Decentralized Organic Waste Management with Small-Scale Anaerobic Digester - A Case Study of Pune, India
Pune generates 2,100 metric tons of municipal solid waste per day, of which 45-50% is organic waste. One of the most successful features of Pune’s waste management is the city’s network of 26 decentralized biodigesters, each processing five to ten tonnes of organic waste per day. These biodigesters provide energy to light the neighborhood and soil amendment to maintain local green spaces. They vastly reduce transportation costs by treating waste locally rather than transporting them to centralized treatment or disposal facilities. The risk of unprocessed waste piling up due to a temporary failure of a single facility is also reduced, since waste can be sent to a number of operational distributed facilities, as opposed to a large centralized facility failing without alternate facilities to process the waste. The diversion of organic waste from landfilling also assists in emissions reduction of methane, a potent greenhouse gas. A number of other large and medium cities in India have conducted site visits to Pune and started to replicate its successful model.
This presentation is based on site visits to multiple facilities and will focus on the technologies, financial models, and challenges observed at these facilities. The technologies adopted at these facilities include those based on up-flow anaerobic sludge blanket technology and conventional anaerobic digestion technology. The plants have a similar financial model with the plants being operated by a private concessionaire receiving tipping fees paid by the municipality. The contracts are for a period of five years for plants installed by the municipal corporation, and ten to fifteen years for plants installed by the private sector. Challenges include problems with the quality of the feedstock and maintenance of the facility. For instance, electricity production at a five tonnes per day facility using a 50 KVA generator operating less than 6 hours per day was 2.09 KWh on average (as observed in March 2018). The possible reasons for low energy output are non-operational scrubbers leading to low purity of biogas and inadequate maintenance of the equipment. While the municipal corporation employs penalties for not processing waste, there is a need to develop monitoring, reporting and verification mechanisms embedded into the system that can track a plant’s performance and thereby increase its efficiency.
This presentation is based on studies conducted by the U.S. Environmental Protection Agency and The Energy and Resources Institute on behalf of the Climate and Clean Air Municipal Solid Waste Initiative. It describes one of the best decentralized organic waste management systems in India, with its key features, pit-falls, and possible methods of replication and adaptation to other cities around the world, especially in developing countries.