Comparison of Down-Flow Hanging Sponge and Woven Fiber
Membrane Systems for Treatment of Polluted Canal Water
by
Ellis Lloyd Andrew Tembo
A thesis submitted in partial fulfillment of the requirements for the
degree of Master of Engineering in
Urban Water Engineering and Management at the Asian Institute of Technology
and
the degree of Master of Science at the UNESCO-IHE
Examination Committee:
Prof. Chettiyappan Visvanathan (Chairperson)
Dr. Carlos Manuel Lopez Vazquez (UNESCO-IHE)
Dr. Sangam Shrestha
Dr. Oleg Shipin
Nationality:
Previous Degree:
Malawian
Bachelor of Science in Mechanical Engineering
University of Malawi, Malawi
Bill and Melinda Gates Foundation/ UNESCO-IHE
– AIT Fellowship
Scholarship Donor:
Asian Institute of Technology
School of Engineering and Technology and School of Environment, Resources and
Development
Thailand
May 2014
Acknowledgements
The author would like to express his profound gratitude and sincere appreciation to his
advisor, Prof. C. Visvanathan for his guidance and overall untiring support during this
study. The author would also like to thank the co-chairman, Dr. Carlos Manuel Lopez
Vazquez for his guidance and support
The author would also like to express his grateful appreciation to his examination
committee members Dr. Oleg Shipin and Dr. Shresha Sangam for their valuable
comments, guidance and support.
Many thanks are extended to Prof. C. Visvanathan’s research group, especially Mr. Paul
Jacobs, and Mr. Thusitha Rathnayake for their regular help and technical support. The
author wishes to thank all laboratory staff specially Mr. Chaiyaporn, Ms. Orathai and Mr.
Panupong for their technical suggestions and help. The Environmental Engineering and
Management (EEM) secretaries Ms. Suchitra and Ms. Chanya are highly appreciated for
their administrative assistance.
The author gratefully acknowledges Bill and Melinda Gate Foundation (BMGF),
UNESCO-IHE and AIT fellowship for the financial support.
In addition, the author would also like to pay his best regards to all his friends, colleagues
and group members for their encouragement and extended help, especially Mr Supawat
Chaikasem, Mr. Vitharuch Yuthawong, Mr. Mov Chimeng, Ms. Wiratchapan Suthapanich,
Ms. Tantima Suwannapan and Mr. Zeng Chengui.
Last but not least, the author would like to convey his sincere gratitude to his beloved son,
Themba, for allowing me to go to school when it was his time to do so.
ii
Abstract
This study investigated the performance of the Down-flow Hanging Sponge (DHS) system
in treating mildly polluted canal water. The DHS system and the Woven Fiber
Microfiltration (WFM) were operated parallel to each other for performance comparison
and the two systems were fed with the same wastewater.
The research was carried out with laboratory scale DHS and WFM modules and the
experiment was set up at the AIT EEM research station. Both systems were operated under
ambient physical conditions. The feed wastewater comprised of a mixture of pond water
and septage. This mixture had characteristics close to those of a typically polluted canal
with COD concentration of 140 ± 20 mg/L. For the DHS reactor, the experiment was
conducted under three concurrent operational runs, with differing organic loading rates
(OLRs) of 1, 2 and 3 kg COD/m3.d. Cleaning of the WFM was done by drying the module
in the sun. The experiment was carried out over a period of over 100 days.
The results showed that the DHS system achieved removal efficiencies of 77 %, 84.7%,
80% for COD, BOD5, TKN respectively and 1.4 log removal for total coliform, at an OLR
of 1 kg COD/m3.d. At an OLR of 2 kg COD/m3.d, the DHS reactor achieved 76% COD
removal, 84% BOD removal, 72% TKN removal and 1.2 log removal of total coliform.
The removal efficiencies at the OLR of 3 kg COD/m3.d were 86% 89% 90%, 95%, for
COD, BOD5, TKN, respectively and 1.3 log removal of total coliforms. The effluent of the
DHS system met reuse standards at all OLR. The average removal efficiencies for the
WFM were 70% for COD, 70% for BOD5, 40% for TKN and 0.5 log removal for total
coliforms. These removal efficiencies were all lower than those of the DHS reactor, and
did not meet reuse standards.
During the study, cleaning of the WFM was done by drying the membrane in the sun. The
membrane performance after the cleaning did not diminish, showing that the cleaning
method was effective.
The optimum OLR for the DHS reactor was found to be 1 kg COD/m3.d and at this OLR.
The WFM average permeate flux was only 2 L/m2.h, which is not economically desirable.
It was concluded that the DHS is a more efficient system than the WFM for treating dilute
wastewater.
iii
Table of Contents
Chapter
Title
Page
Title Page
Acknowledgements
Abstract
Table of Contents
List of Tables
List of Figures
List of Abbreviations
i
ii
iii
iv
vii
viii
ix
1
Introduction
1.1
Background
1.2
Objectives of the Study
1.3
Scope of the Study
1
1
2
2
2
Literature Review
2.1
Surface Water Quality for Thailand
2.1.1 Surface water pollution
2.2
Biofilms
2.2.1 Biofilm formation
2.2.2 Biofilm reactors
2.3
DHS System
2.3.1 DHS system first generation type
2.3.2 Second generation DHS (curtain) type
2.3.3 Third generation DHS (trickling filter) type
2.3.4 Fourth generation DHS (random) type
2.3.5 Fifth generation DHS reactor
2.3.6 Sixth generation DHS reactor
2.3.7 DHS as a stand-alone treatment unit
2.3.8 Role of sponges
2.4
Seed Sludge and Acclimatization
2.5
Synthetic Wastewater
2.6
Organic Loading Rate (OLR)
2.7
Hydraulic Retention Time (HRT )
2.8
Membrane Bioreactors (MBR)
2.9
Woven Fiber Membrane
2.9.1 Woven fiber membrane treatment mechanism
2.9.2 WFM configuration and classification
2.9.3 Transmembrane Pressure (TMP)
3
3
3
5
5
5
6
6
7
7
iv
8
8
8
9
10
11
11
12
12
13
13
14
14
15
3
Methodology
16
3.1
3.2
3.3
3.4
3.5
16
16
17
18
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
3.14
3.15
4
Introduction
DHS Module Description
DHS System Inoculation with Seed Sludge
DHS Reactor Set-up With Synthetic Water
DHS System Acclimatization Run with Synthetic
Wastewater
Operational Conditions of the DHS Reactor During
Acclimatization Run
Laboratory Analysis
Pond Water/ Sewage Mixture Tests
Experimental Setup with Pond Water/Septage Mixture
Down-flow Hanging Sponge System Set Up
Woven Fiber Microfiltration System Set Up
Woven Fiber Membrane Properties
Woven Fiber Membrane Cleaning
Analytical Methods
Operation and Maintenance Guideline
Results and Discussion
4.1
Introduction
4.2
Downflow Hanging Sponge System Acclimatization Run
4.3
Operating Conditions During Acclimatization Run
4.3.1 Temperature
4.3.2 Turbidity
4.3.3 pH
4.3.4 Dissolved oxygen
4.4
Summary of the Operational Conditions for the
Acclimatization Run
4.5
DHS System Performance During the Acclimatization
Run
4.5.1 COD removal
4.5.2 Total solids (TS), total suspended solids (TSS) and
total dissolved solids (TDS)
4.5.3 BOD5 removal
4.5.4 TKN removal
4.6
Pond Water/ Septage Run System Performance
4.7
Operating Conditions for the Pond Water/ Septage Run
4.7.1 Temperature
4.7.2 Turbidity
4.7.3 pH
4.7.4 Dissolved oxygen
4.7.5 DHS dissolved oxygen profile
v
18
19
19
20
21
21
22
23
24
24
24
25
25
25
25
25
26
26
26
26
27
27
27
28
29
29
29
29
29
29
30
30
4.8
4.9
4.10
4.11
4.12
5
Summary of the Operational Conditions for the Pond
Water/Septage Run
WFM System Runs
4.9.1 Woven fiber pure water flux
4.9.2 WFM system performance
Removal Efficiency for the system
4.10.1 COD removal
4.10.2 COD removal profile
4.10.3 BOD5 removal
4.10.4 TKN removal
4.10.5 TKN profile across the DHS reactor
4.10.6 Total solids (TS), total suspended solids (TSS)
and total dissolved solids (TDS)
4.10.7 Total coliforms
Summary of the DHS & WFM Run Efficiency
DHS Performance Compared to other Studies
31
31
31
32
33
33
34
35
35
36
36
37
37
38
Conclusions and Recommendations
5.1
Conclusions
5.2
Recommendations for Future Study
39
39
40
References
42
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
46
47
48
64
67
vi
List of Tables
Table
Title
2.1
2.2
2.3
2.4
2.5
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
4.1
4.2
4.3
4.4
C.1
C.2
C.3
C.4
C.5
D.1
D.2
D.3
D.4
D.5
E.1
Wastewater Reuse Standards in Thailand
Advantages and Disadvantages Low Cost Technologies
DHS Removal Efficiencies at Different OLR
Composition of Synthetic Starch Wastewater
Classification of Membrane
Seed Sludge Characteristics
Operational Conditions of the DHS Reactor
Instruments used for Measuring
Analytical Methods for the Study
Characteristics of Pond Water and Septage
Calculation of Organic Loading Rate (OLR)
Determination of Flow from Various OLR
Flat Sheet Membrane Specification
Acclimatization Run Operational Conditions Summary
Pond Water/Septage Run Operational Conditions Summary
Summary of the DHS & WFM Run Efficiency
DHS Reactor Performance Compared to other Studies
Operational Parameter for the DHS Reactor
Troubleshooting of the system
Operational Parameter for the WFM Reactor
Membrane Specification
WFM System Troubleshooting
Standards used for this research
Typical Pollution of Surface Water
Thailand Surface Water Quality
Thailand Surface Water Quality Parameters and Classification
USEPA Guidelines for Water Reuse
pH, DO, Turbidity Temperature and TDS during DHS
Acclimatization Run
DHS COD and BOD5 Removal during Acclimatization Run
DHS pH, DO, Turbidity Temperature and TDS during Pond
Water/Septage Run
pH, DO, Turbidity Temperature and TDS for WFM System Pond
Water/Septage Run
COD Removal during Pond Water/Septage Mixture Run
BOD5 Removal during Pond Water/Septage Mixture Run
TKN Removal during Pond Water/Septage Mixture Run
Total Coliform Removal during Pond Water/Septage Mixture Run
Pond Water/Septage Mixture Characteristics
WFM Run Pure Water Flux Run
WFM Run Pond Water/Septage Mixture Run
E.2
E.3
E.4
E.5
E.6
E.7
E.8
E.9
E10
E.11
Page
vii
3
4
10
11
14
18
19
19
20
20
21
22
23
26
31
37
38
52
55
59
59
63
64
64
65
65
66
67
68
69
71
73
74
74
74
75
78
77
List of Figures
Figure
Title
2.1
3.1
3.2
3.3
3.4
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
4.14
4.15
4.16
4.17
A.1
A.2
Membrane separation mechanism
Methodology framework
DHS set up with synthetic wastewater
Pond water/septage setup
WFM system setup
Synthetic wastewater temperature range
Synthetic wastewater DO range
Synthetic wastewater DHS COD removal
Synthetic wastewater TS, TSS & TDS removal
Synthetic wastewater BOD5 removal
DHS DO profile for water/septage mixture
Oxygen uptake segment with holes
Pure water flux for both WFM modules
WFM flux and TMP
COD removal
COD removal efficiency
COD profile across the DHS reactor
BOD5 removal
TKN removal
DHS TKN profile for water/septage mixture
TS, TSS, TDS removal
System Coliform Removal for water/septage mixture
DHS system set-up
set
for acclimatization
Pond Water and septage (where the water for the study is
taken)
DHS Reactor module dimensions
System layout at the canal
DHS Reactor setup at the canal
WFM System layout at canal
WFM Set up in treatment tank
WFM Module Cleaning by solar drying
C.1
C.2
C.3
C.4
C.5
C.6
Page
viii
13
17
18
21
23
25
26
27
28
28
30
31
32
32
33
33
34
35
35
36
36
37
46
46
50
52
53
59
61
62
List of Abbreviations
AHR
AIT
APHA
AWWA
BMR
BOD
CAS
CEHA
CFU
COD
DHS
DO
EPS
FC
HLR
HRT
ICE
MBR
MF
MLSS
MPN
OLR
PF
PO43
PV
SBF
SLR
SMBR
SND
SRT
SS
TDS
TKN
TMP
TS
TSS
UASB
WEF
WFM
WHO
WWDR
WWTP
Anaerobic hybrid reactor
Asian Institute of Technology
American Public Health Association
American Water Works Association
Bangkok Metropolitan Region
Biochemical Oxygen Demand
Conventional Activated Sludge
Centre for Environmental Health Activities
Colony Forming Units
Chemical Oxygen Demand
Down-flow Hanging Sponge
Dissolve Oxygen
Extracellular Polymeric Substance
Faecal Coliforms
Hydraulic Loading Rate
Hydraulic Retention Time
Internal Combustion Engine
Membrane Bioreactor
Microfiltration
Mixed Liquor Suspended Solids
Most Probable Number
Organic Loading Rates
Polyurethane foam
Phosphate
Photovoltaic
Sponge Bio-Filter
Solids Loading Rate
Submerged Membrane Bio-Reactor
Simultaneous Nitrification and De-nitrification
Solid Retention Time
Suspended Solids
Total Dissolved Solid
Total Kjeldahl-Nitrogen
Trans Membrane Pressure
Total Solid
Total Suspended Solid
Up-flow Anaerobic Sludge Blanket
Water Environment Federation
Woven Fiber Micro- filtration Membrane Filter
World Health Organisation
World Water Development Report
Wastewater Treatment Plant
ix
Chapter 1
Introduction
1.1
Background
Water is vital in all areas of mans livelihood environmentally, socially and economically.
As such, this asset needs to be managed with great sense of objectiveness, putting the
interests of the community at large. In spite of unprecedented advancement in technology,
globalization and urbanization across the world, a vast number of developing countries are
lagging behind in providing basic sanitation and adequate water supply to their people.
There is water scarcity in most developing countries and the problem will soon be
compounded by the growing population. Demand for water for agricultural, household,
recreational and environmental uses is rapidly increasing due to continuously increasing
population. (Vairavamoorthy et al., 2008). The available water resources are not readily
available for human usage due to the absence of technology for adequate treatment before
use. Discharge of chemicals from various industries, which unfortunately is on the rise in
the developing world, causes hazardous effects on humans, animals and environmental
balances.
The rural areas take the brunt of the water scarcity effects as projects that are undertaken in
water and sanitation are usually directed towards urban areas, leaving the communities to
fend for themselves. It is not strange, therefore, to see that migration to the urban is still
rampart despite a lot of efforts to abate it. People are leaving the rural area due to the
shortage of resources, especially water.
There is a need, therefore, to provide sustainable water sources that can be provided at low
cost using appropriate technologies to these isolated rural areas. Self sustaining,
technologies that require low operation and maintenance cost would be vital for the rural
masses. If these wastewater treatment technologies produce effluents that meet the national
reuse standards, this would be of great benefit both to the communities and the
environment.
According to the World Water Development Report (WWDR 2006), most of the
developing countries in Asia and Africa have less than 2,000 cubic meters of water per
capita per year and are considered water stressed Water stress is illustrated by poor
availability of fresh water and high levels of pollution in fresh water. These factors present
a major problem in many developing countries (Rijsberman, 2004).
Wastewater is mostly discharged into rivers and canals and this act pollutes these
waterways. Most Asian and African countries have tremendous potential for agriaquaculture wastewater reuse. The reuse of wastewater has been practiced for generations
but more on informal/ad-hoc approach. Most of the peri-urban agri-aquaculture activities
depend to a large extent partially treated domestic and industrial wastewater. Nevertheless,
promotion of reuse by the government with appropriate technical and legislative assistance
would pave way for increased reuses enabling added benefits to the farming community.
For wastewater disposal, most rural communities do not have properly working waste
water plants and those that have the plants, do not operate them in an effective way. Most
treatment plants are a responsibility of local governments. However, these local
1
governments depend on the central government for the operation these treatment plants. As
always expected, the funds from the central government are not always enough and so,
when effecting budgets cuts at the local level, treatment plants are the first to suffer. It is
not surprising, therefore, to note that most wastewater is discharged into canals and rivers
without any treatment.
The main pollutants that pose problems to water quality in Thailand are organic wastes,
bacteria, nutrients, and solids. Most rivers have water that is on inferior quality to the
Surface Water Quality Standard and its classification. The major water quality problems
are high coliform bacteria (in term of total and fecal coliform bacteria) high solids (in term
of turbidity and total solids,), total phosphorus (TP), low dissolved oxygen (DO),
Ammonia-nitrogen (NH3-N), and high organic matter. (Simachaya, 2002). The situation in
Thailand is a reflection of most developing countries especially in Asia and Africa.
1.2
Objectives of the Study
The objectives of this study are as follows:
1. Determine the DHS operational parameters and conditions that will give the
effluent characteristics that comply with widely accepted water reuse
standards.
2. Develop a simple operation and maintenance guideline for application of
this system in a rural community.
3. Compare the performance of the DHS system to one other wastewater
treatment systems (Woven Fiber Micro- filtration Membrane)
1.3
Scope of the Study
This study was carried out with an experimental laboratory scale DHS reactor and WFM
module.
1.3.1
1.3.2
1.3.3
The DHS reactor was run with synthetic wastewater for a period of two months
acclimatizing it before the run with wastewater. The following parameters were
monitored: COD, BOD5, TKN, TSS, TS, TDS at an OLR of 2.6 kg COD /m3.day
and HRT of 2 hours.
The DHS was set up to run with a mixture of pond water and septage. The mixture
had similar characteristics to a typical polluted canal. The parameters analysed
were COD, BOD5, TKN, Total Coliforms TSS TDS , TS. The readings of
