1. Internship Report
Name: Pranav C Attavar
Branch: Chemical Engineering (2nd Year)
Institute: Chaitanya Bharati Institute of Technology
Company: Engineers India Limited (EIL)
Department: Environment
Training duration: 8 weeks (2 months)
Start Date: May 6th
End Date: June 28th
Mentor: Mr. P Parameswara Rao
Designation: Engineer
Field of Training: R&D
Area of work: Solid Waste Management with extensive
research on Anaerobic Digester.
Sewage Treatment Plant with A case
study of Bangalore.

2. INDEX
Acknowledgements
I would like to express my heartfelt gratitude to Mr. JK Joshi
(HOD) for giving me this opportunity to intern at this prestigious
consultancy firm. Apart from interacting with the best brains in the
country, I have also been acquainted with contemporary
technologies in the field of Chemical and Environmental
Engineering. A special thanks to Mr. Pari Vallal and Mr. P
Parameswara Rao for spending their valuable time and for
patiently explaining me the concepts when ever needed. Their
encouragement was undoubtedly my incentive to work harder and
make full use of this opportunity given to me.
S.no. Contents Page No.
1. Acknowledgement 2-3
2. Acronyms 3-4
3. Introduction 4-6
4. Solid Waste Management 6-8
5. Anaerobic Digester 8-22
6. A New Idea 22-24
7. Sewage Treatment Plant 24-30
8. Case Study of Bangalore 30-38
9. Improving the sewage condition 38-41
10. Conclusion 41-42
11. Bibliography 42-43

3. Acronyms
SWM: Solid Waste Management
MSW: Municipal Solid Waste
WTP: Waste Treatment Plant
RT: Retention Time
STP: Sewage Treatment Plant
LFG: Land Fill Gas
LPG: Liquefied Petroleum Gas
AD: Anaerobic Digester
CSTR: Continuous Stir Tank Reactor
UASB: Up flow Anaerobic Sludge Blanket
IL: Ionic Liquid
PPM: Parts Per Million
TDS: Total Dissolved Solids
TSS: Total Suspended Solids
BOD: Biological Oxygen Demand
COD: Chemical Oxygen Demand
SBT: Soil Bio Technology
TPD: Twin Pit Disposal

4. Introduction
In this Energy deficient era, energy from every possible source is
required to be exploited and experimented in the laboratories to
check its feasibility for commercialization. In today’s era, the fossil
fuels account for more than 82% of the world’s energy demand.
The remaining 18% is supplied by renewable sources which
include:
 Solar energy
 Wind energy
 Geothermal energy
 Oceanic energy
 Biomass energy
 Hydro energy
As man’s greed for development increased, so did the by-products.
Initially, the term waste engulfed within itself only a few
substances known to man like, human and animal waste (urine,
faeces), dead plants and animals, food waste etc. But, as man’s
greed for development increased so did the meaning of the term
waste. Now for all practical reasons, the term includes a much
wider area ranging from wastes like those from chemical factories,
pharmaceutical industries, paper and pulp industry etc, to solid
wastes like plastic, excrete, electronic items, wood, etc. During the
inception of industrialisation, the need for proper disposal of these
wastes and their potential was not known to mankind. However,
with rising environmental concern and energy deficiency, it has
become necessary to look into this matter in greater detail and to
exploit this potential energy source in every way possible. One
such way is “Solid Waste Management”. It is an ingenious method
of managing solid wastes produced as a result of human

5. endeavours on the path to development. This method includes
proper disposal of solid waste and also generation of alternate
energy (Biogas). This method has gained wide popularity in the
recent days and is studied extensively.
Sewage is another kind of waste which we come across in every
possible nation, irrespective of its developing or developed state.
STP can be considered another method of disposal of waste, this
time the waste includes the household waste, chemical waste, and
rainwater. Humans have known the importance of having a proper
sewage line since the dawn of civilisation. Evidence shows the
existence of sewer lines even during the Mesopotamian and Aryan
civilisation. The treatment of the sewer waste before disposal is a
necessity so as to prevent the disposal site from getting polluted.
The treatment includes many stages ranging from physical,
chemical to biological. The sewage treatment is a very important
factor in determining the socio-economic development of a nation.
Solid Waste Management
SWM is a method which was born during the inception of waste
management. It is an age old method of treating waste, which over
time gained many shapes and now is an ingenious method of waste
management. It not only addresses the issue of proper disposal of
waste, but also harnesses a potential energy source which can
provide energy which is sufficient for human needs. Solid waste
can be managed in a number of ways, viz.:
 Incineration
 Landfill
 Disposal into water bodies after treatment

6.  Land disposal
 Anaerobic digestion
Incineration
By etymology, incineration means “to burn”. The waste is dumped
in an open land and burnt / incinerated releasing green houses gases
like carbon dioxide, carbon monoxide, etc. To our dismay, this
method still finds its place in one of the contemporary methods,
primarily because of its simplicity and relatively less O&M cost. In
earlier days, incineration was widely used due to availability of
land. But the last few decades have seen drastic rise in population
and an acute shortage of land. This has compelled the previous
incinerators to switch to alternate solutions.
Landfill
It can be unequivocally claimed that this was the first solid disposal
method applied by mankind. It is easy, entailing disposal of waste
in a pit dug underground and covered by mud. This method gives
rise to public and environmental issues including:
 Shortage of land
 Release of poisonous gases into the environment
 Harmful effect of these gases on the surrounding
 Polluting nearby ground water
 Effecting the soil fertility
As the process takes place in the absence of air (anaerobic) it
releases bio-gas, due to breakdown of organic matter in the waste
by bacteria. Bio-gas consists of methane, carbon dioxide, hydrogen
sulphide, etc. which are potential green house gases. Moreover,
hydrogen sulphide is a poisonous gas. Release of these gases into

7. the atmosphere can cause serious problems to the environment and
adversely impact the existence of living organisms.
This method seems to be a deceivingly apt solution as the problem
(waste) is hidden from our sight.
Disposal into water bodies after treatment
This is the most widely used method especially for MSW and
chemical wastes. These wastes consist of many poisonous
substances which have to be treated in several stages before
disposal into water bodies. These stages include:
 Physical stage
 Chemical stage
 Biological stage
Physical stage involves the separation of big non-septic substances
like plastic, paper, wood, etc. The technical terminology for the
same is “Screening”. This is followed by the sedimentation process
where heavy sediments like sand, gravel, egg shells, grit, etc. are
removed.
The chemical process involves disinfecting the waste by the
addition of disinfectants like chlorine, chlorine dioxide, ozone, etc.
for treatment. It kills all the pathogens present in the waste and
makes it fit for disposal.
The ultimate step before disposal into water body is the biological
stage. In this stage the bacteria, both Aerobic and Anaerobic are
exploited by utilizing them to break down the organic substances in
the waste to release gases like Carbon dioxide, Methane, etc.,
which are used for other purposes.
Anaerobic Digestion

