Project presentation on treatment of wastewater at Chennai Metropolitan treatment plant

1. PRESENTED BY:
MOHAMMAD ASRAR SHAH (170011601049)
MUZZAMMIL MAMU (170011601054)
MOHAMMED ANEES ANSARI (170011601050)
SAYED ADIL (170011601064)
MOHAMMAD ABDUL HAI (170011601048)

2.  CMWSSB Nesapakkam Sewage Treatment Plant is located on the
western part of Chennai city.
 The plant was commissioned in 1974 which is the first sewage
treatment plant in Chennai.
 Its maximum design capacity is 117 MLD.

3.  The plant receives the sewage
collected from zone 4, covering
the areas like Saidapet, West-
Mambalam, Ashoknagar, M.G.R
Nagar, K.K.Nagar, Thirunagar
etc.
 It is designed to cater for an
average flow of 23 MLD (million
litres per day) with a peak factor
of 2.67.

5. TREATMENT FLOWCHART:
The figure below represents the diagrammatic representation of the
CMWSSB Nesapakkam Sewage Treatment Plant, Chennai.

6. INLET CHAMBER:
The waste water received from the
Southwest part of the city is
collected in the inlet chamber
through concrete pipelines.
 The Inlet chamber is a
rectangular tank with 2 m x 3 m
sides and 6m depth.
At this very step the water gets
received in the receiving tank and
thereafter goes for screening
process.

7. SCREEN CHAMBER:
 Screen chamber is provided with
manually cleaned bar rack of medium
size. Width of the screen chamber is
2.41m and depth is 1.37 m. The bars
are rectangular sharp-edged ones
having 6 mm thickness at clear
spacing of 25 mm.
 At this very step the water gets
screened in order to remove all the
floating objects present in the waste
water.

8. Detritus Tank:
 Side of the square detritus tank is
10m and Side Water Depth is 1.0
m.
 It is the tank where the liquid is
made homogenous.
 The waste water of different
sources having different densities
are combined together to form a
homogenous effluent.

9. Primary Clarifier:
 It is a cylindrical tank with a
scrapper drive. Once the water gets
homogenous it is sent here.
 There are two identical circular
primary clarifiers with 21.4 m
diameter and 2.4 m side water
depth in each.
 The sludge is made to settle at the
bottom of the tank. It is achieved
due to gravitational and centrifugal
forces.

10. Aeration Tank:
 Three numbers of aeration tank of 40
m length, 10 m width and 3.8 m depth
each are provided. The system is
provided with 12 numbers of fixed
aerators having a capacity of 12.5 HP
each.
 The flow in the aeration system is in
completely mixed flow regime.
 It is a 24-hour process where the
bacteria e-coli degrades the organic
and inorganic substances in the water.
Aeration tends to accelerate the gas
exchange and reduce the foul smell of
waste water

11. Secondary Clarifier:
 There are two identical secondary
sedimentation tanks (SST), having
24.5-meter diameter and 3.1m side
water depth, each.
 The process of removal of sludge is
carried out here.
 It is done by using a scrapper
drive.
 The sludge gets filtered out at the
end of the cylindrical tank

12. Final Settling Tank:
 The Final settling tank has a
diameter of 21.4 m and 2.4 m side
water depth.
 The main purpose of the
final settling tanks is to remove
any left suspended solids from the
waste water.
 Finally, the water moves into the
chlorination tanks for disinfection
and from there it gets discharged
into the river bodies.

13. Digestors:
 The primary as well as
secondary digesters are having
24 m diameter and 9.2 m side
water depth.
 In these the organisms present
in water are metabolized by
bacteria anaerobically (in the
absence of oxygen) and methane
gas is produced.
 The daily average gas
production from the plant is
4,800 m3.

14. Sludge Thickener:
 The sludge thickener unit
reduces the sludge volume by
removal of free sludge water.
 Before entering the sludge
thickening tank, the waste
water contains 90% water and
10% of sludge.
 The dimensions of the sludge
thickening tank are: 5m
diameter and 9.2 m height.

15. Sludge Drying Beds:
 The sludge drying beds are 30.5 m
x 11.6 m x 0.3 m size each, which
are meant for dewatering the
sludge.
 The Sludge drying beds are
provided to allow surplus sludge
that is withdrawn from the process
to dry for easier handling.
 A sludge drying bed usually
consists of a bottom layer of gravel
of uniform size over which is laid a
bed of clean sand.

16. Bio-Gas Engine:
 The gas engine provides a high
efficiency generation of electric
power through the methane gas
produced from the sludge.
 The power generated from the
bio-gas engine is approximately
22,18,597 KWh /yr.

17.  At last it is observed that the
Chennai city’s wastewater which
arrives at the CMWSSB
NESAPAKKAM SEWAGE
TREATMENT PLANT, CHENNAI
undergoes various treatment
processes starting from screening
and ending up at chlorination.
 The waste water is treated quite
efficiently and the sludge is
disposed off.
 We also obtain Biogas from the
sludge, which is used in the
production of electricity using Bio-
gas Engine.

18.  The treated water at CMWSSB
NESAPAKKAM SEWAGE
TREATMENT PLANT attains an
overall treatment efficiency of
94.56% for the BOD removal and
that for Total Suspended Solids
removal 93.72%.
 The individual units also performed
well, and their removal efficiencies
were quite satisfactory. BOD and
TSS removal efficiencies of the
primary clarifier are 30.59% and
50.61% respectively. BOD and TSS
removal efficiencies of the activated
sludge plant (Aeration tank +
Secondary clarifier) are 91.27% and
86.76% respectively.