Biogas Production from Co-Digestion of Poultry Manure and Orange Peel through Thermo-Chemical Pre-Treatments in Batch Fermentation

The increasing demand for the treatment of organic wastes from municipalities, faming and industrial activities is a great opportunity to convert organic wastes into energy in a form of biogas. With the aim of producing biogas from co- digestion of Poultry Manure (PM) and Orange Peel (OP) a series of experiments were carried out for 21 consecutive days. Five different proportions of PM and OP (100%PM, 75%MP+25%OP, 50%PM+50%OP, 25%PM+75%OP, 100%OP) were used to obtain the suitable mix ratio (which gives maximum biogas production). Having determined the optimum mix ratio, chemical pre-treatment with CaO (0.5 g, 1.5 g and 2.5 g) and temperature pre-treatment at 60 and 80 oC were applied to compare the results with those obtained with non-pre-treated waste. Cumulative biogas production obtained from 75%PM+25%OP was 768ml, whereas 218.33ml was measured from 100%OP. Increasing the proportion of OP above 25% decreased the amount of gas production, volatile solids (VS) and total solids (TS) reduction. This indicated that addition of PM to mix ratios improves biogas production.Thus 75%PM+25%OPmix was found to be the optimum mix ratio which resulted in high biogas yield. In thermal pre-treatments, maximum cumulative gas production was measured at 80 ºC pre-treated substrate. It exceeded by 11.7% and 6.6% over the control and the 60 ºC pre-treated sample respectively. In case of chemical pre-treatments, the highest cumulative biogas yield was obtained from a substrate treated by 2.5g CaO which exceed by 139, 250 and 356 over 1.5g CaO, 0.5g CaO and control, respectively. Overall the results indicated that the biogas yield and VS and TS reduction of the 75%PM+25%OPmix ratio can be enhanced with the use of thermal and chemical pre-treatments prior to anaerobic digestion