FinalReport

Design of Decentralized Wastewater Treatment System
(Boil Water Advisory)
Project Report
Linnan Zhuang, MED
Zihao Zhang, MED
Yunbo Jia, MED
Yue Gui, MED
Zheming Fan, MED
August, 2016

Executive Summary
To effectively remove contaminants and standardize the way household wastewater
is treated in Township of Wainfleet, a decentralized system is proposed. The proposed
system is cost-effective in the long term with potential to provide environmental and
social benefits to the community.
Biogas system is chosen as our desired system. It has been widely used in Ontario as
well as in other places in the world. There’s even a Canadian Biogas Association which
details that multiple biogas projects have been in use all across Ontario, which greatly
adds to the applicability of our design. Though it’s not as good as MBR in terms of
performance of wastewater treatment, working with a leach field would dispel the
concern. Compared with its performance, its environmental and social value to the
community is much more promising and carries more weight. Biogas-a major byproduct
of the treatment process is a clean and renewable energy which can be used for multiple
purposes including cooking, lighting, power generation, fuel of transportation, etc. Liquid
bio-fertilizer which can be taken from the post-treated wastewater is of manurial value to
this rural and agricultural community, as well.
A type of self-assembled biogas facility provided by a Chinese company specializing
in wastewater treatment technologies is considered. Working with a leach field, it’s able
to treat 40 cubic meters’ household sewage per day with a daily production of 18.15 cubic
meters’ biogas and 95.95 kilograms’ fertilizer.
The capital cost is estimated to be $89712.42 CDN which includes the purchase and
shipping of biogas system, purchase of vacant land, construction materials, piping and
leach field. The permitting cost and the labor and consulting cost incurred in the
installation is excluded. The capital cost would be paid by Township of Wainfleet using
an annual profit of $20919.78 CDN gained from biogas, liquid bio-fertilizer and land tax
with an expected payback period of 4.3 years.
As for routine inspection, operation and necessary maintenance, a third-party
company specializing in the field of O&M would be contracted. The annual O&M cost is
estimated to be $4485.62 CDN which approximately accounts for 5% of the capital cost.
And this part of expenditure is to be paid by people residing in the targeted area.
The concept of decentralized wastewater treatment is continuing to gain ground all
over the world. Likewise, the ideal of “go green and sustainable” in infrastructure
development is spreading like wild fire. Our pilot project is strategically reasonable and
economically feasible by combining these two trendy and catchy ideas in a harmonious
fashion. It could be further utilized in other parts of Wainfleet and serve the whole
township in the years to come.

CONTENTS
CHAPTER 1. BACKGROUND......................................................... 5
CHAPTER 2. PROBLEM STATEMENT ............................................. 6
CHAPTER 3. EXPLORED APPROACH.............................................. 7
CHAPTER 4. RESEARCH METHOD................................................. 8
1. FLOW CHART........................................................................................................ 8
2. ONLINE RESEARCH............................................................................................... 8
3. FIELD TRIP............................................................................................................ 9
4. INDIVIDUAL INTERVIEW ..................................................................................... 10
5. EXPERT INQUIRY................................................................................................ 11
6. COMMUNITY-DRIVEN DISCOVERY...................................................................... 11
7. CASE ANALYSIS.................................................................................................. 11
8. DOCUMENTATION .............................................................................................. 12
9. MIND MAP.......................................................................................................... 12
10. GROUP DISCUSSION............................................................................................ 13
CHAPTER 5. DESIGN DIRECTION ................................................ 14
1. ADVANTAGES OVER CENTRALIZED SYSTEM ....................................................... 14
2. EXISTING EXAMPLE............................................................................................ 15
1) MBR system ................................................................................................. 15
2) Biogas system............................................................................................... 16
3) Drip irrigation field ..................................................................................... 16
3. PROPOSED SOLUTIONS........................................................................................ 17
1) Aeration treatment unit (ATU) system......................................................... 17
a) Strengths...................................................................................................18
b) Limitation .................................................................................................18
c) Cost Estimate ............................................................................................19
2) Biogas septic system .................................................................................... 19
a) Strengths...................................................................................................20
b) Limitations ................................................................................................21
c) Cost Estimate ............................................................................................21
3) Membrane Bioreactor (MBR) System.......................................................... 21
a) Strengths...................................................................................................22
b) Limitations ................................................................................................23
c) Cost Analysis ............................................................................................24
CHAPTER 6. EVALUATION OF PROPOSED SYSTEMS ....................... 25
1. SOCIAL ASPECT .................................................................................................. 25

2. ENVIRONMENTAL ASPECT .................................................................................. 26
3. ECONOMIC ASPECT............................................................................................. 29
4. SCORING MATRIX .............................................................................................. 29
CHAPTER 7. DESIGN OF BIOGAS SYSTEM ..................................... 31
1. BENEFITS ........................................................................................................... 31
2. TARGETED AREA ................................................................................................ 31
3. SCHEMATIC........................................................................................................ 33
4. TECHNOLOGY .................................................................................................... 34
CHAPTER 8. BUSINESS MODEL................................................... 37
1. COST ESTIMATE................................................................................................. 37
1) Capital cost.................................................................................................. 37
2) Operating and Maintenance(O&M) Cost.................................................... 39
2. MONETARY GAIN ...................................................................................................... 39
1) Biogas .......................................................................................................... 39
2) Liquid bio-fertilizer...................................................................................... 40
3) Tax revenue.................................................................................................. 41
3. PAYBACK PERIOD ..................................................................................................... 41
CHAPTER 9. CONCLUSION ........................................................ 42

Chapter 1. Background
Wainfleet is a small rural township in southern Niagara region which includes
communities of Attercliffe, Camelot Beach, Chambers Corners, Long Beach, Morgan's
Point, O'Reilly's Bridge and so on[1]. Figure 1[2] shows the geographic location of
Wainfleet. It’s 271.29 square kilometers with 6356 residents, 2335 private households
and a population density of 29.3 per square kilometer in 2011[3]. There’s a growing
touristic industry along the shore of Lake Erie-long beach, which attracts tourists from
other parts of Ontario and America. Because of this, the density of house properties there
is much higher than that of the rest of Wainfleet. And according to the Environmental
Study Report[4] done by Niagara Region in 2006, the lakeshore community has a greater
density with generally small, densely packed and undersized lots. The Shoreline of Lake
Erie in Wainfleet has approximately 1120 detached residences, of which only about 60%
are permanent and 40% are seasonal[5]. A majority of residents in Wainfleet draw water
from their individual wells, and some residents who live by the lakeshore get their
drinking water from a communal water supply. Municipal sewer service does not exist
here, residents reply on private septic tanks to discharge their household sewage which
gets removed on a regular basis[6].
Figure 1 Location of Township of Wainfleet

Chapter 2. Problem Statement
The residents in Wainfleet have suffered from groundwater contamination for over a
decade and the Lakeshore area has been under a Boil Water Advisory since April 2006[7].
Multiple studies have been done in the past indicative of significant contamination of
groundwater along the shore of Lake Erie. According to Groundwater Impact Assessment
Water Well and Septic System Survey[4] done by MacViro in 2005, 34% of the water
from dwellings had E. Coli. exceedances and 68% of the water from dwellings had total
coliform exceedances. It also indicated that septic systems were polluting groundwater
supply, affecting water wells and deteriorating the water environment along the lakeshore.
Contributing factors included ageing and malfunctioning of septic systems, small lot size,
local high lot density and failing to meet setback requirements between wells, property
lines and septic systems. Moreover, the local geology examination suggested the
existence of bedrock at shallow depths with a thin overburden soil cover, which provides
little or no attenuation to septic effluent discharge from the septic systems into the aquifer.
Lastly, lack of knowledge of water treatment and septic system and the unsustainable
development at the lakeshore area are also exacerbating the problem.

