential to increase explosion risk.
Sulfuric acid is non-flammable. Although sulfuric acid is not flammable or combustible and is
not sensitive to static discharge, it is a strong oxidizing agent and is highly reactive.
Concentrated sulfuric acid is capable of igniting combustible materials, and contact with water or
strong bases can result in a strong exothermic reaction. Contact with common metals can evolve
flammable and potentially explosive hydrogen gas. Sulfur oxides may be produced under fire
conditions.
These risks are mitigated through proper training, system engineering, identification of a suitable
location for the BWTS, the use of chemical storage tanks specifically designed for the chemicals
they hold, and proper tank ventilation. Additionally, the space where the BWTS is located is
kept clean and free of incompatible materials that can react with the precursor chemicals.
Regular inspection and maintenance of the BWTS further reduce any potential risks. The
mitigation measures and engineering controls in place for the precursor chemicals stored onboard
make the risks of fire and/or explosion extremely low.
19
Physical and Chemical Characteristics of Purate®, Case Consulting Laboratories, 2000.
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49
6.1.3.2 Active Substance
Gaseous chlorine dioxide can present explosion hazards under specific conditions. Concentrated
vapors of chlorine dioxide gas can be explosive at temperatures >40ºC and concentrations >10%
v/v in air at 1 atmosphere20. However, under the highly controlled conditions that chlorine
dioxide is generated with the Ecochlor® BWTS, the potential for explosion risk is very unlikely.
Section 3.0.7 discusses the safety features of the BWTS that eliminate the possibility of chlorine
dioxide production under unacceptable conditions.
Once generated, the chlorine dioxide is immediately converted into a dilute aqueous solution
under proper temperature and vacuum conditions in an enclosed system. In solution, chlorine
dioxide is stable and does not present fire or explosion hazards. Additionally, chlorine dioxide is
generated on demand, injected immediately, and never stored onboard. Therefore, the risk of fire
and/or explosion presented by the active substance is extremely low.
6.1.3.3 Other BWTS Components
The electrical components of the Ecochlor® BWTS are intrinsically safe and there is no risk of
fire associated with this aspect of the BWTS.
6.1.4 Chemical Storage
The precursor chemicals (preparations) are the only BWTS chemicals stored onboard at any
time. While 78% sulfuric acid is IMDG Code classified, the BWTS is considered ship’s
equipment and the chemicals are consumables rather than dangerous cargo. Therefore the
provisions of the IMDG Code are not applicable (IMDG CODE 2006 Edition, Amendment 3306, Chapter VII, Part A. Regulation 2).
The active substance, chlorine dioxide, is generated on-demand and is never stored onboard.
Outside of the potential fire and explosion risks discussed in Section 6.1.3, other risks associated
with storing chemicals onboard relate to improper storage containers. This can lead to
unintended chemical release and chemical contact with incompatible materials, as well as
exposure by direct chemical contact (skin/eye) and/or inhalation.
Because proper storage containers designed and engineered specifically for Purate® and sulfuric
acid are utilized with the Ecochlor® BWTS the potential for unintended release, contact with
incompatible materials, or direct chemical exposure to occur is low. (Details of the chemical
storage containers are located in Section 3.0.8). To further ensure proper chemical storage,
temperature control device(s) can be installed if a BWTS is to be located in an area or on a ship
where there is potential for temperature extremes. Additionally, proper training and
implementation of standard operating procedures mitigate the potential risks of chemical storage
onboard. Should a spill occur, chemical spill containment kits are kept onboard with the BWTS,
as well as appropriate fire extinguishing methods. Additional discussion on accidental chemical
release is presented below in Section 6.1.5 and the exposure risks to technicians, ship’s crew,
and/or other personnel are addressed in Section 6.2.1 below.
20
Chlorine Dioxide and Chlorite Toxicological Profile, Agency for Toxic Substances and Disease Registry
(http://www.atsdr.cdc.gov/toxprofiles/tp160-c4.pdf).
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6.1.5 Accidental Chemical Release
The potential for unintended release of chemicals associated with the BWTS relate to storage
tank failure, delivery pipe failure, and chemical re-supply operations. The areas for potential
release are limited to the areas where the storage tanks are located, where pipelines traverse, and
where chemical re-supply operations take place.
