A presentation on Drainage Systems of a building from students of 4th Semester Architecture at VNIT, Nagpur (Jan-March 2015)

1. DRAINAGE SYSTEM
PRESENTED BY
BA13ARC043 SAURABH DEOTALE
BA13ARC044 SHHRRUTI JAIN
BA13ARC045 SHIVANGI NEGI
BA13ARC046 S. SUBHA MALA
BA13ARC047 SWAPNIL PUDKE
BA13ARC048 VRINDA TAPADIA
BA13ARC049 PRASAD THANTHRATEY
BA13ARC050 PAWAN TIRPUDE
BA13ARC051 TUSHAR BANSOD

2. THE DRAINAGE SYSTEM
DRAINAGE- A drainage system in urban and industrial areas
is a facility to dispose off the liquid waste.

3. WHY DO WE NEED A DRAINAGE SYSTEM..??
 IT CONTAINS HARMFUL BACTERIA: These can cause
diseases and it hence becomes a health hazard.
 IT CONTAINS SUSPENDED SOLIDS AND CHEMICALS:
These affect the environment.
 IT STINKS: If we release waste water directly into the
environment, things get smelly very fast.

4. DRAINAGE PROCESS
• Drainage process consist of collection of waste water then
processing it and then disposal of this processed water.
• Waste water is collected from wash basin, kitchen sink,
bathroom and W.C
• whenever you take a bath or wash your hands or utensils from
there the drainage part starts as how it travels from your home
to the treatment system and finally to the sea .
 Waste water from wash basin,
kitchen sink and bathroom is
drained through a pipe from your
home to gully chamber.

5. TYPES OF DRAINAGE SYSTEMS
1. COMBINED SYSTEMS
2. SEPARATE SYSTEMS

6. 1. COMBINED SYSTEM
• This uses a single drain to convey both foul water from sanitary
appliances and rainwater from roofs and other surfaces to a shared
sewer.
• The system is economical to install, but the processing costs at the
sewage treatment plant are high.

7. 2. SEPARATE SYSTEM
•This has foul water from the sanitary appliances conveyed in a foul
water drain to a foul water sewer.
•The rainwater from roofs and other surfaces is conveyed in a surface
water drain into a surface water sewer.
•This system is relatively expensive to install.

8. TYPES OF DRAINAGE SYSTEMS
1.CENTRALIZED
2.DECENTRALIZED/ON SITE

9. ADVANTAGES OF ONSITE DRAINAGE SYSTEMS
Onsite systems are recognized as viable, low-cost, long-term and
decentralized.
 Effective management.

10. DISADVANTAGES OF ONSITE DRAINAGE SYSTEMS
 Unnecessary costs and risks to public health and water resources.
 Constitute the third most common source of ground water
contamination

11. 1. SEPTIC TANKS
2. CESPOOLS
3. LAGOONS
4. SOAK PITS
5. AQUA PRIVY
CONVENTIONAL WASTE WATER
TREATMENT SYSTEMS

12. 1. SEPTIC TANK

13. INTRODUCTION
• The septic tank is a key component of the septic system, a
small treatment system.
• It is a watertight chamber made of:
• Concrete
• Fiberglass
• PVC or plastic

14. SEPTIC TANK LOCATION

15. AIM OF SEPTIC TANK
• “Septic” refers to the anaerobical bacteria which digest the
solids.
• It hence helps in removal of waste generates from
bathroom, kitchen, laundry etc.
• The purpose of having a septic tank is therefore for the
storage and treatment of
* Black water
*Grey water.

16. TREAT SEWAGE SO THAT IT IS MADE HARMLESS.

18. WORKING OF A SEPTIC TANK
• Wastewater flows from the home to the septic
tank through the sewer pipe.
• The septic tank treats the wastewater naturally by
holding it in the tank long enough for solids and
liquids to separate.
• Anaerobic decomposition of settled sludge occurs
in the closed tank.
• Three processes are involved:
Sedimentation
Digestion tank
Storage of digested sludge

19. CONSTRUCTION DETAILS
• The size of the septic tank depends on the number of
bedrooms in the house.
• It consists of a tank or more than one tank of between
4000-7500 litres in size.
• It is a long, continuous flow tank made of RCC and sides
are water proof.
• Facility for gas vent through vent pipe.
• Bottom (slope) is been provided to facilitate pumping of
sludge.
• Manhole facilitates are provided for removal of sludge
• Connections are made via a T-pipe for entry and exit.
• Sometimes baffles to reduce disturbances.