Chapter 3. Explored Approach
To solve this problem, efforts were made and approaches were explored.
Unfortunately, these attempts have proven unsuccessful to root out the groundwater
contamination woe. But they have all helped to pave the way by providing necessary
background information and offering ideas and thoughts on actionable approaches. These
explored approaches are:
1) Background Studies including MOECC study[9] (2003) and MacViro well
monitoring program (2003 – 2005)
2) Environment Assessment and Feasibility study completed for municipal water
service
3) Find, Fix and Replace program including mandatory septic system inspection by
qualified third party engineering company, in which approximate 1200 properties were
inspected and 200 systems were found failed. Those failed systems ware issued Orders by
Township to replace and about half of them were fixed so far.
4) Post monitoring private well sampling program (Jan. - Dec. 2014). The results
discovered sporadic well contamination between individual wells, while they were not
conclusive as not enough samples were taken due to a lack of homeowner interest.

Chapter 4. Research Method
1. Flow chart
Flow chart displays logic and sequences in a graphic fashion by using lines, arrows,
blocks and squares. The information shown in a flow chart is usually clear, vivid and
easy to understand. Therefore, flow chart is deemed a great method to get a general
outline of how issues could be analyzed and tackled.
When we first started the project, we turned to this widely-used method. Figure 2 shows
the flow chart of our preliminary analysis.
Figure 2 Flow chart of the preliminary analysis
2. Online research
After the flow chart was drawn, we did online research to get basic information about
E. Coil via relevant websites and documents. The main purpose was to make assumption
of what E. Coil contamination was really about and possible approaches to tackle the
issue.
Internet provides researchers with different kinds of information on the searched
subject. Users could get a basic understanding of the subject and from there a deeper
exploration of issues could be made. Online research is a great tool which helps us in an
efficient and effective fashion. The information found online proved useful to us and
helped us gain a better understanding of the project.
With the information found online and our existing knowledge of E. Coil and water
contamination, we made some assumptions in terms of the source of E. Coil:
○1 Poor management of septic system:

Septic system is the main breeding ground of E.coli. There are many private septic
tanks in Wainfleet, if these septic tanks are not maintained or managed properly, the
septic could leak into the ground and contaminate the groundwater.
○2 Rainwater runoff:
Feces and other septic on the ground is also an important source of E.coli. Rainwater
might carry all the feces on its way and seep into the ground, thereby causing the
contamination.
○3 Cross leaking and permeation:
Leaking between supply and drainage pipelines is also a possible contributor. The
density of house properties in some certain areas of Wainfleet is high. Therefore, to bury
such pipelines in those areas would further render cross leaking inevitable and further
contribute to the contamination woe.
3. Field trip
Field trip is often used to help researchers identify and fill their knowledge gap.
What’s found online could more often than not fall short in terms of identifying the root
cause of a problem. What’re more, a field trip could help to validate the presumed
hypothesis on what caused the problem and point researchers in the right direction before
they dive into the details. Useful graphic visuals could also be documented during a field
trip which adds to the validity and credibility.
With guesses and assumption as to what caused the E. Coli contamination, we paid
our first field trip to Wainfleet in November???. With the assistance of Trevor, then
official of township of Wainfleet, we got to know that it was the close proximity of the
well and septic system that caused the contamination. Because the septic systems are
generally installed too close to the wells, the contamination through pipelines was
inevitable. In addition, many septic systems inspected by Trevor were either too old or
managed improperly. Failing to meet relevant health standards, leaking from septic
system further exacerbated the contamination problem. The first field trip helped us
validate our assumption and enhance our knowledge as to what really was the root cause
of the groundwater contamination.

Figure 3 First field trip
The design process is iterative rather than linear, which means that as we dive deep
into the details, parameters and variables may look different than when we initiated the
design process. Therefore, more on-site validation and feedback collection from users is
needed.
To collect more feedback about the decentralized wastewater treatment facility, our
team paid another visit to Wainfleet. The second field trip verified our design direction
and further enhanced our existing knowledge of incoming water treatment, sewage
treatment and decentralized system. In figure 4, John, successor of Trevor is showing us
UV chamber that services Township of Wainfleet.
Figure 4 UV chamber
4. Individual interview
Individual interview provided us with opportunities to understand local residents’
thoughts and opinions, which not only helped us learn the way people treat their

incoming water and wastewater, but also deepened our knowledge of our desired
decentralized system. For example, issues like how much the desirable cost of the system
could be, what the general attitude of local residents’ is, what their hopes and expectation
of such a system are were discussed. All of these issues hadn’t been well thought out
until the interview. The individual interviews proved quite effective and useful in that it
helped us identify local residents’ needs.
5. Expert inquiry
Experts could provide technical and in-depth information. More often than not, the
way we go about our project lacks some practicality since our project experience is
lacking. That’s where an expert comes in. Experts could point out practical issues that are
necessary in order for the project to be feasible, but those issues could easily escape our
attention due to multiple reasons. For example, we might overlook factors such as level
of community involvement, applicability within local context, compatibility with
technical specifications, government support, business model, etc. But with the advice of
an expert, those issues would be brought to our agenda.
We had a meeting with Dr. Dickson, an expert in the field of wastewater treatment,
department of Civil Engineering in McMaster University. We explained to her our
desired decentralized wastewater treatment system and she provided us with key
suggestions in terms of how we could align our system to the community, what some
existing examples and technology are locally and globally that we can learn from, what
design details we needed to consider to meet relevant standards and codes, what business
model was in order to market our system, etc. She also provided us with useful online
resources through which we could further our research and make contact with experts in
the industry.
6. Community-driven discovery
Community has been a significant participant in our design process. On one hand,
they are our end users who have the ultimate say of our system, so their opinions of the
system have a great influence on our design. On the other hand, their guidance and
support in the design process could help us fasten the project. A community-oriented
approach could assist us in gaining a comprehensive look at the whole picture and
discovering issues that lay hidden beneath the surface. In addition, community members
with negative attitude or pushback would also help us reflect on the path we have taken
and refine design details from there.
7. Case analysis
Case analysis provided us with a clear angle into how existing examples work. By
looking at those cases, we gained a better understanding of currently available
technologies and their pros and cons, how those technologies are used to maximize its
utility, details that could be improved, issues that require extra attention, etc. Most

importantly of all, an in-depth exploration of existing examples enables us to compare
multiple decentralized systems and ultimately select the best fit.
8. Documentation
Documentation is a powerful way to observe and record information over a long
period of time. We took photos during our field trips, took notes during interviews with
residents and meetings with our professor and mentor and managed information gleaned
from online sources. Documentation enabled us to get a complete record of evidence
necessary to push our project forward. Figure 5 shows the sample decentralized
wastewater treatment system that’s servicing Township of Wainfleet.
Figure 5 sample decentralized wastewater treatment system
9. Mind map
This is a great method to generate ideas by diverging and converging train of thoughts.
A design process usually consists of several parts which deal with different aspects. For
example, our design consists of technology, community engagement, business model, etc.
Random thoughts might occur to us from time to time in all aspects and it is mind map
that helped us select quality ones and grouped them into the corresponding aspect. In
addition, it’s a good way to document issues and ideas in a clear and graphic fashion.
Figure 6 is the mind map we drafted in the design process.

Figure 6 Mind map
10. Group discussion
This method is the most frequently used one in our design process. We held group
discussion on a regular basis discussing issues that are relevant to our project. This has
been effective in helping us get rid of differences in our knowledge and reach an
agreement throughout the whole design process. At various points of the project, any
individual on our team tends to have a different voice regarding the discussed topic. It
might be that someone lacks relevant knowledge or expertise in some area, or he/she
makes a poor judgment, or he/she generalizes issues so that the conclusion is inaccurate
or even he/she takes a wild guess that makes little sense. The goal of discussion is to talk
it over, resolve it and come to an agreement. This method has greatly expedited the whole
project.