6.1.5.1 Storage Tank Failure
The risks to a ship of an unintentional release of Purate® or sulfuric acid from the chemical
storage tanks are related to contact with incompatible materials that may create other hazards
such as fire. A chemical release from the storage tanks is very unlikely, and only a catastrophic
event on the vessel could result in tank failure and simultaneous secondary containment failure.
As discussed above in Sections 3.0.8, 6.1.3 and 6.1.4, properly engineered and designed
chemical storage tanks and secondary containment, along with proper placement and
maintenance of the BWTS, make the risks to a ship from a storage tank failure extremely low.
6.1.5.2 Delivery Pipeline Failure
As with any installation where liquids are transported in a pipeline, potential exists for pipeline
failure. Should a pipeline failure occur, the risks to a ship from chemical release include contact
with incompatible materials. Although unlikely, this could increase risk of fire.
Because the BWTS does not compromise the integrity of the ship’s ballast water system (Section
6.1.1), there would be no risk to vessel stabiliy should a BWTS piping failure occur. In the event
that a pipe failure occurred, emergency stop controls to shut down the BWTS are strategically
located on the vessel. Additionally, a pipeline failure would create unacceptable conditions
within the BWTS, which would be recognized by the PLC and production of chlorine dioxide
would cease.
One important factor in mitigating the potential for a pipeline failure is selection of proper
BWTS construction materials. As presented in Section 3.0.8.3, the piping materials were
specifically selected for application with the Ecochlor® BWTS to ensure that compatible and
sturdy materials are utilized to deliver Purate®, sulfuric acid and chlorine dioxide.
The risks for pipeline damage are further minimized by installing piping in less exposed areas,
using proper labeling, and implementing other protective measures where prudent or required.
For installations where the BWTS may be located in a cargo area, extra precautions are taken to
eliminate risk of damage to piping. These may include, but are not confined to, installation of
hard casings and/or protective barriers around the system where the potential for damage exists.
Preventing exposures and emergency situations begins with proper engineering and construction
of systems that are designed for use onboard ships. Implementation of appropriate mitigation
measures ensure that unacceptable risks to a ship from chemical release do not result from a
BWTS pipeline failure.
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6.2
RISK TO TECHNICIANS AND/OR SHIP’S CREW
6.2.1 System Interaction – Risks to Technicians and Crew
The typical activities for operating and maintaining the Ecochlor® BWTS that present potential
risks to technicians or other personnel are assessed in this section. These tasks include normal
system operation, system maintenance and chemical refill operations. The areas for potential
exposure are limited to the areas where the BWTS and chemical storage tanks are located, where
pipelines traverse, and where chemical re-supply operations take place.
In this section we refer to ‘technicians’, who are trained Ecochlor personnel or properly trained
representatives from distributors or service companies used by Ecochlor. Technicians or
properly trained Ecochlor representatives are the only individuals who will work within close
proximity to the BWTS, perform maintenance, or handle chemicals related to the Ecochlor®
BWTS. As such, technicians are the population group that has the greatest potential for
exposure.
Occasionally, other individuals such as ship crew members, port staff, stevedores, or ship repair
contractors may be working in the vicinity of the Ecochlor® BWTS. In this section, these
persons are referred to as ‘other personnel’ or ‘ship’s crew’. The contact these personnel may
have with the BWTS would be specific to the BWTS location on the vessel and the work
activities taking place in that location (i.e. cargo space vs. engine room vs. deck house). For
example, the BWTS may be located in a designated area of a cargo hold where various work
tasks or cargo operations are performed. Simply working within proximity to the BWTS would
not lead to direct contact with the BWTS or chemicals. Therefore, this subpopulation has a low
potential for exposure and the BWTS does not pose unacceptable risks to ship’s crew or other
personnel who may perform work tasks nearby.
6.2.1.1 Normal System Operation
Operation of the Ecochlor® BWTS does not require technician or ship’s crew involvement,
unless the ship’s ballast system is manual in nature and is not capable of providing electronic
signals regarding the ballast system status. Even in such an installation, a crew member would
only be required to push a remote ‘start’ button and possibly adjust ballast system valves. In
either case, the BWTS automatically delivers the preparation chemicals and the active substance,
and no technicians or crew members are required to be at the location of the BWTS while in
operation. The BWTS automatically starts, stops, and doses the correct amount of chlorine
dioxide. At no time during the normal operation of the system are Ecochlor technicians or ship
crew members required to handle chemicals.