21. ADVANTAGES DISADVANTAGES
- Can be built and repaired with locally
available materials.
- Low reduction in pathogens, solids and
organics.
- Long service life. - Effluent and sludge require secondary
treatment and/or appropriate discharge.
- No real problems with flies or odours if used
correctly
- Requires constant source of water.
- Low capital costs, moderate operating costs
depending on water and emptying.
- Small land area required.
- No electrical energy required.

22. MAINTENANCE OF A SEPTIC TANK
Septic Tanks should be
watertight
The levels of the scum and
sludge should be monitored
The sludge should be removed
annually using a vacuum truck
Not to discharge harsh
chemicals into the Septic Tank

23. DIAGRAM SHOWING A 2-SECTION SEPTIC TANK

24. 2. CESPOOL
•An underground hole or container for holding liquid
waste (such as sewage) from a building
•A cesspit, or CESPOOL, it is either used to describe an
underground holding tank (sealed at the bottom) or a
soak pit (not sealed at the bottom).
•It can be used for the temporary collection and storage
of feces, excreta or faecal sludge as part of an on-
site sanitation system and has some similarities
with septic tanks or with soak pits.
•Traditionally, it was a deep cylindrical chamber dug into
the earth, having approximate dimensions of 1 metre
diameter and 2–3 metres depth. Their appearance was
similar to that of a hand-dug water well.

25. A CESPOOL is purely holding tank without an
outlet.
There is no outlet to treat or discharge the
sewage and the CESPOOL is the simple tank
holding tank to collect and store wastage .
Depending on the size of the tank, the
property and the number of occupants, the
cesspit can fill up quickly and needs to be
emptied regularly, at monthly, quarterly or
annual intervals as required.
The Cesspit will usually be discreetly buried
underground with a single manhole cover
for access by the waste collection team.

26. INSTALLATION OF CESPOOL

27. CESPOOL must be treated to avoid harmful chemicals from forming
and also to empty the pool which is done once in a month. This is the
reason which makes a CESPOOL require a high cost of maintenance.
DISADVANTAGES

28. LIMITATIONS AND PROBLEMS
• CESPOOLs may be like an essential part of life in many places, but
they can be harmful too. For example, if the CESPOOL is kept at a
very deep level, it may come in contact with groundwater and
contaminate it making it unsafe for drinking purposes. That is
why CESPOOLS are kept quite far away from the wells and
underground water sources. The CESPOOLS may prove to be
dangerous because of the fact that the waste material may give
rise to dangerous fumes

29. MAINTENANCE
• CESPOOLs should be pumped out regularly to prevent
excessive solids build-up and minimize clogging the soil
pores in the area surrounding the CESPOOL. A pump-
out every three years is required.
• All other maintenance recommendations for more
modern sewage systems are also applicable to both
CESPOOLs and seepage pit systems, such as careful
water usage, protecting the area of the sewage system
from vehicular traffic, and not putting garbage or toxic
chemicals down the drain.

30. PRECAUTIONS
• Empty the system regularly
• Don’t let flammable or hazardous liquids to enter the
system
• Don’t allow the area around the manhole cover to
become overgrown or obscured

31. Difference between CESPOOL and SEPTIC SYSTEM
SEPTIC TANKS
• A septic system receives
and treats wastewater
from homes before
releasing it back into the
groundwater supply.
• Treatment of wastewater
includes the removal and
storage of inorganic solids,
the processing of sewage
and the biological removal
of harmful bacteria and
viruses.
• The important distinction
is that a septic tank
removes pollutants from
wastewater.
CESPOOLS
•A CESPOOL is any pit or
container that receives
wastewater from a house or
building.
•The term "CESPOOL" is usually
used to refer to an open pit that
is lined with rocks or concrete,
but an underground tank or
holding container that is not
connected to a drainfield can also
be defined as a CESPOOL.
•The main function of CESPOOLs
is the storage of wastewater.

33. INTRODUCTION
•Lagoons are treatment pond provided
with artificial aeration to promote the
biological oxidation of wastewaters.
•Lagoons are constructed and lined
with material, such as clay or an
artificial liner, that will prevent leaks
to the groundwater below
•It uses air(oxygen) and microbial
action to biotreat the pollutants in
wastewater.

34. Types of Lagoons
Suspended Mixed
Facultative
Every lagoon system must be individually designed to fit its specific site and use.
Designs are based on such factors as the type of soil, the amount of land area
available, the climate, and the amount of sunlight and wind in an area.

