Sewage Treatment and case study Sewage Treatment Plant in Delawas, Jaipur

1. SEWAGE TREATMENT Geetika Singla
1916432

2. UNSEWERED AREAS
• 1. SERVICE TYPE LATRINES – CONSERVANCY
SYSTEM
• 2. NON-SERVICE TYPE – SANITARY LATRINES
a. Bore hole latrine
b. Dug well or pit latrine
c. Water seal type
d. Septic tank
• 3. LATRINES SUITABLE FOR CAMPS AND
TEMPORARY USE
a. Shallow trench
b. Deep trench
c. Pit Latrine
d. Bore hole latrine
SEWERED AREAS
• 1. WATER-CARRIAGE SYSTEM AND
SEWAGE TREATMENT
a. Primary treatment
b. Screening
c. Removal of grit
d. Plain sedimentation
• 2. SECONDARY TREATMENT
Trickling filters
Activated sludge process
OTHER METHODS
a. Sea outfall
b. River outfall
c. Sewage farming
d. Oxidation ponds

3. UNSEWERED AREAS
SERVICE TYPE LATRINES (CONSERVANCY SYSTEM)
The collection and removal of nightsoil from bucket or pail latrines by
human agency is called the service type or conservancy system, and the
latrines are called service latrines.
The nightsoil is transported in "nightsoil carts" to the place of final
disposal, where it is disposed off by (i) composting or (ii) burial in
shallow trenches.
DISADVANTAGES
They perpetuate the disease cycle of faecal-borne diseases in the
community. Water and soil pollution, exposed to flies. Requires staff for
collection of nightsoil

4. NON-SERVICE TYPE
(SANITARY LATRINES)
A sanitary latrine is one which fulfils the following criteria :
(1) Excreta should not contaminate the ground or surface water
(2) Excreta should not pollute the soil
(3) Excreta should not be accessible to flies, rodents, animals (pigs, dogs,
cattle, etc.) and other vehicles of transmission.
(4) Excreta should not create a nuisance due to odour or unsightly
appearance

5. NON-SERVICE TYPE
BORE HOLE LATRINE
For a family of 5 or 6 people, a
bore hole of the above description
serves well for over a year.
30 – 40 cm (12” – 16”)
concrete squatting plate with a
central opening and foot rests
is placed over the hole

6. a) there is no need for the
services of a sweeper for daily
removal of nightsoil.
b) the pit is dark and unsuitable
for fly breeding,
c) if located 15 m (50 ft.) away
from a source of water supply,
there should be no danger of
water pollution.
a) the bore hole fills up rapidly
because of its small capacity,
b) a special equipment, the
auger, is required for its
construction which may not be
readily available
c) in many places, the subsoil
water is high and the soil loose,
with the result it may be difficult
to dig a hole deeper than 3 m
(10 ft.).
ADVANTAGES DISADVANTAGES

7. NON-SERVICE TYPE
DUG WELL OR PIT LATRINE
75 cm (30”)
3 to 3.5 m
(10-12 ft.) deep

8. NON-SERVICE TYPE
DUG WELL OR PIT LATRINE
The pit has a longer life than the bore hole because
of greater cubic capacity and will last for about 5
years for a family of 4 to 5 persons.
75 cm (30”)
3 to 3.5 m
(10-12 ft.)
deep

9. NON-SERVICE TYPE
WATER SEAL LATRINE
It prevents access by flies.
That is, the nightsoil is
sealed off from flies.
It prevents escape of odours
and foul gases and thereby
eliminates the nuisance from
smell.

10. (1) Capacity : A capacity of 20-30 gallons per person for household
(2) Length : The length is usually twice the breadth.
(3) Depth : 2 m (5-7 ft.)
(4) Liquid depth : 1.2 m (4 ft.)
(5) Air space: 30 cm (12 in.) between the level of liquid in the tank and the undersurface of the cover.
(6) Bottom : In some septic tanks, the bottom is sloping towards the inlet end. This facilitates retention
of solids.
(7) Cover : by a concrete slab with a manhole.
(8) Retention Period : of 24 hours.
NON-SERVICE TYPE
SEPTIC TANK
The septic tank is a water-tight masonry tank into which household sewage is admitted for treatment. It is a
satisfactory means of disposing excreta and liquid wastes from individual dwellings, small groups of houses and
institutions which have adequate water supplies but do not have access to a public sewerage system.