With the exception of the vent lines on the precursor chemical storage tanks, the BWTS is a
closed system. Chemical tank vent lines are directed either to the atmosphere or to spaces with
proper ventilation (also refer to the discussion in Section 3.0.8.2). The Ecochlor system does not
give off fumes or gases during normal operation. However, a small amount of fumes may be
displaced when the chemical storage tanks are refilled, and sufficient ventilation is necessary
during these operations. See Section 6.2.1.2 below.
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The system does not generate a significant level of noise that would pose hearing damage risks to
technicians or other personnel.
6.3
RISKS TO HUMAN HEALTH
6.3.1 Identification of Chemicals of Potential Concern and Sources
The chemicals of potential concern (COPC) related to the Ecochlor® BWTS are Purate®, sulfuric
acid, and chlorine dioxide. Purate® (40% by weight sodium chlorate and 8% by weight
hydrogen peroxide) and sulfuric acid (78%) are preparation chemicals used to generate chlorine
dioxide.
Although low levels of chlorite ion may persist in treated ballast water, no sources of direct
contact or exposure to the by-product exist for technicians or ship’s crew. Additionally, the
chemical properties and modes of chlorite ion degradation indicate that it will not persist in the
environment or have the potential to bioaccumulate (refer to Section 2.3). As such there is no
mechanism of transport that would allow primary or secondary exposure risks for technicians,
ships crew, persons at the coast or seafood consumers. Chlorite ion is not considered further in
this human health risk assessment.
6.3.2 Exposure Assessment
An exposure pathway describes the course that COPC take from a source to an individual. A
complete exposure pathway consists of the following:
•
A source of the chemical(s) of concern;
•
An environmental medium (i.e. air) containing the chemical(s) of concern;
•
An exposure point or direct contact point with the contaminated medium (i.e. direct
contact with the chemical(s)) or a release mechanism for contact with a secondary
medium (i.e. vaporization of chemicals); and
•
An exposure route for chemical intake by an individual (i.e. inhalation).
The combination of all four components together makes a complete exposure pathway. If one or
more of the components is missing, the exposure pathway is considered incomplete. Incomplete
exposure pathways do not present potential human health hazards.
Areas for potential exposure are defined as areas where both the COPC and human receptors
may come in contact. The onboard areas, or sources of chemicals, with potential for exposure to
Purate®, sulfuric acid and chlorine dioxide are limited to the areas where the BWTS and
chemical storage tanks are located, where pipelines traverse, and where chemical re-supply
operations take place.
The potential media for exposure relating to the Ecochlor® BWTS that have been identified are
direct contact with chemicals and air containing volatiles of the COPC within enclosed ship
spaces. Treated ballast water is not considered as a potential exposure medium to Purate® and
sulfuric acid because these substances are consumed in the chlorine dioxide generation reaction.
Further, chlorine dioxide degradation behavior indicates that chlorine dioxide will not persist in
the environment, nor does it have the potential to bioaccumulate (refer to Section 2.3). Thus,
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there is no complete exposure pathway for contact with treated ballast water containing Purate®,
sulfuric acid or chlorine dioxide for Ecochlor technicians, ships crew, persons at the coast, or
seafood consumers. However, because chlorine dioxide in solution readily volatilizes, a
potentially complete exposure pathway for inhalation of chlorine dioxide from treated ballast
water exists.
The populations with the greatest potential for exposure are Ecochlor technicians, and to a lesser
extent, ships crew and/or other personnel (see explanation of those in this population group in
Section 6.2.1). Technicians have a greater potential for exposure because they will work most
closely with the BWTS (i.e. performing maintenance and chemical re-supply operations, etc.).
Because ship’s crew will never be required to handle chemicals during operation of the BWTS or
be directly involved in chemical-handling operations, the exposure potential for this population
group is extremely low. To fulfill the components necessary for a complete exposure pathway,
chemical exposure would only occur in the event of a pipeline or storage tank failure, or an
emergency situation in the same space where ships crew may be working. In this unlikely event,
the most probable exposure route would be inhalation rather than direct chemical contact.
With the exception of the vent lines on the precursor chemical storage tanks, the chemicals used
with the BWTS are in a closed system. Chemical tank vent lines are directed either to the
atmosphere or to spaces with proper ventilation. Further, ballast tank vents are directed to
atmospheric conditions outside a ship. Thus, chlorine dioxide that may volatilize from treated
water within the ballast water tanks does not present a complete inhalation exposure pathway.