35. SUSPENSION MIXED LAGOONS
(completely suspended lagoon)
In this type the concentration of solids and dissolved oxygen are
maintained fairly uniform and neither the incoming solids nor the biomass
of microorganisms settle.
•To keep the particles in suspension less energy (2.6 W/m3 ) is provided.
•The objective of the lagoon is to act as a biologically assisted flocculator
which converts the soluble biodegradable organics in the influent to a
biomass which is able to settle as a sludge.
•It’s effluent is then passed in a second pond(sedimentation pond) where
the sludge can settle.

36. PROCESS..

37. FACULTATIVE LAGOONS
(aerobic-anaerobic or partially suspended)
•Facultative lagoons have reduced energy requirements (0.8-1 W/m3 )
causing accumulation of solids in the bottom which undergo anaerobic
decomposition, while the upper portions are maintained aerobic.
•insufficient energy provided by the aeration equipment keeps the
sludge in suspension and solids settle to the lagoon floor. The
biodegradable solids in the settled sludge then degrade anaerobically.
•With rate of biological reactions
decrease with increase in
temp.Hence depth is increased.

38. PROCESS…

39. ADVANTAGES DISADVANTAGES
• Lagoon systems are cost effective
• They use less energy than most
wastewater systems
• They are simple to operate and
maintain and generally require
only part time staff
• They can handle intermittent use
and shock loading better (useful
for resorts, or seasonal camps)
• High reduction in BOD and
pathogen
• No real problem of odors if
designed correctly
• Effluents can be reused
• Lagoon system require more land
than other treatment systems
• They are less efficient in cold
climates
• Requires proper maintenance
otherwise turns into breeding
ground for mosquitoes and other
insects
• Not very effective at removing
heavy metals from water
• Effluent Might require
polishing(additional treatment)
before discharging
• Requires a constant
energy/electricity source for
continuous aeration; the technique
does not work in cases of power
failure.

40. 4. SOAK PITS
A layer of sand and fine gravel should be spread across the bottom
to help disperse the flow. The soak pit should be between 1.5 and
4m deep, but never less than 1.5m above the ground water table.

41. ADVANTAGES DISADVANTAGES
- Can be built and repaired with locally
available materials.
- Pre-treatment is required to prevent
clogging, although eventual clogging is
inevitable.
- Small land area required - May negatively affect soil and groundwater
properties.
- Low capital cost; low operating cost.
- Can be built and maintained with locally
available materials.
- Simple technique for all users.

42. ADEQUACY
• These are appropriate for rural and semi-urban settlements.
They depend on soil with a sufficient absorptive capacity.
• They are not appropriate for areas that are prone to flooding
or have high groundwater tables.

44. HEALTH ASPECTS/ACCEPTANCE
• Till the time Soak Pit is not used for raw sewage, and the
previous Collection and Storage/Treatment technology is
functioning well, health concerns are minimal.
• It is important however, that the Soak Pit is located a safe
distance from a drinking water source (ideally 30m).

45. MAINTENANCE
• A well-sized Soak Pit should last between 3 and 5 years
without maintenance.
• The Soak Pit should be kept away from high-traffic areas so
that the soil above and around it is not compacted.
• When the performance of the Soak Pit deteriorates, the
material inside the soak pit can be excavated and refilled.
• To allow for future access, a removable (preferably concrete)
lid should be used to seal the pit until it needs to be
maintained.

46. 5. AQUA PRIVY
• A TANK FILLED WITH WATER INTO WHICH EXCRETA FALL VIA A DROP PIPE
• USE A SIMPLE WATER SEAL TO PREVENT ODOUR GETTING OUT OF THE TANK
• HAVE A SOAK PIT TO DISPOSE OF SULLAGE
• DROP PIPE SHOULD REACH BELOW THE SURFACE OF THE WATER IN THE
TANK TO PREVENT ESCAPE OF ODOUR
• THE TANK SHOULD BE WATERTIGHT TO PREVENT POLLUTION OF
GROUNDWATER
• IT NEEDS TO BE EMPTIED EVERY THREE YEARS

50. TANK FOR AQUA PRIVY
• TANK SHOULD BE DIRECTLY BELOW
THE COVER SLAB
• IT SHOULD BE LINED TO MAKE IT
WATERTIGHT SO PREVENTING
LEAKAGE OF WATER AND THE
BREAKING OF WATER SEAL