Chapter 5. Design Direction
Decentralized wastewater treatment system is chosen as our targeted design direction
due to its many merits such as easy and low management, standard way of
sewage-treating, cost-effectiveness, land-saving. This type of system has been used in a
number of places in the world and has been proven a big success, which lends great
support to our design. In this chapter, its advantages over its counterpart-centralized
system would be explored and existing examples and proposed solutions would be
elaborated on.
1. Advantages over centralized system
Decentralized wastewater treatment consists of a variety of approaches for collection,
treatment, and dispersal or reuse of wastewater for individual dwellings, institutional
facilities, clusters of homes, and entire communities [10]. Decentralized wastewater
technologies differ from conventional centralized systems in that they “treat and reuse or
dispose of wastewater at or near its source of generation”. Under certain conditions,
decentralized technologies may offer benefits over centralized technologies [11].
Centralized wastewater treatment system always consists of a Centralized Plant and a
Pipe System. The discharge volume is large for a centralized system, which results in
high capital cost and O&M cost, as well as large land use. Therefore, centralized
treatment of urban sewage is largely limited to cities with high income and large
population. As limitations are placed on, or occur naturally for the density of
development, the user costs for providing centralized collection and treatment tend to
increase.
A decentralized system is able to treat wastewater in a cost-effective and economical
fashion. By utilizing much less land and energy than its counterpart, it collects and treats
household sewage on a community scale. In so doing, the expense to implement, operate
and maintain such a system is much lower than a centralized system.
In addition, alongside with its treatment capability, it serves to promote a green and
sustainable idea, which is evidently shown in the case of biogas digester or other similar
systems. This type of system epitomizes the add-on benefit of a decentralized system.
Other than the economic side of advantage, its social benefit merits more public attention
in that it serves to create byproduct that could be used to serve the needs of the whole
community. For example, biogas digester produces biogas-a renewable energy that if
properly conditioned and refined, is able to generate electricity. The generation of this
green power not only reduces the emission of greenhouse gas, but also lowers the energy
consumption to a certain degree. The production of liquid fertilizer is also a gift to an
agricultural community since it’s a great supplement to agricultural fertilizing with zero
harm to natural environment.

Lastly, a decentralized system benefits a community in an organizational sense. The
way household wastewater is treated in Wainfleet is improper. A standardized manner to
regulate the disposal and treatment of wastewater is lacking. A locally “centralized” way
to holistically manage wastewater is lacking. The risk of the leaking of septic tank and
polluting of groundwater is highly heightened. By using a decentralized system, the goal
to better manage and treat household sewage could be achieved.
Thus, the need to consider decentralized treatment and disposal systems becomes evident.
This type of system treats relatively small volume of water and works well in rural,
suburban and urban settings.
2. Existing example
1) MBR system
Currently used in Bay Meadows, the MBR system has proven quite effective in
treating wastewater in a scalable fashion. Using a modular design, this decentralized
system is able to phase up its capacity of treating wastewater. And it’s also expected to be
able to meet stringent environmental standards and regulations, such as total suspended
solids (TSS), carbonaceous biochemical oxygen demand (CBODS), phosphorous.
In addition, compared with centralized system that is often used in a city, this system
utilizes much less land. According to a newsletter published by OOWA, traditional
processes require four times the physical footprint of this advanced decentralized system.
This system greatly reduces the land requirement.
With the advantages of self-contained, modular design and less land use, MBR
system is able to treat wastewater in a cost-effective fashion, thereby overcoming the
great financial barrier and achieving sustainability. And as the newsletter says,
“Decentralized systems offer advanced treatment technologies in a very compact
footprint. This modular MBR system at an Ontario RV park treats 83 m3 of sewage per
day yet requires only 16’×40’ of space.[12]”
Figure 7 MBR decentralized system

2) Biogas system
Ghana is a prime example of this decentralized system, figure 8 shows the physical
appearance of biogas system used in Ghana. The use of biogas system in Ghana has gone
through several stages over the course. Due to various reasons such as social acceptance,
government approval, financial support, choice of feed materials, poor decision and
policy-making, the dissemination of biogas system has been thwarted for quite some time
before making big progress [13]. With the involvement of private companies, biogas
system has seen its use in domestic, institutional and community plants [13]. And the
prospect of this technology is promising for Ghana in spite of some challenges.
Figure 8 Biogas system
Biogas system has both financial and non-financial advantages. In spite of the high
cost to install and maintain such a system, the payback period for a new installation is
usually less than 2 years [14]. And it would take somewhere between 2-6 years to get the
money back for institutions that wish to replace septic tank with such a system [14].
As for non-financial advantages, the unpleasant odor and potential risk of vector
contact could be avoided using a biogas system. Biogas could be used as a clean source
of energy for cooking, heating or power generation. And the effluent could be used as
organic fertilizer which improves the crop yield.
3) Drip irrigation field
Targeted at residences in outlying area where soil type is not ideal for septic tanks or
pipelines, drip irrigation field is used as a centralized wastewater treatment field which
collects and treats wastewater from all the serviced residences [10]. Figure 9 shows this
wastewater treatment field.

Figure 9 Drip irrigation field
3. Proposed solutions
Homes not served by public sewers rely on individual or small cluster wastewater
treatment systems to treat and disperse household wastewater. A septic tank followed by
gravity dispersal trenches is the most common onsite wastewater treatment system used
in rural areas [10]. However, there are many households for which the typical septic tank
system is not the best wastewater treatment option. For example, septic tank systems are
not suitable for lots with limited land area or poor soil condition. In these cases, other
decentralized wastewater treatment systems may be good options. Here are some
proposed solutions which are worth considering.
1) Aeration treatment unit (ATU) system
Aeration treatment units (ATUs) are similar to septic tanks in that they both use
natural processes to treat wastewater. But unlike septic tanks that rely on anaerobic
treatment, ATU relies on aerobic treatment.
ATU consists of a main compartment-aeration chamber in which air is mixed with the
wastewater. Some models include a primary settling compartment or an additional tank to
reduce the amount of solids entering the aeration chamber. Air mixes with wastewater in
the aeration chamber and oxygen boosts the growth of aerobic bacteria which breaks
down the organic material in the wastewater. Many ATUs include a final settling
chamber or clarifier where solids and bacteria settle and return to the aeration chamber
[15]. Figure 10 shows a typical ATU system.

Figure 10 ATU system
a) Strengths
High performance
ATUs provide a higher level of wastewater treatment than septic tanks. They
consume organic matter and convert ammonium nitrogen to the nitrate form to achieve
lower BOD and nitrogen and phosphorus reduction.
Safety
While most ATUs contain an alarm that alerts a homeowner to any problem
associated with the system, many septic tanks do not. This is an important feature
because undetected problems can quickly escalate and render the system inactive. With
an alarm, ATUs help homeowners to avoid extensive repair work and system failure.
b) Limitation
Clog easily
Aerobic bacteria is better at breaking down human waste than anaerobic bacteria.
However, they are less able to break down inorganic solids. Therefore, aerobic systems
clog easily.
Costly operation and frequent maintenance required
Aerobic septic systems are more expensive to maintain than anaerobic ones. Because
aerobic septic systems have mechanical parts, which are more prone to mechanical
malfunction and typically require more frequent routine maintenance.
High energy costs
Electricity is required to operate an ATU, so they also increase the electricity bill.
Further treatment process required

Although ATU is able to remove pollutants, the treated wastewater must be further
treated before being discharged. Methods of final treatment and dispersal include a soil
treatment system or lagoon.
c) Cost Estimate
Cost of a suspended growth aerobic treatment system depends upon factors including
wastewater volume and quality, site condition, location of and access to the site and
availability of electrical power. Management cost must always be considered. A qualified
service provider that understands the process is needed [16]. Below are the screenshots of
the cost estimate of an ATU system taken from a report on performance and cost of
decentralized unit processes [16].
Figure 11 Estimated cost to install and maintain a suspended-growth aerobic treatment system at
a single-family residence
Figure 12 Estimated cost to install and maintain a community-scale suspended growth aerobic
treatment system
2) Biogas septic system
Biogas septic systems are designed to naturally break down organic waste and
produce biogas for cooking, lighting and power generation. Figure 13 shows a biogas
system.

