Overview of Available Control
Strategies for Biofouling Mussels
in an Industrial Setting
Renata Claudi MSc.
RNT Consulting Inc.
Fresh Water Biofouling Mussels
Dreissenid family – Zebra,Quagga,Conrad False Mussel
Mytillid family – Golden mussels
Zebra and Quagga Mussels
Dreissenid family
Zebra mussel
1988
Map: New York Sea Grant
Risks Posed to Industrial Facilities by
Mussel Fouling – Reason for Mitigation
• Decreased flow
• Potential plugging of essential
components/systems
• Increased corrosion
Mechanisms of Fouling
• Settlement of veligers during the breeding season
• Translocation of juvenile and adult mussels
• Migration of adults from surrounding areas on to
available surface
• Transport of shells or clumps of shells from
upstream areas into downstream systems
Additional Risk- Macrofouling by Mussels
Can Enhance Metal Corrosion by;
• Mechanical Damage
• Exposure of fresh surfaces to corrosive
factors
• Production of feces and pseudofeces
which in turn support microorganisms
First step in any mitigation, examine the
environmental parameters at the site you
wish to protect and compare them to the
environmental requirements of the mussel
you wish to control
1. Parameter
2. No potential for
adult survival
3. Little potential
for larval
development
4. Moderate potential
for nuisance
infestations
5. High potential for massive
infestations
Chalk Variables
Calcium (mg Ca/L)
<1, >100
1-5
5-10, 80-100
10-80
pH
<3.0, >10
3.0-5.0
5.0-7.0
7.0-9.0
Alkalinity, total (mgCaCO3/L)
<3, >350
3-18
18-35, 280-350
35-280
Hardness, total (mgCaCO3/L)
<3, >350
3-18
18-35, 280-350
35-280
Nutrient Variables
<1 (<10%)
1-3 (10-20%)
3-6 (20-50%)
≥7 (>50%)
0-1, >25
1-2 or 20-25
8-20
2-8
Total phosphorous (μg/L)
?
?
?
?
Total Nitrogen (μg/L)
?
?
?
?
<1, >8
1-2, 6-8
4-6
2.0-4.0
Dissolved Oxygen mg/L (% sat)
Chlorophyll a (μg/L)
Secchi depth (m)
Physical Variables
Temperature, Mean Summer oC
<5, >40
5-15 or 32-40
16-26
26-32
<30, > 25,000
9,000-25,000
3,800-9,000
30-3,800
<0, >17,000
6,000-17,000
2,500-6,000
20-2,500
<0, >15
5-15
1-5
0-1
Turbidity (NTU)
>80
20-80
5-20
<3-65
Total Suspended Solids (mg/L)
>96
28-96
8-28
<8
Conductivity (μS/cm)
Total Dissolved Solids (mg/L)
Salinity mg/L (ppt)
Only after you determine
you will have a problem based
on environmental parameters
of the site do you proceed to
develop a control strategy
Minimizing mussel fouling
•
Proactive
Does not allow
growth of
mussels in the
system or on
the surface
protected
• Reactive
Does allow mussels
to grow in the system
or on the surface.
Established
populations have to
be eliminated
periodically
Options for External
Structures*
*Structures That Are in Direct
Contact With the External
Environment; No Isolation Is
Possible
Reactive Options for External
Structures
Mechanical Cleaning
• de-water and use power-wash
• underwater, scrape and vacuum or
power-wash
Proactive Options for External
Structures
Antifouling and Foul Release Coatings
for both steel and concrete
Foul Release Coatings - Non-toxic, soft
silicone barrier coatings
Antifouling - Toxic, copper/zinc based
coatings (ablative and non-ablative) – EPA
approval required
Coatings
• Number of new formulations on the market
in response to the ban of tributyl tin
coatings in the marine industry
• Given the cost ( $10 - $40/sq.ft) and the
extensive surface preparation required,
ask for multiyear performance data
• Many coatings fail after 12 to 18 months
• Surface preparation is difficult but
essential
Coatings
• Vendors with known successful antifouling
coatings
- CPM Coatings/ Chugoku Paint
Bioclean - Si
- Kansai Paint (Biox Si)
- International Paints (Intersleek)
- GE Coatings (Exsil)
- Fuji Coatings
Coatings
USBR (US Bureau of Reclamation) has
initiated a coating study in 2008 to
examine new generation of coatings.
Results are being posted on their website.
Copper/Beryllium after 2 years
•
Bioclean Silicone after 4 years
Options for Internal Piping
Systems
Reactive Options for Internal
Piping Systems
• Thermal Wash - 32oC for 48 hours (90o F)
40oC for 1 hour (104o F)
• Mechanical Cleaning
- scrape large diameter pipes
- water jetting/hydrolazing
- remote vehicle tools on difficult areas
• Flushing with weak acids
• Oxygen Deprivation
Reactive Options for Internal Piping
Systems – treatment once/year, every 6
month or every 3 month
Non-oxidizing chemical treatment - proprietary
chemicals, most of which have to be de-toxified on
discharge (Betz, Nalco,Buckmann, Bayer, Mexel)
(12 -36 hour treatment)
Potassium salts, copper sulphate, copper ion
generator, Bio-bullets, bacterial product
Oxidizing chemical treatment- chlorine, bromine, chlorine
dioxide, chloramines, ozone, potassium permanganate,
Ferrate
(10+ days treatment at approx.1ppm)
Proprietary Non-oxidizing
chemicals
•
•
•
•
Many based on quaternary amines
Some based on isothiazolones
Some based on other organic compounds
Most require detoxification with bentonite
clay resulting in large volume of material
being deposited in the discharge
• Relatively high cost for the chemicals
Potassium salts
• Potassium compounds are toxic to most
bivalves
• Potassium chloride
20mg/L killed adult zm in 52 days
600mg/L killed adult zm in 48 hours
Used for eradication in small bodies of
water
Copper sulphate
• 14 – 81 µgCu/L caused virtually complete
mortality in zebra mussel veliger in 24
hours
• Applicable where already in use for algae
control
• Used for eradication of zebra mussels
from Offut Base Lake in Nebraska
(massive fish kill)
Copper ion generator
• Copper ion generators used for at least 40 years
to protect ship cooling systems from
macrofouling in salt water
• Tested in fresh water in the 90’s
• Commercialized under the name of Macrotech
• Used by one fossil generating plant on Lake
Michigan since 2003
• 10ppb of copper ion continuously during
breeding season
Zequanox (Bacterial Product) Reactive Treatment
 Chemical substance produced by Pseudomonas
fluorescence bacteria. This species is commonly present
in soil
 Specific strain developed by Dr.Dan Molloy in the U.S.
 This strain when present in high enough concentration
causes mortality in the Dreissenid mussels.
 No mortality observed in any native mussels or clams of
North America
 Currently being commercialized by Marrone Organic
Innovations from California
 Potential for this to be a preventative treatment
BioBullets
• Patented process to coat chemicals for
control of filter feeders in edible coating
and create particles of appropriate size
• Potentially noxious chemical within the
particle is not detected, filter feeder will
keep ingesting the particles and not close
down in self–defence
• Advantage of lower chemical loading to
the environment and quicker kill
Reactive Treatment Using
Oxidizing Chemicals
• chlorine, bromine, chlorine dioxide,
chloramines, ozone, potassium
permanganate
• Most used at 1 – 3 mg/L concentration for
10+ days to eliminate adults
• Length of treament is temperature
dependent
Bruce A/B Treatment
Mussel mortality results
100
90
80
60
50
40
30
20
10
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Percent Mortality
70
Treatment Day
Unit 0 (A)
Unit 5
Unit 3
Unit 6
Unit 4
Unit 7
Unit 0 (B)
Unit 8
Ferrate
• Ferrate is the anion FeO42- in which iron
is in a +6 formal oxidation state. Ferrate
can be formed by oxidizing iron with strong
oxidizing agents under alkaline conditions.
• Cheaper than ozone, more powerful than
chlorine, no by-products of concern.
• On-site generation, most likely to be used
as a once/week treatment
Proactive Options for Internal
Piping Systems
• Sand/media filtration - has to remove all
particles greater than ready to settle
veligers
• Mechanical filtration - has to remove all
particles greater than ready to settle
veligers. Actual mesh size is dependent on
the application and industry using the filter.
Environmental Criteria affecting the
performance of the filter
• Total suspended solids (TSS) load in the incoming water
• Seasonal variation in TSS
• What is the particle size distribution of the TSS
• Continuous operation required to prevent fouling
of the filter
Example of small pore self cleaning filters
Strainer
Discharge
Course Strainer
Chamber
Strainer and
Filter Vent
Pad Eye
Fine Filter
Chamber
Filter Silt
Discharge
Pad Eye
Drive Unit with
1/2 HP Motor
Direction
of Flow
Main Access
Hatch
Fine Filter
Drain
Strainer
Drain
Influent
Raw Water
Access Hatches
Filtered Water
Discharge
37
Mesh Requirements
Square Weave Mesh is
Essential
Robust Support of the
Mesh is Critical
Mechanical filtration test
• Installed at Nanticoke TGS, Lake Erie in
spring of 2000
• 760 l/s (12000 usgpm)
• 40 micron mesh
• Automatic
• backwash
Test Performed at Parker Dam
February 2009
• Self cleaning filter sized to accommodate
flow of 450 USGPM installed to protect
domestic water line
• Interchangeable screens - 40 micron (57
micron absolute) and 80 micron (120
micron absolute) size
40 Mic ron F ilter T es ts
400
300
250
200
B efore
150
A fter
100
80 Mic ron F ilter T es ts
50
600
0
< 100
100-200
200-400
> 400
500
Velig er S iz e (µm)
Number of Velig ers
Numer of Velig ers
350
400
300
B efore
A fter
200
100
0
< 100
100-200
200-400
Velig er S iz e (µm)
> 400
Proactive Options for
Internal Piping Systems –
UV
Environmental Criteria affecting the
performance of UV
• How well does your raw water transmit UV
(various factors such as colour, hardness,
presence of iron and total suspended solids)
• Seasonal variation in above factors
Open channel UV Installation
Sample
Point
UV Lights
UV Host Site: Bruce 5-8 CSW
900 l/s (15,000 usgpm)
20 hi-intensity,
medium pressure lamps
0.07 to 0.1 Watt-seconds/cm2
Sample
Point
4
6
UV Light Bank for open channel
4
In pipe UV Installation
UV Monitor
Access Hatch
Air Release
Wiper Motor Housing
Downstream
Isolation Valve
Direction of Flow
Access to Lamps
(Both ends of chamber)
Electrical Junction Box
(wiring from cabinets)
Upstream Isolation Valve
(Not visible)
48
Proactive Options for Internal
Piping Systems –
Sparker
What is a Sparker - high voltage spark passes
between two electrodes submerged in water
Electrode
UV
Plasma
discharge
P
The spark arcs between the electrodes at predetermined time
intervals (seconds or minutes)
Electrical discharge vaporizes water quickly producing a
plasma bubble (with hot gas/water vapour):
pressure pulse
light pulse
The vapor-filled “bubble” expands and contracts,
producing additional pulses
The electric discharge creates a vacuum and UV light which
break water-molecule bonds in the vicinity of the discharge.
This produces hydroxyl radicals (OH)
Test site
Power
and
Controls
Traveling
Screen
~5m
0.76 m
Sparker
115 m
Zebra bags
Float and Line
Flow
Mussel
Bag
Weighted Disc
Proportion of dead mussles
60%
50%
40%
30%
20%
10%
0%
0.001
0.01
0.1
1
-2
Pulse Energy (J m per pulse)
10
Proactive Use of Oxidizing Chemicals
for Protection of Internal Piping
Systems
• Low levels of the chemical are added
continuously or semi-continuously
throughout the mussel breeding season
to prevent settling by creating a hostile
environment.
Proactive Use of Ozone at
Ontario Power Generation
• Continuous ozone addition system
installed at Lennox TGS, Lake Erie
• 0.3mg/L added continuously during
breeding season
Start-up: September 2000
Proactive Use of Ozone at
Ontario Power Generation
• Intermittent ozone addition system installed in
Bruce 1-4 CWS
• 600 l/s (9500 usgpm)
• 2 kg/day ozone
• 1 kg injected for 5 minutes, 2 times/day
• manufacturer - Mitsubishi
Start-up: October 2000
Proactive Use of Chlorine at
Ontario Power Generation
• Continuously at 0.3 - 0.5ppm TRC (at the
end of the treated system)
• Semi-continuously at 0.3 - 0.5ppm TRC
(at the end of the treated system). Most
often used regime, 15 minute on 30 to 90
minutes off.
Proactive Use of Chlorine at
Ontario Power Generation
• Regulatory limit is 10ppb TRC in the
combined discharge.
• Regulatory objective is 2ppb .
How to Select a Strategy
• Based on clear objective
• Site specific
• Affordable
• Acceptable to the regulator