8. This is among the oldest of methods applied for treatment of waste
like cow dung, agricultural waste and human waste. This same
technology is now being extended to treat sewage waste instead of
simply disposing them into water bodies. This method works on the
principle that under anaerobic conditions, the anaerobes break
down the organic matter to release methane and other gases. These
gases are later used as a co-generator of electricity, fuel with the
contemporary coal and diesel.
Anaerobic Digester
Anaerobic digestion is a collection of processes wherein the
bacteria break down the organic substances present in the substrate
to finally release methane. The process is used for industrial or
domestic purposes to manage waste and or to produce fuels. Much
of the fermentation used industrially to produce food and beverage,
as well as home fermentation, uses anaerobic digestion. Sludge is
produced by anaerobic digestion. The process of digestion starts
with the “Hydrolysis” of the insoluble organic matter like
carbohydrates, proteins, fats which are broken down to smaller
monomers of sugar, fatty acids and amino acids. The next step is
“Acetogenisis” where the acetogenic bacteria break down the
above monomers to organic acid, ammonia and carbon dioxide.
This step is followed by “Acidogenisis”, where the acidogenic
bacteria break down the organic acid into acetic acid. The last and
most important step is “Methenogenisis” where the methanogens
convert the acetic acid into methane, hydrogen, carbon dioxide and
water. The completion of this process takes around 10-15 days
depending on the feed. The end product of this reaction is “Bio-
gas” which is used as a fuel for substituting various other fuels like
LPG, CNG, Diesel, etc. The nutrient rich sludge can be used as

9. manure after secondary treatment. Many microorganisms affect
anaerobic digestion, including acetic acid-forming bacteria
(acetogens) and methane-forming archae (methanogens). These
organisms promote a number of chemical processes in converting
the biomass to biogas. Gaseous oxygen is excluded from the
reactions by physical containment. Anaerobe utilizes electron
acceptors from sources other than oxygen gas. These acceptors can
be the organic material itself or may be supplied by
inorganic oxides from within the input material. When the oxygen
source in an anaerobic system is derived from the organic material
itself, the 'intermediate' end products are
primarily alcohols, aldehydes and organic acids, plus carbon
dioxide. In the presence of specialised methanogens, the
intermediates are converted to the 'final' end products of methane,
carbon dioxide, and trace levels of hydrogen sulphide. In an
anaerobic system, the majority of the chemical energy contained
within the starting material is released by methanogenic bacteria as
methane.
Populations of anaerobic bacteria typically take a significant period
of time to establish themselves to be fully effective. Therefore,
common practice is to introduce anaerobic bacteria from materials
with existing populations, a process known as "seeding", typically
accomplished by the addition of sewage sludge or cattle slurry.
Process flow of anaerobic digestion

10. Anaerobic digester can operate on a number of different process
configurations like:
 Entry of feed: Batch or continuous
 Temperature: Mesophilic or thermophilic
 Solids content: High solids or low solids
 Complexity: Single stage or multistage
Entry of Feed: Batch or Continuous
Anaerobic digestion can be performed as a batch process or a
continuous process. In a batch system biomass is added to the
reactor at the start of the process. The reactor is then sealed
for the duration of the process. In its simplest form, batch
processing needs inoculation (seeding) with already processed
material to start the anaerobic digestion. In a typical scenario,
biogas production will be formed with a normal
distribution pattern over time. This fact is used to determine
when the process of digestion of the organic matter has
completed. There can be severe odour issues if a batch reactor
is opened and emptied before the process is well completed.
The odour issues have been taken care of by re-circulating the
degasified percolate. This also increases the rate of production
of bio-gas and decreases the RT. This is an advanced
technology in the field of AD and is used on a pilot scale. In
continuous digestion processes, organic matter is constantly
added (continuous complete mixed) or added in stages to the

11. reactor (continuous plug flow; first in – first out). Here, the
end products are constantly or periodically removed, resulting
in constant production of biogas. A single or multiple
digesters in sequence may be used. Examples of this form of
anaerobic digestion include continuous stirred-tank reactors
(CSTR), up flow anaerobic sludge blankets
(UASB), expanded granular sludge beds (EGSB) and internal
circulation reactors (ICR).
Temperature: Mesophilic or Thermophilic
The temperature at which the digester runs is determined by
the majority of bacteria present in the digester. If majority of
the bacteria are mesophiles then it is mesophilic, else it is
thermophilic. A brief description is given below:
 Mesophilic: digestion takes place optimally around 30 to
38 °C, or at ambient temperatures between 20 and 45 °C,
where mesophiles are the primary microorganisms
present.
 Thermophilic: digestion takes place optimally around 49
to 57 °C, or at elevated temperatures up to 70 °C, where
thermophiles are the primary microorganisms present.
Mesophilic species outnumber thermophiles, and they are also
more tolerant to changes in environmental conditions than
thermophiles. Mesophilic systems are, therefore, considered
to be more stable than thermophilic digestion systems.
Though thermophilic digestion systems are considered to be
less stable and the energy input is higher, more energy is
removed from the organic matter. The increased temperatures
facilitate faster reaction rates and, hence, faster gas yields.
Operation at higher temperatures facilitates greater
sterilization of the end digestate. A drawback of operating at
thermophilic temperatures is that more heat energy input is
required to achieve the correct operational temperatures,

12. which may not be outweighed by the increase in the outputs
of biogas from the systems. Therefore, it is important to
consider an energy balance for these systems.
Solids content: High solids or low solids
In a typical scenario, three different operational parameters
are associated with the solids content of the feedstock to the
digesters:
 High solids (dry substrate)
 Medium solids (wet substrate)
 Low solids (wet substrate)
High solids (dry) digesters are designed to process materials
with solid content between 25 and 40%. Unlike wet digesters
that have digestible slurries, high solids (dry – stackable
substrate) digesters are designed to process solid substrates
without the addition of water. The primary styles of dry
digesters are continuous vertical plug flow and batch tunnel
horizontal digesters. Continuous vertical plug flow digesters
are upright, cylindrical tanks where feedstock is continuously
fed into the top of the digester, and flows downward by
gravity during digestion. In batch tunnel digesters, the
feedstock is deposited in tunnel-like chambers with a gas-tight
door. Neither approach has mixing inside the digester. The
amount of pre-treatment, such as contaminant removal,
depends both upon the nature of the waste streams being
processed and the desired quality of the digestate. Size
reduction (grinding) is beneficial in continuous vertical
systems, as it accelerates digestion, while batch systems avoid
grinding and instead require structure (e.g. yard waste) to
reduce compaction of the stacked pile. Continuous vertical
dry digesters have a smaller footprint due to the shorter
effective retention time and vertical design. Wet digesters can
be designed to operate in either a high-solids content, with
a total suspended solids (TSS) concentration greater than