11. ANAEROBIC DIGESTION - The solids settle down in the tank, to form
"sludge", while the lighter solids including grease and fat rise to the
surface to form "scum". The solids are attacked by the anaerobic
bacteria and fungi and are broken down into simpler chemical
compounds.
AEROBIC OXIDATION - The liquid which passes out of the outlet pipe
from time to time is called the "effluent". It contains numerous bacteriae,
cysts, helminthic ova and organic matter in solution or fine suspension.
The effluent is allowed to percolate into the sub-soil. Aerobic bacteria in
the upper layers of the soil attack the organic matter present in the
effluent. As a result, the organic matter is oxidized into stable end
products, i.e., nitrates, carbon dioxide and water.
NON-SERVICE TYPE
SEPTIC TANK

13. LATRINES SUITABLE FOR TEMPORARY USE
DEEP TRENCH
This type of latrine is intended for camps
of longer duration, from a few weeks to a
few months.

14. LATRINES SUITABLE FOR TEMPORARY USE
DEEP TRENCH

15. LATRINES SUITABLE FOR TEMPORARY USE
SHALLOW TRENCH

16. SEWERED AREAS
The water carriage system or sewerage system implies collecting and
transporting of human excreta and waste water from residential,
commercial and industrial areas, by a net-work of underground pipes,
called sewers to the place of ultimate disposal.

17. • A water carriage system consists of the following elements.
•1. Household sanitary fittings (plumbing system of buildings) - The usual
household sanitary fittings are : water closet, wash basin.
•2. House drain - The house drain is usually 10 cm (4 in.) in diameter and is laid
in the courtyard about 15 cm (6 in.) below the ground level on a bed of cement
concrete with sufficient gradient towards the . main drain.
•3. Street sewers or trunk sewers - The trunk sewers are not less than 22.5 cm (9
in.) in diameter; bigger ones may be 2 to 3 m (8-10 ft.) in diameter. They are
laid on a bed of cement concrete, about 3 m (10 ft.) below the ground level
•4. Sewer appurtenances: manholes, traps
MANHOLES are openings built into the sewerage system. These openings permit
a man to enter the sewer for inspection, repairs and cleaning.
TRAPS these are devices designed to prevent foul gases entering the houses and
to remove sand, grit and grease from sewage. Traps are placed in three
situations :
(a) under the basin of water closets,
(b) where the house drain joins the public drain (intercepting trap), and
(c) where surface waste water enters the drains.

19. SCREENING - Sewage arriving at a disposal work is first passed
through a metal screen which intercepts large floating objects such as
pieces of wood, rags, masses of garbage and dead animals. Their
removal is necessary to prevent clogging of the treatment plant.
MECHANISM
PRIMARY TREATMENT A - Screen
B - Pipe
C - By pass Pipe

20. GRIT CHAMBER – The chamber is approximately 10 to 20 metres in length.
The function of the grit chamber is to allow the settlement of heavier solids
such as sand and gravel, while permitting the organic matter to pass through.
MECHANISM
PRIMARY TREATMENT

21. PRIMARY SEDIMENTATION - The sewage spends about 6-8 hours in the tank.
Nearly 50-70 per cent of the solids settle down under the influence of
gravity. The organic matter which settles down is called sludge and is removed
by mechanically operated devices, without disturbing the operation in the
tank.
MECHANISM
PRIMARY TREATMENT

