Wetlands Transform a City’s Sewage Through a Bit of Solar Alchemy

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Wetlands Transform a City’s Sewage Through a Bit of Solar Alchemy

The East Kolkata Wetlands at sunset.

Every evening, when the twilight sky casts its spell across Kolkata’s Eastern Metropolitan Bypass, motorists whizzing toward the airport can catch a glimpse of an eerie-looking expanse of water peeking from behind the area’s gaudy billboards along the city’s eastern fringe. Most have no idea that they’re looking at the lungs and kidneys of their city.

The East Kolkata Wetlands (EKW) are a key component of Kolkata’s waste-management resilience. Abutting this city of five million, the 12,500 hectare space, which includes about 4,000 hectares of sewage-fed bheries (fisheries), has managed to survive the onslaught of Kokata’s eastward urbanization. No more than one meter deep, this unique ecological zone’s sewage-fed aquaculture and garbage-fed horticulture provide the city with a natural waste recycling process not quite replicated anywhere else in the world. Indeed, it is the only sewage treatment “facility” that exists within the city limits of Kolkata, and offers a key element of redundancy to the city’s overtaxed waste-management systems.

According to wetlands expert Dr. Dhrubojyoti Ghosh – the man credited with protecting the EKW back when he was a rather disgruntled government official – how the system works is a small miracle of renewable energy usage. In a paper for the Netherlands-based advocacy group Waste, Ghosh describes the recycling sub-region as growing vegetables on a garbage substrate; alternate bands of garbage are layered with elongated trench-like ponds known as jheels.

The wetlands provide a critical source of wastewater processing to a rapidly growing city.

“In these jheels, sewage is detained for some time, after which the treated effluent is used for irrigating the garbage fields for growing vegetables. In the fishponds, the city’s wastewater is made to flow through a network of drainage channels.” he writes. The fish ponds themselves act as solar reactors, using the sun to complete most of their bio-chemical processes.

These processes, fueled by “algal photosynthesis,” are even more effective at cleaning wastewater than industrial sewage treatment plants, removing potentially pathogenic bacteria that a conventional plant wouldn’t. In addition, once the water is drained from the fish ponds, it can be used to irrigate the farmers’ rice patty fields, creating a near-perfect cyclical system of natural recycling.

“The fishpond ecosystem of east Calcutta,” Ghosh concludes, “is one of the rare examples of environmental protection and development management where a complex ecological process has been adopted by the fish producers and farmers for mastering the resource recovery activities.”

Gautam Makhal is one of these local fish producers. A energetic man in his thirties, he works in one of the fisheries at EKW despite holding a business degree.

The wetlands are unique in providing not only sewage treatment, but the opportunity to grow crops.

“After graduation I did not find any decent job, and then I was forced to work here following my father’s footsteps,” he says. “I was unhappy initially, but today it provides me a livelihood.” Going about his daily work, he is unaware of exactly how crucial a role he plays in helping to keep his overpopulated city sustainable.

Ghosh has been able to lead the effort to protect the EKW thanks largely to its designation as a Ramsar site in August 2002. The Ramsar charter, signed at a convention on wetlands in the Iranian city of Ramsar in 1971, provides national action and international cooperation for the conservation and wise use of wetlands.

Despite this, the EKW has weathered some close shaves. It was nearly delisted as a Ramsar site several times, and it took a long time for city leaders and the state government to come up with an integrated wetland management plan. But the EKW proved resilient itself, and in 2006 received an additional measure of legal protection with the passage of the East Kolkata Wetlands (Conservation and Management) Act, passed by the West Bengal government, which provides for more conservation and management of the region.

The first public interest litigation to save it was launched by the Kolkata citizens’ group PUBLIC (People United for Better Living in Calcutta) against a proposed plan to develop 800 acres of the wetland. Says Bonani Kakkar, a moving force behind PUBLIC who is also a member of the East Kolkata Wetlands Management Authority, “Protection of EKW has a lot to do with improving the quality of life in Kolkata, a heavily polluted city.”

Tapan Mandal and his wife farming on the EKW.

“These wetlands help clean up Kolkata’s air [by acting as a carbon sink], reduce flooding in the streets [by receiving the outfall of our drainage system], help recharge our ground water and provide cheap, fresh fish and vegetables to the city,” says Kakkar. “The potential for eco-tourism here is phenomenal, if only we could shake off our standard bricks-and-cement approach to development. Eco-tourism here would provide local employment and a unique opportunity for education, recreation and regeneration of its unique biodiversity.”

According to Ritesh Kumar, the conservation program manager of Wetlands International – South Asia, the EKW shows that when planning for resilient cities we need to focus on more than physical infrastructure.

“Urban planning in Kolkata should see EKW as its own infrastructure,” says Kumar. “But there is still some lacunae in recognizing that in Kolkata. The land use in EKW should be maintained along with regional hydrological capacity.”

On the flip side, warns Kumar, a system built on waste cannot sustain itself forever, and the healthiness of the vegetables and crops grown there should be independently ascertained. Green activists say the city is grateful to the local fish and vegetable farmers of the area. “Despite lucrative offers,” says Kakkar, “many farmers and fishermen have stuck to their traditional livelihood. We wish they could be compensated not just for their produce, but also for their environmental services to the city.”

As the sun was setting over Kolkata one recent evening, I drove down the E.M. Bypass and then took one of the approach roads to EKW for some quick photographs. There, in one of the fields by a fish pond, I met 48-year-old Tapan Mandal and his wife, farming with beaming faces.

“My father was farming here since 1962. I am carrying forward that practice,” he said.

“What we grow here fetches just enough to run the family,” added his wife. “We are happy.”

Photos by Sujoy Dhar

Tags: resilient citiesenvironmenturban farmingpollutionindiakolkata

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