13. 20%, or a low-solids concentration less than 15%.High solids
(wet) digesters process a thick slurry that requires more
energy input to move and process the feedstock. The thickness
of the material may also lead to associated problems with
abrasion. High solids digesters will typically have a lower
land requirement due to the lower volumes associated with the
moisture. High solids digesters also require correction of
conventional performance calculations (e.g. gas production,
retention time, kinetics, etc.) originally based on very dilute
sewage digestion concepts, since larger fractions of the
feedstock mass are potentially convertible to biogas. Low
solids (wet) digesters can transport material through the
system using standard pumps that require significantly lower
energy input. Low solids digesters require a larger amount of
land than high solids due to the increased volumes associated
with the increased liquid-feedstock ratio of the digesters.
There are benefits associated with operation in a liquid
environment, as it enables more thorough circulation of
materials and contact between the bacteria and their food.
This enables the bacteria to more readily access the
substances on which they are feeding (substrate), and
increases the rate of gas production.
Complexity: Single stage or multistage
In a single-stage digestion system (one-stage), all of the
biological reactions occur within a single, sealed reactor or
holding tank. Using a single stage reduces construction costs,
but results in less control of the reactions occurring within the
system. Acidogenic bacteria, through the production of acids,
reduce the pH of the tank. Methanogenic bacteria, as outlined
earlier, operate in a strictly defined pH range. Therefore, the
biological reactions of the different species in a single-stage
reactor can be in direct competition with each other. Another
one-stage reaction system is an anaerobic lagoon. These
lagoons are pond-like, earthen basins used for the treatment

14. and long-term storage of manures. Here the anaerobic
reactions are contained within the natural anaerobic sludge
contained in the pool.
In a two-stage digestion system (multistage), different
digestion vessels are optimised to bring maximum control
over the bacterial communities living within the digesters.
Acidogenic bacteria produce organic acids and more quickly
grow and reproduce than methanogenic bacteria.
Methanogenic bacteria require stable pH and temperature to
optimise their performance. Under typical circumstances,
hydrolysis, acetogenesis, and acidogenesis occur within the
first reaction vessel. The organic material is then heated to the
required operational temperature (either mesophilic or
thermophilic) prior to being pumped into a methanogenic
reactor. The initial hydrolysis or acid genesis tanks prior to
the methanogenic reactor can provide a buffer to the rate at
which feedstock is added. Some European countries require a
degree of elevated heat treatment to kill harmful bacteria in
the input waste. In this instance, there may be a pasteurisation
or sterilisation stage prior to digestion or between the two
digestion tanks. Notably, it is not possible to completely
isolate the different reaction phases, and often some biogas is
produced in the hydrolysis or acidogenesis tanks.
Retention Time
It is the amount of time required by the bacteria to break down
the organic matter present in the substrate to release bio-gas.
The RT of a plant depends on various factors including
 Type of feed
 Temperature

15.  Concentration of bacteria
 Chemical composition of feed
 Digester design
 Bacterial competition etc.
The retention time can be reduced drastically by adding a
“starter”, a starter is basically any methanogenic rich substrate
like cow dung, human waste etc. It initiates the reaction and
helps the bacteria multiply faster. In the case of single-stage
thermophilic digestion, retention time may be in the region of
14 days, which, compared to mesophilic digestion, is
relatively fast. The plug-flow nature of some of these systems
will mean the full degradation of the material may not have
been realised in this timescale. In this event, digestate exiting
the system will be darker in colour and will typically have
higher foul odour. In two-stage mesophilic digestion,
retention time may vary between 15 and 40 days. In the case
of mesophilic UASB digestion, hydraulic retention times can
be 1 hour to 1 day, and solid retention times can be up to 90
days. In this manner, the UASB system is able to separate
solids and hydraulic retention times with the use of sludge
blanket. Continuous digesters have mechanical or hydraulic
devices, depending on the level of solids in the material, to
mix the contents, enabling the bacteria and the food to be in
contact. They also allow excess material to be continuously
extracted to maintain a reasonably constant volume within the
digestion tanks.
Feed to the Digester
This is a very vital component in determining the bio-gas
composition and the extent of production. Almost any organic
material can be processed with anaerobic digestion however,
if biogas production is the aim, the level of digestibility is the
key factor in its successful application. The more digestible
the material, the higher the gas yields possible from the

16. system. Feed-stocks can include biodegradable waste
materials, such as waste paper, grass clippings, leftover food,
sewage, and animal waste. Woody wastes are the exception,
because they are largely unaffected by digestion, as most
anaerobes are unable to degrade lignin. Xylophalgeous
anaerobes (lignin consumers) or using high temperature pre-
treatment, such as pyrolysis, can be used to break down the
lignin. Anaerobic digesters can also be fed with specially
grown energy crops, such as silage, for dedicated biogas
production. Anaerobes can break down material with varying
degrees of success from readily, in the case of short-chain
hydrocarbons such as sugars, to over longer periods of time,
in the case of cellulose and hemicelluloses. Anaerobic
microorganisms are unable to break down long-chain woody
molecules, such as lignin, cellulose etc.AD were designed for
sewage treatment, but the waste in the sewage has already lost
all its potential/energy to the animal. Hence, a mixed feed is
preferred like grass and corn (typical on-farm feedstock), or
various organic by-products, such as slaughterhouse waste,
fats, oils and grease from restaurants, organic household
waste, etc. (typical off-site feedstock).
Application of AD
The purpose of AD has changed over the years. It was initially
designed only for treating sewage waste and later has evolved
for treatment of all kinds of industrial wastes and also as a
source of alternate energy (Bio-Gas) production. It finds its
application in the following areas:
 Replacement of fossil fuels.
 Eliminating the energy footprint of WTP.
 Reducing methane emission from landfills.
 Displacing industrially produced chemical fertilizers.
 Reducing usage of LPG for cooking.

17. Treatment of waste
AD presents a major solution for treatment and proper
disposal of waste. It removes all the pathogens and harmful
gases from the substrate in the digestion process and makes
the sludge fit for disposal. The RT for the above process to
take place naturally is high (around 1-3 years). Catalysts like
Water Hyacinth and duck weed are added to enhance the
production of Bio-Gas and also decrease the RT for dis-
infecting the substrate. This sludge can then be used as
manure and can replace the chemical fertilizers. This can be
an incentive towards a greener future.
Power Generation
Biogas from sewage works is sometimes used to run a gas
engine to produce electrical power, some or all of which can
be used to run the sewage works. Some waste heat from the
engine is then used to heat the digester. The waste heat is, in
general, enough to heat the digester to the required
temperatures. The power potential from sewage works is
limited – in the UK, there are about 80 MW total of such
generation, with the potential to increase to 150 MW, which is
insignificant compared to the average power demand in the
UK of about 35,000 MW. The scope for biogas generation
from non-sewage waste biological matter – energy crops, food
waste, abattoir waste, etc. - is much higher, estimated to be
capable of about 3,000 MW. Farm biogas plants using animal
waste and energy crops are expected to contribute to reducing
CO2 emissions and strengthen the grid, while providing UK
farmers with additional revenues.
Usage of bio-gas for generation of power depends on the
composition of the gas, which in turn depends on the type of
feed. When the feed is organic waste like urine, faeces,
agricultural waste etc then the bio-Gas has about 0.01% of
hydrogen sulphide. A maximum of 30 ppm is allowed for the

18. use of Bio-gas as a fuel in generator. Higher concentrations of
hydrogen sulphide can result to corrosion of the engine.
Products and By-products
Bio Gas
The ultimate product of AD is Bio Gas. It primarily
constitutes Methane, Carbon dioxide, Hydrogen sulphide and
other trace gases like carbon monoxide, nitrogen, oxygen,
hydrogen. This gas has a much higher calorific value than
LPG and achieves flame temperatures of around 120+. Most
of the biogas is produced during the middle of the digestion,
after the bacterial population has grown, and tapers off as the
digestible material is exhausted. The gas is normally stored on
top of the digester in an inflatable gas bubble or extracted and
stored next to the facility in a gas holder. Bio gas is
considered an alternate fuel and is useful in producing
electricity which can be added to the power grid to reduce the
dependence on non-renewable fuel. It requires further
scrubbing for the removal of hydrogen sulphide, which
happens to be a poisonous gas and causes harm to both animal
life and machines when the concentration is above 0.2%.
Digestate
Digestate is the solid remains of the original input material to
the digesters that the microbes cannot use. It also consists of
the mineralised remains of the dead bacteria from within the
digesters. Digestate can come in three forms: fibrous, liquor,
or a sludge-based (combination of the two fractions). In two-
stage systems, different forms of digestate come from
different digestion tanks. In single-stage digestion systems,
the two fractions will be combined and, if desired, separated
by further processing. Sludge is an excellent source of organic
manure after it dries. In the pre-treatment stages, the waste
consists of pathogens and other harmful chemicals associated

19. with it. After storage for a gestation period of 1-3 years, it is
removed and can be directly used as manure.
AD Construction for Human Excrete
The human excrete is a rich source of organic matter and
hence has a high BOD. This fact can be exploited for the
production of bio gas. Typically, two types of AD exist for
domestic purposes namely
 Floating drum type Bio Gas Plant
 Deenbandhu type Bio Gas plant.
The latter is a developed version of the former. A
Deenbandhu type Bio Gas plant has a fixed Gas Bubble which
stores the gas and has an input pipe for the inlet of feed. The
pressure developed by the gas forces the liquid in the sludge
to accumulate in the collection tank for further treatment. A
typically Deenbandhu type model is suggested for a
population of 900 people.
Process description
The digester is initially filled with 5kg of cow dung which
acts as a starter for the digestion process. The feed is sent into
the digester through a 300 mm PVC pipe, this feed mixes with
the cow dung and the digestion process starts. A residual time
of 2-4 days is considered and the produced bio gas is removed
from the digester using a pipe and is stored in the Gas
Storage. The bio gas creates a positive pressure on the liquid
in the sludge. This pushes the water into the collection which
is sent for further treatment. The solids in the sludge are taken
out by using a 250 mm PVC and a pump, these solids are
stored and are converted to manure over a period of time. The
secondary treatment of the water includes sedimentation,
filtration, and UV filtration. The water can be used for
domestic purposes.

20. Process Flow Diagram
Process Flow Diagram
StorageTank Digester
CollectionTank for Liquid
Secondary Treatment
(Sedimentation,sand
filteration,aeration,UV
filter)
From the Waste
Generating
source(Washroom
and Kitchen)
Solid From
Sludge
Manure
Equipment Required
Equipment Required
PVC (300 mm)
PVC (250 mm)
PVC (150 mm)
Pump (50 LPM,24 barr)
Concrete
RCC Slab
Design statistics
Storage tank design
Storage Tank Dimension Units
Internal length 2.2 Meters
External length 2.35 Meters
Height 2 Meters

21. Breadth 2.2 Meters
Volume 2.2*2*2.2 Cu. M.
Digester tank design
Digester Dimension Units
External diameter 1.15 Meters
Internal diameter 1.00 Meters
Height 4.00 Meters
Volume 25 Cu. M.
Inlet of Feed above base of
Digester
0.75 Meters
Outlet of Liquid from base 1.2 Meters
Collection Tank
Collection Tank Dimension Units
Internal length 1.2 Meters
External length 1.35 Meters
Height 2 Meters
Breadth 1.2 Meters
Volume 1.2*2*1.2 Cu. M.
Chemical Composition of Gas

22. Composition of Gas Percentage by
Volume
Methane 60-65%
Carbon dioxide 30-38%
Hydrogen Sulphide <10ppm
Oxygen <0.5%
Nitrogen <0.5%
Carbon monoxide Negligible
Hydrogen Negligible
A New Idea
Contemporary methods of using bio gas involve its production
from AD and then sending the produced gas to a scrubber
which scrubs the hydrogen sulphide gas from the feed. The
scrubbing reduces the concentration to about 0.01% or less.
Initially, the concentration of the gas in the feed is about 1%
(10,000ppm) for a typical sewage feed. The general process
includes chemical or biological scrubbing. Chemical
scrubbing involves using Sodium Hydroxide and ferric
Chloride as the scrubbing agent. The product is Bio CNG and
is free of Hydrogen Sulphide. The biological method includes
addition of bacteria, nutrient and air. The bacteria convert
sulphide to sulphate and reduce the poisonous gas up to 99%.
Another method proposed is the one by using IL. Ionic liquids
are salt solutions which are excellent absorbers. They
completely absorb the required gas from a mixture of gases.
One such IL is 1-n-butyl 3-ethylimidazolium
hexaflourophosphate. This IL is an excellent absorber of
Hydrogen Sulphide and Carbon Di Oxide gas. This property
can be exploited to remove both these gases from the Bio-Gas
in the plant itself. A membrane carrying this fluid can run
through the gas bubble and can absorb these gases and reduce