22. TRICKLING FILTER: The trickling filter or percolating filter is a bed of crushed stones or cinker, 1 to 2 m
deep and 2 to 30 m in diameter, depending upon the size of the population. The effluent from the
primary sedimentation tank is sprinkled uniformly on the surface of the bed by a revolving device. Over
the surface and down through the filter, a very complex biological growth consisting of algae, fungi,
protozoa and bacteria of many kinds occurs. This is known as the "zoogleal layer". As the effluent
percolates through the filter bed, it gets oxidized by the bacterial flora in the zoogleal layer.
MECHANISM
SECONDARY TREATMENT

23. The effluent from the primary sedimentation tank is mixed with sludge
drawn from the final settling tank.
The proportion of activated sludge to the incoming effluent is of the
order of 20 to 30 per cent. The mixture is subjected to aeration in the
aeration chamber for about 6 to 8 hours.
During the process of aeration, the organic matter of the sewage gets
oxidized into carbon dioxide, nitrates and water with the help of the
aerobic bacteria in the activated sludge. The typhoid and cholera
organisms are definitely destroyed, and the coliforms greatly
reduced.
MECHANISM
ACTIVATED SLUDGE PROCESS

24. The oxidized sewage from the trickling filter or aeration chamber is led into the secondary
sedimentation tank where it is detained for 2-3 hours.
The sludge that collects in the secondary sedimentation tank is called 'aerated sludge' or
activated sludge, because it is fully aerated.
MECHANISM
SECONDARY SEDIMENTATION
It differs from
the sludge in
the primary
sedimentation
tank in that it is
practically
inoffensive and
is rich in
bacteriae,
nitrogen and
phosphates. It
is a valuable
manure, if
dehydrated.

25. CASE STUDY ON SEWAGE TREATMENT PLANT (STP)
DELAWAS, JAIPUR
The raw sewage first collects here. After commencement of water in inlet section it
is screened through automated screens.
Screens are inclined at an angle of 45
degree.
Figure.1. Inlet section Figure.2. Showing automated screening

26. CASE STUDY ON SEWAGE TREATMENT PLANT (STP)
DELAWAS, JAIPUR
After removing the solid waste from water, it transfers to grit chamber for removing the
grit; the grit obtained from this chamber is highly nutritious for crops. The chamber is
trapezoidal in shape for easy collection of grit. The whole process is fully automatic.
Figure.3. Showing the inner view of grit chamber Figure.4. View mechanism of grit separator

27. After grit separation, the water is send to
primary clarifier for further processing
through Parshall Flume for regulating the
flow velocity. This is generally made at an
angle varies from 1 -12degree in STPs. By
this mechanism, we are capable to increase
the retention period in primary clarifier.
CASE STUDY ON SEWAGE TREATMENT PLANT (STP)
DELAWAS, JAIPUR
In primary clarifier, the sludge remove
through gravity separation method. Then it
transfers to secondary clarifier passing via
aeration tank for activated sludge process.
Figure.5. View of Parashall Flume Figure.6. Primary Clarifier

28. In aeration tank, oxygen is providing with the
help of blower for survival of bacteria. A small
quantity of sludge returned from secondary
clarifier to aeration tank for activated sludge
process. Air blowers are being operated with
variable frequency drive (VFD). Man Machine
Interface(MMI) is provided through
CASE STUDY ON SEWAGE TREATMENT PLANT (STP)
DELAWAS, JAIPUR
Figure.7. Aeration Tank
From aeration tank, the wastewater goes to
secondary clarifier. This is the final treatment
process for water in this plant. The water from
here opens to Amanisah runnel finally.
Figure.8. Secondary Clarifier

29. The sludge collected at different steps of process sent to the sump and then to the digester
dome. The sludge is dewatered by using centrifugal pumps and the thickened sludge is sent
to dome for anaerobic digestion. This process gives biogas and digested sludge, which use
as manure by local farmers. The gas produce is using for revenue collection. The gas sent to
CNG bottling plant, whichgives them cost price of 6.50 RSPNm3.
CASE STUDY ON SEWAGE TREATMENT PLANT (STP)
DELAWAS, JAIPUR
Figure.9. View of sludge digester Figure.10. Showing disposal process of sludge