Page last updated 30/08/2018
The future of anaerobic digestion (AD) technology in LDCs lies in converting food wastes and food processing residues into energy and compost. In South Asia, the use of AD fed with cattle dung is less appealing. The number of cattle in countries such as India and Nepal is reducing. Farmers prefer using tractors to bullocks for transport and farm work. In urban areas, the numbers of wandering cattle on roads is reduced because the traffic is growing rapidly. The land value in urban areas means that the gardens in which animals can stay are disappearing for building sites. A further factor is the migration of young people, who usually look after animals, to work and earn money in other places. In Nepal, reports suggest that many plants built to use cattle dung as a feed material are not now being used, as a result of these changes. Some people have realised that they can feed their plant with the food wastes they used to give to the animals and still obtain gas for cooking. In the developed world many anaerobic digestion systems have been built to use the organic fraction of municipal solid wastes (OFMSW), but these systems are too large, complicated and expensive to use widely in LDCs. Research and Development is required to find low cost approaches to making biogas plants that can use OFMSW and also local food wastes and food processing residues to generate energy and compost. There are two challenges: making digesters that are big enough to process larger quantities of material finding low cost ways to pre-process raw organic matter. There are many groups in India offering AD systems to process OFMSW and food processing residues, but these systems are not considered economic. The Nisargruna system was developed by BARC (Bhabha Atomic Research Centre) in Mumbai. It uses a pulveriser to break up the organic material. The main digester is a large KVIC drum plant. A report that included an economic analysis suggests that the system is cost-effective, although companies that have licensed this system are struggling to make it successful. Biotech Ltd, based in Trivandrum in South India, use predigesters made from glass-fibre reinforced plastic  (grp). Their older systems used KVIC drum digesters, but later systems use main digesters also made from grp. The economics of these systems is marginal.    The success of the domestic systems made from masonry suggests that larger systems made in the same way would be cheaper to build. Large Deenbandhu plants have been made by KIST in Rwanda and also BTAL Ltd in Ghana. Kingdom Bioenergy Ltd designed a large dome plant, which was constructed by SKG Sangha for CMC (Christian Medical College) in Vellore, South India to use in their Recycling Centre. The capital cost was estimated to be 1/3 less than for a similar KVIC plant. New research is needed to find a way to make large concrete dome plants. It is hoped to test the use of inflatable moulds over which concrete domes can be cast. The use of pulverisers to preprocess organic materials works well, but these machines are expensive to install and operate. They also use energy to run. A predigester uses microbial action (hydrolysis) to remove digestible matter, which dissolves in the liquor (the contents of a digester), from indigestible matter, such as lignin. If the liquor is recycled, by passing it from the main digester to the predigester and back again, the indigestible matter is left in the predigester and can be removed from there. It can then be turned into compost. Since the dissolved matter contains obnoxious smelling VFAs which are converted into biogas, the remaining compost is almost odour free.  If liquor flows through solid matter, is is called a “leach bed”. Research has shown that leach beds work better when the liquor flows from the bottom (upward flow or counter flow). Research is being done on CFLB (counter-flow leach bed) digesters. More information on biogas technology in developing countries can be found in “Small-scale, Rural Biogas Programmes” and “Running a Biogas Programme”.

Future of Biogas Technology

Food waste digester built by Biotech Ltd, South India Nisargruna plant for food wastes in Mumbai Large biogas plant built by KIST in Rwanda
Biotech Ltd digester
Newer Biotech Ltd system
Nisargruna system
KIST dome digester
Large dome built for CMC Vellore
Mailhen food-waste plant in Pune, Central India
Commercial plant Mailhem group in Pune
Biotech Ltd market waste biogas plant in South India Large brick dome plant built for CMC Vellore, South India Next Last
Page last updated 30/08/2018
The future of anaerobic digestion (AD) technology in LDCs lies in converting food wastes and food processing residues into energy and compost. In South Asia, the use of AD fed with cattle dung is less appealing. The number of cattle in countries such as India and Nepal is reducing. Farmers prefer using tractors to bullocks for transport and farm work. In urban areas, the numbers of wandering cattle on roads is reduced because the traffic is growing rapidly. The land value in urban areas means that the gardens in which animals can stay are disappearing for building sites. A further factor is the migration of young people, who usually look after animals, to work and earn money in other places. In Nepal, reports suggest that many plants built to use cattle dung as a feed material are not now being used, as a result of these changes. Some people have realised that they can feed their plant with the food wastes they used to give to the animals and still obtain gas for cooking. In the developed world many anaerobic digestion systems have been built to use the organic fraction of municipal solid wastes (OFMSW), but these systems are too large, complicated and expensive to use widely in LDCs. Research and Development is required to find low cost approaches to making biogas plants that can use OFMSW and also local food wastes and food processing residues to generate energy and compost. There are two challenges: making digesters that are big enough to process larger quantities of material finding low cost ways to pre-process raw organic matter. There are many groups in India offering AD systems to process OFMSW and food processing residues, but these systems are not considered economic. The Nisargruna system was developed by BARC (Bhabha Atomic Research Centre) in Mumbai. It uses a pulveriser to break up the organic material. The main digester is a large KVIC drum plant. A report that included an economic analysis suggests that the system is cost-effective, although companies that have licensed this system are struggling to make it successful. Biotech Ltd, based in Trivandrum in South India, use predigesters made from glass-fibre reinforced plastic (grp). Their older systems used KVIC drum digesters, but later systems use main digesters also made from grp. The economics of these systems is marginal.    The success of the domestic systems made from masonry suggests that larger systems made in the same way would be cheaper to build. Large Deenbandhu plants have been made by KIST in Rwanda and also BTAL Ltd in Ghana. Kingdom Bioenergy Ltd designed a large dome plant, which was constructed by SKG Sangha for CMC (Christian Medical College) in Vellore, South India to use in their Recycling Centre. The capital cost was estimated to be 1/3 less than for a similar KVIC plant. New research is needed to find a way to make large concrete dome plants. It is hoped to test the use of inflatable moulds over which concrete domes can be cast. The use of pulverisers to preprocess organic materials works well, but these machines are expensive to install and operate. They also use energy to run. A predigester uses microbial action (hydrolysis) to remove digestible matter, which dissolves in the liquor (the contents of a digester), from indigestible matter, such as lignin. If the liquor is recycled, by passing it from the main digester to the predigester and back again, the indigestible matter is left in the predigester and can be removed from there. It can then be turned into compost. Since the dissolved matter contains obnoxious smelling VFAs which are converted into biogas, the remaining compost is almost odour free.  If liquor flows through solid matter, is is called a “leach bed”. Research has shown that leach beds work better when the liquor flows from the bottom (upward flow or counter flow). Research is being done on CFLB (counter-flow leach bed) digesters. More information on biogas technology in developing countries can be found in “Small- scale, Rural Biogas Programmes” and “Running a Biogas Programme”.

Future of Biogas

Technology

Food waste digester built by Biotech Ltd, South India Nisargruna plant for food wastes in Mumbai Large biogas plant built by KIST in Rwanda Mailhen food-waste plant in Pune, Central India Large brick biogas dome built for CMC Vellore, South India Biotech Ltd biogas plant for market wastes in South India