23. the cost on scrubbing. The bio-gas can be directly sent for
conversion into fuel. IL’s are much more cost effective than
the contemporary methods and can be very useful in an
economic point of view.
Sewage Treatment Plant
Sewage treatment is an integral part of our society. Since
ages, mankind has been developing methods to treat the
sewage waste. Sewage systems came into existence from as
long as the Mesopotamian and ancient Greek civilisation. The
only thing that has changed over time is the way the sewage is
being managed and the various treatment processes. Over the
years, the word sewage has engulfed in itself many products
ranging from human waste to chemical waste. Initially,
sewage waste included only human and animal waste, but as
society developed and industrialisation began to show its
fruits, many other products like paper waste, pharmaceutical
waste, Agro based waste, Chemical waste etc were included.
A typical sewage waste can be categorised into three
categories namely
 Low strength sewage waste
 Medium strength sewage waste
 High strength sewage waste
These categories are based on the strength of the sewage.
Strength includes in itself the BOD, COD, TSS, TDS etc.
Before the waste can be disposed into water bodies, it must
meet the effluent characteristics set by the environment
department of the country. The effluent characteristics vary
according to the surrounding environment and hence are
different for different countries. The treatment of sewage
includes physical treatment, chemical treatment and biological
treatment. Physical treatment encapsulates in itself screen
separation, grit separation, sedimentation, clarification etc.
Chemical includes sedimentation by alum, sludge thickening,

24. sludge drying etc. The biological includes sludge digestion,
aeration. These three processes together reduce the
contaminants by a considerable amount and make it fit for
disposal. The general disposal sites include lakes, ponds, river
stream, oceans, seas etc. The natural process of cleaning in
flowing streams is another method applied for the cleaning of
sewage water. The sewage system is managed separately by
the municipal co-operation of the state which has a separate
body for the water supply and sewage treatment of the place.
The basic idea followed by the government is to reduce the
contaminant level and then disposing the sewage into water
source. This is a waste of the degradable material in the
sewage waste. After the first stage of screening, the solid
waste is thrown into dumping lands and is then incinerated to
reduce the volume of the waste. The ability to generate biogas
is still latent in materials like Human waste, Cow dung,
Food/Agro waste etc. When these materials are degraded an-
aerobically, they release bio-gas which is an excellent
substitute for the contemporary fossil fuels.
Process Description
Sewage can be treated close to the source of production like in
septic tanks, bio-filters or aerobic treatment systems, or be
collected and transported to a nearby municipal treatment
plant (MTP).Sewage collection and treatment is typically
subjected to local, state and central regulations and standards.
Industrial sources of sewage often require specialized
treatment processes. Sewage treatment generally involves
three stages, called primary, secondary and tertiary treatment.
 Primary treatment consists of temporarily holding the
sewage in a basin where heavy solids can settle to the
bottom while oil, grease and lighter solids float to the
surface. The settled and floating materials are removed

25. and the remaining liquid may be discharged or subjected
to secondary treatment.
 Secondary treatment removes dissolved and suspended
biological matter. Secondary treatment is typically
performed by water-borne micro-organisms in a
controlled environment. Secondary treatment may
require a separation process to remove the micro-
organisms from the treated water prior to discharge or
tertiary treatment.
 Tertiary treatment is sometimes defined as anything
more than primary and secondary treatment in order to
allow rejection into a highly sensitive ecosystem (rivers,
inland ponds, Lakes etc). Treated water is sometimes
disinfected chemically or physically (for example, by
lagoons and microfiltration) prior to discharge into a
stream, river, bay, lagoon or wetland, or it can be used
for the irrigation of a golf course, green way or park. If it
is sufficiently clean, it can also be used for groundwater
recharge or agricultural purposes.
A typical sewage treatment plant includes the following
processes.
 Screening
 Grit removal
 Flow equalization
 Grease and oil removal
 Sedimentation
 Aeration
 Secondary clarification
 Sludge thickening
 Sludge digestion
 Sludge drying
Screening

26. This is the first process which removes the large solid waste
like paper, plastic, wood pieces etc. It basically consists of
iron rods of 40 mm dia placed at a distance of 20 mm each.
The solids get stuck to this and can be removes manually or
mechanically. These solids are then removed from the screens
and are sent to the dumping lands for disposal. These screens
are placed along the pipeline and they reduce the TSS of the
sewage.
Grit Removal
The heavy in-organic solids like gravel, glass, egg shell, sand,
grit etc can be removed by using sedimentation. The
sedimentation time is less than 60 seconds and is very
effective. Grit removal takes place in the settling tank. These
pre-treatment processes are very useful in reducing the
sewage feed to the required feed.
Flow equalization
The clarifiers and the secondary treatment work better when
the flow is uniform. For this purpose a flow basin can be used
which stores the sewage on a temporary basis and can adjust
the sewage flow for further treatment. In this way, the plant
can run even during maintenance and also increases the
efficiency of the treatment.
Grease and oil removal
The grease, oil and fats present in the sewage can pose a
serious threat in an environment point of view. They can be
removed by using skimmers and air blowers which collect the
fat, oil and grease as froth. These processes generally take
place in primary clarifiers. It is generally present in the
downstream of the pre-treatment.
Sedimentation or primary clarifiers

27. In this process the lighter in-organic substance are removed
and generally has a residual time of 2-2.5 hours. This is an
effective method for reducing the BOD by 30-35%. These are
done in the settling tank which is equipped with mechanically
driven scrappers. These scrappers ensure that the sludge is
effectively removed and sent for secondary treatment if
required.
Aeration
The aerobic bacteria present in the sewage uses the oxygen to
break down the organic matter and helps to release carbon
dioxide, ammonia, water etc. Air is bubbled into the tank with
the help of aerators which are present at the bottom of the
tank. This helps in reducing the organic matter present in the
sewage and hence decreasing the BOD levels. The aerobic
method is preferred over the an-aerobic one because of the
RT. Aerobic has a much less RT and even lesser odour
problems.
Secondary clarification
The secondary treatment is designed for the treatment of
biological content of the sewage. This is generally originated
from the organic matter like human waste, animal waste etc.
The secondary treatment includes in itself trickling filters.
These wastes are removed by the an-aerobic and aerobic
bacteria present in the sewage. The filter removes a small
percentage of organic matter and the rest are removed by the
bacteria through oxidation, nitrification etc.
Sludge Disposal
When a liquid sludge is produced, further treatment may be
required to make it suitable for final disposal. Typically,
sludge is thickened to reduce the volumes transported off-site
for disposal. There is no process which completely eliminates

