Sprawling over a huge area of 125 square kilometres, the world’s largest sewage management system is situated right on the city’s outskirts. The East Kolkata wetlands were declared to be a Ramsar site, which implies a wetland of international importance, in the year 2002. It is an ecological wonder, a network of natural and manmade wetlands that composes an efficient sewage management system. The meshwork contains small water bodies, sewage farms, salt meadows and low-lying salt marshes that enhance organic sewage treatment.
The ecosystem is maintained by local farmers and fishermen who understand the infinite importance of the place. Apart from efficiently purifying the city’s sewage naturally with the help of adequate oxygen, sunlight and decomposing microbes, it is also a reservoir of rich, flourishing biodiversity. The organic water generated is used as fish feed, and to grow paddy and vegetables on the banks. The treated water is devoid of potentially harmful waste products and seethes with nutrients and essential compounds required by the human body. The entire process is termed as bio-remediation and continuously purifies the accumulated wastewater in 20 days, without misbalancing the intricate ecology. In spite of having no sewage treatment plant in the core of the city, the 750 million litres of wastewater and sewage produced every day is purified by this miraculous system. When the entire Gangetic delta is prone to flooding, the wetlands also serve as natural flood control for the city. Gravitational force takes the gradient of water from the sewage and drainage systems to the wetlands, which acts as a sponge basin, neutralising flood threats.
Due to the city’s increasing real estate market, this natural gift is dwindling and will no longer exist if proper precautions are not taken. The ever-increasing greed for lands has led to contractors filling up the shallow fish ponds which act as veins and arteries for the wetlands. Many environmentalists are trying their best to increase awareness about the wetlands and preserve its existence.