Kolkata proposes to introduce biomining for the first time in the city to tackle its Municipal Solid Waste (MSW) management challenge and Mollar Bheri in the eastern part of the city will pave the way.
A portion of land in this shallow flat-bottom waste water-fed fishery, located within the East Kolkata Wetlands, was being used by Urban Local Bodies (ULBs) as a dumping ground. It was alleged that the Bidhan Nagar Municipal Corporation, the Nabadiganta Industrial Township Authority (NDITA) and New Town Kolkata Development Authority (NKDA) — all in the greater Kolkata region — had been disposing of waste in the wetland for over two decades.
This, despite the fact that the East Kolkata Wetlands (EKW) is an internationally recognised wetland area, listed by Ramsar as a ‘Wetland of International Importance.’ EKW enjoys the distinction of being the world’s largest “wastewater-fed aquaculture system”, where the city’s sewage undergoes a natural purification process and is used in agriculture and pisciculture. The area is protected by an order from the Calcutta High Court passed in the early 1990s. Moreover, the Central Wetlands Rules 2017 also prohibit any contamination and pollution in the wetland area spread over 12,500 hectares.
However, over the years, substantial portions have been encroached for human activity and recent satellite images raise fears over whether the site will exist at all if things continue the way they are now. Mollar Bheri is one part that has seen reckless conversion into a landfill area with mountains of mixed waste dotting the landscape. The biomining proposal thus raises hope of restoration of the wetlands to some extent.
The current initiative by the government comes in the wake of a National Green Tribunal (NGT) Order. In August 2019, the NGT had fined the Bidhannagar Municipal Corporation (BMC) Rs 10 lakh for failing to comply with the Tribunal’s earlier order of cordoning off the garbage dump area at Mollar Bheri to stop polluting leachate from contaminating the water bodies around.
The main entrance to the dumping site at Mollar Bheri. Pic: Mou Chakraborty
In its order dated December 18, 2019 the Tribunal stated that it would be in public interest “if the current waste is disposed of by the three ULBs strictly in accordance with the Solid Waste Management Rules, 2016 to be disposed off scientifically elsewhere.” The Tribunal directed the Bidhan Nagar Municipal Corporation to take actions expeditiously in a time bound manner.
The Urban Development and Municipal Affairs Department of the Government of West Bengal put out a call for biomining project proposals from interested parties on November 22nd. The details of the applications or selection are still under wraps, though. But if and when it goes through, this will be Kolkata’s first attempt at biomining, which will not only segregate MSW and get it treated scientifically but will also help to rid the soil of the area of its toxicity. This will, in turn, stop the contamination of nearby water bodies and land areas.
What is biomining?
The process of bio-mining starts at the source of garbage collection where dry waste and wet waste is segregated. The West Bengal government has already launched a campaign related to the same and has been distributing booklets to the city dwellers. But for dumping grounds like Mollar Bheri, the garbage heap will first have be stabilized and converted into fractions where garbage with calorific values will be converted to Refuse Derived Fuel (RDF) and can be used in various ways to produce electricity. One part of the waste will be converted into compost through a technique which entails loosening the waste by harrowing and then spraying it with compositing bio-cultures.
Sadhan Kumar Ghosh, Dean of Faculty of Engineering and Technology at Jadavpur University, Kolkata, was on the expert committee set up by the Union Ministry of Housing and Urban Affairs (MoHUA) for the ‘Preparation of standards for RDF for utilisation in cement plants and other industries’. “Usually, mixed material or waste cannot be used to make compost,” he said, explaining how safe it is to convert toxic waste into RDF and compost, “Compost comes from organic waste and should not have heavy metals or other hazardous elements. Ideally waste should be segregated at source for composting, but our municipalities generate mixed waste. However, technology provides a way out.”
This is through bioremediation, also known as biomining, which involves digging of the waste, followed by segregation and then treatment and separation of the toxin. Once done, the soil has to be treated with pathogen and bacteria to cleanse it. The compost made out of the segregated waste has to be tested, and if required, treated again for removal of residual toxin. “It is an expensive method, but doable,” said Sadhan Kumar Ghosh, as he explained the method.
Explaining further, he added, “India’s 2016 rules for management of hazardous waste suggests incineration of non-compostable and non-bio-degradable waste in a controlled environment where emissions do not go out. The rule specifies different treatment methods for various kinds of hazardous material. Non-bio-degradable waste like plastic, glass, metals and batteries can be recycled while non-recyclable waste having calorific value of 1500 K/cal/kg or more can be utilised for generating energy through RDF which can be used in cement plants.”
Kolkata plans
The West Bengal government had sent a delegation to Nagpur to study the biomining technique in practice for some time now. The Nagpur Municipal Corporation (NMC), with the help of Zigma Global Environ Solutions, a private solid waste management services company, is carrying out biomining of 8 lakh tones of MSW spread across 50 acres in Nagpur.
To begin with, biomining will be initiated in an area spread across 55 acres of land at Mollar Bheri and will look at stabilizing and treating the 12 feet high mountain of garbage, created by about 3 lakh metric ton of MSW generated from Bidhannagar, New Town and Sector 5. According to officials, it is going to take around 10 months to complete biomining of the accumulated waste and will cost about Rs 21 crore.
“The problem is that our society had never imagined that waste disposal could be such a complex technical operation,” said Subrata Gupta, IAS, Principal Secretary to Government of West Bengal, Urban Development & Municipal Affairs Department and also Vice Chairman, NKGSCCL (Newtown Kolkata Green Smart City Corporation Ltd), “We have always carried waste from one point, dumped it at another point and looked away. But this can’t work anymore. We not only have a dearth of land now, but the land being used for the purpose is also contaminating the soil and water around it. We need to treat it scientifically and look at ways of recycling.”
Ultimately, the entire area has to be cleaned and restored to its former glory. “We have spoken to many agencies, there are technologies which can help us achieve this. But our estimate suggests that we will still end up with about 10% of the material which cannot be reused; this will have to be kept in sanitary landfills at various sites,” Subrata Gupta added.
Along with Mollar Bheri, a few other dumpyards in and around Kolkata are also expected to be sanitised through biomining. These include Promodnagar dump, Howrah dump, Baidyabati dump, Habra dump and Ashoknagar dump. Proposal requests for the first two have already been sought by the state government.
In addition, the state government has already acquired a 20-acre plot in the Rajarhat area to set up a biomethane plant with a capacity of 200 tons of fuel output per day. The land will also house a Material Recovery Facility (MRF) where the waste collected from Rajarhat, NDITA, parts of Kolkata and Salt Lake will be processed and then fed to the biomethane plant. “We will set it up once we finalize the agency. This will also take care of the demand for green energy in the area,” Gupta said.
While the idea of biomining is apt and attractive from an environmental perspective, many, including Professor Ghosh, question its sustainability. “Bioremediation or biomining is the need of the hour in sites like Mollar Bheri, where there has been an accumulation of municipal mixed waste over the years. The proposition is, however, very expensive. Sustaining these projects, which need an average of two years (to make an impact), does not seem sustainable especially when investment is a challenge and the government will have to prioritize between investing in development projects and treating accumulated municipal waste,” he said.