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The big projects in China, India and Nepal used animal dung as a feed stock. It is seen as a rural technology, so has less attention from governments interested in helping people in rapidly growing urban areas.

Recent developments in India use biogas to process food wastes, so it is gaining an urban dimension. One approach is plastic floating drum plants for individual households. Groups using this approach are ARTI in Pune, Maharashtra; VK Nardep in Kanyakumari, Tamil Nadu; and Biotech In Trivandrum, Kerela. People can save up to 30% LPG for cooking by processing their own wastes, or up to 100%, using waste food from elsewhere.  

Biotech have larger sized plants to process food wastes and sewage from institutions. Similar systems are used with market wastes, run by local authorities, mainly in Kerala. These plants use floating steel drums, but newer ones use tanks made from fibre reinforced plastic.

Two very successful projects use fixed dome designs to process human sewage in Africa. The KIST project in Rwanda was built by a Tanzanian engineer for sewage from prisons. BTAL in Ghana use similar designs for sewage from hospitals, schools, universities and hotels.

Food waste is a growing problem in Indian cities. High land values mean the gardens where the cattle who used to eat food waste could live are being built on. Biogas plants can generate energy and compost from these wastes.  

Processing food wastes can cause problems with biogas plants, as fibrous materials do not digest well and can clog up the system. Pre-processing allows the fibres to be removed from the feed before it is added to the digester. Food waste can be ground up fine, or a predigester can be used. Approaches have been developed by Bioplex Ltd and other groups.

A food waste digester has been built in South India, in CMC Vellore, that uses large fixed dome digesters with predigesters. Further R&D is being done to improve the process of food waste digestion using a Counter-Flow Leach-Bed (CFLB) predigester.

History of Biogas 4 ARTIplant

ARTI plastic domestic plant

Biotech market waste plant

Biotechpic KISTplant

Sewage plant built  by KIST

Dome plant in CMC Vellore