temperature, dissolved oxygen, conductivity, pH and turbidity, were monitored on a
daily basis.
A Woven Fiber Microfiltration Membrane, (WFM) system was set to run in
parallel to the DHS reactor, using the same pond water/ septage mixture, to
compare its performance.
2
Chapter 2
Literature Review
2.1 Surface Water Quality for Thailand
Standards of surface water use in Thailand are put into classes, from 1 to 5, the best class
being 1 and the last class 5, as shown in Appendix D, Tables D.1, D.2 and D.3. Table D.4
lists USEPA standards, which are used by other African and Asian countries. Allowable
parameters for each class are laid out and these are the standards for use. Our main interest
is in agricultural water reuse, which falls in class number 3. For this class, number 3, Table
2.1 shows the accepted limits of the parameters.
Table 2.1 Wastewater Reuse Standards in Thailand (OEPP, 1999)
Parameter
Units
Range
Method of Examination
BOD5
mg/L
10 - 30
DO
mg/L
>2
Azide Modification at 20°C, 5
days
Azide modification
6-9
Electrometric pH
20,000
Multiple Tube Fermentation
1,000
Multiple Tube Fermentation
5.0
Cadmium Reduction
<5
Not more than 3o
Change
Distillation Nesslerization
pH
Total Coliform
Bacteria
Fecal Coliform
Bateria
NO3 –N
MPN/100
ml
MPN/100
ml
mg/L
NH4 –N
mg/L
Temperature
o
C
Thermometer
Several low cost technologies for wastewater treatment are available. Even though most of
these technologies are comparatively cheap and readily available, politics in these
countries prevent their implementation. Politicians put very little emphasis on wastewater
discharge. Table 2.2 is a tabulation of the advantages and disadvantages of some of the
low cost technologies.
2.1.1 Surface water pollution
Pollution due to human activities contribute to the degradation of surface water. Organic
pollution occurs when large quantities of organic compounds, which act as substrates for
microorganisms, are released into water courses. During the decomposition process, the
dissolved oxygen in the receiving water may be used up at a greater rate than it can be
replenished, causing oxygen depletion and having severe consequences for the stream
biota. Organic pollution of surface waters deprives these waters of dissolved oxygen,
which is essential for aquatic life. Organic pollutants consist of proteins, carbohydrates,
fats and nucleic acids in a multiplicity of combinations. Organic wastes from people and
their animals may also be rich in disease-causing (pathogenic) organisms.
3
Excess nitrogen in the agriculture water can potentially cause nitrogen injury, excessive
vegetative growth, delayed growing season and maturity, all which are not desirable to the
farmer. (Asano et al., 1985). Excessive amount of nitrogen can also cause eutrophication, if
discharged to water ways.
Table 2.2 Advantages and Disadvantages Low Cost Technologies (UNEP, 1998)
Treatment
Advantages
Type
Aquatic Systems
Stabilization
Low
capital
cost
lagoons
Low operation and maintenance costs
Low
technical
manpower
requirement
Aerated
Requires relatively little land area
lagoons
Produces few undesirable odors
Disadvantages
Requires a large area of land
May produce undesirable odours
Requires mechanical devices to
aerate
the
basins
Produces effluents with a high
suspended solids concentration
Terrestrial Systems
Septic tanks
Can be used by individual Provides a low treatment
households
efficiency
Easy to operate and maintain Must be pumped occasionally
Can be built in rural areas
Requires a landfill for periodic
disposal of sludge and septage
Constructed
Removes up to 70% of solids and Remains largely experimental
wetlands
bacteria
Requires periodic removal of
Minimal
capital
cost excess
plant
material
Low operation and maintenance Best used in areas where suitable
requirements and costs
native plants are available
Mechanical Systems
Filtration
Minimal land requirements; can be Requires mechanical devices
systems
used for household-scale treatment
Relatively
low
cost
Easy to operate
Vertical
Highly efficient treatment method High
cost
biological
Requires
little
land
area Complex
technology
reactors
Applicable to small communities for Requires technically skilled
local-scale treatment and to big cities manpower for operation and
for regional-scale treatment
maintenance
Needs
spare-parts-availability
Has a high energy requirement
Activated
Highly efficient treatment method High
cost
sludge
Requires
little
land
area Requires sludge disposal area
Applicable to small communities for (sludge is usually land-spread)
local-scale treatment and to big cities Requires technically skilled
for regional-scale treatment
manpower for operation and
maintenance
4
2.2 Biofilms
2.2.1 Biofilm formation
Biofilm formation is the accumulation of microorganisms, including extracellular
compounds, on a surface due to either deposition or growth or both. (Hamilton, 1985).
Biofouling is the extent of biofilm formation on the surface, hampering smooth operation
of a membrane. Biofouling causes operational problems and these may include. pressure
drop, flux reduction, salt passage increase. The biofilm is held together by excreted organic
polymer matrix of microbial origin called extracellular polymeric substances, EPS,
(Allison et al., 1984). It is often the this biofilm matrix that causes many of the economic
problems associated with biofilm formation since it acts as a layer of immobilized water
Biofilms can contain many different types of microorganisms, e.g. bacteria, protozoa, fungi
and algae.
Formation of a biofilm usually involves three subsequent phases:
(i)
adhesion and attachment of microorganisms to a surface,
(ii)
growth,
(iii) stationary phase.
Especially in the stationary phase in laboratory biofilm systems, biomass detachment is
observed by erosion and sloughing. Sloughing refers to the removal of biomass layer by
fluid frictional forces. It can result in the removal of large sections of biofilm.
2.2.2 Biofilm reactors
In biological wastewater treatment, two conditions exist:
(i)
active microorganisms have to be concentrated within the system,
(ii)
microorganisms have to be removed from the treated effluent before the water
leaves the system. (Henze et al., 2008).
In biofilm reactors, microorganisms are immobilized in a dense layer growing attached to a
solid surface. Maintaining active biomass in the biofilm reactor does not require a settler.
Bacteria in suspension can be washed out with the water flow, but in biofilms, the bacteria
is protected from washout and can grow in locations where their food supply remains
abundant. Bacteria is imbedded in a matrix of extracellular polymeric substance (EPS)
containing polysaccharide proteins, free nucleic acids, and water (Sutherland 2001). The
EPS is basically the glue that holds the biofilm in place.
Biofilms behave in the following way:
(i)
convert compounds available in the bulk liquid which is used in biological
wastewater for the removal of unwanted compounds,
(ii)
take up space and interfere with bulk water flow, which in some cases is
desirable and other, is detrimental,
(iii) harbor pathogenic microorganisms that are difficult to remove within the
biofilm.
In all types of biofilm reactors, the following conditions have to be met:
(i)
retention of microorganisms is based on attachment of biomass to the surface of
the support medium, rather than using solid liquid separation and biomass
recycle,
5
(ii)
(iii)
water containing the polluting compounds is brought into contact with the
biofilm and local mixing conditions and turbulence will determine the effective
mass transport from the bulk water to the biofilm,
biofilm growth has to be balanced with biofilm detachment to avoid clogging of
the reactor while retaining sufficient active biomass in a stable biofilm.
There are three groups of bioreactor: non-submerged systems, submerged fixed bed
biofilm reactors and fluidized bed reactors. Key differences between these groups is the
specific surface area, mechanism for removing excess biomass and gas transfer. (Henze et
al, 2008)
2.3 DHS System
The lastest entry to the family of non-submerged biofilm reactors is the Down flow
Hanging Sponge (DHS) system. The system was developed by Harada and his research
group at Nagaoka University of Technology, Japan, for the treatment of sewage in
developing countries. The DHS reactor is composed of several modules, each 2-4 meters
vertical length filled with hundreds of series-connected hanging sponge-cubes. The tubular
vessel is filled with sponge cubes which are diagonally linked using nylon strings. A large
surface area is thus created and this is where the microbial growth takes place in nonsubmerged conditions. Wastewater is supplied at the top end of each module, and trickles
down toward the lowest end of the module, (Machdar et al., 1997).
As wastewater is trickling downwards through the sponges, the microorganisms take up
nutrients from the wastewater. No mechanical air device is used in the DHS system even
though the process is aerobic (Tandukar et al., 2006). As the sponges in DHS reactor are
not submerged and freely hang in the air, oxygen dissolves into the wastewater as it flows
down. This repeated phenomenon maintains dissolved oxygen (DO) concentration in the
wastewater at a level which exceeds the need of microorganisms that reside in DHS sludge
(Tandukar et al., 2006)
The DHS system can be operated under anaerobic conditions and provide for the recovery
of dissolved methane gas. In 2010, Matsuura et al., investigated a two stage DHS system
for the post treatment of UASB effluent in Nagaoka, Japan. Most of the dissolved methane
(99%) was recovered by the two stage system, whereas about 76.8% of influent dissolved
methane was recovered by the first stage operated at 2 hours hydraulic retention time
(HRT). The second DHS reactor was mainly used for oxidation of the residual methane
and polishing of the remaining organic carbons. The removal of COD and BOD5 in the
first stage was insignificant as there was no air supply; however, high removals were
expected in the second stage due to sufficient supply of air, which quickly oxidize the
residual dissolve methane in the upper reactor portion before being emitted to the
atmosphere as off-gas.
2.3.1 DHS system first generation type
Since its inception, the DHS system has been developed through several pilot experimental
researches. This was due to the desire to develop a more affordable treatment technology
for the developing countries.
6
In 1997, Agrawal developed to a "first generation type" or "cube type" DHS reactor. The
reactor used sponge cubes each 1.5cm connected to each other diagonally with a nylon
string and arranged in series. (Agrawal et al., 1997; Machdar et al., 2000). The full scale
reactor had three segments, each two meters high. Each segment was filled with 120
sponge cubes, which measured 1.5 cm, and were linked diagonally with a nylon string.
Inoculation was done by placing the segments and the cubes into activated sludge for 48
hours. The sponges occupied about 28% of the DHS reactor volume. The reactor was fed
by the effluent of a UASB reactor. The reactor was operated at a hydraulic loading rate
(HLR) of 0.06 m3/m2d, with a flow of approximately 30 liters per day in winter time and
an HLR of 0.11 m3/m2d (flow of 60 L/d) in summer time. The DHS reactor was evaluated
for residual organics removal and nitrification under natural air intake only. The influent
COD was in the range of 100 – 135 mg/L and the average ammonia concentration was 35
mg NH4-N/liter. During the evaluation, it was observed that with post de-nitrification and
an external carbon source, 84% in average N (NO3 + NO2) was removed with a hydraulic
retention time (HRT) of less than 1 hour, for temperature range of 13 to 30 0C. The effluent
contained a negligible amount of SS and total COD was only in the range of 10 to 25
mg/L. The DHS reactor was capable of stabilizing total nitrogen through nitrification,
which ranged from 73-78% (Agrawal, et al., 1997)
2.3.2 Second generation DHS (curtain) type
Since then, a second generation or "Curtain type" reactor has been developed. The sponge
shape changed to triangular strips, 75 cm long and 3cm wide for the second generation
reactor. The sponges were tiled on both sides of a plastic sheet with a height of 2 meters.
(Machdar et al., 2000). All the other measurements of the cube type DHS reactor remained
the same. The influent also came from the effluent of a UASB reactor, as before. The
reactor was operated for a total of 550 days. The reactor was operated at a HRT of 2 hour
and a temperature of 25o Celsius. The DHS reactor successfully achieved 92% of BOD5
removal, 62% of COD removal, and 79% of TSS removal, and 61% of NH4-N removal As
in the first generation type, the complete system neither requires external aeration input nor
withdrawal of excess sludge. The final BOD5 effluent concentration was 6 to 9 mg/L.
Similarly, FC removal was 3.5 log with a final count of 103 to 104 MPN/100mL in the
effluent. Nitrification and de-nitrification in DHS accounted for 72% removal of total
nitrogen (effluent concentration of 11 mg N/L) and 60% removal of ammonium nitrogen
(effluent NH4-N of 9 mg N/L) over the total operational period. The system was a
combined UASB+DHS (Machdar et al, 2000)
2.3.3 Third generation DHS (trickling filter) type
A third generation type or "trickling filter type" was developed by Mahmoud et al in 2009.
The reactor utilized small sponge pieces encased in a supporting material on the outside.
(Tawfik et al., 2006) The DHS system had a capacity of 133 liters, consisting four
segments connected vertically. Each segment was filled with 6 liters of polyurethane foam
(PF), wrapped with perforated polypropylene plastic material, randomly distributed in the
whole reactor. The foam occupied 18% of the reactor volume. The reactor was fed with the
effluent from an Anaerobic hybrid reactor (AHR). The reactor was operated at an HRT of
2 hours, organic loading rate of 2.1 kg COD/m3.d and a flow of 0.288 m3/day. The system
achieved 87% of BOD5 removal, 69 % of COD removal, 66% of TKN removal and 85% of
NH4-N removal. The reported results indicated that the third generation DHS reactor is
very effective not only for the reduction of chemical oxygen demand (COD),
7
biochemical oxygen demand (BOD5) and ammonia but also for faecal coliform removal
(Mahmoud et al., 2009)
2.3.4 Fourth generation DHS (random) type
A fourth generation DHS reactor (Tandukar et al., 2006), had box modules with long
sponge strips, placed inside a net-like cylindrical plastic cover. This provided rigidity to
the sponges. The strips measured 2.5cm x 2.5cm x 50cm. (Tandukar et al.,2005). The
system was developed to enhance the dissolution of air into the wastewater and to avert the
possible clogging of the reactor. The DHS reactor had a volume of 375 liters and consisted
of four modules put one above the other with a gap in between, giving a total height of 4
meters. The sponges were put inside a net-like cylindrical plastic cover to provide rigidity.
Fifteen such sponge units were arranged in a row, and were then stacked one above another
but in directions 90o to each other to make 20 rows. Gaps between consecutive rows were
maintained at 0.7 –1.0 cm. Three hundred sponges, in total were put inside the module and
this represented 39% of the reactor volume. The reactor was fed with the effluent from a
UASB reactor using a peristaltic master-flex pump. The reactor was operated at a HRT of
2 hours with a temperature range of 20o C – 25o C. to simulate an annual average ambient
temperature of most of the developing countries in tropical and subtropical regions. The
DHS system was started with clean sponge saturated with water without the use of
inoculation. The start-up period was less than two weeks. The DHS system achieved 90%
of BOD5 removal, 76 % of COD removal, 30% of TKN removal and 28% of NH4-N
removal. Investigation on DHS sludge was made by quantifying it and evaluating oxygen
uptake rates with various substrates. Average concentration of trapped biomass was 26 gVSS/L of sponge volume, increasing the SRT of the system to 100-125 days. Removal of
coliforms obtained was 3-4 log10 with the final count of 10(3) to 10(4) MPN/100 ml in
DHS effluent. (Tandukar et al, 2006).
2.3.5 Fifth generation DHS reactor
The fifth generation reactor (Tandukar et al., 2007) made improvements to the sponge
arrangement for the second generation reactor by lining up several sponge sheets. The
reactor had total volume of 480 L, based on the sponge volume. Polyurethane sponge with
pore size of 0.63 mm was used for the construction of DHS. Void ratio of sponge was
more than 90%, The DHS reactor was filled with sponges arranged in a curtain,
constructed by adhering the sponge with undulating surface on both sides of a thin plastic
sheet. The reactor was fed with effluent from a UASB reactor, without any pretreatment. .
The flow from the UASB reactor was by gravity. The HRT for the DHS reactor was 2.5
hours, and was operated for 300 days. DHS system was comparable to that of activated
sludge process (ASP). Unfiltered BOD5 removal was more than 90%. COD removal of
over 70%, TKN removal of over 60% and a 3 log removal of Fecal Coliforms.
2.3.6 Sixth generation DHS reactor
The sixth generation reactor has the basic design similar to the third generation reactor but
utilizes rigid sponge media which is manufactured by copolymerizing polyurethane with
epoxy resins. (Onodera et al., 2014). The reactor consisted of four segments, each segment
being 76.5 cm tall and 24 cm in diameter separated by 15 cm connecting segments. The
