Methane gas has around 25 times the global warming potential of CO2, with over 56 times the heat trapping capacity. India’s greenhouse gas (GHG) emissions are 29% methane gas, with 6% emitted from waste – both higher than the global averages. Kolkata’s climate change risks have been exacerbated by unsanitary disposal and waste dumping. Prior to the KSWMIP, waste was piled up to 15 meters (50ft) high at dumping sites, polluting land, water and air. Poor sewage management and waste dumping in the Ganga River had resulted in the extinction of several hundred aquatic animals and insects, damaging biodiversity.
The Solid Waste Management Project has achieved 60-80% (depending on site) segregation of waste at its source, with further waste segregation occurring at transfer stations. Transfer of waste directly to a sanitary landfill site, or through a transfer station, has reduced open dumping by 35% – 120 tonnes per day (TPD). Ten to twenty TPD is composted and the remaining 100TPD is transferred to sanitary landfill sites. Five composting plants have been built, providing a 150TPD capacity, with three already functioning. Composting of biodegradable waste at these stations prevents uncontrolled bacterial decomposition of the waste, reducing methane gas and CO2 emissions. It has also reduced associated hygiene hazards and ground water contamination.
Municipalities are able to earn revenue from selling the compost from the plants, and also by raising user fees from families, institutions, markets and any other waste-generating agency. For example, a municipality the size of Uttarpara Kotrung (10.9km2) can now produce more that 25 tonnes of compost a day, which is sold for $41 per tonne and can thus generate around $1000 per day. The current collection services charge is $10 per household, per month. The project has also provided employment for unskilled labourers.
Adoption and promotion of the ‘3R’ principles (reduce, reuse, recycle) has had positive environmental effects, drastically reducing indiscriminate waste dumping in the city. The project has increased public awareness about health and hygiene along with appropriate waste management and disposal practices. This has aided a reduction in the prevalence of diseases previously associated with the waste dumps. Public participation in the project is high and a sense of commonality and community have been created through establishing a shared citizen behaviour of household waste separation.
The KSWMIP will monitor Kolkata’s ambient air quality, recording changing levels of both methane and CO2. The project aims to eradicate open dumping and burning of waste through segregation at source and waste transfer to the city’s composting and sanitary landfill sites. It is hoped that this will help achieve a further target of limiting the concentration of methane gas generated in landfill sites to 25% of the lower explosive limit. Measures are also in place to preserve ground water quality within 50m of the landfill site periphery.
Neither the sanitary landfill site, nor the composting plants are currently operating at full capacity, indicating that even greater performance indicators (e.g., reduction in dumping, TPD handled at sites and methane gas emissions reduction) could be recorded in the future.