Present Sewerage
System
The Nagpur city has 3 natural drainage zones (Figure
1), namely, north, central, south on account of the topography of the city. The
sewerage system of the city mainly consists of gravity sewers with only one
pumping station and treatment plant located at Bhandewadi. Part of the flow
generated in the central zone is treated in this treatment plant. But sewage
that flows from northern and southern zones flows to the stream without any
treatment. Zone wise details of existing sewerage system are as shown in Table 1.
Table 1: Present sewerage system
|
Zone |
Year |
Sewage collection system
(Branches/laterals) |
Sewage Treatment Plant |
Effluent Disposal |
|||||
|
Nalla |
Reuse for irrigation |
||||||||
|
Dia.* mm |
Length Kms |
Cap.# MLD |
Cap. MLD |
Type of Treatment |
|||||
|
Central |
1922-1943 |
200-1800 |
19 |
|
- |
No Treatment |
In Nalla |
- |
|
|
1956 |
200-1800 |
33 |
100 |
45 |
Primary Treatment (not in
use) |
55 MLD |
45MLD for 487 Ha. |
||
|
2001 |
No sewerage Network |
100 |
Primary & secondary
Treatment |
100 MLD |
Under con-sideration |
||||
|
North |
1956 |
225-975 |
7.352 |
|
- |
- |
In Nalla |
- |
|
|
South |
1956 |
225-1050 |
12.026 |
|
- |
- |
In Nalla |
- |
|
|
*
Dia. = Diameter, # Cap. = Capacity |
|||||||||
100 MLD capacity sewage treatment plant is recently commissioned in March 2001. The scheme envisages primary and secondary treatment of 100 MLD sewage. Details of the scheme executed are as under:
·
Connecting existing outfall sewer of 1800 mm diameter to raw
sewage sump
·
Raw sewage sump and pump house of capacity 16.72 lakh Liters
·
Prestressed concrete Rising main of 1200 mm diameter with design
pressure of 16 Kg/cm² and length of 2.095 Kms from sump to STP at Bhandewadi.
·
Pumping machinery
·
Sewage treatment plant of capacity 100 MLD at Bhandewadi.
The annual operating cost of 100 MLD capacity sewage
treatment plant scheme and self-supporting taxation structure are shown in
Table 2 and 3 and also depicted in Figure 2.
Table 2: Annual
Operating Cost
|
Operating head |
Cost (Rs.
Lakh) |
|
Repayment of loan and depreciation |
366.65 |
|
Maintenance and repairs |
61.05 |
|
Establishment |
69.30 |
|
Energy charges |
525.00 |
|
Total |
1022.00 |
Table 3:
Taxation structure
|
Sr.No. |
Particulars |
Amount
(Rs.in lakh) |
|
1 |
Water cess (for 1212 Ha @ Rs. 5875 per Ha per
annum ) |
71.00 |
|
2 |
Sewerage tax (for 123000 houses @ Rs. 700 per
house per annum) |
861.00 |
|
3 |
Sale of manure (for 9000 MT @ Rs. 1000/MT) |
90.00 |
|
|
Total revenue expected per annum |
1022.00 |
Figure 2: Operating cost and taxation structure