Paper short abstract:

The paper critically analyses the role of local knowledge of the indigenous people in the purification of sewage and waste water and supplying the varieties of fish and agricultural produce to Kolkatans without damaging the rich biodiversity of the wetland.

Paper long abstract:

Ecologically subsidized Kolkata metropolis has a geological advantage has a slope towards east which facilitates the drainage system carrying sewage and waste water into vast swampy, marshy land in the eastern part of Kolkata acts as a 'sink'. This sink undergoes a continuous pressure of a rampant growth of urban built and infrastructure through wetland reclamation ignoring the importance of drainage and purification of sewage as well as the rich biodiversity of wetland. Many of the performance of wetland functions go unnoticed because of its slow mechanism of chemical-biological-physical processes by filtering out pollutants to maintain the water quality before it enters into the distributaries of Bay of Bengal. Wetland dwellers with their knowledge of precision technology (for e.g. linkage between solid waste and compost manure, animal waste and fish feed, plant waste(Hyacinth) and cattle as well as fish feed ) inherited from the older generation to convert the wastewater into resource recovery system are reflected into an aqua cultural and agricultural cultivation despite several interferences. Human populations are directly or indirectly benefited by wetland ecosystem goods (e.g. food) and services (e.g. waste assimilation) to utilize the flow of waste water from the outfall channel particularly by maintaining the 4 level resource recovery systems such as garbage vegetable farms; wastewater-fed fishponds; paddy fields using fishpond effluent; and sewage-fed brackish water aquaculture would be the important of our study.