28. the need for dispose of bio solids. There is however, an
additional step involving the superheating of sludge and
converting it into small pelletized granules that are high in
nitrogen and other organic materials. In New York City, for
example, several sewage treatment plants have dewatering
facilities that use large centrifuges along with the addition of
chemicals such as polymer to further remove liquid from the
sludge. The removed fluid, called concentrate, is typically
reintroduced into the wastewater process. The product which
is left is called cake and that is picked up by companies which
turn it into fertilizer pellets. This product is then sold to local
farmers and turf farms as fertilizer, reducing the amount of
space required to dispose of sludge in landfills. Most of the
sludge originating from commercial or industrial areas is
contaminated with toxic materials that are released into the
sewers from the industrial processes. Elevated concentrations
of such materials may make the sludge unsuitable for
agricultural use and it may then have to be incinerated or
disposed of to landfill.
Natural Treatment of Waste Water
Many processes in the wastewater treatment plant are
designed to mimic the natural treatment processes that occur
in the environment, whether that environment is a natural
water body or the ground. If not overloaded, bacteria in the
environment will consume organic contaminants, although
this will reduce the levels of oxygen in the water and may
significantly change the overall ecology of the receiving
water. Bacterial populations feed on the organic contaminants,
and the numbers of disease-causing microorganisms are
reduced by natural environmental conditions such as
predation or exposure to ultraviolet radiation. Consequently,
in cases where the receiving environment provides a high
level of dilution, a high degree of wastewater treatment may
not be required. In the US and EU, uncontrolled discharges of

29. wastewater to the environment are not permitted under law,
and strict water quality requirements are to be met, as clean
drinking water is essential. A significant threat in the coming
decades will be the increasing uncontrolled discharges of
wastewater within rapidly developing countries.
Case Study- Bangalore
Bangalore is located on the watershed of two rivers arkavathi
and pennar. The city has three main valleys and the landscape
gradually reduces its inclination towards the south. The Three
principal valleys are known as Vrishabhavathi, Koramangala
and Chellaghatta and three valleys run generally in a north to
the south direction and divide the greater part of the
metropolitan area which lies to the south of the ridge into
three separate and distinct drainage zones. A fourth valley
system referred to as the Hebbal series forms drainage zone to
the north of the ridge and runs in north easterly direction. Five
minor valleys, the Kathriguppa and Tavarekere to the south,
the Arkavathi and Kethamaranahally to the northwest and
Marathhally to the east, lie outside the tributary area of the
major valleys and they drain independently to the other areas
which form the remainder of the metropolitan area. The
natural topography of the city has given it a natural hydraulic
gradient and avoids the usage of pumps. Both sewerage and
storm water flow by gravity beyond the city. The system of
sewers for the conveyance of domestic and industrial waste
water through underground drainage system was introduced in
the year 1922. The system introduced initially was confined to
heavily populated area in the heart of the city and although a
gradual increase was noted then onwards. It was not until
1950 that a major programme of sewer construction was
commenced. With the formation of the Board (BWSSB) in
1964, the programme to provide Sewerage system in the un-
sewered areas was taken up on a large scale and the treatment
of sewage before it is led into the natural valleys was also

30. handled. At present, Bangalore city has a well designed and
regularly maintained underground sewerage system (for only
40% of the city). Stoneware pipes are used (300 mm dia.)
RCC pipes varying (300 mm to 2100 mm) for sub-
mains/mains/outfall sewers. In order to facilitate easy cleaning
in sewer lines whenever blockage occurs, adequate manholes
are provided at regular intervals. Manholes with cast iron
frames and covers are provided in heavy traffic roads, on
small lanes and cross roads with less traffic with RCC frames
and covers for the manholes. In the time period of 1970 to
1980, two primary treatment plants at K & C Valley
and V Valley were established. Subsequently, the above
treatment plants were upgraded to Secondary level and one
more treatment plant was established at Hebbal. Two Tertiary
level treatment plants were established for recycling of
wastewater under Cauvery Water Supply Scheme (CWSS)
Stage II, Stage III and Indo French Protocol i.e. prior to
CWSS Stage IV Phase I. There was rapid growth
in the city forcing the Board to augment water to an extent of
270 MLD from the River Cauvery. The project was taken up
under CWSS Stage IV Phase I. The additional water supplied
to the city in turn converts in to wastewater and there was
necessity to convey and treat this additional wastewater. For
treating this Board has constructed seven treatment plants.
The details treatment plants are furnished below.
Wastewater Treatment Plants:
1) Koramangala and Challaghatta Valley treatment plant-248MLD
2) Vrishabhavathi valley treatment plant – 180 MLD
3) Hebbal valley treatment plant – 60 MLD
4) Madivala water reclamation plant – 4 MLD
5) Kempambudhi water reclamation plant – 1 MLD
6) Yelahanka Tertiary treatment plant – 10 MLD.
7) Mylasandra – 75 MLD
8) Kadabesanahalli – 50 MLD
9) KrishnarajaPurum – 20 MLD

31. 10) Jakkur – 10 MLD
11) Raja canal – 40 MLD
12) Nagasandra – 20 MLD
13) Cubbon Park – 1.50 MLD
14) Lalbagh – 1.50 MLD
Total – 721 MLD.
Contemporary treatment process
The contemporary methods applied for the treatment of sewer is
mentioned below:
1) Screening
2) Grit removal
3) Primary clarification
4) Aerobic process (Trickling filters)
5) Secondary clarification
6) Sludge thickening
7) Sludge digesting
8) Sludge drying.
The above mentioned processes are briefly described below:
Screening: Screening is adopted to remove larger floating solids
and organic solids, which are not digestible. The screens are
basically flat iron rods welded to the horizontal bars. They are 40
mm in diameter and are placed at an equal interval of 20 mm.
These screens are placed perpendicular to the direction of flow
and floating matter stuck to the screens is removed manually/
mechanically. The screenings are disposed off as land fill or sent
to AD for generation of Biogas, the choice depends on the type of
material retrieved from the screen.
Grit removal: The heavier inorganic matters are removed in this

