Design Of A Household Anaerobic Digester For Rural Areas In Sudan

Abstract, International Journal of Energy Applications and Technologies, 2017

This study is aimed at developing an anaerobic digestion system, optimized for economic manufacture and suited to the climate conditions in rural Sudan, which can efficiently produce biogas for cooking purposes at the household level. A lab-scale batch digester was designed and constructed using polypropylene material with a capacity of 20 liters, and with the biogas captured in a floating-top gas reservoir. This initial small-scale construction was mainly to study some important parameters of the anaerobic fermentation process. The parameters studied were: biogas production from various types of organic material, the levels of acidity and dry matter of the organic material, the affect of temperature within the container, along with an evaluation of the time scale and rate of gas production. Four types of organic material were used: fresh and dry cow dung with dry matter content of 20% and 90% respectively, chicken manure with dry matter content of 95%, and food waste with dry matter content of 10%. The results from the lab-scale reactors revealed that the gas production rate was directly proportional to the reactor temperature, and that all commonly available feedstocks produced biogas in predicted volumes, provided the feedstocks were within the recommended carbon: nitrogen balance and were not previously degraded by anaerobic or aerobic microorganisms. Using results from the lab-scale reactor, the digester design was improved and scaled up using a cylindrical water tank with a capacity of 225 liters. Biogas testing covered the methane percentage, calorific value of gas produced and gas consumption rate. The results were that the methane percentage was 57%, the calorific value of the biogas was 20.52 MJ/m3 and the biogas consumption was 342 liters per hour during a simulation of normal operation for household cooking use.