Figure 13 Biogas system
Through anaerobic digestion, biogas system is able to remove pathogen and
contaminants in wastewater and provides a renewable source of energy. Liquid fertilizer
taken from the treated wastewater is of manurial value to the agricultural community, as
well. Such a sustainable and environmental-friendly approach is highly favorable.
a) Strengths
Provide a renewable source of energy
Biogas can be used as a source of clean energy for:
Electricity and heat for local power networks
Immediate use (stored in gas cylinders and for sale)
Transportation fuel (Compressed Natural Gas or CNG)
Provide clean liquid fertilizer
The effluent from the biogas system can be used as organic fertilizer improving the
crop yield and reducing the need of water for irrigation.
Low environmental impact
No greenhouse gas is emitted to the air and no unpleasant odor generated, which is
conducive to reducing global warming potential.
Short payback period
The payback period for such systems in new installations is usually less than 2 years.
For institutions that wish to substitute their septic tank with biogas system, the payback
period ranges between 2-6 years [14].
Easy installation and low management

Biogas system is generally easy to install, and low operation and maintenance is
required when it’s in place.
b) Limitations
It might be economically feasible in the long term, but the upfront cost associated
with excavation and installation is high. To implement such a system might only make
sense when it’s used in a prolonged period. In addition, the biogas digester has a latent
potential risk of explosion, which necessitates routine inspection and maintenance. Lastly,
it’s only capable in removing contaminants to a limited degree. A leach field or a lagoon
is needed to further absorb pollutants before the treated water seeps into the ground.
c) Cost Estimate
A report on Waste Agricultural Biomass Utilization as Energy/Resource [17] suggests
the economic feasibility of a biogas plant based on the financial analysis of capital cost,
O&M cost and generated profits.
The system life of the project is estimated to be around 30 years and the upfront
investment is returned within 2-6 years. Figure 14 is a screenshot of cost estimate taken
from a study “Economic and Environmental Feasibility and Recommendation on Policies
for the Pilot Scale Project of Biogas Plant”[18].
Figure 14 Cost estimate of a biogas system
3) Membrane Bioreactor (MBR) System
Membrane Bioreactors (MBRs) combine a traditional activated sludge biological
removal system with a membrane to provide solids removal and improved effluent
quality. The system uses membrane as a filter to remove the solid materials produced
from the biological process and render the treated effluent clarified and disinfected. A
typical MBR consists of a pretreatment unit, a bioreactor and a membrane unit.

Figure 15 MBR system
The modular MBR packaged plant is one of the most commonly used technologies
for small communities, and has been customized and successfully operated in small-scale
flow conditions. MBR process is cleaner and has a smaller physical footprint than ASP
(Activated Sludge Process). Figure 16 shows the Newterra Modular MBR sewage
treatment system that’s currently in use in Bay Meadow RV park, Ontario.
Figure 16 Newterra MBR
a) Strengths
Exceptional treatment performance
MBR system provides exceptional permeate quality. Analysis of treated effluent
shows that all parameters (BOD, TSS, TNC) have been reduced to levels much lower
than current and anticipated regulatory requirements.

No Costly On-Site Construction
The modular systems are constructed in MET-certified facility. Prior to shipping,
they are pre-plumbed, pre-wired and undergo comprehensive testing, allowing fast
installation and minimal site work [19].
Water Reuse Potential
A very good effluent quality can be achieved by this technology. Effluent from
MBRs could be reclaimed and used for irrigation, utilities or toilet flushing, even as a
source of potable water.
Very little floor space occupied
MBR system offers a flexible design to fit in a smaller footprint than conventional
septic system. The membrane in the system removes the need of a sedimentation chamber
and media filtration for separating the biomass, thereby reducing the use of space [12].
Reduced footprint makes MBR ideal for use in residential areas. And modular system is
easily expandable and scalable.
Operator-Friendly & Minimal Maintenance
Modular MBR system is a good example of reducing operation and lowering
maintenance cost. Air scouring and periodic membrane relaxation helps prevent fouling,
and chemical cleaning is required only 1-2 times per year [19].
b) Limitations
High cost of energy consumption
MBR reduces both the cost and space requirements of secondary clarification,
aeration and filtration. However, the increased treatment capacity is accompanied by
increased electrical cost because great aeration capacity and pressurization is needed to
operate a MBR at its full potential.
Complexity
MBR combines a biological wastewater purification system with a physical process,
which increases the complexity. In addition, to remove nitrogen and phosphorus,
additional unit process must be added to the MBR.
Membrane fouling
If MBRs aren’t properly protected, they typically have higher O&M cost than
conventional systems associated with membrane cleaning, fouling control, and even
potential membrane replacement.
High potential cost of periodic membrane replacement
MBR is a relatively new technology, and limited data is available on membrane life.
There is a potential for high recurring costs for membrane replacement. Membrane

manufacturers typically mention that membranes have a replacement period of 7-10 years
[20].
c) Cost Analysis
While MBR technology is not always the best solution of wastewater treatment,
sometimes it can be far more expensive than other solutions. The major downside of
MBR over traditional methods is the high initial cost of membrane modules.
Construction Cost
According to a report published by the Water Reuse Research Foundation, based on
data acquired from 24 conventional MBR plants all over the country, the average unit
construction cost was $3.0 million for a 50,000 gpd (gallon per day) plant, $4.5 million
for a 100,000 gpd plant.
O&M Cost
The same study collected information on annual O&M cost. However, only 5 of the
24 plants surveyed had sufficient O&M data, since it is a relatively new technology.
Based on this, a 50,000 gpd plant was estimated to have an average annual O&M cost for
materials, electricity, and labor of $73,000 every year. A 100,000 gpd plant was
estimated to have an average annual O&M cost of $109,500 every year [20].

Chapter 6. Evaluation of Proposed Systems
Of all three systems mentioned above, it’s no easy job to choose one as our proposed
design. Due to the fact that each one has its pros and cons, a good way to holistically
evaluate these three systems is by using assessment criteria. The criteria would help us
evaluate how effective each decentralized system is in social aspect, environmental
aspect and economic aspect. Scores in different categories of the criteria would help us
comprehensively compare their performance and ultimately decide which system delivers
the best overall performance.
The decision matrix uses a numerical scoring approach. System that has the optimal
performance scores 3, while a score of 2 means that a system delivers less desirable
performance and 1 indicates the least desirable performance. The numbers are assigned in
a qualitative and quantitative approach. Below is the description of evaluation aspect and
corresponding scoring method.
1. Social aspect
Social aspect mainly refers to the system’s impact in a community perspective. It can
be subdivided into three categories: aesthetics, health-risk of vector contact, educational
opportunity and employment opportunity. Each category can further be divided into
subcategory.
Aesthetics: this category is designed to evaluate the sensory impact of the system,
which includes odor, visual and noise.
Odor: this indicator refers to the olfactory impact of the system. Certain chemical
products might be generated during the treatment process, and some would carry
unpleasant odor to a certain degree.
Scoring method: In order to score 3, no odor is associated with the wastewater
treatment process. Score 2 means that the system has the potential to produce
unpleasant odor. Score 1 refers to a system with an increased potential of odor.
Visual: this indicator investigates the impact of the system on the visual aesthetics.
For example, system installed underground would have little visual aesthetic effect,
while a big above-ground system would bring down the aesthetics.
Scoring method: Score 3 reflects systems with zero visual impact. 2 means that a
system has little negative visual impact, while 1 refers to a system with noticeable
negative visual impact.
Noise: this measure refers to the level of noise associated with the treatment process.

