Abstract:
Biogas generation or Biomethanation offers a viable option in simultaneous solid waste
management and energy generation. The technology is quite well developed and is not only
confined to developing countries as commonly perceived by many. However, the scale of
practice and the objectives in developing and developed countries vary. A biogas program
has been active in Sri Lanka as well, though this has not achieved the popularity or
acceptance as in countries like China, India and Nepal. The Sri Lankan program however,
has been successful in giving rise to a new design which is termed the Dry Batch digester.
The work has been mainly done by the National Engineering Research and Design Centre
(NERD). The concept is different to the two main types due to the use of an essentially ‘dry*
mixture of organic waste, and the batch type operation.
In urban areas biomass such as straw or animal wastes such as cowdung cannot be found in
such quantities to have biogas systems of continuous nature. The NERD version of batch
type could be effectively employed in institutions where organic wastes are generated, or to
employ solid wastes such as market garbage. Their biomethanation kinetics favour the batch
approach. The objective of the research program undertaken by the Department of Chemical
Engineering was to do detailed evaluation of scientific, technological and social aspects of
biogas systems as a means of pollution prevention with simultaneous energy generation.
Laboratory studies have been done on various industrial waste streams ranging from food
processing wastes to textile industry effluents which arc quite toxic to micro-organisms in
general. This paper introduces the basic concepts and some of the methodologies followed
by the research team. To support dissemination of biogas technology, a pictorial step-bystep
guide detailing out all stages involved in the building and operation of a digester and a
gas holder system has been prepared as part of this work.