total volume of the reactor was 136 liters and the sponges occupied 33.8% of the volume.
The connecting segments had removable windows to allow the reactor to be ventilated and
8
wastewater samples to be collected. It had a rotary distributor at the top of the reactor. The
reactor was operated at a hydraulic retention time (HRT) of 2 hours, calculated on the
sponge volume. Fed with effluent from a UASB reactor, it was started without any
inoculation. The system gave reasonable organic and nitrogen removal efficiencies. The
reactor achieved a BOD5 removal efficiency of 96 % TKN removal efficiency of 43%. The
nitrification performance was good, this being attributed to the rigid sponge media. There
was a high concentration of dissolved oxygen under natural ventilation.
2.3.7 DHS as a stand-alone treatment unit
The DHS system has mostly been used for the post treatment of effluent from system like
the UASB. (Mohamed et al., 2011; Agrawal et al., 1997; Machdar et al., 2000). Although
DHS reactor has many advantages, it is not appropriate for the treatment of raw wastewater
which contains high concentrations of suspended solids (SS). The presence of high SS
concentrations in the influent interferes with the transfer of oxygen and substrates into the
biofilm (Guo et al., 2010). It is therefore, recommended to remove coarse suspended solids
prior to entering DHS reactor.
In 2011, Uemura et al., conducted research on direct treatment of sewage sludge using
three DHS reactors which employed different sizes of sponge media but with the same
total sponge volume of 240 cm3. Three identical DHS reactors, 2000 mm in working height
and 20 mm in width, were used. The largest sponge medium used was the same size as that
used in previous pilot and demonstration studies of curtain type DHS units (Machdar et al.,
2000). All the reactors were seeded with concentrated activated sludge by soaking the
sponges in the sludge. The reactors were fed with wastewater drawn from the primary
settlement tank of the sewage treatment plant, making sure that the liquid was drawn at
exactly the same time every day of the experiment. The reactors were run at an HRT of 2
hours with a controlled room temperature of 25o C and were operated for more than 130
days. All the reactors showed excellent performance in the removal of COD, ammonium
nitrogen, and fecal coliform at a fixed hydraulic retention time of 2.0 h based on the
sponge volume. It was also shown that smaller sponge media produced better removal
efficiencies for all the parameters listed above. The most reasonable explanation for this
might be that smaller sponge media allows better oxygen uptake in the stream flowing
down through the reactors.
DHS as a stand-alone system was carried in 2013, by a at the Asian Institute of
Technology, AIT (Ehsas, 2013). A laboratory scale DHS reactor was used which had a
volume of 35.3 liters, made from plexi-glass. The reactor had four segments, each 0.5
meters in length and a gap of 0.1 m in between. The material forming part of the 0.1 m gap
was perforated with holes which allow the diffusion of air. The module was randomly
packed with polyurethane cylindrical sponges, measuring 3 cm x 3cm and they occupied
30% of the module’s volume. The system was inoculated with seed sludge taken from the
AIT Wastewater Treatment Plant (AIT WWTP), mixed with canal water. The system was
acclimatized for two weeks before starting observing it performance. The reactor was run
with three different OLR runs of 0.29, 0.65 and 4.8 kg COD/m3d. Synthetic wastewater,
made from dog food, was used as the influent to the DHS system. The removal efficiencies
obtained from the research were as follows as in Table 2.1..
9
Table 2.3 DHS Removal Efficiencies at Different OLR (Ehsas, 2013)
Run
Run 1
Influ.
Efflu.
%R
Run 2
Influ.
Efflu.
%R
Run 3
Influ.
Efflu.
%R
HRT OLR
(h)
(kg
COD/m3d)
3
0.29
2
0.65
1
4.8
TSS
COD
BOD5 TKN
NH4-N
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Total
Coliform
(mg/L)
6
1.3
78.3
40
18.1
54.7
28.6
12.2
57.5
4.6
0.9
81
1.9
0.2
90.5
17000
8900
47.6
11.3
0.3
97
54
13
76
33
3.1
90.6
2.3
0.4
81.3
0.3
0
100
13500
6000
55.5
102.2
42.5
58.4
200
88.2
56
162
38
76.5
10.4
5
51.4
0.8
0.1
83.3
11000
1700
84.5
The effluent qualities at kg COD/m3 d of 0.29 kg COD/m3.d and 0.65 kg COD/m3.d
met the agriculture reuse standards except for Total Coliform; on the other hand the
effluent qualities at kg COD/m3.d 4.8 kg COD/m3 d for TSS, COD, BOD5 and Total
Coliform did not meet the agriculture reuse standards.
2.3.8 Role of sponges
In the year 2010, Guo et al investigated the role of sponges as an active mobile carrier for
attached-growth biomass in three typical types of aerobic bioreactors to treat a high
strength synthetic wastewater. Different pore sizes of reticulated polyester urethane sponge
(S45R, S60R and S90R) from Joyce Foam Products, Australia, were used in this study and
occupied 10% of the reactor volume. The sponges were cut in shape and acclimatized to
wastewater before use. Synthetic wastewater was pumped into the reactor using a feeding
pump to control the feed rate while the effluent flow rate was controlled by a suction
pump. A level sensor was used to control the wastewater volume in the reactor. For
Dissolved Organic Carbon (DOC) removal, the removal efficiencies of S45R and S90R
dropped 15% with 3 cm thickness of the sponge, while there were only slight changes in
DOC removal efficiencies of 1 and 2 cm sponges. As the NO3–N and NO2–N
concentrations in the effluent were less than 0.5 and 0.01 mg/L, respectively. This
demonstrated that the sponge itself has a function of simultaneous nitrification and
denitrification (SND). This phenomenon was also verified the decreasing DO gradient
occurring inside of the sponge cubes. The 1 cm sponge exhibited the best T-N and T-P
removal (39.9% and 61.0% for S45R and 51.7% and 89.1% for S90R, respectively)
compared to 2 and 3 cm sponges, which indicated there is an optimum thickness for active
biomass working on and inside the sponge. Moreover, it could be seen visually that a thin
layer of biofilm formed faster on 1 cm sponge than those on 2 and 3 cm sponges. The
conclusion from these results was that sponge thickness deteriorated the organic and
nutrient removal and 1cm is the optimum thickness for fixed-bed sponge biofilter (SBF).
The sponge volume had significant impact on phosphorus removal rather than organic or
nitrogen removal, and 20% volume of sponge could achieve 100% T-P removal within 3h
10
in a sponge batch reactor (SBR). Sponges show a better performance when coupled with
submerged membrane bioreactor (SMBR).
2.3 Seed Sludge and Acclimatization
For biological wastewater treatment, a considerable time is involved in the start-up of the
process, especially when certain restrictions set for the initial loading rate and its increase
are not obeyed. (Zeeuw ,1981). The biomass also needs to be acclimatized to the substrate
that it is meant to treat. The main task in the start-up is to develop, in a period as short as
possible, a highly active and settleable sludge from the poor quality seed sludge. A careful
start-up procedure entails seeding the bioreactor with sludge, supplying proper nutrients to
facilitate bacterial growth and applying appropriate loading rates that do not exceed the
maximum potential of the biomass in the bioreactor or cause biomass washout.
In his pioneering experimenting on the first generation DHS, Machdar (1997), inoculated
the DHS unit by soaking it into activated sludge, mixed liquor, for one day prior to startup. In subsequent experiments, the DHS unit was not seeded as it received effluent directly
from the primary treatment unit which had prior seeding. (Mahmoud et al. 2009).
2.4 Synthetic Wastewater
There are various compositions of synthetic wastewater, as given by various publications.
These various compositions are to simulate various desired wastewater to be treated.
Tapioca starch synthetic wastewater According to Chen et al., (1991), tap water was used
to dilute a mixture of Glucose (C6H12O6), Ammonium Chloride (NH4Cl) and phosphate
(PO43) as the source of carbon, nitrogen and phosphorus source, respectively. To add
alkalinity, Sodium Bicarbonate (NaHCO3) was added to the synthetic wastewater.
Thailand is one of the largest producers and exporters of Tapioca (Roh et al., 2006) and the
abundance of the crop might mean that the polluted open water will contain tapioca waste.
In simulating the wastewaters of open waters in Thailand, it makes sense to use tapioca
starch based synthetic wastewater. In the preparation of their synthetic wastewater for the
treatment of starch waste by digester membrane system, Roh et al., (2006) used the
compositions as in the Table 2.4.
Table 2.4 Composition of Synthetic Starch Wastewater (Roh et al. 2006)
Components
Starch
(NH4)2SO4
MgSO4. H2O
FeCl3.H2O
CaCl2
KH2 PO4
K2 HPO4
MnSO4.H2O
NaHCO3
Concentration (mg/L)
2000
250
50
0.25
3.75
263.5
535
5
2000
11
2.6 Organic Loading Rate (OLR)
Organic loading rate (OLR) is defined as the application of soluble and particulate organic
matter. It is typically expressed as kilogrames of BOD5 per cubic meter day, such as
(Otis, 2001; Siegrist, 1987). Control of organic loading can be accomplished by reducing
the BOD5 and TSS concentrations or by increasing the size of the infiltration area to reduce
the mass loading per unit area. (WA DOH, 2002)
For biological wastewater treatment system, OLR refers to the rate at which biomass
(BOD5) is fed into the system. As biomass contains the substrate on which the microorganisms feed, OLR indicates the rate at which the substrate is supplied to the organism.
As in any other animal, how much food is supplied directly affects the rate of growth of the
organism. If too much food is given out, only a little will be utilized and the rest will go
untouched and if too little is supplied, the organisms will starve to death. In terms of
wastewater treatment, allowing a lot of biomass not to be utilised means the treatment is
not effective. The undesirable substance that was meant to be removed will just passing
through the system. It is, important, therefore, to supply the right amount of substrate that
can optimally be digested by the organisms.
The organic loading rate, in our system, depends on the available organic matter (Biomass)
in the waters, the flow of the water into the reactor and the reactor cross section area.
/
Organic Loading Rate, (OLR) =
Equation. 2.1
Mahmoud et al. (2011), operated the DHS reactor at organic loading rates of 6.2, 4.8, and
3.2 kg COD/m3d and concluded that the increase in OLR leads to decrease in the produced
oxidized nitrogen form (NOx-N). It was also noted that the performance of DHS reactor
was quite good for carbonaceous and nitrogenous compounds removal even at an OLR of
4.8 kg COD/m3d.
2.7 Hydraulic Retention Time (HRT )
The amount of time the fluid stays in the treatment system is referred to as the hydraulic
retention time (HRT). It is the average time spent by the influent in the reactor, before it is
discharged as the effluent. The higher the inflow rate Q, the sooner the influent wastewater
will reach the outlet and therefore the lower will be the residence time or hydraulic
retention. It is calculated by dividing the reactor volume by the flow rate. A long HRT
increases the chances of the biomass being utilized by the organisms.
=
24 ( ℎ)
Equation. 2.2
HRT for the DHS reactor is calculated as volume occupied by sponge divided by the flow
rate. (Global Environment Centre Foundation, 2005).
The rate of flow of the fluid to the reactor is the flow rate. It is the volume in a unit time.
This can be expressed in liters per second per cubic meters per day. The flow rate can be
used to vary the organic loading rate.
12
2.8 Membrane Bioreactors (MBR)
Membrane Bioreactor (MBR) process consists of a biological reactor integrated with
membranes that combine clarification and filtration of an activated sludge process into a
simplified, single step process. The membrane is an absolute barrier to suspended matter
and microorganisms and it offers the possibility of operating the system at high mixed
liquor suspended solids (MLSS) concentration. The implication of maintenance of high
MLSS are— requirement of a smaller footprint and operation at high solids retention time
(SRT) under low F/M ratio, hence, yielding reduced excess sludge. In the operation of an
MBR conventional activated sludge plants become single step processes, which produce
high quality effluent potentially suitable for reuse. (Hai et al, 2010).
2.9 Woven Fiber Membrane
A membrane can be defined as a selective barrier that permits separation of certain species
in a fluid by a combination of sieving and sorption diffusion mechanisms (Singh, 2000). It
is a thin sheet of natural or synthetic material that is permeable to certain substances and
prevents the passage of others in solution. Figure 2.1 shows the membrane separation
mechanism. In terms of energy, membrane separation have an important advantage in that,
unlike evaporation and distillation, no change of phase is involved in the process, thus
avoiding latent heat requirements. No heat is necessarily required with membranes, and it
is very possible to produce products with functional properties superior in some respect to
those produced by conventional processes.
Phase 1
Membrane
Feed
Phase 2
Permeate
Driving force
Figure 2.1 Membrane separation mechanism
A wide range of particle sizes and Molecular weight can be separated by a membrane. The
sizes range from macromolecular, materials such as starch and protein, to mono-valent
ions. A membrane should be selected such that the sizes of the pores are smaller than the
size of the smallest particle in the feed stream that is to be retained by the membrane.
Membranes are available in several different configurations i.e. tubular, hollow fiber, plate
and frame, and spiral-wound. Some of these designs may work better than the others for a
13
particular application, depending on such factors as viscosity, concentration of suspended
solids, particle size, and temperature.
Woven fiber membrane is another alternative to conventional wastewater treatment
process. However, its main disadvantage include operation high costs, mainly due to
membrane fouling. Membrane fouling is caused by the deposition of biomass and
suspended solids on the membrane surfaces and within the membrane pore. This
deposition leads to an increase of the hydraulic resistance and reduced permeate flux
(Cho, 2002). If the challenges faced by fouled and the associated cleaning costs are
addressed, this technology could become very attractive for wastewater treatment.
2.9.1
Woven fiber membrane treatment mechanism
Woven fiber technology underwent significant development at the Pollution Research
Group, University of Natal, in the 1980s, (Pillay, 1998). The system consists of two layers
of a woven polymer material, stitched together to form rows of parallel filter tubes, called a
"curtain". Feeding the system is done from the inside. Clear liquid permeates the tube wall,
and runs down the outside of the tubes as permeate. The system is used in cross-flow or
dead-end mode.
Physical or chemical cleaning of the membrane is required to remove foulant and maintain
optimum membrane performance in long term operation. Fouling can be limited by
maintaining the permeate flux below critical flux (Jc). This flux is related to flux and
transmembrane pressure (TMP). Above critical flux fouling takes place and cleaning
practice are necessary to restore membrane flux. It has been observed that the critical
flux decreases with the increase of sludge concentration and it could be enhanced by
improving the aeration intensity.
Fiber membranes have different pore sizes that are used in treatment of wastewater and the
choice of the pore size depends on the desired final effluent.
2.9.2
WFM configuration and classification
Membranes are classified according to their pore size. The membrane with the smallest
pore size is the reverse osmosis and microfiltration membranes have the largest pore sizes.
Table 2.5 shows the four classification of membranes and the range of pore size and
operation pressures.
Table 2.5 Classification of Membrane (Mulder, 1996)
Classification
Reverse Osmosis (RO)
Nano Filtration (NO)
Ultra Filtration (UF)
Micro Filtration (MF)
Pore Size Operational pressure Flux Range (L/m2.h)
(µm)
(bars)
10-4 – 10-3
30 – 60
> 50
-3
-2
10 – 10
10 – 20
10 - 50
-2
-1
10 – 10
1 – 10
1.4 - 12
0.1 – 1
<1
0.05– 1.4
14
The woven fiber membrane can be configured to run in two categories, spiral wound and
flat sheet and operated in either cross flow or dead end mode. In cross flow operation, the
feed is pumped tangential to the surface of the membrane, to maintain a continuous
removal of rejected solids from the surface. In dead end mode, the feed is pump parallel to
the permeate, through the membrane. Rejected solids in dead end mode, accumulate on the
surface and must be removed by backwashing.
2.9.3 Transmembrane Pressure (TMP)
Transmembrane pressure is defined as the difference in pressure between the feed side of
the membrane and the permeate side of the membrane. The driving force affects the TPM
of the membrane. TPM is the overall indicator of feed pressure requirements and is used,
together with flux, to determine whether there is fouling on a membrane. (WEP press,
2006).
15
Chapter 3
Methodology
3.1 Introduction
To achieve the objectives stipulated in the first chapter, the research was undertaken in
three phases. These phases, as shown in figure 3.1, are as follows:


