Recent Developments
The big projects in China, India and Nepal were based on the use of animal dung as
a feed stock. It has therefore been seen as a primarily rural technology, so has
received less attention from governments more interested in helping people in rapidly
growing urban areas.
More recent developments in India have used biogas technology to process food wastes,
so the technology is gaining an urban dimension. One approach is the development
of plastic floating drum plants for individual households. Three groups looking at
this approach are ARTI in Pune, Maharashtra; VK Nardep in Kanyakumari, Tamil Nadu;
and Biotech In Trivandrum, Kerela. People can save up to 30%of the LPG they use for
cooking by processing their own wastes, or up to 100%, if they obtain waste food
from elsewhere.
Biotech and also produce larger sized plants with steel drums to process food wastes
and sewage from institutions such as schools to save. Similar systems can be used
to process waste from markets, so local authorities in India are becoming very interested.
There are a few systems processing domestic waste collected by local authorities
in Kerala.
Rural biogas plants using animal dung have not had the success in Africa that they
have enjoyed in Asia. However, two very successful projects use fixed dome designs
to process human sewage. The KIST project has built plants in several prisons, most
of which were housing over 10,000 inmates (now much fewer). BTWAL in Ghana use similar
designs to deal with sewage from hospitals, schools, universities and hotels.
The processing of 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. Bioplex Ltd has developed
a “portagester” that enables this to be done.
