Sewage fed aquaculture in Kolkata
Farmers around Kolkata city in India developed a technique of using domestic sewage for fish culture almost a century ago. This technique is widely used to meet the growing demand for fish in this thickly populated Indian city. The technique is considered to be unique and is the largest operational system in the world to convert waste in to consumable products.
The system appears to have started nearly a century ago although large-scale usage of sewage for fish culture began in the 1930s. Early success of fish culture in stabilized sewage ponds, which were used as a source of water for growing vegetables, provided stimulus for the large-scale expansion of sewage fed fish culture system. The area under this unique system of culture peaked at 12,000 ha, but in recent years there has been a steep decline in the area due to the increasing pressure from urbanization. Currently, the area under the sewage fed culture system has been reduced to less than 4,000 ha and the poor people dependent on these wetlands for their livelihood have been severely affected. However, even today, a considerable amount of fish consumed in Kolkata city is produced from this system. There are appeals to Government to declare the existing sewage fed aquaculture area as sanctuaries and to protect them from further encroachment by the rapidly expanding population of Kolkata city.
The waste recycling system that has evolved in Kolkata city involves garbage based vegetable farms, wastewater fed fishponds, paddy fields using fish pond effluent and sewage fed brackish water aquaculture. The practice of using pond effluent for paddy cultivation is of recent origin
C.A.C Systems 