Scoring method: In order to score 3, no noise is generated in the treatment process. A
system producing negligible noise scores 2, while system generating significant noise
scores 1.
Health-risk of vector contact: this refers to the impact on the wellbeing of
community members. Risk of vector contact is assessed in particular.
Scoring method: a system with no risk of vector contact scores 3. A system with
minimal risk of vector contact scores 2, while 1 means increased risk.
Educational opportunity: this refers to the potential of the system to educate the
community, promote their environmental awareness and enhance their knowledge of
relevant issues. For example, biogas system provides community members with the
opportunities to learn more about the treatment process and the possible use of its
by-product. However, ATU is not equipped with such potential apart from treating
effluents.
Scoring method: In order to score 3, a system generates the most education potential
for the community. 2 refers to a system with little education potential, while 1 means
no education potential at all.
Employment opportunity: this indicates the ability of the system to provide job
opportunities. For example, ATU requires regular operation and maintenance which
creates job opportunities.
Scoring method: a system creating many job opportunities scores 3, while 2 refers to
a system with few job opportunities. Systems contributing to zero job opportunity
scores 1.
2. Environmental aspect
Environmental implication is closely related to the system’s ability to remove
pathogen and bacterial content from the wastewater. It’s designed to assess the system’s
ability of effluent treatment. Indicators such as reliability, performance, site constraint,
by-product creation potential are included in this category.
Reliability: this indicator is designed to assess the general durability of the system
and level of variation in effluent. It is inevitable that such systems might age and
malfunction over a long period of time. System with a complex structure is more prone to
failure than its counterpart with a simpler structure.
Scoring method: in order to score 3, a system has to have consistently minimal
variation in effluent, which means a consistently optimal treatment performance. A
system with only seasonal variation in effluent scores 2, while 1 refers to a system
with noticeable variation in effluent.

Performance: this indicator measures the ability to remove pathogen and microbial
content from the sewage. It includes TSS (total suspended solids), TNC (total nitrogen
concentration), BOD (biochemical oxygen demand) and potential pathogen.
Scoring method: due to a lack of practical test of effluents, this weighting method is
based on literature. A system that removes the most particulate matter, nitrogen
compounds, pathogen content and so on receives a score of 3, and 2 and 1 refers to
worse and the worst performance, respectively.
TSS: It describes the amount of particulate matter content in a water sample. In the
assessment criteria, TSS refers to the milligrams per liter of total suspended solids
expected in the treated effluent. Figure 17 shows TSS performance of the compared
systems based on data from a study on decentralized wastewater treatment options
[11].
Figure 17 TSS performance
TNC: It describes the amount of nitrogen compounds in a water sample. Here it refers
to the milligrams per liter of nitrogen content expected in the treated effluent. Figure
18 shows TNC performance of the compared systems[11].
0
5
10
15
20
ATU biogas MBR Leach field
AverageTSSConcentration
(mg/L)
Decentralized Technologies
AverageTSS Concentration in Treated Effluent by
System

Figure 18 TNC performance
BOD: It measures the amount of dissolved oxygen required for aerobic biological
organisms in a water sample to break down organic material. In the matrix, BOD is
expressed in milligrams per liter of BOD in the treated effluent. Figure 19 shows
BOD performance of the compared systems[11].
Figure 19 BOD performance
Potential pathogen: Total coliform is the major pathogen content in water. This
indicator measures the ability of a system to remove pathogen content.
Site constraint: this refers to the impact of physical characteristics of the site on the
system. For example, a subsurface system is more prone to the constraint of special site
condition, while above-ground system like MBR is not affected by this at all.
0
5
10
15
20
25
TotalNitrogen(mg/L)
AverageTotal Nitrogen Concentration in Treated
Effluent by System
0
2
4
6
8
10
12
14
16
BODConcentration(mg/L)
AverageBOD Concentration in Treated Effluent by
System

Scoring method: in order to receive 3, a system is not affected by the physical
features of the site such as soil type, slope. 2 refers to a system which is minimally
constrained by the site. A system susceptible to the site condition receives a score of
1.
By-product creation potential: this measure is related to the extent of potential to
which the process of sewage-treating is able to produce by-product. It evaluates the
system’s potential in creating by-product that can be used in other purposes with positive
social or economic benefit. For example, biogas produced in the biogas system can be
used for purpose of heating, cooking or power generation, which makes great use of the
by-product produced in the process of sewage treatment. And the sludge generated from
the treatment process can be used as fertilizer.
Scoring method: A system with marked potential to create by-product receives a
score of 3, whereas a system with little potential and no potential receives a score of 2
and 1, respectively.
3. Economic aspect
Economic section in the assessment criteria refers to the initial, ongoing and
long-term costs associated with the purchase, construction, operation and maintenance of
the system. This includes capital cost and O&M (Operation and Maintenance) cost.
Scoring method: due to the scarcity of accurate data regarding fees incurred in the
process, cost estimate in this section is done in a qualitative and empirical approach.
The system with the lowest cost receives a score of 3, and 1 is given to the one with
the highest cost. This scoring method applies to both the capital cost and O&M cost
below.
Capital cost: this refers to the initial costs associated with the purchase and
construction of a system such as labor and implementation.
Operation and maintenance cost: this refers to the ongoing cost incurred in the
operation and maintenance process which includes routine check and operation, labor,
energy use, chemical use, etc.
4. Scoring Matrix
Each aspect and category is weighted due to its relative importance. Economic aspect
is deemed the most important part in our analysis, thus 50% is given. A large part of
environmental aspect is directed at the ability of the system to remove harmful particulate
matter and pathogen content, thus 30% is given. The last 20% is attributed to social
aspect.
A scoring matrix is conducted which is shown in table 1. Information necessary to
design the valuation matrix and score each category is obtained from sources including:

 Technical reviews and guidelines from reports township of Wainfleet
 Scientific literature
 Expert interview and inquiry
Table 1 Scoring matrix
Valuation Category
Proposed system
ATU Biogas MBR
Social (20%)
Aesthetics
(15%)
Odor (5%) 3 2 3
Visual (5%) 3 3 1
Noise (5%) 1 3 2
Health-Risk of vector contact
(50%)
2 2 3
Educational opportunity
(20%)
1 3 2
Employment opportunity
(15%)
3 2 2
Environmental
(30%)
Reliability (20%) 2 1 3
Performance
(40%)
TSS (10%) 2 1 3
TNC (10%) 2 1 3
BOD (10%) 2 1 3
Potential
pathogen
(10%)
2 1 3
Site constraint (10%) 1 2 3
By-product creation potential
(30%)
1 3 1
Economic
(50%)
Capital cost (60%) 2 3 1
Operation and maintenance
cost (40%)
1 2 1
Note: number 1, 2, 3 refers to the score each category receives, and percentage refers to the allotted
weight.
Based on the scoring matrix, each system receives a total score. As it turns out,
biogas system scores the highest of all three. And biogas system is thus chosen as our
desired system. Next step, an in-depth analysis of biogas system will be conducted. Issues
like technical detail, lay-out plan, business model and method of community engagement
will be explored.

Chapter 7. Design of Biogas System
1. Benefits
Working with a leach field, biogas chamber’s ability to remove pathogen and
contaminants is marked. And because the water supply is relatively far from the targeted
area, the incoming water wouldn’t be contaminated by the effluents.
The environmental benefit is also noticeable. It converts household sewage into clean,
renewable energy which can be used for the purpose of cooking, heating and power
generation. It could also be used as a replacement for typical non-renewable fossil fuel
which is environmental friendly. What’s left after the treatment process can further be
used to irrigate farmland. Given the fact that a large portion of Wainfleet is rural, the
liquid and solid fertilizer could improve crop yield and benefit the argricultural
community there.
Furthermore, it serves as a disemination tool to raise public awareness among the
residents who generally have little or no knowledge of the benefits of a decentralized
system. Being a pilot project, our design could work to promote the utility of such a
system which if possible, could be implemented all across Wainfleet in the years to come.
A company based in Shenzhen, China was brought to our attention after lengthy web
search. This company specializes in decentralized wastewater treatment technologies and
solutions. Their products have been widely used in many places in the world. And their
decentralized systems are able to treat sewage ranging from 10 cubic meters that meets a
small household’s need, to 200 cubic meters that meets the need of a plant on a small
community scale.
2. Targeted area
Bordering Lake Erie, long beach area is densely populated and it is a major touristic
attraction especially in summer. American people come here to enjoy their short term
vacation. And it’s known for the conservation area which provides multiple summertime
activities such as fishing, swimming, sunbathing and boating.
According to “On-site Sewage Disposal Sustainability Study”, an environmental
study done by AMEC in 2005, the lots built there are heavily compact and a majority of
those have serious risk in groundwater contamination. 67% of the residential lots do not
meet minimum on-site disposal requirements per Ontario Building Code and 54% of the
studied residential lots get drinking water from groundwater that is significantly
contaminated [4]. Figure 20 shows the lots in that area that fail to meet those standards
and thus are considered “dangerous”.