52. ADVANTAGES
• They cannot be blocked with bulky and cleansing materials
• They can be connected to sewerage systems at a later date
• There are few problems with odour and flies
DISADVANTAGES
• They are expensive to build
• They need large volumes of water to work
• The water seal can be hard to maintain
• Tank must be emptied about every 3 years

53. SOME ADDITIONAL WASTE WATER
TREATMENT TECHNIQUES
1.MANHOLE
2.INSPECTION CHAMBER

54. Types of chambers….
Inspection chamber….
Are intended to provide simple access for
cursory inspection, and access for drain
rods and other cursory equipments. Not
provided to give access for maintenance
and are only 600mm deep.
Manhole….
Larger than access chambers. Diameter
more than 450mm. They provide access
for maintenance equipments but tend to
have more branches and are generally
1000mm deep.

55. 1. INSPECTION CHAMBER
 The waste water or sewage is carried further
to the inspection chamber which is at least at
a distance of 3‘-5’ from gully chamber
 At every 6meter distance inspection
chamber is placed which helps to maintain
drainage system.
Maximum 6 connections can be given to
inspection chamber.
 The final or the last inspection
chamber is known as Disconnecting
chamber which does not allow the
sewage from sewer pipes to enter
into the premises.
This disconnecting chamber is
connected to the Manhole and which
is further carried out into the Sea.

56. Inspection Chambers, sometimes referred
to as manholes, are available with 110mm
and 160mm connections. Shallow
Inspection Chambers have 110mm
connections and are used where the depth
will not exceed 600mm.
 The purpose of an Inspection
Chamber is to provide a
means of access for
inspecting the drain or sewer
and to allow cleaning.

57. Typical Plastic Inspection Chamber

58. Inspection chambers should be provided in the following
situations:
1. At all changes of direction on drains (except for drains
where the change in direction is not too great for cleaning).
2. At all changes of gradient on drains (except for drains
where the change in gradient is not too great for cleaning).
3. At all drain junctions where cleaning is not otherwise
possible.
4. On a drain within 12m from a junction between that drain
and another drain. unless there is an inspection chamber
situated at that junction.
5. At the head of each length of drain.
6. At all changes in pipe diameter.

59.  Extremely durable and resistant to attack by sulphates in
the chasoil, plastic inspection chambers will give many
years of trouble and maintenance-free service.
These chambers may be constructed from the following
materials.
1.Class B engineering bricks
2.Precast concrete sections surrounded in concrete
3.In-situ concrete
4.Glass-fibre plastic
 Inspection Chambers are not large enough for man-entry
but allow the drain to be reached from ground level.
 Plastic chambers offer considerable time and financial
savings in installation as well as significant health and
safety advantages over so-called ‘traditional’ manholes.

60. TYPES OF INSPECTION CHAMBERS
1. Shallow inspection chamber:
250mm diameter polypropylene inspection chamber for adoptable
and non-adoptable applications Designed for maximum 0.6m invert
depth. Shaft may be cut to length to achieve required invert depth.
External shaft diameter: 250mm+Maximum
installation depth: 0.6m Benefits
 Fast, easy installation: no wet trades
 Lightweight: no lifting equipment required
 Shaft can be cut to required length.
Round cover and
frame
Square Cover &
Adjustable Frame

61. 2.Multi-base inspection chambers:
315mm diameter polypropylene inspection
chambers for adoptable and non-adoptable
applications
Designed for maximum 0.9m invert depth
Benefits:
Multiple options for maximum installation
flexibility-
•Fast, easy installation: no wet trades
•Lightweight: no lifting equipment required
• Push-fit shaft sections: one or more can
be used to achieve required invert depth
•Final shaft section can be cut to required
length
•No additional trench excavation required

62. 3. Universal Inspection Chambers:
450mm diameter polypropylene inspection chambers for adoptable and non-adoptable
applications.
Applications
For above ground access and maintenance inspection of buried pipework up to 1.2 metres
deep
For loading applications up to Invert depth of base:
– 295mm [for 110mm system]
– 270mm [for 150mm and 160mm systems]
Key Features & Benefits
l Fast, easy installation: no wet trades
l Lightweight: no lifting equipment required
l Push-fit shaft sections: one or more can
be used to achieve required invert depth
l Final shaft section can be cut to required length
l No additional trench excavation required
Key Dimensions
l External shaft diameter: 450mm
l Shaft section length: 508mm
l Maximum installation depth: 1.2m

63. straight channel
straight channel with
single 90° branch
straight channel with
single 45° branch
straight channel with
two 45° branches
90° bent channel
straight channel with 45°
and 90° branches
straight channel with two
90° branches
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66. MANHOLE
A manhole is the name given to the construction of an access point to
pipes in both sewage drains (foul) and surface water drains (storm). These
access points are usually situated at the beginning, end, or change of
direction, diameter, level or at intermediate points in a long straight line of
pipe. Their use is to provide access to the pipe for inspection.

