PRODUCTION OF BIO-GAS FROM ANAEROBIC CO-DIGESTION OF GOAT MANURE MIXED WITH CABBAGE (Brassica oleracea) AND CARROT (Daucus carota) WASTES.

Abstract

Biogas is a methane gas produced through anaerobic digestion fermentation of organic matter. The aim of this study was to determine the optimal mix ratio for biogas production from anaerobic digestion of vegetable waste (carrot and cabbage waste) and goat manure. The experiment was batch operated and daily gas yield from the mixture was monitored for 30 days. The parameters measured were total solids (TS), volatile solids (VS), organic carbon, and moisture content. For the experimental design, different mix ratios were adopted for the eight digesters employed. In this case, for the first digester, 100% goat manure (GM), 2nd digester 100% carrot waste (CW), Third digester 100% cabbage waste (CaW), 4th digester 70% goat manure waste (GM) +30% carrot waste (CW), 5th digester 30%goat manure (GM) +70% carrot waste (CW), 6th digester 70%goat manure (GM) +30% cabbage waste (CaW), 7th digester 30% goat manure (GM) +70%cabbage waste (CaW) and 8th digester 33.3% goat manure (GM) +33.3% carrot waste (CW)+33.3% cabbage waste (CaW) were used. The gas production rate was measured on daily basis using water displacement method. Gas production was noticed in all of the substrates types from the first and second day of digestion and went to decline at about 30 days in all digesters. Before anaerobic digestion the percentage of total solids (TS), volatile solids (VS), organic carbon and carbon nitrogen ratio(C: N) range will be between 21-30, 5156, 45-54 and 22-27 respectively but After anaerobic digestion the result was within 17-26, 4750, 42-48 and 20-22 respectively. The experimental data shows a greatest gas output of 1991 ml of gas production in the mix ratio of 33.3% goat manure (GM) +33.3% carrot waste (CW) +33.3% cabbage waste (CaW), suggesting mix ratio of the three substrates is an optimal mix to yield the highest biogas production. All measured total solids (TS), volatile solids (VS), and organic carbon (OC) were significantly varied between before and after anaerobic digestion. Overall results indicate that the biogas yield, volatile solid and total solid reduction can be significantly enhanced when goat manure mixed with Carrot and cabbage waste.