Experimental Study On Dry Anaerobic Digestion Using Cow Manure Mixed With Crop Straw

African countries are endowed with a number of renewable energy resources, but the use of these resources is still a major challenge. The agricultural waste such as cowdung and corn straw which remain after the processing of the crop are left in field instead of promoting improved energy sources, such as biogas aiming to reduce high reliance on traditional biomass fuels that has had negative environmental impacts through indoor pollution, deforestation and soil depletion. The main objective of this study is to carry out investigation on dry anaerobic digestion of cowdung mixed with corn straw aiming to avail information on its co-digestion characteristics, focusing on different substrate ratios, digestion temperature and HRT at a laboratory work level. The conclusion of the whole study work was as follows:I. During the startup phase, the reactor was running under ambient temperature of22-28℃followed by semi-continuous anaerobic digestion at mesophilic temperature (35±1℃). The startup process of cowdung and corn straw co-digestion performed well and has been completed after28days, in which the highest gas production was8.63L-d-1occurred at eighth day of startup and declined at1.32L d-1on its twenty-eighth day.Ⅱ. The C/N of feed stock has been promoted by cow dung mixed with corn straw meanwhile the porosity of digestion material has to be improved for smooth handling. Under mesophilic temperature, the best result of volumetric gas production rate was1.30L·(L·d)-1and0.57L·(gVS)-1of material production rate achieved by a30day HRT and1:4.3substrate ratios of corn straw and cowdung.Ⅲ. The dry anaerobic digestion under thermophilic temperature55±1℃presented some operational difficulties than at mesophilic temperature at35±1℃. The increase of gas production was seen increasing with the quantity of feeding material and has achieved the highest daily gas production of32.95L.d-1. The use of inoculum for startup and other useful methods promoted the whole thermophilic dry anaerobic digestion process.Ⅳ. Under a same30HRT and1:4.3substrate ratio of corn straw and cowdung, the thermophilic digestion achieved higher volumetric gas production rate of1.53L·(L·d)-1,15%higher than that one achieved by mesophilic digestion, meanwhile its material gas production rate was0.45L-(gVS)-1,21%lower compared with mesophilic process.The study work showed that the co-digestion of cowdung and corn straw for the both mesophilic and thermophilic conditions could be materialized and has the potential to boost the use of agricultural wastes and raise benefits which accrue at the household level.