67. ROLE
• To provide access for humans to carry out operation
and maintenance (surveys and inspections) of the
pipe (main pipe).
Manholes shall not be located in the following locations:
• Inaccessible areas.
• Gutters and other depressions or areas subject to inundation.
• In sidewalks or crosswalks.
• In driveways.
• In freeway ramps.
• Between railroad or trolley tracks. Manholes within a railroad or trolley right-of-
way shall be located a minimum of fifteen feet (15’) from the track bed.

68. CONSTRUCTION
• The most common materials used to construct
manholes are bricks and mortar or precast concrete.
• Newer materials are being innovatively used in
manhole construction today, such as high density
polyethylene, polymer concrete and fiberglass .
• Manholes are also access points for the wastewater
collection system, so each is typically finished with a
cast iron frame and cover.

69. Brick Built Manholes
 Brick manholes tend to be more conical in shape
from the manhole rim to invert and more slender
than precast concrete manholes
 The brick manhole wall is typically thicker at the
base than a comparable precast manhole in order
to support the traffic and loads necessary for
deeper manholes.
Over-benching branch channel
Stepped Invert Connection

70. Over-benching branch channel
Stepped Invert Connection

71. mortar or
precast
concrete
Shallow manholes located at the surface or within four feet of the ground
surface can be refurbished or replaced at a relatively low expense since
they are readily accessible. Manholes deeper than four feet below grade are
more often repaired or renewed as opposed to being replaced.

72. Manhole covers
Shatterproof type
Old type
Double cover
(pressure cover)
Square cover

75. PRESENT DAY
TECHNIQUES

76. DEWATS
Stands for “Decentralized Water Treatment System”.
DEWATS are low cost and reliable in operation.
It can treat organic wastewater from both domestic and industrial source
with flows from 1 to 1000 m3 per day.
DEWATS
Stands for “Decentralized Water Treatment System”.
DEWATS are low cost and reliable in operation.
It can treat organic wastewater from both domestic and
industrial source with flows from 1 to 1000 m3 per day.

77. FOUR MAIN DEWAT TREATMENT
PROCESSES ARE:
oPrimary treatment and sedimentation (settler)
oSecondary (anaerobic) treatment in baffled upstream reactors
oTertiary (aerobic/anaerobic) in a planted gravel filter
oTertiary aerobic treatment in ponds
FOUR MAIN DEWAT TREATMENT PROCESSES
ARE:
oPrimary treatment and sedimentation (settler)
oSecondary (anaerobic) treatment in baffled upstream
reactors
oTertiary (aerobic/anaerobic) in a planted gravel filter
oTertiary aerobic treatment in ponds

78. Primary treatment and sedimentation
(settler):
Pre-treatment is done in a Settler
A device which separates the liquid from the
solid
Retention time is only 2 hours.
Pollution reduction is around 30%

79. Secondary (anaerobic) treatment in baffled
upstream reactors:
First treatment takes place in a Baffled Tank
A device with several identical chambers
through which the effluent moves
from top to bottom.
Retention time is 24 hours.
Pollution reduction is around 80%

80. Tertiary (aerobic/anaerobic) in a planted gravel
filter:
Second treatment takes place in an anaerobic filter
A device filled with a filter material (cinder) through
which the effluent moves from top to bottom.
Retention time is around 8 hours.
Total pollution reduction is around 90%
At this stage CPCB standards are met
but the effluent still has an odour

81. Third treatment takes place in a planted gravel
filter
A structure filled with gravel material and
planted with water resistant plants, who
provide oxygen to the passing effluent.
Retention time is 1½ day.
Pollution reduction is around 90%

82. POST TREATMENT:Tertiary aerobic
treatment in ponds
Post treatment takes place in polishing ponds
fitted with aquatic plants and fishes.
It is through this device that the water transforms
from a lifeless state into living water again.
Ponds with aquatic plants are an efficient way
to combine wastewater treatment,
landscaping, aesthetics and water reuse,
the pond can also act as a storage device.