Figure 20 The contaminated area along the shoreline
A small area along the shore of Lake Erie was considered as our targeted area, which
is shown in Figure 21[21]. There are several lines of reasoning behind this choice: first of
all, residents in this area get their incoming from a clean communal water supply, which
is over 400 meters from this area. Therefore, the risk of incoming water being
contaminated by household effluents is removed. The highlighted section in figure 22[21]
is the long beach water supply. In addition, properties in this section are densely clustered
and the need to treat their wastewater is high. There’s a piece of unoccupied land nearby
that could be used to install leaching field where the treated effluents could be discharged.
Lastly, the residents living in this area are under an association which has almost the
same voice on public issues. It’s more likely to implement the decentralized system here.
This area would be an ideal place for our pilot project.
Figure 21 Targeted area

Figure 22 Long beach water supply
3. Schematic
Figure 23 shows the schematic layout of our design. In order to alleviate the impact
on the community in terms of construction and aesthetics, only branch pipes and central
pipes are designed in the targeted area, and the leach field is installed at a distance from
the area. In this way, the decentralized system is indeed a centralized one serving a
community on a much smaller scale.
Figure 23 Schematic layout
Daily design sanitary sewage flow is calculated according to table 8.2.1.3.A of the
2012 Ontario Building Code[22]. Those small lots along the road are treated as trailer
parks with only one bedroom, the long property is treated to have 10 bedrooms, and the
rest of the house properties are treated as regular dwellings with 3 bedrooms. The daily
sewage flow is estimated to be 36.3 cubic meters.

4. Technology
With daily design flow in mind, a system with the treatment capacity of 20 cubic
meters is considered, and two systems are needed to service this area. The schematic
above shows how two biogas digesters work. Figure 24[23] shows how such a system
works. Through the inlet pipe the household sewage goes into the anaerobic digester
where organic compounds are broken down and biogas is produced. The biogas rises and
gets collected in the gas holder. The storage pool serves as a buffer reservoir before the
treated effluents go to the leaching field. The other byproduct-liquid fertilizer can be
obtained from the pool on a regular basis.
Figure 24 Schematic of a household biogas system
Figure 25[23] shows the structual layout. A steel mould would be first assembled in
the gound, which is followed by casting concrete into the mould. After the concrete is
formed, the steel mould need be dismantled. And construction would be finished with the
installation of associated fittings and appliances.
Figure 25 Structual layout

Figure26[23] shows what such a system looks like in real life.
Figure 26 Real-life visual
According to the test results from a sample of effluents provided by the vendor, the
treated wastewater contains 8.0 mg/L of BOD5, 0 fecal coliforms per L, 1.39 mg/L
ammonia nitrogen, etc. All of these numbers meet standards of water quality and suggest
a dischargeable quality of treated wastewater.
Eventually, the treated wastewater goes to a leach field where the pathogen and
contaminants are further absorbed before the wastewater eventually seeps into the ground.
The leach field is shown in figure 27[24].
Figure 27 Leach field
A leach field, sometimes referred to as a drain field, is a component of a septic
system that receives partially-treated wastewater from the septic tank and distributes it
evenly to the soil through pipes for further treatment[25]. Anaerobic septic systems
typically require leach fields for better wastewater quality. A leach field should be
installed at least 10 feet from properties, wells or any body of water, and 10 feet from
gardens and edible plants. Many leach fields are laid out as a number of parallel trenches
connected via pipes to the biogas system. Each drain-field trench should be at least 3 to 4
feet wide and 3 to 4 feet deep[26].

Based on the sewage volume 36300 L/d (9589.475 gallon/d) and soil absorption rate
2.5 gallon/ (d·ft2), the size of the leach field should be:
9589.475/2.5=3835.79ft2
(1)
The depth is assumed to be 4ft and length 200ft (perforated pipe is 100ft long),
leaving the width:
3835.79/200=19.18ft (2)
Trenches are in parallel and are dug in length of the field. Width of each trench is 10
inches with an interval of 14 inches. So the number of trench is:
19.18ft×12/(10inch+14inch)=9.6≈10 (3)
Therefore, 20 100-feet perforated drain pipes are needed. This number is to be used
in the calculation of piping fee later.
The treated wastewater is pumped into perforated pipes laid in the leach field, which
is filled with sand and gravel underneath. As the wastewater seeps out of the pipes, the
solid material is filtered by the gravel, leaving the liquid part seeping downwards into the
sand. With the anaerobic treatment in the digester and the filtration of the gravel, the rest
of the wastewater poses no harm to the soil. Figure 28[27] shows how a leach field works
with septic tank.
Figure 28 Septic tank and leaching field

Chapter 8. Business Model
1. Cost Estimate
The cost to implement such a biogas system is split into two parts: capital cost and
O&M cost (operation and maintenance).
1) Capital cost
Capital cost refers to the cost associated with the purchase and shipping of the
system, purchase of vacant land and materials for the construction such as concrete,
cement and gravel. All the relevant components needed to build this system are
directly purchased from China. Customs duty and tax is also payable which is
included in the purchase and shipping fee.
Relevant fees incurred in the purchase of the system are provided by the vendor.
Customs duty rate is 8.56%[28] on average and tax rate is 5%. The payable customs
duty and tax is calculated according to an online example[29]:
For imported goods with a value of $100 (CDN), customs duty is $8.56 (CDN),
and the taxable value is 108.56. So payable tax is:
108.56 × 5% = $5.428 CDN (4)
Total of customs duty and tax is:
8.56 + 5.428 = $13.988 CDN (5)
The cost breakdown of the purchase and shipping fee is listed in table 2. The
exchange rate for USD to CDN is 1.29, which means that 1 USD equals 1.29 CDN.
The exchange rate applies in all the conversions throughout this chapter.
Table 2 Cost Breakdown of Purchase and Shipping
Purchase and
Shipping
Item Amount/USD Amount/CDN
FOB $17005.00 $21936.45
Shipping $1109.00 $1430.61
Customs duty and tax $2378.66 $3068.47
Domestic shipping $750.00 $967.50
Total (USD) $21242.66 $27403.03
Since the Township does not own the vacant land, land that is needed for the
biogas chambers and leach field is required to be purchased at the market value.
According to “Land Value trends in South Western Ontraio”[30], the value of vacant
land is estimated to be between 8000 CDN to 14000 CDN per acre. Here 12000
CDN per acre is considered. The total area of biogas chambers and leach field is
3987.88 ft2 (0.092 acre). Therefore, the cost of land is:
12000 × 0.092 = 1104 CDN (6)
Due to the large variance of permit fees across municipal jurisdiction and labour
costs between contractors, these two parts are left out of our cost estimate. Therefore,
construction cost refers to that of necessary materials such as cement, sand, gravel,
bricks, PVC pipes. Table 3 is the cost breakdown of the materials needed to build the
biogas system. The material column shows the types of material with their respective
properties. The quantity column shows the quantity of items needed to build two 20