As such, with the exception of an emergency situation, a complete exposure pathway for
inhalation or direct chemical contact exposure routes does not exist while the BWTS is in normal
operation.
During routine system maintenance and chemical re-supply operations chlorine dioxide would
not be generated. Thus, these operations would only involve potential exposure to Purate®
and/or sulfuric acid for Ecochlor technicians. Based on this evaluation, potential exposure to
chlorine dioxide could only occur for technicians during an emergency situation (i.e. pipeline
failure). For ships crew, potential exposure to Purate®, sulfuric acid and/or chlorine dioxide
could only occur during an emergency situation involving the BWTS (i.e. storage tank or
pipeline failure).
Emergency situations onboard that are not related to the BWTS (i.e. ingress of water, fire on
board) would not necessarily create completed chemical exposure pathways. For instance, if
ingress of water onto the ship occurred, this would not necessarily alter the integrity of the
chemical tanks and cause a tank or pipeline failure. Additionally, the BWTS is a closed system
and water would not be able to enter the chemical tanks. Similarly, a fire onboard that is
unrelated to the BWTS would not necessarily create a completed exposure pathway. This is
because the chemical solutions are not flammable or explosive. Even if the fire is nearby
causing the chemicals to heat, the vapors would be vented.
Additionally, the standard operating procedures that would be implemented in an emergency
situation that is not related to the Ecochlor® BWTS (i.e. ingress of water, fire onboard) are not
changed as a result of the system being onboard.
54
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6.3.3 Potential Exposure Health Risks
The components of Purate® (sodium chlorate and hydrogen peroxide), as well as sulfuric acid,
are considered non-carcinogenic substances. Insufficient data is available for classification of
chlorine dioxide as a human carcinogen8.
Inhalation of Purate® vapors and/or mists is irritating to the mucous membranes, and may cause
nausea, headache and/or weakness. Inhalation exposure can have an oxidizing effect, and
oxidizes hemoglobin in the blood to methaemoglobinemia, causing a reduced ability to transport
oxygen. This can lead to a lack of oxygen in body tissues.
Inhalation of sulfuric acid mists or sprays can cause pulmonary irritation, irritation of the mucous
membranes, coughing and sore throat. Inhalation of high concentrations may cause respiratory
tissue damage, causing lung disorders (chemical pneumonitis and pulmonary edema) and erosion
of tooth enamel.
Chlorine dioxide is a strong, corrosive respiratory irritant, and the respiratory tract appears to the
primary target of toxicity in human and animal studies8. Reported symptoms include cough,
wheezing, headache, nausea, pulmonary edema and shortness of breath.
Direct chemical contact with Purate® may cause moderate irritation to the skin, and can cause
severe eye irritation, tearing and blurred vision, with irreversible corneal damage and possible
blindness in instances of overexposure.
Direct chemical contact of sulfuric acid with the skin or eyes can cause severe irritation, burns
and permanent tissue damage. Absorption through the skin is not anticipated to be a significant
route of over-exposure.
Direct dermal contact with chlorine dioxide solution may cause redness and skin burns, and may
cause severe eye irritation, pain, blurred vision, tearing corneal injury and burns.
6.3.4 Risk Characterization
The exposure assessment identified potentially complete exposure pathways for Purate®, sulfuric
acid and chlorine dioxide with inhalation or direct chemical contact as the exposure routes.
Exposure risks are present during system maintenance and chemical re-supply operations, or
during emergency situations involving the BWTS.
The Ecochlor® BWTS requires approximately 6 hours of preventative maintenance per year, and
chemical re-supply operations will typically take place two - three times per year. Therefore,
operations where potential exposure risks exist are limited in duration and frequency.
Preventing exposures and emergency situations begins with proper engineering and construction
of systems that are designed for use onboard ships. Thorough administrative measures,
technician and crew training, engineering controls and standard operating procedures further
mitigate potential exposures to the COPC. PPE worn by technicians greatly reduces the potential
for the exposure pathways to be completed. For instance, during chemical re-supply operations,
the required PPE consists of eye protection (chemical goggles), and/or a face shield, along with
chemical resistant clothing and gloves designed for use with Purate® and sulfuric acid. These
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55
operations are only conducted in well-ventilated areas or with the use of appropriate engineering
controls to prevent inhalation risks. However, in the event of an emergency situation where
inhalation exposure may occur, respiratory protection devices would be added to the required
PPE.
