Embedded control system for biogas digesters

Abstract

[Abstract]: Biogas is also known as dump gas, marsh gas or sewer gas and is produced in a common, naturally occurring biological decomposition process. It is composed mainly of methane, CH4, carbon dioxide, CO2, and hydrogen sulphide, H2S. Smaller quantities of hydrogen, H oxygen O2, nitrogen, N and ammonia, NH3 may also be present. Methanogens occur naturally in the digestive systems of ruminant animals such as cattle, in marshes, brackish waters and sewage works, where, in addition to laboratories, much knowledge of them has been gained. Literature review reveals that biogas production and thus rate of decomposition is influenced by temperature, and additionally that the loading conditions of a digester may be deduced by monitoring the concentrations of individual component gasses of the biogas produced. It is the objective of this project to: - Develop an electronic nose to monitor the biogas composition, - Develop a fuzzy logic controller to increase or decrease the temperature of the digester vessel, thus controlling the rate of decomposition, and - Notify users of the digester state using semaphore style indicator lights.