m3 biogas system as aforementioned. This was provided by the vendor, and all of the
unit prices were obtained online.
Table 3 Cost Breakdown of Construction Materials (Biogas digesters)
Item Material Quantity Unit Price/USD
Amount/U
SD
Amount/C
DN
1
Smashed stone (#9
gravel)[31]
16m3
$2.00/5 gallon $1691.33 $2181.82
2
Sand
(1601.85kg/m3
[32])
14m3
$7.50/ton[33] $168.19 $216.97
3
Cement (grade above
325)[34]
4800kg $8.90/42.6kg $1002.81 $1293.62
4
Brick
(60×120×240mm)[35]
200 $13.99/5 pieces $559.60 $721.88
5
PVC pipe
(ɸ6''×1800mm)[36]
4 $9.25/ft $54.62 $70.46
6
Reinforced steel bar
(ɸ6mm)[37]
40kg $397.92/ton $15.92 $20.54
Total $3492.48 $4505.30
There are two types of pipes that are needed to discharge household effluents to
the biogas system: branch pipe and a central main pipe. As shown and described in
the schematic layout, the branch pipes serve to connect each property to the central
pipe which further serves to discharge the effluents into the biogas chamber. PVC
piping is proposed due to its merits such as lightweight, erosion-resistant and durable.
The branch pipe is 6 inch in diameter and central pipe is 14 inch in diameter. Table 4
shows the cost of these two types of pipe. The measurement feature of Niagara
region GIS mapping[21] was used to estimate the length of pipe based on the
schematic layout. The unit price was obtained online.
Table 4 Cost Breakdown of Sewage Pipes
Item Material Length/m Unit Price/USD Amount/USD Amount/CDN
1 PVC pipe (ɸ6'')[38] 657.84 25.99/10ft $5609.27 $7235.96
2 PVC pipe (ɸ14'')[39] 265.3 300.05/10ft $26116.24 $33689.95
Total $31725.51 $40925.91
Lastly, there will be a cost to build the leaching bed. Gravel, sand and perforated
drain pipes are needed in this part. Table 5 shows the cost breakdown.
Table 5 Cost Breakdown of Leach Field
Item Material Quantity
Unit
Price/USD
Amount/USD Amount/CDN
1 #8 Gravel[31] 666.67ft3
2.25/0.5ft3
$3333.33 $4300.00
2 Sand (1601.85kg/m3
[32]) 325.85m3
7.50/ton $3914.72 $5049.99
3
Perforated drain
pipe(ɸ6'')[40]
2000ft 249/100ft $4980.00 $6424.20
Total $12228.05 $15774.18
With all the relevant costs above, a grand total cost can be calculated, which is

shown in table 6
Table 6 Capital Cost
Item Amount/CDN
Purchase and shipping of
biogas chambers
$27403.03
Purchase of land $1104
Construction (Biogas
Digesters)
$4505.30
Piping $40925.91
Leach field $15774.18
Total $89712.42
2) Operating and Maintenance(O&M) Cost
O&M cost mainly refers to that of inspection, operation and necessary
maintenance. The system is robust and durable. Therefore, the inspection and
maintenance is only needed every three months just in case there’s a leak in the gas
holder or major congestion in the inlet or outlet pipe. The whole process is able to
work by itself which renders human operation redundant. However, the liquid
fertilizer does need human operation. Settled at the bottom of the storage pool, the
fertilizer needs to be removed on a biweekly basis.
There are some companies that provide general and specialized operation and
maintenance service in the field of decentralized wastewater treatment. The operation
and maintenance work would be contracted out to such a third-party company. By
our estimation, 5% of the capital cost ($4485.62 CDN) each year is expected to be
paid to this company by people residing in this area. That number is roughly the
annual follow-up O&M cost for routine inspection and regular operation. This part of
expenditure could be partially subsidized by Township of Wainfleet and Niagara
region.
2. Monetary gain
The type of system proposed has multiple monetary benefits for the users. The
monetary gain is grouped into three categories: biogas, liquid bio-fertilizer and property
tax revenue.
1) Biogas
The biogas system is expected to produce biogas that equals 50% of the volume
of daily wastewater (36.3 m3). Biogas is typically composed of bio-methane, CO2, N2,
etc.[41]. The proposed biogas system does not include a facility used for biogas
conditioning and refining, so only a certain amount of biogas is equivalent to
bio-methane. According to online research and a case study provided by the vendor,
70% of the biogas is estimated equivalent to bio-methane.
Daily biogas production:
36.3𝑚3/d × 50% = 18.15 𝑚3/𝑑 (7)
Daily volume of equivalent bio-methane:
18.15𝑚3/d × 70% = 12.705 𝑚3/𝑑 (8)
According to a market price of energy obtained online, the equivalent
bio-methane is worth 12 USD per MMBTU (1 MMBTU equals approximately

28.264 m3 of natural gas at defined temperature and pressure[42]). The daily and
annual profit of equivalent bio-methane is:
12.705𝑚3/d × 12/28.264𝑚3 = 5.394 USD/d (9)
5.394 × 365 = 1968.861 USD/year
(10)
Relevant numbers and results are listed in table 7.
Table 7 Biogas Profit
Daily Biogas Production/m3
18.15
Daily Equivalent Bio-methane/m3
12.705
Energy price[43]/
(USD/MMBTU)
12
Daily Profit/USD $5.39
Annual Profit/USD $1968.86
Annual Profit/CDN $2539.83
2) Liquid bio-fertilizer
Daily volume of liquid effluent is assumed to be 50% of the design sewage flow,
which is 36.3 m3. Of the post-treatment liquid effluent, 98% is water and 2% is
organic material. The organic material contains 40% moisture, and its density is
1322.8838 kg/m3[44]. With proper treatment, one third of dehydrated
non-moisturized organic material can be converted to liquid bio-fertilizer.
Daily mass of organic material:
36.3𝑚3 × 50% × 2% × 1322.8838kg/𝑚3 = 480.2068kg
(11)
Whereas:
50%-the percentage of liquid effluent out of the daily design flow;
2%-the percentage of organic material out of the post-treated liquid effluent;
1322.8838kg/𝑚3-the density of the organic material.
Daily mass of liquid bio-fertilizer:
480.2068kg × 60% × 33.3% = 95.945kg
(12)
Whereas:
60%-the percentage of non-moisture part out of the organic material;
33.3%-the percentage of usable liquid bio-fertilizer out of the dehydrated organic
material.
With the unit price obtained online[45], daily and annual profit of the liquid
bio-fertilizer can be calculated:
95.945kg × 0.4 USD/kg = $38.38 USD
(13)
38.38 × 365 = $14008.7 USD/year
(14)
Relevant numbers and results are listed in table 8.
Table 8 Profit of Liquid Bio-fertilizer
Daily Volume of Liquid Effluent/m3
18.15
Water Content of Effluent 98.00%
Density of Effluent/(kg/m3
) 1322.8838kg/m3
Daily Mass of liquid bio-fertilizer/kg 95.945

Price of liquid
bio-fertilizer/(USD/kg)
0.4
Daily Profit/USD 38.38
Annual Profit/USD 14008.70
Annual Profit/CDN 18071.22
3) Tax revenue
The property value within the targeted area is likely to rise if the pilot project serves
the area well. Therefore, land tax could be levied on residents there. However, a high
property tax would deter them. By our estimation, 20 USD each month would be suitable
for both Township of Wainfleet and residents.
Table 9 Annual Tax Revenue
Annual Tax Revenue/USD 240
Annual Tax Revenue/CDN 309.6
3. Payback Period
Capital cost is estimated to be 89712.42 CDN. Annual profits consist of three parts:
biogas, liquid bio-fertilizer and tax revenue. Annual profits are used to offset the capital
cost, and the annual O&M cost would be paid by residents. Table 10 shows the makeup
of the annual profits.
Table10 Makeup of annual profits
Item Amount
Biogas $1968.86
Liquid Bio-fertilizer $14008.02
Tax Revenue $240.00
Total Annual Profits (USD) $16216.88
Total Annual Profits (CDN) $20919.78
Table 11 shows the capital cost and annual profit.
Table 11 Capital Cost and Annual Profits
Item Amount/CDN
Capital Cost $89712.42
Annual Profits $20919.78
The payback period is:
$89712.42/$20919.78 = 4.2884 years≈4.3 years (15)
After the payback period, the Township or Wainfleet can continue to profit from the
project. It is recommended these profits be put into a reserve fund to collect interest and
can be used for future maintenance and repairs.