Phase I:
Phase II:

Phase III:
Acclimatization of the DHS system with synthetic wastewater.
Running the DHS and WFM systems with pond water/septage
mixture.
Instructional manual write-up.
3.2 DHS Module Description
A laboratory scale DHS (random type) module was used. Fabricated from acrylic, the
module has an internal diameter of 0.15 m and a volume of 35.3 liters. It has four identical
segments connected vertically in series. Each segment is 0.5 m high and between each
segment there is be a gap of 0.1 m (Refer to Figure A.1, in the Appendix A). The pieces in
the gaps are perforated with holes, for oxygen diffusion. Each segment of the reactor is
randomly packed with polyurethane cylindrical sponge measuring 3 cm by 3 cm and the
sponges are supported by perforated polypropylene plastic material woven into a mesh, to
keep them rigid. For even distribution of water, a sprinkler is placed at the top of the
reactor. The sponges occupy 30% of the reactor volume.
16
PHASE I: ACCLIMATIZE WITH SYNTHETIC WATER
PHASE II: RUN WITH CANAL WATER
PHASE III
Wastewater Characterization
Monitor:
COD, BOD, TKN
DO, pH, TSS,TS,TDS, T
Turbidity
DHS System Inoculation with Seed
Sludge
DHS System Run for Two Months
(ACCLIMATIZATION)
Pond Water/ Septage
Mixture
Woven Fiber
Membrane System Set
Up
Monitor: Flux, TPM COD, BOD, TKN,
DO, pH T. Coliforms, Temp., E. Coli
TDS, TSS, TS
DHS System Set Up
System Acclimatization
WFM System Run
(Flux and TMP
Monitoring)
Monitor: COD, BOD, TKN, DO, pH, T.
Coliforms, Temp., E. Coli, TDS, TSS,
TS. Turbidity
DHS System Run
(Varying OLR)
Simple Guideline Development
Figure 3.1 Methodology framework
3.3 DHS System Inoculation with Seed Sludge
To introduce microorganisms into the system, the DHS reactor was inoculated with seed
sludge. Inoculation was done in a separate tank and lasted for three days. The activated
sludge was taken from AIT Wastewater Treatment Plant (AIT WWTP), and mixed with
ordinary tap water. The table below shows the characteristics of the sludge:
17
Table 3.1 Seed Sludge Characteristics
Parameter
pH
Suspended Solids
COD
TDS
Temperature
Unit
mg/L
mg/L
mg/L
O
C
Value
7.64
70
80
260
30
3.4 DHS Reactor Set-up with Synthetic Water
The DHS system was set behind the AIT EEM Ambient laboratory. The reactor was
supported on a wooden plank which was laid up against the building’s wall. The synthetic
wastewater was mixed in a 200 liter tank. The water was fed to the top of the reactor using
a peristaltic pump. There was no recirculation of the treated water. The set up was as
shown in Figure 3.2.
Figure 3.2 DHS set up with synthetic wastewater
3.5 DHS System Acclimatization Run with Synthetic Wastewater
In the set up, tapioca starch was used to make the synthetic wastewater. This tapioca starch
is made from cassava and is available commercially. To the mixture, a nitrogen and
phosphorus buffer were added using Potassium Sulphate, (KH2PO4) and Ammonium
Chloride (NH4Cl). Tap water is used for dilution of the mixture. Following the rule that
C:N:P ratio should be in the range between 100:10:1 and 100:5:1., 25g of starch is added to
1.25g of Ammonium Bicarbonate (NH4HCO3)and 0.25 g of Potassium
Phosphate.(KH2PO4) giving a C:N:P ratio of 100:5:1 The calculation of the OLR was
done as in Appendix C.
Effluent
The system was run for sixty one (61) days. This start up is the most crucial stage and
determines the subsequent performance of the system. The acclimatization determines if a
highly active biomass with good settling abilities, the two important desired characteristics,
are formed in the reactor. During the acclimatization, microorganisms required for the
18
process are allowed to grow until a sufficiently active population is present in the biomass
to enable digestion to progress stably.
3.6 Operational Conditions of the DHS Reactor During Acclimatization Run
Table 3.2 shows the operational parameters during the acclimatization run with synthetic
wastewater.
Table 3.2 Operational Conditions of the DHS Reactor
Parameter
HRT (h)
Temperature (◦C)
Flow rate (m3/d)
Organic loading rate (kg COD/m3 d)
Down flow velocity (m/h)
Operational conditions
2
28 ± 2
0.185
2.6
1.3
3.7 Laboratory Analysis
Grab samples were taken for lab analysis once a day, every day. Around the same time,
the physical parameters that could be measured immediately with on sight instrument were
taken. These parameters are: temperature, dissolved oxygen, pH, conductivity and
turbidity. Table 3.3 shows the instruments that were used for measuring the physical
parameters and table 3.4 shows the methods used in analysis.
Table 3.3 Instruments Used for Measuring
Parameter
Temperature
Dissolved Oxygen
pH
Conductivity
Turbidity
Instrument Used
DO meter (YSI model 550 A)
DO meter (YSI model 550 A)
pH meter (Mettler Toledo AG SG2)
Conductivity meter (DKK TOA CM-21P)
Turbidimeter (HACH 2100P)
19
Table 3.4 Analytical Methods for the Study
Parameter
Unit
Method
Equipment
Freq.
Ref.
BOD5
mg/L
Titration
Once a week
COD
mg/L
Azide
Modification
Closed reflux
Titration
Twice a week
TKN
mg/L
mg/L
Semi-micro
Kjeldahl
Filter/Oven
Once a week
Total Solids
TSS
mg/L
T.
Coliforms
E. Coli
MPN/100ml
Semi-micro
Kjeldahl
Dry at 103105oC
Dry at 103 105oC
MPN
MPN/100ml
MPN
APHA et al,
2005
APHA et al,
2005
APHA et al,
2005
APHA et al,
2005
APHA et al,
2005
APHA et al,
2005
APHA et al,
2005
DO
mg/L
Filter/Oven/
Water bath
Every 2 weeks
Temperature
Turbidity
mg/L
O
Twice a week
Every 2 weeks
pH
Conductivity
Twice a week
C
NTU
Do meter
Daily
pH meter
Daily
EC meter
Daily
Thermometer
Daily
Turbidimeter
Daily
3.8 Pond Water/ Sewage Mixture Tests
After acclimatization, the DHS set up was moved to the AIT EEM Research Station for the
polluted water study. The water for the study was obtained from an existing pond. The
water was pumped into a tank and the mixed with septage.
Tests were carried out to see which mixture of the pond water to sewage could replicate a
typical polluted canal (COD 140 mg/L ± 20 and BOD5 of 50 mg/L ± 10).
Table 3.5 Characteristics of Pond Water and Septage
Parameter
COD
BOD5
TS
TSS
TDS
pH
Turbidity
VSS
TKN
Unit
mg/L
mg/L
mg/L
mg/L
mg/L
Pond Water
50
18
191
51
140
6.8
11
-
NTU
mg/L
mg/L
20
Septage
11,300
3,390
9,986
7
7,570
481
3.9 Experimental Setup with Pond Water/Septage Mixture
For the study, the experiment was setup at the AIT EEM research station, under an existing
shed. The setup was as in figure 3.4.
Figure 3.3 Pond water/septage setup
The pond water was pumped into a 1000 liter tank and then mixed with septage according
to the calculated mixing ratio. This mixture was then distributed to the two tank: DHS
influent tank, and WFM treatment tank using submersible pumps placed inside the mixing
tank. The septage addition to the tank was done manually using a 10 liter bucket as the
quantities were manageable.
Water level in both the DHS tank and WFM tank was kept at a constant level using a level
sensor. Every time the water dropped to a certain level, the pump was automatically
switched on and the tank was refilled and this ensured that there was water in the tank at all
times.
3.10
Down-flow Hanging
anging Sponge System Set Up
The DHS reactor was set up in a slightly different way to the set up for acclimatization for
the acclimatization stage
age as described in section 3.4, the main difference being the method
of water feeding to the reactor. The reactor was supported by a wooden plank which rested
on an existing tank which is not in use.
use. The feed tank was above the reactor and so water
flow into the reactor by gravity.
Table 3.6 Calculation of Organic Loading Rate (OLR)
COD
(mg/L)
120
COD
(kg/m3)
0.12
Flow
(m3/d)
0.41
COD Load
(kg COD/d)
0.049
21
Reactor Vol. OLR
(m3)
(kg COD/m3.d)
0.035
1.4
All the parameters, apart from flow, for the system setup can be assumed constant.
Therefore, to run the reactor at various OLR the flow into the reactor has to be varied and
the following is the determination of the OLR and the corresponding flow.
Table 3.7 Determination of Flow from Various OLR
COD
(mg/L)
140
140
140
140
140
140
140
3.11
COD
(kg/m3)
0.14
0.14
0.14
0.14
0.14
0.14
0.14
OLR
(kg COD/m3.d)
1
1.6
2.6
3.6
4.6
5.6
6.6
Vol. of Reactor
(m3)
0.035
0.035
0.035
0.035
0.035
0.035
0.035
Flow (Q)
(m3/d)
0.25
0.40
0.66
0.91
1.16
1.41
1.66
Flow (Q)
(L/d)
252
403
656
908
1160
1412
1664
Woven Fiber Microfiltration System Set Up
The WFM was immersed in put in a 300 liter tank, which contained the water to be treated,
and a peristaltic pump was used for suction, as shown in Figure 3.5. Just like for the DHS
reactor, a level sensor was used to control the level of the water in the tank.
The membranes run for a period of ten (10) days before they could foul and hence be
removed for cleaning. There were two sets of the module and while one was running, the
other one was drying for cleaning.
22
Figure 3.4 WFM system setup
3.12
Woven Fiber Membrane Properties
The membranes that were used had specifications as shown in table 3.8
Table 3.8 Flat Sheet Membrane Specification
Item
Unit
Property
Membrane type
-
Filter
-
Material
-
Dead-end mode, outside-in, flat sheet
2 sheets (fixed) + 1 steel screen (between the
sheets)
Woven Fiber
Pore size
µm
1-3
cm x cm
37.0 x 25.5
Size: L x W
Total membrane area
Pure Water Flux
m
2
0.9435
2
LMH (L/m .h)
12 (at 12 kPa)
23
A pure water flux test was done on the membrane on the day before mounting the module
into the treatment tank.
3.13
Woven Fiber Membrane Cleaning
Cleaning of the fouled WFM module was done by solar drying. The fouled membrane was
taken out of the treatment tank and put in the sun to dry. It took less than six hours for the
sludge on the module to start peeling off. Pictures of the drying process are shown in
Appendix C.
3.14 Analytical Methods
Analytical methods to evaluate the removal efficiencies were done in the same way as for
the synthetic wastewater, according to the standard method described in APHA et al
(2005), as shown in table 3.4
3.15 Operation and Maintenance Guideline
A simple guideline for operation was written. This guide line is simple enough to be
followed and understood by people with low literacy levels and is aimed at rural
population. The guideline is included in Appendix C.
Power consumption of the two systems was compared to see which one is more
sustainable. This was a simple power consumption calculation based on the amount of
electricity used by the pumps, amount of time spent in setting up reactor and amount of
time dedicated to operation of the system.
24
Chapter 4
Results and Discussion
4.1 Introduction
In this chapter, the results for the study on the laboratory scale DHS reactor and WFM
systems are presented. The results comprise of the study from the acclimatization stage on
the DHS system, and the run with pond water/septage mixture. The acclimatization stage
was run over a period sixty days, using synthetic wastewater as a feed to the DHS reactor.
The acclimatization stage was mainly to acclimatize the DHS reactor and also to study the
performance of the reactor when run under controlled stable conditions. Only the DHS
system was studied in this phase. For both setups, the following parameters were analysed:
pH, DO, temperature, turbidity, TDS, TS, TSS, COD BOD5 and TKN. The study with
pond water/septage mixture was done with three runs of differing OLR of 1, 2 and 3
kgCOD/m3.d. Besides these parameters, for the WFM, flux and TMP were also analysed.
4.2 Downflow Hanging Sponge System Acclimatization Run
This phase was mainly to let the microorganisms in the DHS reactor adjust to the
environment and also see the performance of the reactor under more controlled conditions.
4.3 Operating Conditions During Acclimatization Run
The following were the operating conditions for the system, during the acclimatization run:
4.3.1 Temperature
32
Temperature (oC)
31
30
29
28
Influent T
27
effluent T
26
25
0
20
40
60
Time (days)
Figure 4.1 Synthetic wastewater temperature range
Figure 4.1 shows the influent and effluent temperature for the DHS system during the run.
Temperature for the run ranged from 26 to 32 oC and. This is the normal temperature
variation for Thailand and most wastewater treatment systems in the country are to the
same temperature range.
25
4.3.2 Turbidity
It was very difficult to keep the turbidity to a steady value. The influent turbidity fluctuated
between 10 and 64 NTU. For most of the treatment period, the system removed a steady
amount of turbidity regardless of the fluctuations.
.
4.3.3 pH
The pH fluctuated between 5.5 and 8. The lower limit for pH in most studies has been 6.5
and so, this wastewater sometimes fell below the limit. However the average pH was 6.5.
4.3.4 Dissolved oxygen
DO (mg/L)
The DHS system is an aerobic system and therefore needs a good supply of oxygen. The
oxygen for the system is naturally supplied through the holes in the segments on the
module and there is no mechanical means of air supply through a compressor. Figure 4.2
shows the influent and effluent oxygen for the DHS system.
8
7
6
5
4
3
2
1
0
Influent DO
Effluent DO
0
20
40
Time (days)
60
Figure 4.2 Synthetic wastewater DO range
The system shows an average DO oxygen uptake of 4 mg/L which his sufficient for
microorganism activities in the reactor.
4.4 Summary of the Operational Conditions for the Acclimatization Run
Table 4.1 Acclimatization Run Operational Conditions Summary
Parameter
Temperature
pH
Turbidity
Dissolved oxygen
Hydraulic retention time
Flow rate
Organic loading rate
Unit
C
NTU
mg/L
h
m3/d
kgCOd/m3.d
Operational Condition
28 ± 4
6.4 ± 1.0
40 ± 20
5 ± 1.0
2.0 ± 0.5
0.200 ± 0.020
2.6 ± 0.3
o
26
4.5 DHS System Performance During the Acclimatization Run
With the operating conditions discussed above, the following was the performance of the
system in the acclimatization phase with synthetic wastewater.
500
100
400
80
300
60
200
40
100
20
0
0
0
20
Time (days)
40
Removal Efficiency (%)
COD (mg/L)
4.5.1 COD removal
60
Effluent COD
Influent COD
Organics Removal
Rate
Figure 4.3 Synthetic wastewater DHS COD removal
The system COD removal was as shown in Figure 4.3. The average COD removal
efficiency was 86 ± 10 %. This efficiency is comparable to the removal rate obtained by
Racho in the treatment of tapioca starch wastewater, which was 89 ± 6 % (Racho 2009).
From the results, the reactor had stabilized to fully efficient by day 15 of the run and by
this time, it could be regarded as acclimatized. Further COD tests were done to determine
the soluble COD and it the results were as follows:
Influent soluble COD
Effluent soluble COD
Removal efficient
330 mg/L
37 mg/L
89 %
Soluble COD indicate biological activity in the wastewater treatment and this high
percentage shows that the system is fully acclimatized and the microorganisms are fully
active.
4.5.2 Total solids (TS), total suspended solids (TSS) and total dissolved solids (TDS)
As a filter, the DHS rector showed a good performance in the removal of total suspended
solids (TSS). However, the total solids (TS) remained high in the effluent because the
reactor is not designed to remove total dissolved solids (TDS). Figure 4.4 shows the
removal of TS, TSS and TDS.
27
250
(mg/L)
200
150
Influent
100
Effluent
50
0
TDS
TSS
TS
Figure 4.4 Synthetic wastewater TS, TSS & TDS removal
TDS calculated from the daily electrical conductivity reading gave a slightly different
value from the measured one. The value is lower by a 100 mg/L. The TDS for both
influent and effluent, ranged from 130 to 160 mg/L. A factor of 6.4 was used to convert
electrical conductivity to TDS. This might be the main cause of such a difference.
However, the most importance fact to note is that the DHS system is not designed to
remove TDS. The TDS measured during the acclimatization run values are given in
Appendix E, Table E.1.
4.5.3 BOD5 removal
Influent BOD
Effluent BOD
Removal Efficiency
100
BOD (mg/L)
120
80
100
80
60
60
40
40
20
20
0
Removal Efficiency (%)
140
0
0
10
20
30
Time (Days)
40
50
Figure 4.5 Synthetic wastewater BOD5 removal
BOD5 removal for the system is pressented in Figure 4.5. The BOD5 for the system
removal averaged 71%, and this is considered reasonably good for the treatment of tapioca
starch synthetic wastewater.
28
4.5.4 TKN removal
The system removed considerable amount of TKN with synthetic wastewater and the
average removal was as follows:
Influent TKN
Effluent TKN
Removal efficiency
42 mg/L
3 mg/L
93%
4.6 Pond Water/ Septage Run System Performance
After being satisfied with the acclimatization of the reactor, the system was moved to the
research station where a comparative study with woven fiber microfiltration membrane
(WFM) system was carried out. The DHS system was fed with the same wastewater as the
WFM system and a mixture of pond water and septage was used.
The DHS study was done in three runs of differing OLR for over a period of 100 days. The
operational runs were as follows:
First run
Second run
Third run
12 December 2013 to 8th January 2014
9th January to 17th February 2014
18th February to 31st March 2014
The organic loading rates for the runs were 1, 2 and 3 kgCOD/m3.d respectively.
4.7 Operating Conditions for the Pond Water/ Septage Run
The following were the operating conditions for the study at the research station:
4.7.1 Temperature
The coldest temperature was in January (around 20 oC) and the hottest temperature was in
March (32 oC). Even though the average temperature was higher than the one used in the
synthetic wastewater run, the temperatures are within the range used for the other DHS
studies (Machdar et al., 1997, Mahmoud et al., 2011)
4.7.2 Turbidity
For the first run, turbidity was kept under check and there was not much variation. But for
the second and third run, turbidity varied much. This was mainly due to the much
concentrated pond water/septage mixture. The influent turbidity for the DHS system
ranged from 6 to 610 NTU and for the WFM, it ranged from 4 to 520 NTU. Both systems
seemed to coped well with the high turbidities produced effluent with low turbidity.
4.7.3 pH
The study was operated under a pH range of between 6.5 and 8. This range is the same as
for the synthetic wastewater acclimatization run and also is the recommended range for
biological wastewater treatment systems, as microorganism do well in the pH range of 6.5
to 8.5
29
4.7.4 Dissolved oxygen
The DHS system, which is aerobic, needs oxygen for the wastewater treatment. This
oxygen is supplied naturally through the holes on the DHS module. During the colder
month of January, the levels of oxygen in the DHS intake reached as high as 7 mg/L and
dropped to around 5.5 mg/L during the hottest month of March. The WFM system main
mode of removal is filtration and so DO is not very important for this system. This amount
of DO was more than enough for all the biological processes in the DHS reactor.
4.7.5 DHS dissolved oxygen profile
0
2
DO (mg/L)
4
Influent
6
8
0.2 mg/L
Distance from the top of the reactor
(m)
0.0
1
5.5 mg/L
0.5
2
1.0
5.2 mg/L
3
1.5
4.6 mg/L
4
2.0
6 mg/L
Effluent
Figure 4.6 DHS DO profile for water/septage mixture
.
Figure 4.6 shows the dissolved oxygen profile across the DHS reactor. Almost all the
needed oxygen is supplied from the first segment, as the DO increases from 0.2 mg/L in
the influent to 5.5 mg/L as the water enters the second segment. Segment number three
seems to use more oxygen than the rest of the segments. This oxygen might be utilized in
the nitrification and denitrification. Mahmoud et al., 2009 found that there was a gradual
increase in dissolved oxygen, with the first segment having the least value and the last
segment having the highest value. This difference comes because of the differences in the
oxygen uptake windows on the reactor module. For Mahmoud study, the windows were
small as compared to this study. The sections between the two segments of the reactor
were aligned with holes for the entire length 0.1m, as shown in the picture in Figure 4.7.
Also the top plate of the module has got a lot of hole that let the reactor take up oxygen.
This design has greatly improved the oxygen uptake.
30
Figure 4.7
4. Oxygen uptake segment with holes
4.8 Summary of the Operational Conditions for the Pond Water/Septage Run
Table 4.2 Pond Water/Septage Run Operational Conditions Summary
Parameter
Temperature
pH
Turbidity
Dissolved oxygen
Hydraulic retention time
Flow rate
Organic loading rate
Unit
o
C
NTU
mg/L
h
m3/d
kgCOD/m3.d
Operational Condition
27 ± 6
7.5 ± 1
50 - 600
6.0 ± 1.5
2 ± 0.5
0.250 ± 0.03
1-3
4.9 WFM System Runs
There were two identical WFM modules (designated module 1 and module 2) that were
used alternatively for the study. Cleaning of the fouled module was done by drying in the
sun, and no chemical was used (pictures
(
in Appendix C, Figure C.5).
). The alternate running
of the modules allowed the study to run concurrently with the DHS reactor without a
break.
4.9.1 Woven fiber pure water flux
f
A pure water flux test was done on each module at the very beginning of the study. The
pure water flux is a measure of how much pure water (water that contains no foulants)
passes through a membrane.
31
80
Flux (L/m2.h)
70
y = 6.5442x + 10.973
R² = 0.9394
60
y = 6.4461x + 7.3107
R² = 0.9504
50
40
30
Module No 1
Module No 2
20
10
0
0
2
4
6
TMP (kPa)
8
10
12
Figure 4.8 Pure water flux for both WFM modules
Figure 4.8 shows the results of pure water flux test for both WFM modules. The test
showed that both membranes were performing normally, giving increased flux with
increased TMP and were both capable of giving a flux of 60 L/m2.h at a TMP of 8 kPa.
The flux, with polluted water, at the same trans-membrane pressures, is expected to be
lower.
4.9.2 WFM system performance
TPM
9
8
7
6
5
4
3
2
1
0
60
50
40
30
20
TPM (kPa)
Flux (L/m2.h)
Flux
10
0
200
400
600
Time (hrs)
800
0
1000
Figure 4.9 WFM flux and TMP
Figure 4.9 shows the performance of the WFM module. For the first few hours after
starting the treatment, the WFM produced a flux of up to 8 L/m2.h. The flux then dropped
as the membrane became more and more fouled and settled to a steady value of around 1.5
L/m2.h. Trans-membrane pressure, on the other hand, increased with increased fouling.
The module attained a TMP of 50 kPa, before being cleaned. The actual values of flux and
TMP measurements are presented in Appendix E, Table E.10.
32
4.10 Removal Efficiency for the System
4.10.1 COD removal
Figure 4.10 shows COD removal and Figure 4.11 shows the COD removal efficiency for
both systems. COD removal for the first run showed that the DHS meets the reuse standard
while the WFM is slightly above the reuse standard. For the second run both the WFM
and DHS effluents are above the reuse standard. For COD concentration of above 200
mg/L, the effluent for the DHS system is slightly above reuse standards but for COD
concentration of 160 mg/L or below, the effluent meets e reuse standards.
DHS Influent COD
WFM Effluent COD
DHS Effluent COD
Reuse standard
1st Run
2nd Run
WFM Influent COD
3rd Run
300
200
100
0
0
20
40
60
Time (days)
80
100
Figure 4.10 COD removal
WFM COD Removal efficiency
1st Run
100
Removal efficiency (%)
COD (mg/L)
400
2nd Run
3rd Run
80
60
40
20
0
0
20
40
60
Time (days)
Figure 4.11 COD removal efficiency
33
80
100
The removal efficiency in the pond water/septage mixture run is almost the same as for the
acclimatization stage. The detailed COD removal are presented in Appendix E, Table E.5.
4.10.2 COD removal profile
Distance from the top of the
reactor (m)
0
COD (mg/L)
200
400
Influent
600
0.0
394 mg/L
1
0.5
337 mg/L
2
1.0
183 mg/L
1.5
3
158 mg/L
2.0
4
25 mg/L
Effluent
Figure 4.12 COD profile across the DHS reactor
The reactor removes considerable amount of COD in the third and fourth segments of the
module, as shown in Figure 4.12. This is mainly due to filtration, as the water gets more
and more filtered as it goes down the module. This result is comparable to the results found
by Mahmoud et al (2009).
Filtered COD was measured on two days, day 46 and day 58. On day 46, the unfiltered
COD removal efficiency was 92 % and on day 54 the unfiltered COD removal efficiency
had dropped to 29%. The filtered COD removal efficiency was 67% on day 46 and only
11% on day 54. This shows that when the reactor’s performance is good, it removed a lot
of filtered COD. Filtered COD is removed through biological means. On both days the
filtered COD removal for the WFM is very low which shows that there is not much
biological activity on the membrane.
34
4.10.3 BOD5 removal
BOD (mg/L)
1st Run
2nd Run
3rd Run
90
80
70
60
50
40
30
20
10
0
DHS Influent BOD
DHS Effluent BOD
WFM Influent BOD
WFM Effluent BOD
Reuse Standard
0
20
40
60
80
Time (days)
100
120
Figure 4.13 BOD5 removal
BOD5 Removal for the system was as shown in figure 4.13. The average effluent BOD5 for
the entire study was 10 mg/L against an average influent BOD5 of 60 mg/L. The DHS
effluent for all the three runs met reuse standards. As for the WFM, only the first run met
reuse standards but for the second and third runs did not meet reuse standards. The detailed
BOD5 removal is presented in Appendix E, Table E.6.
4.10.4 TKN removal
TKN removal (mg/L)
DHS Infl.
DHS Effl
1st Run
50
WFM Infl.
WFM Effl
2nd Run
3rd Run
60
80
Time (days)
100
40
30
20
10
0
0
20
40
120
Figure 4.14 TKN removal
TKN removal, for both the systems, is shown in Figure 4.14. Although the influent TKN is
already below the reuse standards, the DHS TKN removal efficiency shows that the system
is capable of good TKN removal with average removal rate of 85 %. The WFM TKN
average removal efficiency, on the other hand is only 40%. Table E.7 in Appendix E gives
the actual TKN removals for both systems.
35
4.10.5 TKN profile across the DHS reactor
Distance from the top of the
reactor (m)
0
10
TKN (mg/L)
20
Influent
30
37.7 mg/L
40
0.0
1
15.4 mg/L
0.5
2
1.0
9.2 mg/L
3
1.5
4.8 mg/L
2.0
4
5.3 mg/L
Effluent
Figure 4.15 DHS TKN profile for water/septage mixture
Figure 4.15 shows the TKN profile across the DHS reactor. According to Agrawal et al.
(1997), nitrification occurs in the second and third segments of the reactor. This was also
collaborated by Machdar et al., (2000) and Mahmoud et al., (2009). However, for the study
on the ten segment DHS reactor module by Kubota et al (2014), on day number 301 and
day number 401, the rector removed nitrogen mainly from box number 2 downwards. This
means right after the second segment, nitrification occurred. Since box number 2 was 0.5
meters from the top this means nitrification started after the water had moved just one
eighth (1/8) of the reactor. This distance in our two meter high reactor falls within the first
segment of the reactor. Therefore, the TKN profile is similar to the nitrogen profile found
presented by Kubota et al., 2014 The abundance of oxygen in the first segment also
contributes to the TKN removal in the first segment.
4.10.6 Total solids (TS), total suspended solids (TSS) and total dissolved solids (TDS)
400
300
TS
200
TSS
100
TDS
0
Influent
Effluent
Influent
DHS
Effluent
WFM
Figure 4.16 TS, TSS, TDS removal
Figure 4.16 shows TS, TSS and TDS removal. The TDS increased from the first run the
third run. This is due to the increase in concentration of the mixture. Both systems clearly
show that they are not good at removing TDS. However, water with a TDS value of below
36
1000 mg/L is classified as excellent for irrigation. Since the DHS is not designed to
remove TDS, the system should not be used for the treatment of waters with a TDS of
greater than 1000 mg/L, especially when the effluent is intended for agricultural reuse.
Log Removal
4.10.7 Total coliforms
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
DHS
WFM
Run 1
Run 2
Run 3
Figure 4.17 System Coliform Removal for water/septage mixture
Total Coliform removal by the system was not particularly good as shown in Figure 4.17.
In the recent study by Onodera et al (2014), the DHS reactor was reported to have a 2.5 log
removal of total coliform, which represents an efficiency of 99.69%. However, the
percentages are higher than those found by Ehsas (2013) on the same reactor module that
is in use, using synthetic wastewater. Ehsas run the reactor for only 45 days as compared to
over 100 days for this study. It should be noted that in the study by Onodera, the value for
the coliform removal were obtained in the second operational year of running the reactor
(i.e. after day 366). This reactor would definitely perform in the same way or better if run
for more than. 365 days. Table E.8 in Appendix E shows the actual numbers for the total
coliform removal for the system
4.11 Summary of the DHS & WFM Run Efficiency
Table 4.3 Summary of the DHS & WFM Run Efficiency
Parameter 1st Run
RS
Met
2nd
Run
RS
Met
3rd
Run
RS
Met
WFM
COD
77%
Yes
76%
No
86%
No
70%
RS
Met
No
BOD
84%
Yes
84%
Yes
89%
Yes
70%
No
TKN
80%
Yes
72%
Yes
90%
Yes
40%
No
TS
95%
Yes
90%
Yes
80%
No
90%
Yes
TC
1.4 Log
No
1.2 Log
No
1.3 Log
No
0.5 Log
No
RS = Reuse Standards
37
Aver.
4.12 DHS Performance Compared to other Studies
Table 4.4 DHS Reactor Performance Compared to Other Studies
DHS
Type
HRT
(h)
Temp
(oC)
pH
G1
1
13-30
G2
2
G3
OLR
(kgCOD/m3.d
1.9
Removal Rates (%)
BOD5 TKN T/Coli.
SS
COD
6.8
100
75
-
-
-
25
6-8
36
60
92
57
-
11-21
-
74
75
-
77
-
G4
2
20-25
-
74
76
88
30
99.41
G5
2.5
9-32
-
56
63
88
72
99.93
G6
2
2
9-27
6-7
61
72
87
86
99.69
This
Study
1
2
22-34
7-8
56
85
85
85
95.76
Ref.
Agrawal
et al.,
(1997)
Machdar
(2000)
Tawfik et
al. (2006)
Tandukar
et al.,
(2005)
Tandukar
et al.,
(2007)
Onodera
et al.,
(2014)
This
Study
The performance of the DHS reactor in comparison to other studies done as shown in table
4.3.
38
Chapter 5
Conclusions and Recommendations
This research focused on the ability of the down-flow hanging sponge (DHS) reactor in
treating dilute polluted wastewater. The DHS reactor was operated in three concurrent
operational runs, with differing organic loading rates (OLRs) of 1, 2 and 3 kg COD/m3.d.
A woven microfiltration membrane system was set-up in parallel to the DHS reactor, for
performance comparison. The two systems were fed with the same wastewater. The
wastewater characteristics resembled those of a typically polluted canal.
Specific conclusions achieved from this research are presented in the following part with
recommendations for further studies in this research area.
5.1 Conclusions
The DHS reactor had the ability of treating dilute wastewater to the point of giving effluent
that meets reuse standards for most Asian and African countries.