32. process. The heavier inorganic matters like grit, sand, egg shells,
gravel etc are removed by sedimentation of the particles which can
settle in basin in time of 60 seconds. The settled matter will be
pushed to the sides and classifiers will transport the matter to the
required place.
Primary clarification: Primary clarifier is settling basin where
inorganic matter will settle. The RT in this tank is 2 to 2.5 hours.
The clarifiers may be of circular or rectangular in shape. The
settled matter will be scraped to the centre by the raker arms and
the primary sludge will be taken to the primary sludge pump
house to pump the sludge to sludge digesters. In primary clarifiers
about 30 – 35% of the BOD and 60 – 65% of the TSS are
removed.
Aerobic Process: Aerobic process takes place in the presence of
aerobic microorganisms. These bacteria are present in abundance
in the substrate and when they come in contact with polymers like
carbohydrates, fats, proteins etc, they break them down into
monomers and releases carbon dioxide, ammonia and water as the
end product. The biological process converts the polymers into
finely divided organic matter which can be easily removed by the
process of sedimentation. The oxygen required for the biological
process is supplied by surface aerators installed in the basin. The
surface aerator will suck the wastewater from the bottom of the
tank and splashes it over the surface of the aeration tank. The tiny
molecules of wastewater will absorb oxygen from the atmosphere
before dropping into the aeration tank. The biomass from the
aerated wastewater is separated in the secondary Clarifier and
recycled continuously to the aeration tank.
Secondary clarifiers: Secondary Clarifier is a settling basin
where organic matter settles down by the virtue of gravity. The RT

33. is about 1.5 to 2.0 hours. The Clarifier is circular in shape to
promote the easiness of scrapping the settled matter to the centre
with the help of raker arms. The secondary sludge will be taken to
the recirculation sludge pump house to pump the sludge to
Aeration tank or Trickling filters, excess sludge is pumped to
sludge thickeners. In secondary clarifiers about 80 – 90% of the
BOD and 80–90% of the TSS is removed.
Sludge Thickening: Sludge thickener is used to separate excess
water content in the sludge. The effluent will be taken back to
drier and thickened sludge will be pumped to sludge digester.
Sludge Digester: The sludge digester is an AD where sludge is
digested. The digested sludge will be taken to the drying beds for
drying.
Sludge Drying Beds: The digested sludge will be spread over
boulder, sand media for drying. The dried sludge will be used as
manure. This is an excellent alternative for the chemical
manure/fertilizer.
Tertiary Treatment: In the Tertiary treatment, the BOD and TSS
will be brought down to less than 5 mg/ L by using chlorine as a
disinfectant. Currently two tertiary treatment plants are installed in
order to save precious water which is used for non–potable
purposes. The tertiary treated water is supplied to industries for
non–potable purposes such as gardening, cooling purposes, floor
washing, vehicle washing etc.
A description of the working of WTP is given below:
1) Koramangal & Challaghatta Valley treatment plant (248 MLD)
To treat the wastewater generated in the Koramangala and
Challaghatta valley, WTP at B Nagasandra has been established.
Primary treatment plant was established during 1974 and it was

34. upgraded to Secondary level during 1990. The capacity of the
treatment plant was 163 MLD and the treatment process adopted
was Conventional Activated Sludge Process. Under Cauvery
Water Supply Scheme (CWSS) Stage IV Phase I, one more plant
of 30 MLD was established and Extended Aeration process was
adopted. Since the flow into the plant was exceeding 163 MLD,
another plant of 55 MLD was provided during 2006. Thus, the
total capacity of the treatment facility available is 248
MLD.
2) Vrishabhavathi valley treatment plant (180 MLD)
For treating the wastewater generated in the western part of the
city, a primary treatment plant was established near
Nayandanahalli on the Mysore Road. It was upgraded to
Secondary level and Trickling filter process was adopted.
Due to the existing demand for the Tertiary treated wastewater, a
plant of 60 MLD was established during 2004 under Indo French
Protocol. The tertiary treated water would be supplied to the
upcoming Power plant near Bidadi as raw water.
3) Hebbal valley treatment plant (60MLD)
Hebbal wastewater treatment plant was established to treat the
wastewater generated in the Northern part of the city. The capacity
was 60 MLD and Conventional Activated Sludge process was
adopted, the treated wastewater is let into Nagavara Lake.
4) Madivala water reclamation plant (4MLD)
The Madivala Lake is in the Southern part of the city and is one of
the biggest lakes in the city. There was no fresh water source
during non rainy days. Hence, to replenish the lake, a wastewater
treatment plant of 4 MLD was established

35. with a UASB Reactor. The treated wastewater from UASB is
further polished in Oxidation ponds. The outlet from the Oxidation
ponds is let into Wet lands and the over flow from the wet land
system will enter the main Lake.
5) Kempambudhi water reclamation plant (1MLD)
Kempambudhi Lake exists in the southern part of the city and is
deficient of fresh water. Hence, a 1 MLD water reclamation plant
was established with extended aeration process. This plant
replenishes the ground water level and increase the fresh water
source.
6) Yelahanka Tertiary treatment plant (10MLD)
Bangalore International Airport was proposed near Devanhalli and
authorities wanted treated wastewater as a raw material for
construction. Hence, steps were taken to establish a tertiary
treatment plant near the New Town area of Yelahanka. The 10
MLD treatment plant was established with Conventional
Activated Sludge Process followed by filtration
and disinfection. The treated wastewater is supplied to BIAL,
Bharth Electronic Limited, Indian Tobacco Company, Rail Wheel
Factory and Indian Air Force as raw water.
7) Mylasandra (75MLD)
On the downstream of V Valley treatment plant another treatment
plant of 75 MLD was established with Extended Aeration process
under CWSS Stage IV Phase I. The treated wastewater is let into
Vrishabhavathi valley.
8) Kadabeesanahalli (50MLD)

36. Kadabeesanahalli wastewater treatment plant was established to
treat the wastewater generated in the eastern part of the city. It was
established under CWSS Stage IV Phase I with extended Aeration
process.
9) KrishnarajaPurum (20MLD)
This plant was established under CWSS Stage IV Phase I with
UASB process. The wastewater of the eastern part is being treated
in this plant.
10) Jakkur (10MLD)
The wastewater from northern part of the city flows into this plant
which has been established under CWSS Stage IV Phase I. UASB
is the treatment process adopted in this plant.
11) Raja canal (40 MLD)
Raja Canal treatment plant is of 40 MLD plant and is of
Extended Aeration Process. The north eastern parts
wastewater flows into this plant.
12) Nagasandra (20 MLD)
Nagasandra plant was built on Tumkur road to treat the
wastewater generated on the western part of the city. The
treatment plant is provided with extended aeration system.
13) Cubbon Park (1.50 MLD)
Cubbon Park is one of the prime parks of Bangalore and it is
located in the heart of the city. The deficiency of water was
the incentive for the establishment of a tertiary treatment plant
in the region. Membrane technology is adopted in this plant

