Study on possibilities of low cost waste water management in urban India
fisheries in bheries (wetlands), irrigation water for vegetable gardens and finally
irrigation water for agricultural crop (mainly paddy) production consecutively at
the eastern part of the city. There are 264 fish farms ( bheries ) are operating on a
commercial basis in EKW and they cover a total area of about 2858.65 ha (Ghosh,
1999).
The technical system developed in EKW for treatment of wastewater works as
follows. The wastewater of the city brought by the canals to these bheries and
passed through the few small sedimentation tanks (anaerobic tank) and where
the water is treated manually using either liming by CaO (Calcium Oxide) or
biochemical. Water hyacinth is usually grown in these anaerobic tanks to facilitate
absorption of the oil and grease in the effluent. Then the water allowed entering
into the bheries for pisiculture and the excess water left out through sluice gate
into the crop field for their irrigation. The regular netting and rowing (by paddle
boat) at some fisheries helps in re-oxygenation from the atmospheric oxygen in
the water bodies. Vegetable gardens situated nearby on the garbage substrate also
use this water as irrigation water from bheries. Through this system EKW recovers
nutrient for fish, crop and vegetables as well as fresh water of primary treated
quality. An estimated 13000 MT of fish per year and 150 MT of vegetables per day
produced in this area (dfid.stir.ac.uk).
Table 4. Production, productivity and return from sale of fish of BFCSL during
1999-2000 to 2003-2004
Production
Productivity
Return from sale of fish
Year
Total
CGR
CGR
Total return
Return/ha
CGR
MT/ha
(M.T)
(%)
(%)
( ` )
( ` /ha)
(%)
1999-00
66.30
6.63
16,67,995.00
1,66,799.50
2000-01
83.30
8.33
22,88,275.85
2,28,827.58
2001-02
69.40
1.46
6.94
2.40
18,31,822.10
1,83,182.21
5.90
2002-03
74.29
7.42
20,06,456.05
2,00,645.60
2003-04
75.50
7.55
23,72,335.50
2,37,233.55
Source: Bonhooghly Fishermen’s Co-operative Society Ltd.
It has been estimated that establishment of wastewater treatment plants for
secondary wastewater treatment with ‘Reverse Osmosis’ system requires a huge
investment of ` 1.81 crore/Million Litre Daily (MLD) as initial cost as well
as ` 43,000/MLD as operating cost (cseindia.org). On the contrary, the initial
investment in west fed aquaculture is much less amounting to ` 30 lakh/MLD.
It may also provide an additional year-round employment at the rate of 2 people/
ha besides treatment of wastewater (Ghosh, 1999). Analysis of wastewater in
different times at this place proved that each hectare of wetland removes 237 kg
of BOD per day (Ghosh, 1999). However, water-testing centres have yet been
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