When feeding the reactor with wastewater, the OLR for the DHS reactor should not
exceed 1.5 kg COD/m3.d. Operating the reactor at this OLR ensures that the flow
rate of the water is not too high to cause a washout of the micro-organisms from the
reactor.

The optimum physical operating parameter ranges are as follows: temperature 25 ±
5 oC, pH 6.5 ± 1, turbidity of less than 200 NTU, dissolved oxygen (DO) 6 ± 1
mg/L. The design of the DHS reactor allows the system to take up enough DO for
the treatment. The effluent water temperature never increased during the process
and this was within the surface water discharge standards.

The COD removal efficiency for all the three runs of OLR 1, 2 and 3 kg COD/m3.d
were 77%, 76% and 86% respectively. The effluent COD for run 1 met the reuse
standard but for run 2 and 3 were higher than the reuse standard. The OLR of 2 and
3 kg COD/m3.d were obtained by increasing the influent COD concentration, and
hence the higher effluent COD despite the high removal efficiency.

All the effluent BOD5 at the OLR of 1, 2 and 3 kg COD/m3.d met the reuse
standard and the removal efficiencies were 84%, 84% and 89% respectively. For
the dilute wastewater, the BOD5 were all below 100 mg/L and so the treated
effluent easily met the reuse standards.

The effluent TKN values for all the three runs met the reuse standards. The removal
efficiencies at 1, 2 and 3 kg COD/m3/L OLR were 80%, 72% and 90% respectively
and the residual TKN was not a threat to cause eutrophication if the water
overspills to the water bodies.

For all the three operational runs, the DHS removed enough TSS and the effluent
meets the reuse standards. The removal efficiency for all the runs at an OLR of 1, 2
and 3 kg COD/m3/L were 95%, 90% and 80% respectively. The DHS reactor,
39
however, is not designed to remove TDS and therefore should not be used for water
with a very high TDS.

Total Coliform removal for all the three runs averages 1.2 log removal. This
removal is fairly high enough but the effluent does not meet the reuse standards at
all the three OLR.
In comparing the performance of the DHS to the WFM systems, the DHS reactor
performed better than the WFM. The operating conditions were the same as those of the
DHS reactor. The WFM runs lasted for 10 days each and the membrane module was
removed for cleaning by drying in the sun. The flux of the WFM for all the runs averaged
1.5 L/m2.h, which was no high enough for economical reuse.

The COD removal efficiency for all the WFM runs averaged 70 %, which is lower
than for all the three DHS runs and the effluent COD was above reuse standard.
The WFM treatment is only by filtration and therefore the system does not remove
any soluble COD. The average filtered COD removal efficiency for the DHS
reactor for all the three runs was 60% while for the WFM removed 30%.

The WFM effluent BOD5 for all the runs did not meet the reuse standard and the
average removal efficiency was 70%. The DHS removal was better than the WFM
for all the three runs.

The average TKN removal efficiency for the WFM runs was 40%, which is lower
than the DHS TKN removal efficiency. This clearly shows that the DHS system
performance was superior to the WFM in the removal of TKN.

The WFM performed better than the DHS system in the removal of TSS, with an
average removal efficiency of 90% as opposed to 70% for the DHS system.
However, for the WFM system, when the influent TSS is increased, the flux
reduces while for the DHS reactor, the increase in influent TS does not affect the
quantity of the effluent. For both the systems, the effluent TSS meets the reuse
standard.

The total coliform removal for the WFM system was lower than that of the DHS
system, with an average log removal of only 0.5. The effluent total coliform for the
WFM system does not meet reuse standards.
The operation of both the DHS and WFM systems is simple enough for the rural people to
follow.
5.2 Recommendations for Future Study
Based on the results obtained, the following recommendations are suggested for future
study in this field:

Sustainability of the DHS system in rural area where electricity is not readily
available should be studied. The possibility of using solar power for pumping of
water should be studied further. The study should also include minimum energy
needs of the DHS reactor.
40

There is a possibility of using gravity as a suction pressure for the WFM and this
should be studied further. Using gravity suction pressure, coupled with the solar
cleaning of the membrane would further reduce treatment power needs, and make
the system more attractive for use by less privileged communities.