6.4
RISKS TO THE AQUATIC ENVIRONMENT
With respect to risk, toxicity to aquatic organisms appears to be the most significant potential
exposure for chlorine dioxide because it is not persistent in the environment and is not expected
to bioaccumulate or adsorb to sediments2. However, when the Ecochlor® BWTS is utilized as
directed by Ecochlor, the treated ballast water discharge will contain undetectable concentrations
of chlorine dioxide. Therefore, unacceptable risks to the aquatic environment from chlorine
dioxide are not expected.
With respect to risk, toxicity to aquatic organisms appears to be the most significant potential
exposure for chlorite ion because it is not persistent in the environment and is not expected to
bioaccumulate or adsorb to sediments2. The chlorite ion measured in treated ballast water ranges
from <0.1 mg/L to 2.37 mg/L. Because treated ballast water may contain residual chlorite ion
when discharged, a dilution to approximately 12% has been calculated to achieve the chronic
NOEC for M. bahia to chlorite ion (see Section 5.2.1.1). The calculated dilution to 12% was
based on toxicity tests done with the upper range of chlorite ion measured in treated ballast water
(2.35 mg/L), and with the chronic NOEC for M. bahia, which was identified as the species most
sensitive to chlorite ion.
Additionally, dilution to 12% (v/v) is considered conservative because none of the other species
tested would require dilution of treated ballast water to reach the chronic chlorite NOEC. For
instance, the next most sensitive species tested (A. affinis, chronic NOEC 13.8 mg/L) was almost
two orders of magnitude less sensitive to chlorite.
Therefore, dilution to 12% (v/v) is considered highly conservative and protective of aquatic
organisms to ensure there are no unacceptable risks to the aquatic environment.
6.5 ASSESSMENT REPORT (G9: 4.3)
6.5.1 Overview of Data and Endpoints
As constituents potentially present in ballast water treated with the Ecochlor® BWTS, chlorine
dioxide and chlorite ion were evaluated in regards to persistence, bioaccumulation, and toxicity.
In regards to persistence, chlorine dioxide was reported to have a half-life of 3.9 minutes in
freshwater2, and the half-life of chlorite ion in sea water was measured as <1 hour. The
estimated log Kow values for chlorine dioxide and chlorite are -3.22 and -7.173, respectively.
These Kow values, the physical and chemical characteristics (i.e. highly soluble, non-organic),
along with well-documented degradation behavior, indicate that chlorine dioxide and chlorite ion
would not be expected to bioaccumulate. In regards to toxicity, the lowest chronic NOEC was
0.09 mg/L and 0.18 mg/L for chlorine dioxide and chlorite ion, respectively. Therefore, chlorine
dioxide and chlorite ion do not meet the criteria to be classified as PBT substances.
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56
In a toxicity evaluation of treated ballast water, the lowest acute LC50 was 37.7% (v/v) for
Mysidopsis bahia and the lowest chronic EC50 was >81% (v/v) for Mytilus sp. (Tables T2.9 and
T2.10). By calculation, these values compare well with the chlorite ion toxicity observed for M.
bahia (Table T2.10 and Section 5.3.8). The evaluation of treated ballast water toxicity resulted
in a calculated dilution to 12% (v/v) to achieve the chronic NOEC for M. bahia to chlorite ion.
This dilution was derived using the upper limits of chlorite ion that may be present, as well as the
most sensitive species in toxicity tests (see Section 6.4) to incorporate a sufficient safety margin.
Ecochlor has conducted a significant number of tests on various waters to determine the holding
time necessary, and evaluate the effects of differing water conditions (i.e. organic load, pH,
salinity, temperature). Although additional studies are planned to increase the available data set
for treated ballast water, Ecochlor is confident in the data that has been generated through
laboratory analysis and onboard testing.
As presented in Sections 2.3.3 and 5.3.1, both chlorine dioxide and chlorite ion are oxidizing
agents that do not produce harmful organic by-products. Additionally, chlorine dioxide degrades
rapidly in marine and fresh waters, predominantly forming chlorite ion as a degradation byproduct2. Degradation of both substances is by abiotic mechanisms and is predominantly a result
of oxidative reactions.
