Asia-Pacific Water Forum

RECYCLING OF URBAN WASTEWATER FOR FOOD PRODUCTION

Best Practice Example from Kolkata, India

The cities consume water but disposal of waste water has become a problem. There is growing awareness of recycling of wastewater for aquaculture for fish production and irrigation and utilisation of sludge for vegetable production. Throughout Asia in many cities sewage fed waste water is used with benefits of employment, improved environment, and food production. It is cost effective process. Kolkata, a megacity in India has the largest recycling district in the world. Kolkata metropolis is built on marshy land and there are many wetlands. There is indigenous technology of waste water treatment.

From the city’s nearest drainage outfall and canals and through inlet and outlet connection with periodical exchange of sewagefed waste water in wetlands or ponds, each a lagoon type facilitating natural aeration upto a shallow depth to allow sunlight to reach its bottom to promote growth of algae and photosynthetic oxygen. Using aquatic plant like water hyacinth and duckweed, dirt and some metals are removed and it is also purified by exposure to sunlight and aeration. The high productivity of these fish ponds is mainly due to rich nutrient element and the high alkanity stimulates production in the fish food chain. It geneates abundant quantity of algael photo-synthetic oxygen. Another aspect is the integration of aquaculture with agriculture-vegetable production based on natural compost out of solid waste disposal. Some fishermen’s cooperative societies have been formed and there is participatory development. Several development, some with the support of local municipalities are in Kolkata Metropolitan area. In Southeast Kolkata in Mudially, a nature park has been developed based on ecological development of waste water treatment. This is one of the best practices for sustainable development.

Centre for Built Environment, Kolkata made presentations on these aspects, at many International Conferences and World Water Forum. For further details : Centre for Built Environment. e-mail : (sghoshcbe@rediffmail.com).

(Poster: Prof. Santosh Ghosh)