This study was conducted over a period of just over 100 days. A study with longer
period should be undertaken, using real canal water. The longer period study will
help to reveal how the DHS reactor behaves in all seasonal weather changes for the
entire year.
41
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45
Appendix A
Pictures of Experiment Location
Figure A.1
A DHS system set-up
up for acclimatization
Figure A.2 Pond Water and septage (where the water for the study is taken)
46
Appendix B
OLR Calculations for Synthetic Wastewater
The following are the exact proportions of the synthetic wastewater mixture
Tapioca starch,
Ammonium Bicarbonate
Potassium Phosphate
Frequency of feeding:
(NH4HCO3)
(KH2PO4)
25 g
1.25 g
0.25 g
Twice a day: at 07:30 hrs and 19:30 hrs
The reactor was run at an Organic Loading Rate (OLR) of 2.6 kg/m3.d. The inlet flow
was kept constant and the OLR was varied by the amount of tapioca starch that was fed to
the reactor per day.
Organic loading rate was calculated using equation 2.1:
Average COD
Volume of reactor
Flow
OLR
=
=
=
300 mg/L
0.353 m3
310 L/d
=
=
.
= 2.6 kg COD/m3.d
=
47
.
.
Appendix C
Appendix C – 1
Operation and Maintenance Manual
Down
Down-flow
Hanging Sponge System
48
Table of Contents
Required Apparatus ……………………………………………………
50
Operational Parameters………………………………………………..
52
DHS set-up at the canal………………………………………………..
52
DHS start up and operation……………………………………………
53
System monitoring and cleaning………………………………………. 54
Trouble shooting………………………………………………………... 55
49
1.
Required Apparatus
 DHS Reactor Module
DHS Module (Figure C.1)
 4 x segments randomly packed with
sponges.
Sponges:: 30 mm x 30 mm each
 150±20
20 sponges in each segment
= 0.353 m3
Volume
Figure C.1 DHS Reactor module dimensions
50
 Tanks
1 x Buffer tank
1 x DHS Feed tank
1 x Effluent storage tank
 Submersible pumps:
1 x from canal to buffer tank
1 x from buffer tank to DHS tank
 Mixing pumps
[Ty
1 x pump for buffer tank
1 x pump for DHS tank
[Ty
pe a
[T
51
2.
Operational Parameters
Table C.1 Operational Parameter for the DHS Reactor
Parameter
Temperature
pH
Turbidity
Hydraulic retention time
Flow rate
Organic loading rate
3.
Unit
o
C
NTU
h
m3/d
kg COD/m3.d
Minimum Value
20
6
1.5
0.200
1
DHS System Set-up Outline at a Canal
Figure C.2 System layout at canal
52
Maximum Value
35
8
200
2.5
0.300
3
Figure C.3 DHS Reactor setup at the canal
4.
DHS startup and operation
(A) Start-up
 Inoculation with seed sludge – done in separate tank
 Sock the sponges in water using a sixty liter bucket
 Add 5 liters of septage from a septic tank.
tank
 Insert air pipes,, from a compressor, into the mixture.
 Switch on the air compressor and let it run for at least 24 hours before turning of
off.
53
 Leave the mixture for another two days after switching off the compressor.
 After three days, carefully fill each segment of the DHS module with 150 sponges
sponges.
(B) Operation
 Assemble the DHS reactor, with inoculated sponges inside.
inside
 Carefully tighten the nuts, making sure there is no leakage from the module.
 Connect the influent pipe to the DHS reactor inlet pipe valve
 Turn on the inlet pipe valve.
 Adjust the flow rate to 200mL /minute (using a graduated cylinder)
 Connect the pipe to the DHS reactor
5.
System Monitoring and cleaning
 Check for pipe clogging as listed in Table E.3
54
 Observe water and its velocity into DHS Module.
 Clean sprinkler, pipes and overhead tanks every three weeks.
 Remove algae growth every time the growth appears. If the reactor module is made
of transparent material, cover the module with a black cloth. Use only opaque
pipes.
6.
Troubleshooting
Table C.2 Troubleshooting of the system
Problem
Probable Cause
Influent pipe or sprinkler
blockage
Possible Solution
Clean the pipe thoroughly. Clean the,
pipes, sprinkler and DHS tank is every
three weeks.
No effluent
DHS Module clogging
and flooding. Too high
OLR
Turbid effluent
Too high inflow velocity
causing through-flow
Water flowing
Reactor not well
along the reactor
vertically aligned
wall
Algae growth
Micro fauna
invasion (flies,
snails)
Accumulation of
sludge in feed
tank
Close the inlet pipe valve to the reactor.
Open the effluent pipe and let tall the
water drain out. Reduce the flow of the
water into the reactor.
Reduce the flow velocity of water into
the reactor.
Realign the reactor vertically. Use a line
level for the alignment
System exposed to
sunlight
Cover all transparent parts with
preferably a black cloth. Use only
opaque pipes for the system
Flies attracted to the
sludge inside the reactor
Cover all holes on the DHS reactor with
a mesh, but don’t block aeration holes.
Solids settling at the
bottom of the DHS tank
Cleaning the tanks every three weeks and
replace the feed water.
55
Appendix C – 2
Operation and Maintenance Manual
Woven Fiber Microfiltration System
56
Table of Contents
Required Apparatus ……………………………………………………
58
Operational Parameters………………………………………………..
59
WFM set-up at the canal……………………………………………….. 59
Installation………………………………………………………………
60
WFM start up and operation…………………………………………… 61
System monitoring and cleaning………………………………………. 61
Trouble shooting………………………………………………………... 63
57
1. Required Apparatus
Woven fiber Microfiltration sheets & Frame
Flat sheet membrane
Hole in which
the steel rod
is inserted
Woven fiber flat sheet
Membrane
1 x support frame
Sheet size:
Length: 370 mm
Width: 225 mm
Tubes and fittings
Tanks
1 x treatment tank
1 x effluent storage tank
Pumps
1 x peristaltic pump (for suction)
1 x submersible pump
58
Pressure gauge
2. Operational Parameters
Table C.3 Operational Parameter for the WFM Reactor
Parameter
Temperature
pH
Turbidity
Unit
C
NTU
o
Minimum Value
20
6
-
Maximum Value
35
8
200
Table C.4 Membrane Specification
ITEM
UNIT
PROPERTY
Membrane type
-
Filter
-
Material
-
Dead-end mode, outside-in, flat sheet
2 sheets (fixed) + 1 steel screen (between the
sheets)
Woven Fiber
Pore size
µm
1-3
cm x cm
37 x 25.5
Size: L x W
Total
membrane
m2
0.9435 (Depend on number of sheets)
area
LMH (L/m2.h)
12 (at 12 kPa)
Pure Water Flux
3. WFM set-up at the canal
Figure C.4 WFM System layout at canal
59
4. WFM Installation
Connect filter ends of the membrane plate to the connecting tube.
 Connect the other end of the tube to the pipe leading to the suction pump
pump. Insert the
steel rod into the membrane plate holes on the corners of the sheet
Steel
rod
inserted
through the membrane
 Connect at least five membrane sheets to form one unit module
Flat sheet connected into one
module
 Complete the set up by inserting the flat sheet module into the treatment tank
60
Figure C.5 WFM Set up in treatment tank
5. WFM start up and operation
 Pump speed set to 2
 Turn on pump
 Check flow and pressure every six hours.
 Once flux drops, increase pump speed
6. System monitoring and cleaning
 Regularly check pressure reading
 Once pressure gauge reaches 60 kPa, turn off the pump
 Remove the dirty membrane and place in the sun
 After 24 hours, remove the dry sludge from the membrane
 Use a soft brush to remove the dry sludge.
61
a
b
c
e
d
( a, b ): Fouled module taken out of the treatment tank
( c ): Fouled module next to a clean module
( d ): Module drying in the sun and peeling off the sludge
( e ): Collected peeled off sludge
Figure C.6 WFM Module Cleaning by solar drying
62
7.
Trouble shooting
Table C.5 WFM System Troubleshooting
Problem
No Permeate but
pump running
No permeate but
pressure gauge
giving a high
reading
Algae growth
Probable Cause
Loose connection
causing pressure lose
Possible Solution
(ii)
Make sure all connectors are
secured tightly and there is no pressure
leakage
Membrane fouled
Remove membrane and clean
System exposed to
sunlight
Use opaque pipes.
Clean off the algae regularly
63
Appendix D
Surface Water Quality
Table D.1 Standards used for this research
Parameter
Unit
BOD
mg/L
COD
mg/L
TKN
mg/L
TS
mg/L
TSS
mg/L
TDS
mg/L
Total Coliform
MPN/100mL
Dissolved Oxygen
mg/L
O
Temperature
C
pH
* Discharge limits
** TDS + TSS = TDS
Standard
10
30*
< 5*
< 480**
< 30
< 450
< 1000
2
Not more than 3o Change
6-9
Reference
OEPP,1999
WHO, 2006
WHO, 2006
USEPA, (2012)
USEPA, (2012)
USEPA, (2012)
WHO, 2006
OEPP,1999
OEPP,1999
OEPP,1999
Table D.2 Typical Pollution of Surface Water
Malawi
BOD5
(mg/L)
35- 70
Egypt
30 - 170
Sri
40 - 100
Lanka
Thailand 35 -65
COD
(mg/L)
-
46
153
170300
TDS
pH
(mg/L)
586 - 6.8 – 7.5
244
1000 - 7.2 -7.6
1400
270
5.5 -8.9
64
DO
(mg/L)
Turbidity
(NTU)
0.4 – 5.8
2.0 – 3.7
0.5 – 3.3
1-2
285
Reference
Sajidu
et
(2007)
Shaban et
(2010)
Jinadasa et
(2012)
Ongsakul et
(2006)
al.,
al.,
al.,
al.,
Table D.3 Thailand Surface Water Quality
Classification
Objective/Condition and beneficial use
Class 1
Extra clean fresh surface water resources used for :
(1) Conservation not necessary pass through water treatment process
require only ordinary process for pathogenic destruction
(2) Ecosystem conservation where basic organisms can breed naturally
Class 2
Very clean fresh surface water resources used for :
(1) Consumption which requires ordinary water treatment process before
use.
(2) Aquatic organism of conservation.
(3) Fisheries.
(4) Recreation.
Class 3
Medium clean fresh surface water resources used for :
(1) Consumption, but passing through an ordinary treatment process
before using.
(2) Agriculture
Class 4
Fairly clean fresh surface water resources used for :
(1) Consumption, but requires special water treatment process before
using
(2) Industry
Class 5
The sources which are not classification in class 1-4 and used for
navigation
Table D.4 Thailand Surface Water Quality Parameters their Classification
Parameter
Temperature
pH
Dissolved Oxygen (DO)
BOD (5 days, 20°C)
Total Coliform Bacteria
NO3 -N
NH3 -N
Unit
o
C
mg/L
mg/L
MPN/100 mL
mg/L
mg/L
Class 1
N
N
N
N
N
N
N
N = Natural, Source: (NNEB, 1994)
65
Class 2
N
5-9
6
1.5
5,000
5
0.5
Classification
Class 3 Class 4
N
N
5-9
5-9
4
2
3
4
20,000
5
5
0.5
0.5
Class 5
-
Table D.5 USEPA Guidelines for Water Reuse
Type of Category & description
Impoundments
Unrestricted:
The use of reclaimed water in an impoundment in
which no limitations are imposed on body-contact
Restricted
The use of reclaimed water in an impoundment
body- where contact is restricted.
Environmental Reuse:
The use of reclaimed water to create
wetlands, enhance natural wetlands,
or sustain stream flows.
Agricultural
food crops:
The use of reclaimed water for surface or spray
irrigation of food crops which are intended for
human consumption, consumed raw
Processed Food Crops
The use of reclaimed water for surface irrigation
of food crops which are intended for human
consumption, commercially processed.
Treatment
Required
Secondary,
Filtration,
Disinfection
Reclaimed Water
Quality
pH = 6 to 9
BOD ≤ 10 mg/L
Turbidity ≤ 2 NTU
Secondary
Disinfection
BOD ≤ 30 mg/l
TSS ≤ 30 mg/l
FC ≤ 200 /100 mL
BOD ≤ 30 mg/L
TSS = 30mg/L
FC ≤ 200/100mL
Variable
Secondary,
Disinfection
Secondary,
Filtration,
Disinfection
Secondary
Disinfection
Non-Food Crops:
The use of reclaimed water for irrigation of crops
which are not consumed by humans, including
fodder, fiber, and seed crops, or to irrigate pasture
land, commercial nurseries, and sod farms
Source: USEPA (2012) Design Manual: Guidelines for Water Reuse
66
pH = 6 to 9
BOD ≤ 10 mg/L
FC ≤ 0/100mL
Turbidity ≤ 2 NTU
pH = 6 - 9
BOD ≤ 30 mg/l
BOD (7)
TSS ≤ 30 mg/l
TSS
FC ≤ 200 /100 mL
Appendix E
Experimental Results
Table E.1 pH, DO, Turbidity, Temperature and TDS during DHS Acclimatization
Run
Day
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
