INVESTIGATION ON CO - GENERATION OF BIOGAS FROM SELECTEDFOOD WASTES

Abstract

The study focuses on co-generation of biogas from cooked and uncooked food wastes using plastic drums as digesters. The constituents of substrates used for cooked food wastes are cooked rice with stew and pounded yam while that of uncooked food wastes are yam peel, plantain peel and cassava peel. These food wastes (cooked and cooked) were milled separately, weighed and mixed together with equal amount of water respectively before being poured into different digesters. The substrates are grouped in to A, B, C & D categories. Category A: cooked (C) and uncooked (UC) food wastes without cow dung (CWD) placed indoor; Category B is of cooked and uncooked food wastes with cow dung (CWD) placed in-door; Category C contained cooked and uncooked food wastes with cow dung (CWD) placed outdoor and Category D had the uncooked (UC) food wastes plus cow dung with and without NaOH placed in door. The experimental set up was observed for 19 days (retention time). The pressure,temperature of the digesters and the ambient temperature were daily monitored. Biogas production started within 24 hours but there was no pressure rise in Category A digesters all through the 19days retention time. The specific volume of biogas produced for Category B which contained cow dung were 4.74 m3/kg and 5.88 m3/kg; Category C produced 3.95 m3/kg and 4.22 m3/kg while 5.46 m3/kg and 4.33 m3/kg were recorded for Category D resectively. Addition of cow dung to the substrates in the digesters greatly influenced the biogas production. Statistical analysis using Anova revealed that the differences in biogas production across the treatments were significant (p < 0.05). There were significant differences (p < 0.05) in the specific volumes of biogas produced from UC food wastes mixed with cow dung compared with C food wastes mixed with cow dung. Also noted through the use of ANOVA was increase in temperature and pressure corresponding to an increase in biogas yield. A significant difference (p < 0.05) was noted for the mixture of uncooked with cow dung