When the Ecochlor® BWTS is utilized as directed by Ecochlor, the concentration of chlorine
dioxide is expected to be at undetectable levels when treated ballast water is discharged. Thus,
the predicted environmental concentration (PEC) for chlorine dioxide is 0 mg/L. Ion
chromatographic analysis of ballast water treated with 5.0 mg/L of chlorine dioxide indicate
chlorite ion concentrations ranging from <0.1 g/L to 2.37 mg/L. Therefore, the PEC for chlorite
ion in treated ballast water is <0.1 mg/L to 2.37 mg/L. This range is a result of the varied
chlorite ion demand of different waters and factors such as organic load, pH and temperature that
affect the decay rate. Section 2.0.3.2 discusses chlorite ion demand / decay in greater detail.
The Ecochlor® BWTS can safely and effectively treat ballast water for AIS to comply with the
performance standards in Regulation D-2 of the International Convention for the Control and
Management of Ship’s Ballast Water and Sediments, as well as standards proposed in the US
Ballast Water Management Act of 2005 (Senate Bill S.363). Based on laboratory analysis and
shipboard data of treated ballast water, no related adverse effects from the use of the Ecochlor®
BWTS to comply with the Convention can be reasonably anticipated. The level of uncertainty in
the data supporting this opinion is low. Additional data continues to be collected on the
Ecochlor® BWTS, further increasing the confidence in the results obtained through various
analyses.
The potential risks to the safety of ships, human health and the environment are mitigated by
engineering and constructing systems that are designed for use onboard ships, proper chemical
production, dosing, storage and handling, as well as thorough personnel training and use of PPE.
The automatic dosing of chlorine dioxide treatment based on the amount of ballast water being
brought onboard limits chlorine dioxide production, ensuring safe discharge of treated water to
the environment. The substances used with the Ecochlor® BWTS are not expected to persist in
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57
the environment or bioaccumulate, thereby presenting no risks to resources (i.e. beaches,
fisheries).
The active substance is generated on demand, applied in situ, and is never stored onboard. After
injection into the ballast water, the concentration of chlorine dioxide decays quickly (within than
24 hours). When used as directed, the ballast water treated with Ecochlor® BWTS will have
undetectable concentrations of chlorine dioxide at the time of discharge. Thus the PEC for
chlorine dioxide is 0 mg/L. Therefore, a situation where the PEC/PNEC ratio is >1 at discharge
is not anticipated. Further, no waste stream is created during the treatment process.
6.5.2 Test Report Data Quality
Test reports used in this application were from a variety of sources, including, but not limited to,
OECD SIDS, Eka Chemicals (performed by independent laboratories), independent research,
USEPA, and the National Toxicology Program. The reports were evaluated to ensure that the
data presented was generated by accredited laboratories using accepted standard methodologies
and laboratory practices. The data met acceptable confidence intervals (i.e. >95%), indicating a
low level of uncertainty associated with the data. For example, the following is quoted text from
one mammalian toxicity study used in the risk characterization (Eka Study 86-31125):
“Results of the inspections made by the Quality Assurance Unit at BIO/dynamics, Inc.
indicate that this study was conducted in compliance with applicable United States
Environmental Protection Agency’s Good Laboratory Practice Standards and applicable
Standard Operating Procedures. No significant deviates were noted. Minor deviations
may be include in the raw data”
The studies referenced in this application are listed in the “Reference Documents” portion of the
Table of Contents and are included in a complete copy of the application.