Infl.
pH
Effl.
pH
6.69
7.34
7.06
7.22
6.21
5.76
5.82
5.54
6.55
6.28
6.28
5.95
6.91
6.39
6.25
-
6.52
7.50
7.34
7.90
6.89
6.45
6.56
6.56
6.39
6.61
6.52
7
6.91
6.67
6.79
-
6.51
6.09
6.63
7.07
6.53
6.32
5.90
6.67
6.96
6.60
6.49
6.40
6.90
6.73
6.79
6.48
7.09
7.11
6.93
6.85
6.29
5.78
7.88
7.23
7.10
7.03
7.11
7.06
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
6.49
5.89
2.97
2.81
0.78
0.29
0.18
0.19
0.19
0.31
2.07
0.35
1.58
1.01
0.98
0.28
0.29
0.27
0.31
0.44
0.21
0.44
1.28
2.34
0.23
0.25
0.65
0.25
0.26
0.28
0.21
0.30
0.38
0.23
0.23
5.87
5.27
5.65
7.20
4.42
3.12
2.84
3.08
3.08
2.36
3.57
2.59
2.94
2.93
3.24
3.08
2.52
1.91
2.36
2.98
2.89
3.08
3.70
3.71
3.56
3.88
3.03
3.47
3.56
2.81
2.72
1.95
3.01
1.57
2.43
150
153
148
146
150
147
146
137
130
144
137
139
137
135
139
144
146
143
143
148
151
140
145
145
146
144
148
147
149
149
151
158
156
152
150
153
147
146
150
147
145
134
130
143
135
140
140
135
141
146
146
150
145
150
152
144
147
147
152
144
147
147
147
152
152
157
155
152
22.53
6.80
53.17
7.33
7.35
20.43
63.67
53.33
9.35
33.67
58.93
36.07
13.70
27.77
40.23
34.17
26.57
39.83
29.87
31.30
16.40
28.57
24.10
28.23
67
8.97
7.80
16.87
10.88
9.00
7.90
14.17
8.16
7.72
9.03
34.83
22.20
5.03
10.28
14.50
14.13
10.13
16.87
19.53
14.13
16.20
14.23
17.00
15.50
26.7
27.3
28.0
27.4
28.0
26.7
27.2
27.3
27.8
28.3
27.5
29.0
28.3
26.7
28.1
28.7
27.5
27.8
27.4
27.4
28.9
30.3
29.4
29.4
30.0
27.8
27.0
27.3
27.5
27.4
28.0
28.4
28.0
28.7
27.8
27.8
(oC)
27.6
28.1
29.1
29.1
28.9
27.1
28.0
28.4
29.0
29.4
26.8
29.6
27.9
26.2
29.0
29.5
28.2
27.5
27.2
27.2
30.0
31.5
30.6
30.6
30.4
27.6
27.0
28.2
28.1
28.1
28.8
29.3
28.8
29.4
28.4
28.9
Day
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
56
61
Infl.
pH
Effl.
pH
6.51
6.47
6.34
6.32
6.33
6.78
6.19
6.82
6.81
6.44
6.28
6.18
6.56
6.56
6.57
6.21
6.38
Note: Infl.
Effl.
TU
6.88
6.64
6.76
6.54
6.58
6.89
6.48
6.59
6.43
6.59
6.59
6.28
6.44
6.68
6.53
6.53
6.87
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
0.31
0.25
0.12
0.26
0.38
6.27
2.42
0.40
2.68
2.78
0.41
0.28
0.34
0.26
0.30
0.28
0.33
0.29
2.10
2.31
2.18
1.14
3.22
5.44
5.22
4.63
5.14
3.60
2.66
4.13
2.48
2.75
2.65
3.07
3.19
3.87
149
148
150
152
148
153
153
152
153
159
150
150
152
155
148
147
147
155
151
155
19.23
28.23
18.03
21.37
25.50
32.80
19.33
32.50
22.47
18.13
31.00
24.07
17.50
29.40
33.97
47.87
41.30
34.17
8.90
15.57
7.81
10.60
11.14
3.25
7.31
22.67
10.53
10.49
14.37
12.77
13.57
16.70
20.53
28.13
20.63
15.80
(oC)
28.4
29.0
29.1
29.1
29.3
28.8
28.5
30.1
29.1
29.7
28.8
28.2
28.5
28.6
29.1
28.6
29.3
29.5
26.4
29.6
29.9
29.5
29.6
31.0
29.9
29.2
28.6
29.2
28.5
29.1
28.6
29.0
= Influent
= Effluent
= Turbidity
Table E.2 DHS COD and BOD5 Removal during Acclimatization Run
Day
3
5
9
13
16
29
30
34
38
42
51
Infl.
COD
(mg/L)
46
117
277
310
316
410
203
311
Effl. COD
(mg/L)
150
292
24
34
8
21
7
36
Removal
(%)
Infl. BOD5
(mg/L)
Effl. BOD5
(mg/L)
Removal
(%)
69
60
94
89
97
95
96
89
138
42
50
57
26
-
60
10
11
14
4
-
57
76
77
76
84
-
68
Table E.3 DHS pH, DO, Turbidity Temperature and TDS during Pond
Water/Septage Run
Day
1
2
3
4
5
6
7
8
9
11
12
14
15
16
17
19
20
28
29
30
31
32
34
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
Infl.
pH
7.72
7.49
7.55
7.49
7.46
7.58
7.61
7.59
7.23
7.42
7.42
7.3
7.3
7.19
7.23
7.46
7.45
7.39
7.24
7.2
7.31
7.39
7.6
7.55
7.77
7.32
7.4
7.41
7.36
7.26
7.34
7.34
7.49
7.14
Effl.
pH
7.49
7.18
7.58
7.59
7.4
7.54
7.81
7.97
7.49
7.54
7.60
7.67
7.56
7.57
7.74
7.79
7.57
7.93
7.85
7.73
7.56
7.43
7.58
7.85
7.87
7.36
7.32
7.31
7.29
7.12
7.3
7.29
7.44
7.06
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
1.8
2.13
1.29
1.53
1.13
1.18
0.95
1.2
1.33
1.24
1.67
1.38
1.15
1.03
1.32
1.33
1.44
0.99
1.87
0.33
0.79
0.77
1.12
0.47
0.32
0.45
0.24
0.37
0.48
0.46
0.76
0.9
0.96
0.50
0.76
0.56
0.37
0.31
0.19
5.3
5.01
6.14
6.08
5.13
5.14
6.32
6.9
6.3
7.7
7.24
7.5
7.66
7.5
7.05
7.54
7.50
7.55
7.10
7.36
7.53
7.30
7.30
7.73
7.50
7.29
7.05
7.5
7.4
7.5
7.44
7.28
7.05
7.20
6.53
6.80
6.39
7.28
6.34
224
231
236
245
255
254
260
260
267
264
259
278
284
256
273
265
260
268
269
284
288
296
277
267
244
242
261
270
274
296
307
304
332
324
335
220
225
241
234
243
243
241
243
251
259
253
272
271
253
263
289
264
264
266
272
275
269
268
269
242
241
252
259
262
277
286
286
310
301
321
22.6
15.8
10.6
5.93
8.07
5.36
10.2
19.5
11.8
15.9
7.07
14.7
20.7
44.9
6.91
96.6
96.9
19.2
15.1
106
482
443
324
169
110
165
119
75.9
50.9
113
59.9
122
120
113
69
2.39
2
4.53
2.52
3.36
2.84
2.04
7.87
1.89
3.69
2.41
2.91
5.19
4.3
3.46
2.66
1.58
1.20
2.81
3.73
7.09
31.9
2.84
4.27
6.86
12.3
9.89
10.1
8.96
9.12
44.8
40.9
45.3
53.4
27.2
26.8
27.1
27.8
28.6
28.3
24.6
24.1
23
22.7
22.6
23.2
23.3
22.8
21.7
21.5
26.2
26.1
27.1
27.5
26.7
26.5
23.1
21.9
22.2
24.4
22.5
21.8
22.5
23.1
21.6
21.5
21.2
23.8
23.7
27
24.9
25.2
(oC)
27.5
26.3
27.2
28.2
29.3
27.8
24.3
24.7
23.4
22.5
23.3
22.7
23.2
23.5
21.8
22.2
26.4
26.3
26.1
26.8
27.9
27.3
22.3
23
22.4
25
23.2
22.1
22.8
24
22.1
22.4
21.5
25.8
24.2
28.4
25.3
25.7
Day
53
54
55
56
57
58
60
61
62
63
64
65
66
67
69
70
71
72
73
74
76
77
78
79
81
82
83
84
85
86
88
89
90
92
93
94
95
98
99
101
102
104
Infl.
pH
7.09
6.98
7.24
7.21
7.23
7.31
7.4
7.41
7.38
7.5
7.47
7.42
7.52
7.47
7.36
7.39
7.17
7.58
7.38
7.41
7.49
7.49
7.41
7.44
7.35
7.24
7.33
7.87
7.94
7.41
7.45
7.35
7.42
7.31
7.48
7.87
7.56
7.43
7.30
7.45
7.45
-
Effl.
pH
6.92
6.71
6.84
7.19
7.09
7.08
6.94
7.12
7.33
7.27
7.19
7.15
7.26
7.26
7.04
7.07
6.88
7.5
7.5
7.65
7.35
7.38
7.28
7.25
7.26
6.95
7.05
7.78
7.6
7.58
7.39
7.34
7.42
7.58
7.58
7.45
7.46
7.56
7.65
7.3
7.21
-
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
0.31
0.2
0.17
0.15
0.18
0.19
0.16
0.32
0.30
0.3
0.14
0.27
0.33
0.14
0.17
0.16
0.17
0.2
0.27
0.17
0.18
0.27
0.17
0.18
0.14
0.22
0.13
0.17
0.19
0.14
0.17
0.29
0.18
0.12
0.13
0.12
0.13
0.14
0.16
0.24
6.50
4.3
5.60
6.00
5.52
5
5.40
6.74
6.50
6.3
6.10
6.20
6.50
6.1
6.42
6.30
6.30
6.39
6.10
6.10
6.12
6.01
6.12
6.10
6.13
6.24
6.11
6.30
6
6
6.30
6.40
6.15
6.26
6.41
6.11
6.35
5.5
6.32
5.75
333
340
341
350
346
318
363
399
397
364
365
391
410
422
435
455
450
451
433
407
444
468
474
478
500
494
498
520
461
468
479
480
467
422
426
429
436
461
481
454
434
312
325
317
331
301
317
341
345
346
317
349
349
361
353
423
413
419
407
367
339
406
438
457
440
436
458
451
458
396
419
435
434
430
362
395
362
370
398
440
407
397
95.4
173
104
176
209
67.5
63.5
62.1
44.3
97
48
80.4
110
71.2
168
125
76.3
125
138
82.4
409
140
113
92.1
487
205
145
173
201
348
173
191
200
173
611
336
257
357
371
187
190
201
70
59.1
84.1
112
104
62.9
23
33.5
22.5
31.4
33.2
34.6
11
25.9
30.7
35.9
28.2
46.2
26.5
66.5
43.3
41.2
69.2
58.5
57.2
17.9
46.6
18.8
20
24
5.37
39
31.9
32
13.9
99.2
66.6
21.5
31.7
53.7
107
104
68.8
25.3
26.9
28.5
27.1
29.9
29.2
28.9
28.6
26.3
26.1
27
28
27.9
27.7
28.2
27.5
28.7
27.4
24.9
28
28.7
28.5
28.3
29.5
28.4
29.1
29.4
28.5
28.6
30.1
30.7
29.5
29.6
29.5
29.8
29.6
30.7
30.8
33.8
30.4
31.9
(oC)
24.5
27.7
29.4
25.8
29.9
30.6
30
29.6
24.7
25.1
27.7
27.9
27.8
27.6
28.4
28.2
28.3
26
23.7
29
29.1
30.4
28.6
30.2
28.4
29.4
30
28.8
28.4
30.1
30.6
29.3
27.3
29.1
30.1
28.5
30.5
30.9
34.5
28.7
32.4
Day
105
107
111
114
118
122
Infl.
pH
Effl.
pH
7.7
7.34
7.29
7.25
7.51
7.27
7.87
7.26
7.2
7.22
7.22
7.10
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
0.18
0.17
0.16
0.13
0.24
0.13
5.55
5.5
5.90
5.70
5.30
5.6
426
478
500
525
484
-
369
408
424
427
424
-
178
218
129
226
72.1
441
51.2
43.4
13.5
19.2
19.2
21
30.7
31.4
31.2
31.1
28.8
31.5
(oC)
31.1
29.3
30.8
30.6
29.7
30.8
Table E.4 pH, DO, Turbidity Temperature and TDS for WFM System Pond
Water/Septage Run
Day
1
2
3
4
5
6
7
8
9
11
12
14
15
16
17
28
29
30
31
32
37
38
39
40
41
42
43
44
45
46
Infl.
pH
Effl.
pH
7.66
7.73
7.76
7.71
7.67
8.11
8.14
8.15
7.71
7.51
7.33
7.33
7.46
7.38
7.7
7.42
7.35
7.34
7.34
7.37
7.62
7.81
7.74
7.37
7.32
7.36
7.37
7.68
7.64
7.69
7.70
7.68
7.95
8.06
8.06
7.58
7.34
7.28
7.30
7.12
7.32
7.65
7.46
7.62
7.08
7.42
7.25
7.65
7.85
7.71
7.41
7.44
7.51
7.62
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
0.97
2.54
2.12
2.1
0.87
0.98
3.96
5.58
6.18
6.15
5.13
3.98
3.97
5.05
4.5
4.20
2.50
0.88
1.15
3.03
2.22
0.35
0.29
0.25
0.29
0.57
0.22
0.36
0.4
0.62
5.49
5.83
4.56
5.64
5.50
5.90
5.75
7.00
7.38
7.12
7.30
6.5
7.35
7.5
6.30
6.30
4.50
4.61
5.30
5.30
2.36
1.80
6.88
5.42
6.5
3.8
6
5.94
5.87
6.72
21.6
17.60
7.79
6.39
7.47
3.72
33.2
46.6
12.4
7.08
11.9
8.42
8.23
11.3
10
9.38
8.02
18.60
34.8
120
158
395
193
234
110
132
79.5
29
1.07
0.78
0.54
0.8
0.92
0.56
1.13
0.54
0.85
0.73
0.42
0.58
0.77
0.93
0.48
0.8
0.84
0.77
32.4
29.5
0.7
1.15
0.84
1
1.74
1.59
0.72
1.6
237
246
250
257
266
273
278
282
281
285
273
269
270
270
273
282
275
275
291
295
303
298
244
255
257
266
271
278
227
237
248
250
260
264
272
278
251
279
269
266
265
259
263
276
268
268
291
288
291
284
238
250
253
252
262
265
71
26.8
26.4
26.9
27.6
27.9
28
25
23.7
22.8
22.2
22.8
22.7
22.8
22.6
26
26.1
26.9
27.2
26.7
23.1
22
22.2
23.4
22.7
21.9
22.5
22.1
20.8
21.1
(oC)
27.5
28.8
28.2
30.3
27.6
28.2
25.5
24
25.7
24.5
24.4
23.7
23.5
23.6
27.4
27.5
28.2
27.6
27.3
23.1
21.9
23.5
24.4
23.3
23.1
22.7
23.5
22.6
22.5
Day
47
48
49
50
51
52
53
54
55
56
57
58
60
61
62
63
64
65
66
67
69
71
72
73
74
76
77
78
79
83
84
85
86
88
89
90
92
93
94
95
98
99
Infl.
pH
Effl.
pH
7.25
7.31
7.34
7.49
7.55
6.97
6.77
7.07
7.22
7.21
7.42
7.44
7.44
7.45
7.52
7.51
7.46
7.52
7.52
7.40
7.04
7.62
7.45
7.92
7.47
7.54
7.37
7.49
7.48
7.82
7.53
7.54
7.56
7.46
7.98
7.51
7.56
7.48
8.12
7.46
7.49
7.87
7.6
7.9
7.71
7.19
6.97
6.96
7.37
7.33
7.56
7.48
7.46
7.47
7.48
7.57
7.53
7.47
7.50
7.68
7.41
7.06
7.63
7.59
7.48
7.45
7.61
7.37
7.47
7.56
7.4
7.93
7.54
7.49
7.32
7.88
7.49
7.44
7.31
7.4
7.42
7.51
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
0.82
0.8
0.68
0.42
0.54
0.32
0.44
0.24
0.16
0.24
0.12
0.13
0.25
0.27
0.28
0.30
0.18
0.21
0.25
0.27
0.34
0.25
0.24
0.14
0.39
0.32
0.19
1.76
0.22
0.17
0.19
0.14
0.15
0.31
3.18
0.17
0.1
0.11
0.13
0.15
7.09
7.26
6.6
4.58
3.37
0.44
0.57
2
2.88
2.55
1.48
2.08
2.47
3.58
2.81
2.11
2.24
3.36
1.86
2.21
0.57
2.40
1.21
0.73
1.02
1.32
1.52
4.7
3.78
3.6
3.7
3.84
3.24
3.85
0.16
3.48
3
3.06
2.28
2.25
44
30.9
18.1
47.5
36.4
31.8
46.7
43.9
46.1
61.7
49.9
39.8
64.3
34.9
46.4
34.2
28.1
38.1
38.8
47.3
65.9
79.9
189
101
143
142
81.6
58.8
467
127.5
268
521
341
242
416
296
401
426
374
639
563
1.65
2.24
2.53
44.6
34.5
29
37.7
42.2
39.3
68.5
47.2
5.5
7.11
9.61
9.26
8.4
7.33
9.43
14.6
12.5
59.7
65
6.87
2.64
14.4
3.07
1.9
1.78
6.99
1.3
1.15
1.38
3.39
3.83
7.19
14.7
9.17
14.1
12.2
16.7
15
287
296
296
322
323
333
330
340
345
358
352
323
394
399
399
366
390
403
417
422
437
448
454
438
419
455
468
472
475
509
512
467
483
502
490
484
472
472
472
467
481
278
282
288
321
326
334
342
344
348
359
351
333
391
392
396
351
365
397
408
422
424
455
407
415
403
456
465
469
470
513
513
448
481
503
510
483
467
471
488
461
486
72
21.2
23.2
23.6
26.5
25.3
25.8
25
26.4
28.1
27
29.1
29.2
29
28.3
25.9
25.8
27.8
28.2
28.2
28
28.5
28.8
27.6
24.7
28.5
28.9
28.5
28.3
28.7
29.4
28.4
28.8
29.9
30.2
28.8
30.8
29.6
29.8
29.4
30.6
30.5
(oC)
23.7
24.9
24.5
28.5
26.3
26.6
25.4
27.4
29.1
27.2
30.5
30.5
29.7
29.1
24.7
26.4
28.4
28
29.1
28.7
28.8
29
26.2
24.4
31
30.2
30.4
28.6
29.8
32
29.6
30.3
31.5
32.9
30.9
29
31
31.2
31.2
31.6
30
Day
101
102
104
105
107
111
114
118
122
Infl.
pH
Effl.
pH
7.38
7.45
7.76
7.4
7.34
7.34
7.6
7.29
7.36
7.38
7.52
7.39
7.22
7.07
7.51
7.22
Infl.
DO
Effl.
DO
Infl.
TU
Effl.
TU
Infl.
Effl.
Inf.
Temp Temp TDS
Effl.
TDS
(mg/L)
(mg/L)
(NTU)
(NTU)
(oC)
(mg/L)
(mg/L)
0.12
0.15
0.17
0.28
0.13
0.2
0.14
0.17
0.14
2.5
2.85
1.04
1.25
4.4
3.5
2.25
3.5
2
423
442
247
200
332
146
118
1000
572
9.5
24.9
2.83
1.1
0.78
5.77
10.5
1.03
15
506
482
420
419
450
476
506
499
-
502
476
410
369
436
472
497
506
-
(oC)
32.7
30.3
31.2
30.7
31.3
31.4
31
28.9
31.4
33.6
31.6
30.8
31.5
30.7
31.3
31.2
31.3
32.3
Table E.5 COD Removal during Pond Water/Septage Mixture Run
Day
1
2
7
9
11
16
23
30
39
42
46
54
58
63
69
75
86
95
Infl.
COD
(mg/L)
65
75
36
30
42
156
120
214
576
316
130 (33)*
240 (70)
166
160
252
251
511
394
DHS
Effl. COD
(mg/L)
Removal
(%)
47
56
36
28
26
36
36
60
56
59
10 (10)
170 (62)
166
96
114
50
89
25
28
25
0
8
39
77
70
72
90
81
92 (67)
29 (11)
0
40
55
80
83
94
Infl. COD
(mg/L)
WFM
Effl. COD
(mg/L)
Removal
(%)
65
83
88
40
49
88
236
358
127 (47)
124 (93)
166
132
114
137
627
444
58
38
16
3
29
32
112
63
43 (40)
101(54)
155
48
35
42
50
39
11
55
82
94
41
64
53
82
66 (14)
19 (43)
7
64
69
69
92
91
Note (*) the figure in brackets are for filtered COD
73
Table E.6 BOD5 Removal during Pond Water/Septage Mixture Run
Day
Infl. BOD5
(mg/L)
DHS
Effl. BOD5
(mg/L)
1
2
9
32
47
75
84
98
72
27
51
52.5
60
66
60
81
15
6
7.8
2.55
9.6
10.2
7.2
7.95
Removal
(%)
79
78
85
95
84
85
88
90
Infl. BOD5
(mg/L)
WFM
Effl. BOD5
(mg/L)
Removal
(%)
27
34.5
46.5
52.5
72
63
85.5
5.1
13.2
3.6
16.2
24.45
17.4
24.45
81
62
92
69
66
72
71
Table E.7 TKN Removal during Pond Water/Septage Mixture Run
Day
1
3
31
44
60
86
99
Infl.
TKN
(mg/L)
20.44
27.16
20.72
23.8
33.04
36.68
DHS
Effl. TKN
(mg/L)
Removal
(%)
1.40
2.52
9.24
2.52
1.96
5.32
93
91
55
89
94
85
Infl. TKN
(mg/L)
WFM
Effl. TKN
(mg/L)
Removal
(%)
30.8
21
25.2
21.84
20.44
45.64
31.64
8.96
16.52
14
14.56
10.08
21.28
18.2
71
21
44
33
51
53
42
Table E.8 Total Coliform Removal during Pond Water/Septage Mixture Run
Run
No.
Influent
(MPN/100m
L)
DHS System
Effluent
Log
(MPN/100mL) Rem
Rem.
%
(MPN/100mL)
WFM System
Effluent
Log
(MPN/100mL) Rem
Influent
Rem.
%
Run
1
9.2 x 10 4
3.9 x 103
1.37
96
2.2 x 104
4.7 x 103
0.67
79
Run
2
3.5 x 105
2.2 x 10 4
1.2
94
2.4 x 104
1.2 x 104
0.30
50
Run
3
2.4 x 104
1.3 x 103
1.27
95
1.6 x 10 5
3.5 x 104
0.66
78
Note: Rem. = Removal
74
Table E.9 Pond Water/Septage Mixture Characteristics
Day COD
BOD5 TKN
TS
TSS
TDS
pH
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
1
2
3
4
5
6
7
8
9
11
12
14
15
16
17
19
20
23
28
29
30
31
32
34
37
38
39
40
41
42
43
44
45
46
47
48
49
68
68
32
52
140
148
-
14
54
-
20.16
25.48
20.44
-
264
300.5
294.5
509
-
18
9
25.5
-
101
456
236
80
-
52.5
73.5
-
50
51
52
53
-
-
-
337
-
44.5
75
232
(246)*
253
253
255
274
273
273
271
283
276
278
288
290
298
289
(292)
(269)
272
270
275
275
289
305
308
269
232
239
274
276
274
278
314
309
302
338
(293)
328
348
342
Temp DO
Turb
(oC)
(mg/L) (NTU)
7.77
7.77
7.85
7.72
7.76
7.81
7.81
7.88
7.68
7.47
8.01
7.42
7.47
7.38
7.48
7.62
7.48
7.41
7.08
7.39
7.37
7.47
7.6
7.83
7.75
7.81
7.39
7.42
7.34
7.23
7.37
7.43
28.5
27.4
28
28.6
29.2
28.4
24.6
26.4
24.4
24.4
23.8
23.5
24.1
24.3
23.9
23.1
28
26.7
27.3
27.3
27.7
27.8
24.2
23.8
23.7
26
24.1
22.6
22.7
23.7
26.8
22.7
23.7
25.2
23.6
1.03
4.8
0.5
1.18
0.49
1.05
0.4
0.65
2.35
2.7
1.25
1.32
1.35
1.15
0.97
1.75
1.07
0.87
1.22
0.29
0.43
0.49
0.79
0.58
0.28
0.21
0.31
0.74
0.54
4
0.76
0.63
0.33
1.01
0.65
0.23
19
49.1
17.6
8.22
9.99
6.1
20.9
15.8
10.1
14.7
8.38
18.2
10.2
10.2
8.23
14.3
8.83
19.6
44.1
25.2
289
194
152
86.3
50.1
101
47.5
31.4
53.9
37.9
30.2
-
7.7
7.57
7.17
27.3
25.6
25.7
25
0.73
0.24
0.19
0.28
36.3
38.8
44.6
63.6
Day COD
BOD5 TKN
TS
TSS
TDS
pH
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
54
55
56
57
58
60
61
62
63
163
178
148
-
21.84
-
-
-
64
65
66
67
69
70
71
72
73
74
75
76
77
78
79
81
82
83
84
85
86
88
89
90
92
93
94
95
98
99
100
101
102
104
105
107
111
165
145
248
168
-
81
64.5
81
-
26.6
30.52
-
385
-
44.5
76
349
356
364
356
336
413
408
405
392
390
(341)
394
435
429
456
453
454
454
431
407
489
492
480
483
515
504
517
510
449
445
480
472
417
416
422
431
412
448
461
450
418
420
493
502
Temp DO
Turb
(oC)
(mg/L) (NTU)
6.93
7.17
7.27
7.43
7.38
7.51
7.47
7.48
7.59
27.5
29.4
27
28.7
28.5
29.5
28.6
26.4
0.27
0.17
0.32
0.31
29.5
0.14
0.34
56.1
57.2
54.3
50.8
61.2
45.6
71
41.3
34.3
7.55
7.49
7.59
7.56
7.41
7.47
7.32
7.39
7.42
7.86
7.65
7.6
7.4
7.45
7.51
7.34
7.42
7.76
7.69
7.53
7.49
7.42
7.97
7.53
7.59
7.45
7.45
7.43
7.44
7.43
7.4
7.68
7.36
6.92
26.2
27.3
28.2
28.5
27.9
28.8
28.2
28.5
27.7
25.2
29.1
29.3
28.5
28.4
29.4
28.8
29.5
28.2
28.5
28.9
29.4
30.1
29.4
29.7
29.4
30
29.8
30.2
31.1
32.5
30
30.8
30.1
30.9
31
0.18
0.21
0.28
0.63
0.31
0.24
0.38
0.3
0.35
0.23
2.15
1.1
0.43
247
1.1
0.14
0.19
0.2
3.02
0.18
0.4
0.17
283
0.14
1.58
0.19
0.19
0.1
0.17
0.14
0.12
0.16
0.24
0.32
0.37
51.6
41.8
34.4
50.3
44.3
76.5
59.9
48.3
71.8
84.7
64.2
212
92.1
85.8
74.6
232
99.9
84.8
76.4
465
138
94.4
98.1
124
89.5
165
78.9
64
128
97.1
88.3
90
88.1
66.3
77.4
Day COD
BOD5 TKN
TS
TSS
TDS
pH
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Temp DO
Turb
(oC)
(mg/L) (NTU)
114
118
122
30.9
29.2
30.8
-
-
-
-
-
527
460
-
7.23
7.52
7.28
0.16
0.17
0.13
39.2
75.6
95.1
Note * Number in brackets is the TDS obtained by lab analysis
Table E.10 WFM Run Pure Water Flux Run
Pure Water Flux (Module 1)
Pump
Pressure
Actual
speed
Reading Pressure
(kPa)
(kPa)
1
2.6
0.4
1.5
2.8
0.6
2
3.1
0.9
2.5
3.4
1.2
3
3.8
1.6
3.5
4.1
1.9
4
4.8
2.6
4.5
5.6
3.4
5
6.8
4.6
5.5
7.7
5.5
6
8
5.8
6.5
8.9
6.7
7
10.5
8.3
7.5
12.6
10.4
Pure Water Flux (Module 2)
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
2.4
2.4
2.6
2.8
3.1
3.5
3.9
4.4
5.4
6.9
7.8
8.7
9.9
10.4
0.2
0.2
0.4
0.6
0.9
1.3
1.7
2.2
3.2
4.7
5.6
6.5
7.7
8.2
Volume
(L)
Time
(h)
Q
(L/h)
Area
(m2)
Flux
(LMH)
TMP
(kPa)
0.025
0.107
0.169
0.224
0.304
0.352
0.44
0.52
0.614
0.698
0.784
0.868
0.942
1.026
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
1.5
6.42
10.14
13.44
18.24
21.12
26.4
31.2
36.84
41.88
47.04
52.08
56.52
61.56
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
1.6
6.8
10.7
14.2
19.3
22.4
28
33.1
39
44.4
49.9
55.2
59.9
65.2
0.4
0.6
0.9
1.2
1.6
1.9
2.6
3.4
4.6
5.5
5.8
6.7
8.3
10.4
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
0.9435
2.5
6.6
10.9
14.3
18.6
22.5
27.2
31.8
38.3
45.8
48.4
52.1
57.2
61.4
0.2
0.2
0.4
0.6
0.9
1.3
1.7
2.2
3.2
4.7
5.6
6.5
7.7
8.2
0.04
0.104
0.172
0.225
0.292
0.354
0.427
0.5
0.602
0.72
0.761
0.82
0.9
0.965
77
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
0.017
2.4
6.24
10.32
13.5
17.52
21.24
25.62
30
36.12
43.2
45.66
49.2
54
57.9
Table E.11 WFM Run Pond Water/Septage Mixture Run
Module No 1
Cum.
Run No Time
Time
(h)
(h)
1st Run
0.0
0.0
1.0
1.0
2.0
2.0
3.0
3.0
4.0
4.0
18.8
18.8
22.3
22.3
26.5
26.5
39.0
39.0
43.0
43.0
46.7
46.7
51.0
51.0
67.0
67.0
71.0
71.0
74.0
74.0
nd
2 Run
0
74.0
4
78.0
8
82.0
Flux
(L/m2.h)
TMP
(kPa)
0.7
1.3
2.4
3.4
4.1
9.5
6.4
12.5
43.3
56.8
56.3
55.6
49.9
56.7
57.9
2.6
8.8
5.3
5.7
5.7
5.7
5.7
5.7
5.4
5.4
5.3
3.4
3.9
3.3
3.1
2.4
2.7
2.7
5.6
5.3
5.6
78
Module No 2
Cum.
Time
Time
(h)
(h)
0
0.0
1
1.0
4
4.0
8
8.0
17
16.5
20
20.0
23
23.0
26
26.0
28
28.0
32
32.0
41
41.0
48
48.0
50
50.0
53
53.0
63
63.0
69
69.0
74.5
74.5
91
91.0
95.5
95.5
99.5
99.5
115
115.0
117.5
117.5
124.5
124.5
138.5
138.5
142
142.0
147
147.0
164.5
164.5
170
170.0
173.5
173.5
188
188.0
191.8
191.8
197
197.0
212
212.0
217.5
217.5
221.5
221.5
235.8
235.8
240
240.0
0
240.0
1
241.0
4
244.0
Flux
(L/m2.h)
TMP
(kPa)
6.9
14.6
24.8
40
39.9
46.1
48
48.9
48.4
48.3
50.1
49.3
49.3
48.5
48.7
51.7
47.1
45.6
49.4
49.1
50
50.6
50.2
50.8
50.5
50.8
50.6
51.7
51.2
50.6
51.3
50.8
50.5
50.7
50.7
50.9
50.9
15.3
33.9
38.1
5.4
4.1
3.5
4.7
3.6
3.4
3.4
3.4
3.4
3.1
2.8
2.8
2.8
2.7
2.5
2.5
2.4
2.2
2.5
2.5
2.4
2.4
2.4
2.4
2.3
2.3
2.1
2.1
2.1
2.1
2.2
2.1
2.1
2.1
2.4
2.2
2.2
7.9
6.0
4.5
Module No 1
Cum.
Run No Time
Time
(h)
(h)
16.5
90.5
24
98.0
28
102.0
32
106.0
40.5
114.5
46.5
120.5
52.5
126.5
66
140.0
71
145.0
76
150.0
91.5
165.5
97
171.0
100.5
174.5
115.5
189.5
121
195.0
125
199.0
138.5
212.5
142.5
216.5
150
224.0
163
237.0
167.5
241.5
173
247.0
186.5
260.5
192
266.0
197.5
271.5
211
285.0
rd
3 Run
0
285.0
1
286.0
4
289.0
18
303.0
32.5
317.5
36
321.0
42.5
327.5
56.5
341.5
59.5
344.5
66.5
351.5
80.5
365.5
84.5
369.5
89.5
374.5
104.5
389.5
108.5
393.5
Flux
(L/m2.h)
TMP
(kPa)
6.2
3.5
4.8
3.7
4.3
4.3
8.6
7.2
4.8
4.5
9.2
9.6
9.3
10.5
10.6
11
26.3
12.6
15.9
15.9
15.8
15.7
16
17.4
18
17.5
3
8.5
13.6
17.2
10.3
24.4
47.4
46.6
46.9
46.6
47.1
47.8
47.7
48.1
48.1
5.6
5.6
5.5
5.5
5.5
5.5
5.5
5.5
5.7
5.6
5.2
5.5
5.6
5.4
5.6
5.5
4.4
8.1
8.0
8.0
8.0
8.1
8.1
8.1
7.9
7.9
8.0
8.0
7.8
7.5
8.0
7.0
2.5
1.9
1.9
1.9
1.7
1.7
1.7
1.7
1.7
79
Module No 2
Cum.
Time
Time
(h)
(h)
18
258.0
22
262.0
27.5
267.5
42
282.0
45.5
285.5
51
291.0
66
306.0
69.5
309.5
75.5
315.5
89.5
329.5
93.5
333.5
100
340.0
113.5
353.5
118
358.0
123
363.0
138
378.0
142
382.0
147.5
387.5
162.5
402.5
166.5
406.5
171
411.0
186.5
426.5
190.5
430.5
197.5
437.5
209.5
449.5
215
455.0
219
459.0
234
474.0
241
481.0
0
481.0
3
484.0
6
487.0
20.5
501.5
24
505.0
30.5
511.5
44
525.0
48.5
529.5
54
535.0
68.4
549.4
71.9
552.9
78.5
559.5
93
574.0
96.5
577.5
102.5
583.5
Flux
(L/m2.h)
TMP
(kPa)
43.8
44.2
43.6
41.8
43.5
43.3
42.8
43
42.4
44.2
45
44.4
43.4
45.6
45.1
45.3
45.6
44.1
45.2
45.8
45.4
45.4
45.4
45.1
45.4
45.5
46
46.4
51.7
28.4
37.8
39.1
41.6
42.5
43
43
44
44.1
43.9
44
43.8
43.8
44.2
43.5
3.2
3.2
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.3
2.3
2.2
2.3
2.3
2.3
2.2
2.0
2.2
2.0
2.0
2.0
1.9
1.9
2.0
1.9
1.9
1.9
1.8
1.9
5.7
3.9
3.3
2.5
2.7
2.5
2.3
2.3
2.3
2.0
2.0
2.0
1.9
1.9
1.9
Module No 1
Cum.
Run No Time
Time
(h)
(h)
123.5
408.5
127
412.0
133
418.0
147.5
432.5
153.5
438.5
167
452.0
175
460.0
192
477.0
196
481.0
200.5
485.5
th
4 Run
0
485.5
3.5
489.0
15.5
501.0
20.5
506.0
24.5
510.0
40
525.5
45.5
531.0
50.5
536.0
63
548.5
69.5
555.0
Flux
(L/m2.h)
TMP
(kPa)
47.4
48.3
47.9
47.7
47.7
47.7
48.2
47.8
47.9
47.4
41.3
47.2
47.5
47.9
47.3
46.9
45.3
41.9
37.8
38.6
1.5
1.5
1.7
1.5
1.5
1.4
1.5
1.4
1.5
1.4
4.5
2.3
1.8
1.8
1.8
1.7
1.7
1.5
1.4
1.3
80
Module No 2
Cum.
Time
Time
(h)
(h)
117
598.0
120.5
601.5
127
608.0
141
622.0
145
626.0
163.5
644.5
168.5
649.5
196
677.0
212.5
693.5
222
703.0
237.5
718.5
246
727.0
261.5
742.5
266.5
747.5
284
765.0
290
771.0
294
775.0
310.5
791.5
314.5
795.5
319
800.0
333
814.0
338.5
819.5
343
824.0
357
838.0
362
843.0
376
857.0
380
861.0
385.5
866.5
400.5
881.5
406.5
887.5
425.5
906.5
429.5
910.5
433.5
914.5
448.5
929.5
0
929.5
3
932.5
8
937.5
25
954.5
32
961.5
48
977.5
53.5
983.0
59
988.5
71
1000.5
76
1005.5
Flux
(L/m2.h)
TMP
(kPa)
44
43.9
43.6
44.5
44.4
44.5
45.5
46.8
46.4
45.8
46.3
46.3
46.8
46.6
47
46.6
47.4
47.2
46.6
47.1
47.1
46.8
47.1
47.1
46.5
47.2
47.1
46.9
47.2
47.2
47.2
47.1
46.6
46.8
2.5
21.6
25.0
29.5
30.8
35.7
35.8
36.2
37.8
38.3
1.8
1.9
1.8
1.8
1.8
1.7
1.7
1.9
1.7
1.7
1.4
1.4
1.4
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.1
1.1
1.1
1.1
7.4
2.5
2.3
2.4
2.3
2.3
2.3
2.3
2.2
2.2
Module No 1
Cum.
Run No Time
Time
(h)
(h)
75.5
561.0
88.5
574.0
93.5
579.0
98.5
584.0
112.5
598.0
116.5
602.0
121.5
607.0
136.5
622.0
143.5
629.0
160.0
645.5
165.5
651.0
183.5
669.0
192.5
678.0
208.0
693.5
212.5
698.0
230.5
716.0
236.0
721.5
242.0
727.5
256.5
742.0
263.5
749.0
280.50
766.0
289.50
775.0
304.00
789.5
327.00
812.5
Flux
(L/m2.h)
TMP
(kPa)
43.3
40.8
42.2
40.9
43.8
44.8
42.9
47.9
47.7
47.1
41.5
41.0
39.0
43.8
43.9
44.7
45.8
44.5
45.6
44.7
46.8
45.1
46.7
46.5
1.4
1.4
1.4
1.4
1.4
1.3
1.3
1.4
1.4
1.4
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.1
81
Module No 2
Cum.
Time
Time
(h)
(h)
83
1012.5
95.5
1025.0
101
1030.5
107
1036.5
120
1049.5
126.5
1056.0
143
1072.5
150
1079.5
168.5
1098.0
174.5
1104.0
191.0
1120.5
195.0
1124.5
201.0
1130.5
216.5
1146.0
-
Flux
(L/m2.h)
TMP
(kPa)
37.4
40.3
41.1
41.6
42.8
42.9
43.3
43.7
43.9
44.4
44.0
44.9
45.1
45.8
-
1.9
1.9
1.9
1.9
1.9
1.9
1.8
1.8
1.8
1.8
1.8
1.7
1.7
1.7
-