Wastewater-Based Circular Economy Operations in East Kolkata Wetlands (the Largest Ramasar Site in South Asia), India

Abstract

Wastewater generated from domestic and industrial sources contains a cocktail of countless beneficial and harmful chemicals. Conventional wastewater treatment plants used for removing toxic metals and nutrients from wastewater are not considered a viable option in developing countries because of their energy and capital-intensive nature. Nevertheless, wastewater treatment should not let nutrients wasted down the drains and cause eutrophication and environmental deterioration of the receiving water bodies. Rather it is desired to accomplish recovery and recycling of nutrients and water to bioregenerative use by closing the loop through circular economy approach towards sustainable development. Ecotechnology has evolved as an economical ecofriendly holistic approach to wastewater remediation, for fulfilling human needs while protecting environment from pollution, by harnessing and subtly manipulating ecosystem components and natural forces to leverage their beneficial effects. The East Kolkata Wetland (EKW), a Ramsar site located at the east of Kolkata city and composed of salt marshes, agricultural fields, sewage-fed fish farms and settling ponds, exemplifies an eco-engineered natural wastewater treatment system, receiving daily up to 65% of Kolkata’s sewage and reusing it for producing fish and vegetables by local communities. the present book chapter portrays the genesis and the state-of-the-art of ecotechnological practices spearheaded by wastewater-fed aquaculture (WWFA) sustaining in the East Kolkata Wetlands (EKW), its present problems and future scope for improved circular economic approaches to converting ‘waste into wealth’ in meeting the win–win goals of environmental protection and livelihood security. However, some of these activities pose potential risk for the environment and human health due to presence of toxic heavy metals, and pathogenic microorganisms, which warrants comprehensive ecotoxicologicl risk assessment studies.