ABSTRACT
India is a densely populated country with an ever-increasing population. While increase in population creates a crunch in resources, a lot of waste is also generated, especially in cities and towns. Waste disposal and management is one of the major problems facing the municipal authorities, with an increase in the urbanisation process. Studies on composition of wastes have revealed that around 75–85% of the waste generated is either biodegradable or recyclable. Composting of waste is one of the oldest methods of waste valorisation. It reduces the waste through biological processes and the end product can be used as soil vitaliser. However, a lot of space and time is required for waste to biodegrade by this process. Anaerobic biodegradation of waste to form biogas is a beneficial technology for waste valorisation. Biogas derived from the biomethanation process can be used to replace conventional cooking gas. It can be compressed, bottled, and marketed as compressed biogas. It can also be used to generate electricity. The slurry, the end product of anaerobic digestion, is rich in nutrients and can be used as soil enhancer. Thermal degradation techniques are being used to derive energy from waste. Bioethanol can be produced by the process of fermentation from waste. It is in high demand after governments of several countries, including India, have mandated the blending of bioethanol with traditional fossil fuels like petrol and diesel.
This chapter focuses on different valorisation techniques of municipal solid waste with special emphasis on biomethanation, or anaerobic digestion. Both the quality and quantity of waste generated changes with time, and optimisation is required for a constant output. This is especially true for emerging economies like India, where most of the waste is dumped in landfills. The cost/benefit analysis shows that anaerobic digestion is perhaps the best valorisation process because of its high economic and environmental benefits.