Chapter 9. Conclusion
Decentralized wastewater treatment system has multiple advantages over its
counterpart, centralized system. It’s been widely used by communities all over the world
because it’s effective in removing pathogen and contaminants. Compared with a
centralized wastewater treatment plant, the overall expenditure to implement, operate and
maintain a decentralized one is much less. In addition, in terms of land use, a
decentralized system shows another edge over its counterpart. It proves effective in
treating wastewater with much less land.
Biogas system is one select choice of decentralized system in that it’s green and
sustainable. The process of wastewater-treating eliminates the emission of greenhouse
gas, and therefore, has low environmental impact. It produces biogas-a clean and
renewable energy which can be used for purposes of heating, cooking, power generation.
This system helps promote the concept of “net-zero”-energy generated onsite is used to
offset the energy consumption. The overall cost of the biogas system combined with a
leach field is also much lower than other decentralized systems, which further adds to its
supremacy. In Ontario, there are plenty of biogas projects. They have proved to be
successful in serving farms and small rural communities. Given this context, Township of
Wainfleet is believed to ideal for biogas system due to its rural and agricultural nature.
The targeted area for our proposed system is relatively small. What is considered in
this small community is 14 one-bedroom properties, 13 three-bedroom houses and one
10-bedroom dwelling. The design daily sewage flow is estimated to be 36.3 cubic meters
according to table 8.2.1.3.A of the 2012 Ontario Building Code[22].
The proposed biogas system consists of two biogas chambers, a leach field, pipelines
and necessary facilities. The capital cost is estimated to be $89712.42 CDN which
includes the purchase and shipping of biogas system, purchase of vacant land,
construction materials, piping and leach field. The cost of permitting and physical labor is
excluded in our cost estimate. Operation and maintenance cost is estimated to be
$4485.62 CDN per year (approximately 5% of the capital cost). The annual profits are
estimated to be $20919.78 CDN. With the capital cost and annual profits, the payback
period is estimated to be 4.3 years.
The targeted area falls under an association, which means that people residing in this
area have the same voice towards community events. This adds to the feasibility of our
proposed system. If implemented and managed ideally, this pilot project could be further
utilized in other similar areas, which is likely to serve to treat wastewater in a regulated
and standard fashion and alleviate the risk of wastewater contaminating incoming
drinking water.
However, given that residents in Wainfleet generally lack knowledge of
decentralized wastewater treatment system, the dissemination of the proposed biogas

system seems inevitable. More educational workshops and council meetings need be held
to broadcast the benefits of the system. Residents need more exposure to the concept of
decentralized wastewater treatment. They need be told in terms of issues such as how
such a system works, how effective it is, how much it generally costs, how long it takes
to get the investment back, how operation and maintenance is done, etc. Website is
another great way to raise awareness among the populace. Facts about the proposed
system can be provided to give people a clear idea of the project. Status of project’s
progress, potential funding, status of approval and future direction need be shown to them
as well. Furthermore, other relevant links can help capture some attention, too. Links
such as EPA (environmental protection agency), Biogas Association in Ontario, OOWA
(Ontario Onsite Wastewater Association) serve to further enhance the knowledge of
interested residents in terms of what the general climate of wastewater-treating is, what
other available and cost-effective decentralized technologies are, what the current trend
of biogas system is in Ontario and elsewhere, where the biogas system can be improved,
etc.

Reference:
[1] https://en.wikipedia.org/wiki/Wainfleet,_Ontario
[2] Picture of geographic location of Wainfleet:
http://www.wainfleet.ca/geographical-profile
[3] Demographic information of Wainfleet, 2011 census:
https://www12.statcan.gc.ca/census-recensement/2011/as-sa/fogs-spg/Facts-csd-eng.cfm?LANG=Eng
&GK=CSD&GC=3526014
[4] Environmental study report, Niagara Region
[5] Wainfleet PWA_Sept 18 07, Niagara Region
[6] Wainfleet Boil Water Advisory: https://www.niagararegion.ca/living/health_wellness/wainfleet/
[7] Boil Water Advisory issued for Wainfleet, Public Health
[8] Facts on drinking Water:
http://www2.gnb.ca/content/dam/gnb/Departments/h-s/pdf/en/HealthyEnvironments/water/Coliforme.
pdf
[9] http://owwco.ca/the-ministry-of-the-environment-and-climate-change-moecc/
[10] Decentralized wastewater treatment:a sensible solution:
https://www.epa.gov/sites/production/files/2015-06/documents/mou-intro-paper-081712-pdf-adobe-ac
robat-pro.pdf
[11] Assessing decentralized wastewater treatment options in Santa Barbara county. Kiernan Btalik,
Marina Feraud, et al.
[12] OOWA, Newsletter Bay Meadow Article
[13] Biogas technology dissemination in Ghana: history, current status, future prospects, and policy
significance. Edem Cudjoe Bensah, Abeeku Brew-Hammond
[14] Biogas in Sub-Saharan Africa provides many advantages. Newsletter
[15] An Onsite Wastewater Treatment System Owner’s Manual
[16] Performance & Cost of Decentralized Unit Processes, Water Environment Research Foundation
[17] Report on Stakeholder’s Consultation Workshops on Waste Agricultural Biomass Utilization as
Energy/Resource, Converting Waste Agricultural Biomass into Energy Source, study
[18] Economic and Environmental Feasibility and Recommendation on Policies for the pilot scale
project of Biogas plant, Converting Waste Agricultural Biomass into Energy Source, study
[19] Newterra Membrane Bioreactor: http://www.newterra.com/technologies/membrane-bioreactor
[20] Decentralized Wastewater Treatment in the City of Sugar Land and Sugar Land’s Extra
Territorial Jurisdictions.
[21] Niagara region GIS mapping: https://maps-beta.niagararegion.ca/Navigator/

[22] Table 8.2.1.3.A. Residential Occupancy, Ontario Building Code
[23] Puxin PX-SM-6/10M3 Technology: http://en.puxintech.com/PXSM10M3
[24] Real-life picture of leach field: http://www.clayseptic.com/13143/index.html
[25] Directions for installing a leach field:
http://www.ehow.com/way_5770281_directions-installing-leach-field.html
[26] How to build a septic drain field:
http://www.ehow.com/how_5039124_build-septic-drain-field.html
[27] Schematic of leaching field and septic tank:
http://premiersepticpumping.com/leaching-field-treatment-restoration/
[28] Customs duty rate: http://www.dutycalculator.com/
[29] Example of customs duty and tax: http://www.cbsa-asfc.gc.ca/import/guide-eng.html
[30] Land value trends in South Western Ontario, pdf.
[31] Unit price of gravel (smashed stone): http://www.allrocksrus.com/#!gravel/c1mf9
[32] Density of concrete sand:
http://concretematerialscompany.com/aggregate-asphalt/sand-gravel/concrete-sand
[33] Unit price of concrete sand: http://www.weidle.com/html/pricelist.html
[34] Unit Price of portland cement:
http://www.homedepot.com/p/94-lb-Portland-Cement-112494/100570364
[35] Unit price of brick:
http://www.ebay.com/itm/Case-of-5-Fire-Bricks-Firebricks-8-3-4-x-4-3-8-x-1-1-4-/331914621863
[36] Unit price of 6-inch PVC pipe:
http://www.usplastic.com/catalog/item.aspx?itemid=38267&catid=727
[37] Unit price of reinforced steel bar:
http://www.recycleinme.com/scrapresources/DetailedPriceOther.aspx?psect=4&cat=Steel&subcat=Re
inforcing%20Bars
[38] Unit price of 6-inch PVC sewage pipe:
http://www.homedepot.com/p/JM-eagle-6-in-x-10-ft-PVC-Schedule-40-DWV-Foamcore-Plain-End-P
ipe-10181/100346975
[39] Unit price of 14-inch PVC sewage pipe:
http://www.usplastic.com/catalog/item.aspx?itemid=65220&catid=727
[40] Unit price of 6-inch perforated drain pipe:
http://www.homedepot.com/p/6-in-x-100-ft-Corex-Drain-Pipe-Perforated-6010100/100210876

[41] Biogas composition:
http://www.biogas-renewable-energy.info/biogas_composition.html
[42] Explanation of MMBTU:
http://www.indexmundi.com/commodities/glossary/mmbtu
[43] Average unit price of biogas:
https://www.socalgas.com/for-your-business/power-generation/biogas-biomethane
[44] Density of the organic material in post-treatment liquid effluent: Estimated Physical
Characteristic of Fertilizer Material. Paper
[45] Estimated unit price of liquid bio-fertilizer:
http://www.inbazar.biz/#!organic-fertilizers-from-china/cb74

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