83. ADVANTAGES
oProvides treatment for industrial and domestic wastewater
oLow initial investment costs as no imported materials or
components are needed
o Efficient treatment for daily wastewater flows of up to 1000m3
oModular design of all components
oTolerant towards inflow fluctuations
oReliable and long-lasting construction design
o Low maintenance costs

84. ROOT ZONE WASTEWATER
TREATMENT
(RZWT)
The RZWT system utilises nature’s way of biologically
processing domestic & industrial effluents. This effective
technology called Decentralised Wastewater Systems
(DEWATS) was developed in 1970s in Germany and has been
successfully implemented in different countries mainly in
Europe and America.

85. • ‘Root Zone’ is a scientific term used to cover all the
biological activity among different types of microbes,
the roots of plants, water soil and the sun.
• The root zone wastewater treatment system makes use
of biological and physical-treatment processes to
remove pollutants from wastewater.
• Due to its natural process, there is no need to add any
input such as chemicals, mechanical pumps or external
energy. This reduces both the maintenance and energy
costs.

86. ADVANTAGES
• Require simple construction methods,
• Low capital costs
• Low operating and maintenance costs
• No chemicals required for the treatment process
• Absence of by-products requiring treatment
• Technical expertise for the operation not required
• Effective treatment resulting in near-tertiary standards

87. PROCESS
• Pre-treatment done in a Settler– A device
that separates the liquid from the solid

88. • First treatment takes place in a Anaerobic
Baffled Reactor–
A device with several identical chambers through
which the effluent moves from top to bottom.

89. • Second treatment happens in an Anaerobic
Filter–
A device filled with a filter material (cinder),
through which the effluent moves from top to
bottom.

90. • Third treatment takes place in a Planted Gravel
Filter–
A structure filled with gravel material and planted
with water-resistant reed plants, which provide
oxygen to the passing effluent.

91. APPLICATIONS
• Domestic and industrial wastewater containing
biodegradable matter
• Not easily biodegradable substances requiring increased
retention time but with lesservolumetric loading
• On-site treatment of domestic sewage
• Dispersed settlements, where no connection to the
sewerage lines exist
• Main treatment or polishing stage.

92. BIOGAS TREATMENT PLANT
PRINCIPLE
Biogas is produced as a result of
anaerobic fermentation of biomass
in the presence of water.

93. Working
• The various forms of biomass are mixed with an equal quantity of water
in the mixing tank. This forms the slurry.
• The slurry is fed into the digester through the inlet chamber.
• When the digester is partially filled with the slurry, the introduction of
slurry is stopped and the plant is left unused for about two months.
• During these two months, anaerobic bacteria present in the slurry
decomposes or ferments the biomass in the presence of water.
• As a result of anaerobic fermentation, biogas is formed, which starts
collecting in the dome of the digester.
• As more and more biogas starts collecting, the pressure exerted by the
biogas forces the spent slurry into the outlet chamber.
• From the outlet chamber, the spent slurry overflows into the overflow
tank.
• The spent slurry is manually removed from the overflow tank and used
as manure for plants.
• The gas valve connected to a system of pipelines is opened when a
supply of biogas is required.

94. WORKING AND PRINCIPLE

95. CONSTRUCTION
The biogas plant is a brick and cement structure having the
following five sections
• Mixing tank: Present above the ground level.
• Inlet chamber/pipe: The mixing tank opens underground into
a sloping inlet chamber.
• Digester: The inlet chamber opens from below into the
digester which is a huge tank with a dome like ceiling. The
ceiling of the digester has an outlet with a valve for the supply
of biogas.
• Outlet chamber: The digester opens from below into an outlet
chamber.
• Overflow tank: The outlet chamber opens from the top into a
small over flow tank.

96. ADVANTAGES OF BIOGAS AS FUEL
• High calorific value
• Clean fuel
• No residue produced
• No smoke produced
• Non polluting
• Economical
• Can be supplied through pipe lines
• Burns readily - has a convenient ignition temperature

97. ADVANTAGES OF BIOGAS PLANTS
• Reduces burden on forests and fossil fuels.
• Combined treatment of different organic waste and
wastewaters.
• Provides nutrient rich (N & P) manure for plants
• Controls water pollution by decomposing sewage, animal
dung and human excreta.
• Produces a clean fuel - helps in controlling air pollution.

98. FIXED-DOME PLANTS

99. THANK YOU