The Utilization of Non-edible Oil Cake Along With Cow Dung for Methane-enriched Biogas Production Using Mixed Inoculum

Abstract

Different proportions (i.e., 25, 50 and 75%) of each of the non-edible oil cakes such as jatropha, karanja and safflower along with cow dung was studied for biogas production in a 1 L batch reactor using mixed inoculum IRP (a combination of inoculum from a biogas plant, municipal waste digester and rice paddy soil adopted on cow dung). The range of average yields of methane were 0.236 to 0.363 Lg-1VS; carbon dioxide 0.139 to 0.181 Lg-1VS; and biogas 0.497 to 0.521 Lg-1VS were obtained during 41 days of digestion at 35°C from various combinations of the previously-mentioned feed materials. Whereas average yields of methane were 0.324, 0.363, and 0.337 Lg-1VS; carbon dioxide 0.172, 0.143 and 0.160 Lg-1VS in corresponding biogas 0.513, 0.523, and 0.512 Lg-1VS were produced from feed materials of (1:1) mixture of cow dung and one of the non-edible oil cakes (i.e., jatropha, karanja, and safflower). This study found that the respective average methane yields in biogas were 2.5, 14.8 and 6.6% higher as compared to cow dung alone (0.316 Lg-1VS) and other combinations of non-edible oil cakes and cow dung. Hence each one of these non-edible oil cakes along with cow dung (1:1) can be utilized for methane enriched biogas production.