As urban India’s landfills swell and air quality deteriorates, innovative waste solutions are no longer optional but necessary. In Delhi alone, over 10,000 tonnes of waste are generated daily, the Municipal Corporation of Delhi told the Supreme Court of India earlier this year, the majority of which is added to the overflowing landfill sites at Ghazipur, Bhalswa and Okhla.
Multiple questions arise when we think of waste management: What is the composition of waste in India? Why is it important to tackle wet waste? What is the situation with waste in the national capital?
Only 12 wards in the city practice proper waste segregation, the Economic Survey 2023-24 report had revealed. Approximately 30-35 per cent of the waste generated in urban India is dry and 50-60 per cent is wet, a 2022 paper by the Central Pollution Control Board (CPCB) stated.
While efforts have been made to promote recycling, wet waste is often overlooked, with the assumption that it will naturally decompose. However, mixed waste hinders recycling. Mixed waste frequently ends up in landfills, where the anaerobic decomposition of wet organic matter produces methane, a potent greenhouse gas.
Methane buildup can fuel landfill fires, releasing harmful chemicals such as carbon monoxide (CO), volatile organic compounds (VOCs), dioxins and furans. In 2022, fires at Delhi’s Bhalswa landfill alone contributed nearly 20 per cent of hazardous emissions for the year, exacerbating the city’s pollution crisis, the CPCB report stated.
Waste-to-Energy (WtE) plants, which aim to incinerate waste for energy, face similar risks. WtE plants in Delhi have often struggled with efficiency due to the high moisture content of waste, leading to incomplete combustion and higher emissions, according to a 2021 document by policy research organisation The Energy and Resources Institute (TERI).
When mixed waste is incinerated, it releases carbon dioxide, nitrogen oxides, sulphur dioxide and particulate matter, further worsening Delhi’s severe air pollution.
Perhaps one of the least discussed aspects of this crisis is its impact on the health and safety of waste pickers, who play a crucial role in Delhi’s recycling ecosystem.
Waste pickers in Delhi contribute to recycling nearly 20 per cent of the city’s solid waste but face increased occupational hazards due to poor waste segregation, according to a 2022 paper by nonprofit Chintan. Wet waste contamination also reduces the quality of recyclables, adding to their workload and lowering the value of the materials they collect.
Biogas plants offer an eco-friendly solution to the challenges of wet waste. By processing organic wet waste through anaerobic digestion, biogas plants convert this waste into renewable energy — biogas — which can be used for electricity, heating or cooking.
This process is far more environmentally friendly than incineration. The technology is also accessible: small-scale biogas plants can be set up in households under supervision. By storing biogas in simple containers like tyres, communities can generate the fuel they need for everyday activities.
In Delhi, the annual cycle of addressing open burning and air pollution during winters often places undue pressure on security guards and the informal sector. Residential Welfare Associations (RWA) are directed to provide electric heaters and blankets for security guards, yet practical challenges remain: Who covers the electricity bill? Are there sufficient power sources for these heaters?
This electricity could be generated from biogas. Imagine if every society, apartment building, or RWA provided wet waste (which is free) to the security guards and, under supervision, biogas was generated for cooking and electricity needs throughout the year.
This would not only improve the living and working conditions for these essential workers and save on electricity bills but also address the issue of biomass burning. Additionally, the digestate byproduct from biogas plants can be used as a nutrient-rich fertiliser, promoting sustainable agricultural practices.
Several Delhi RWAs have already piloted these small-scale systems. For instance, in Dwarka Sector 9, a biogas plant set up by a local RWA has successfully reduced wet waste by 30 per cent, while powering community kitchens and heaters during winter, the TERI paper suggested.
In densely populated urban areas like Delhi, space is a major constraint, but small-scale, scalable models offer a practical solution. Household biogas digesters, requiring just 1-2 square metres, can process 1-3 kilogrammes of kitchen waste daily and generate enough biogas for cooking one or two meals. These systems can be installed in balconies, backyards, or small common areas within apartment complexes.
For larger communities, small community biogas plants that take up about 4-5 square metres can process 50-100 kg of organic waste per day, providing biogas for communal cooking or electricity for security guard heaters. These compact systems can be placed in basements, unused parking spaces or rooftops.
These space-efficient biogas models allow for decentralised waste management, reduce the strain on landfills and create opportunities for RWAs and communities to handle organic waste locally. Households and RWAs can receive subsidies for setting up biogas plants, according to the National Biogas and Manure Management Programme.
This is part of the GOBARdhan scheme, which promotes converting waste into wealth. By implementing these small-scale biogas systems, Delhi can address its waste management challenges without needing large plots of land, while generating renewable energy and reducing pollution.
The adoption of biogas plants in Delhi could also significantly enhance the role of waste pickers in the recycling process. Formalising their roles through government policy and ensuring better working conditions would protect their health and strengthen the city's recycling process. Pilot programmes across Delhi have shown that integrating waste pickers into the operations of biogas plants can increase the quality of recyclables by 40 per cent and reduce the volume of mixed waste sent to landfills, showed the Chintan paper.
Integrating biogas plants into Delhi’s waste management system can transform how we address the waste crisis, treating wet waste as a resource. Key benefits include reducing landfill fires, decreasing open burning, improving WtE plants and empowering waste pickers. RWAs and communities should adopt small-scale biogas systems, with government support through subsidies and formalised roles for waste pickers.
Citizens can contribute by segregating wet waste and supporting local biogas projects. This approach mitigates environmental and health risks, fostering a sustainable city. Collaboration between citizens, policymakers and residents is essential to integrate biogas solutions, reduce air pollution and advance climate goals.
Kezia is an independent socio-environmental researcher.
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth.