Biogas Production by Co-digestion of Apple Pomace and Pine Needles

Abstract

Apple pomace and pine needles are food and agricultural wastes, respectively, that causes disposal problems. As a solution, both of the substrates can be converted to a useful energy source i.e. biogas, through the process of anaerobic digestion. This study describes the suitability of apple pomace and pine needles as substrates for biogas production. Four digesters each of 40 litre named as digester 1 (D1), digester 2 (D2), digester 3 (D3) and digester 4 (D4) were fed with apple pomace, pine needles, 90% apple pomace with 10% pine needles and 75% apple pomace with 25% pine needles, respectively. The batch digesters were operated at ambient mesophilic conditions, they were fed at a period of every five days with 0.04 g VS/L/day as organic loading rate (OLR). The total solids, volatile solids and daily pH and temperature variations were observed. During the period of 28 days, 6.97 L, 15.86 L, 25.38 L and 9.67 L of biogas was produced in D1, D2, D3 and D4, respectively. The highest methane content was 84.4% obtained from pine needles.