37. and treated water is being disinfected. The treated water is
being supplied to the plants and to keep the Park green.
14) Lalbagh (1.50 MLD)
Lalbagh is the largest park in Bangalore with an acute water
shortage problem, to meet the water demands a 1.50 MLD
treatment plant was established with extended aeration
process. The treated wastewater is filtered and disinfected
with UV Rays.
Epitome of the technologies used in STP
Plant Capacity(MLD) Technology
Vrishabhavathi
Valley
180 Secondary (Trickling filters)
K & C Valley 248 Secondary (Activated sludge)
Hebbal Valley 60 Secondary (Activated sludge)
Madivala 04 Secondary (UASB+Oxidation)
Kempambudhi 01 Secondary(Extended aerated)
Yelahanka 10 Activated sludge
Mylasandra 75 Secondary(Extended aeration)
Nagasandra 20 Secondary (Extended aeration)
Jakkur 10 Secondary (UASB+Extended)
K. R. Puram 20 Secondary (UASB+Extended)
Kadabeesanahalli 50 Secondary (Extended aerated)
Raja canal 40 Secondary (Extended aerated)
Cubbon Park 1.5 Membrane bio reactor
Lalbagh 1.5 Extended aeration + plate
settlers
Characteristics of Sewage water:
Parameter Average Value (mg/l)
TSS 650
TDS 1500-3000

38. Ph 7-9
Oil and Grease 10-15
Ammonical nitrogen 25-40
Total kjeldahal nitrogen 30-85
Free nitrogen 5-25
BOD 400
COD 300-1000
Sulphates 10-60
Chlorides 1-6
Nitrate nitrogen 90-120
Desired effluent characteristics:
Parameter Value (mg/l)
TSS <30
TDS 1000
Ph 5.5-9
Oil and Grease <10
Ammonical Nitrogen <50
Total kjeldahal nitrogen <100
Free nitrogen <5
BOD <20
COD <250
Sulphates <2
Chlorides <1
Nitrate Nitrogen <10
Present scenario
The existing sewage system was planned and implemented
about 30 years ago. Initially, the city occupied an area of 598
km2 which is about 25% of the present area. This throws light

39. on the fact that more than 70% of the city lacks proper sewage
lines and are still practising traditional methods of urinating in
the open and polluting the surrounding. The sewage lines
receive only 43% of the generated waste. The remainder is
directly dumped into water bodies without ant treatment. This
not only affects the aquatic life, but also pollutes the
environment and increases the concern for proper sanitation.
A very common, yet regretted condition is the blockage of
sewage lines. The lines were constructed such that, it will
carry the sewage without any blockage only if the 150 litres of
sewage liquid is produced per person per day. This outrageous
figure is very difficult to accomplish and hence causing
blockage. There are 17 STP having of total capacity of 721
MLD, but this figure seems to be more theoretical than actual.
In reality, these STP are only treating 251 MLD which is
about 32% of the installed capacity.
Improving the sewage condition
With the present prevailing conditions, it is logically viable to
implement back yard methods to improve the sewage
conditions in the city. As more than 70% of the city is devoid
of a proper sewage system, more R&D in sanitation and
economical technologies is important. A few such
technologies are mentioned below
 Soil Bio Technology
 Honey Suckers
 AD
 Twin Pit Disposal
Soil Bio Technology (SBT)
SBT is an ingenious way of treating the sewage waste by
using natural cleansing processes. It utilises the natural
cleansing bacteria present in the soil and also uses sand,
gravel as a filter source. The waste water is spread over a

40. small area having natural soil around it, the various aerobic
bacteria present in the sand breakdown the organic matter and
utilise the released gases for various plant need. The water
soaks in and passes through two layers of sand and gravel.
The clean water is collected in tanks present at the bottom and
can be used for irrigation purposes. This process reduces the
BOD, COD by about 95%.
Honey Suckers
In areas where sewage lines are not available, then these
trucks can be used to collect the septic waste and then dispose
it properly either in the STP or by using natural method like
SBT.
AD
Anaerobic Digester is a technology which can be used to
digest the organic matter present in waste to release Biogas.
This gas can be used as an alternate fuel to co-generate
electricity with coal or as a fuel for cooking. This technology
can be set up with the most basic of equipments and requires a
very less O&M cost. Cattle slurry can be added as a starter to
reduce the RT and increase the bacterial multiplication
Twin Pit Disposal (TPD)
In places where land is a shortage and where the technological
assistance for AD is not available, then a TPD can be used.
This technology requires the digging two pits which are
connected to the bathroom. The waste is stored in these pits
and over the years the faeces is converted into rich manure
which is devoid of all the pathogens and harmful gases. This
method is the most cost efficient of all the methods and
requires least participation of skilled labour.

41. Conclusion
Energy is a very important factor in the socio-economic
development of a nation. With the depleting non-renewable
energy sources, it is a necessity to find alternate energy in
every way possible. One such excellent source of energy is
the organic matter present in almost every possible waste.
This organic waste can be degraded and biogas can be
produced. This method not only ensures better management of
waste, but it also provides us with energy. SWM is a much
better method than the previously existing methods like
incineration, land fill, dumping into water bodies etc.
Sewage lines have been laid from as long as the
Mesopotamian and Aryan dynasty. They are very important to
maintain cleanliness in the surrounding. In the inception, the
sewage waste were collected in a place and disposed of into
oceans, rivers, land etc, but with increasing concerns of
environment safety and safety of fellow species, they are
being treated to a considerable level (decided by the
government). It is only after the achievement of this level that
the waste is discarded. In places where proper sewage system
is absent, other methods like SBT, AD, and TPD can be used.
These methods have come into existence after a lot of R&D
and provide very competitive sewage waste management
solutions.

42. Bibliography
 New Renewable Energy Resources-A guide to future
 Energy–Environment-Development by R.K.Pachauri, Leena
Srivastava, Kapil Thukural
 Anaerobic Digestion- a Waste Treatment Technology by
Andrew Wheatley
 Sewage Treatment-Basic principles and trends by R.L.Bolton
 Disposal Of Sewage And Other Water Born Wastes by Imhoff
miller
 Energy From Solid Waste by Dekker
 Solid Waste Management in India by Arakeri
 Sustainable Energy And Environment Technology by
Greenfield, Tay, Lu, Lua & Toh
 Canadian Journal Of chemical Engineers
 International journal of Energy and Environment
 AIChE Journal
 Journal Of Environmental Engineering