****
LIST OF TABLES
Table T2.1 – Overview of Chemical Identification
Table T2.2 – Ecochlor Chlorine Dioxide Demand Study, 4ºC
Table T2.3 – Ecochlor Chlorine Dioxide Demand Study, 12ºC
Table T2.4 – Ecochlor Chlorine Dioxide Demand Study, 24ºC
Table T2.5 – Ecochlor Chlorite Ion Demand Study, 20ºC
Table T2.6 – Chlorite Ion Dilution / Demand Study, New Jersey Water
Table T2.7 – Chlorite Ion Dilution / Demand Study, Maryland Water
Table T2.8 – Analysis of Ballast Water Treated Onboard the M/V Moku Pahu
Table T2.9 – Overview of Acute Aquatic Toxicity
Table T2.10 – Overview of Chronic Aquatic Toxicity
Table T2.11 – Acute Mammalian Toxicity Data
Table T2.12 – Skin, Eye and Dermal Effects
Table T2.13 – Repeated-Dose Toxicity
Table T2.14 – Chronic Mammalian Toxicity
Table T2.15 – Physical and Chemical Properties
Table T3.1 – List of BWTS Monitoring & Control Devices
Table T3.2 – Eka Chlorine Dioxide Generator Operational Reliability Data
Table T5.1 – PBT Criteria for Chlorine Dioxide & Chlorite Ion
Table T6.1 – Comparison of Corrosion Rates
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LIST OF FIGURES
Figure F2.1 – Example of Chlorine Dioxide Demand Curve, 4°C
Figure F2.2 – Example of Chlorine Dioxide Demand Curve, 12°C
Figure F2.3 – Example of Chlorine Dioxide Demand Curve, 24°C
Figure F2.4 – Example of Chlorite Ion Demand Curve, Newark, NJ Water
Figure F2.5 – Chlorite Ion Dilution / Demand Study, New Jersey Water
Figure F2.6 – Chlorite Ion Dilution / Demand Study, Maryland Water
®
Figure F3.1 – Photo of Full Scale Ecochlor BWTS
®
Figure F3.2 – Ecochlor BWTS Process Flow Diagram
Figure F6.1 – Salt Content and Water Corrosivity
Figure F6.2 – Dissolved Oxygen and pH
REFERENCE DOCUMENTS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
OECD SIDS SIAR, SIAM 11 (January 2001), UNEP Publications.
Review of the Environmental Fate and Effects of Chlorine Dioxide and Chlorite, Nautilus
Environmental, 2007.
USEPA Reregistration Eligibility Decision (RED) for Chlorine Dioxide and Sodium Chlorite
(Case 4023), August 2006.
Concise International Chemical Assessment Document (CICADS) 37, Chlorine Dioxide (Gas), 2002.
Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study of Sodium Chlorate in the Rat via
Gavage.
Barrett, D.S. (1987) A Subchronic (3 Month) Oral Toxicity Study in the Dog via Gavage
Administration with Sodium Chlorate.
Scientific Committee on Consumer Products (SCCP), Opinion on Hydrogen Peroxide in Tooth
Whitening Products, 2005.
USEPA Toxicological Review of Chlorine Dioxide and Chlorite, September 2000.
NTP Technical Report on the Toxicology and Carcinogenesis Studies of Sodium Chlorate in F344/N
Rats and B6C3F1 Mice (Drinking Water Studies), 2005. NTP TR 517, NIH Publication No. 06-4457.
European Chemicals Bureau (2003) Hydrogen Peroxide Summary Risk Assessment Report,
Special Publication I.03.148.
Smith, D.J., Anderson, R. C., Ellig, E.A., and Larsen, G.L. (2005) Tissue Distribution, Elimination,
and Metabolism of Dietary Sodium [36Cl}Chlorate in Beef Cattle.
Abdel-Rahman, M.S., Couri, D., and Bull, R.J. (1982) Metabolism and Pharmacokinetics of Alternate
Drinking Water Disinfectants. Environmental Health Perspectives, v46, pp19-23.
EPA Guidance Manual, Alternative Disinfectants and Oxidants, Chlorine Dioxide, 1999
(http://www.epa.gov/safewater/mdbp/pdf/alter/chapt_4.pdf).
Simpson, G.D., Miller, R.F., Laxton, G.D., Clements, W.R., A Focus on Chlorine Dioxide:
The “Ideal” Biocide.
Mosser, Mark L., Sermatech International Inc., September 15, 2005.
The Sulphur Institute Online, Glossary of Terms
(http://www.sulphurinstitute.org/webarticles/anmviewer.asp?a=109&z=30).
®
Heidersbach, Bob; Dr. Rust, Inc.; Ballast Water Corrosion Rates Using the Ecochlor Ballast
Water Treatment System, May 2007.
Corrosion Analysis Data Report, Metal Samples, Co., 2005.
®
Physical and Chemical Characteristics of Purate , Case Consulting Laboratories, 2000.
Chlorine Dioxide and Chlorite Toxicological Profile, Agency for Toxic Substances and Disease
Registry (http://www.atsdr.cdc.gov/toxprofiles/tp160-c4.pdf).
****
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