Methane Digestors. Third World Science.

This unit, developed by the Third World Science Project, is designed to add a multicultural element to existing science syllabi (for students aged 11-16) in the United Kingdom. The project seeks to develop an appreciation of the: boundless fascination of the natural world; knowledge, skills, and expertise possessed by men/women everywhere; application of knowledge and skills to solve the practical problems of everyday life; impact of modern technology in the world; and the influence of the cultural background on the perception of knowledge, problems, and solutions. The unit begins with a discussion of the viability of and technology involved in producing methane from waste materials, followed by information on: physical/chemical properties of biogas; basic theory of anaerobic breakdown of materials into methane; differences between aerobic/anaerobic methods in methane digestors; reproduction of the anaerobic process in air-tight containers; and role of different bacteria in the biological breakdown of wastes in digestors. A discussion of what kind of digestor should be built and best way of using gas/slurry produced follows. A report on the role of the integrated biogas system in Sri Lanka (illustrating benefits for a country lacking in fossil fuels) and a description of how small digestors can be constructed using school materials are included. (JN)