Co-digestion of Poultry Manure with Corn Cobs for Biogas Production

Abstract

ABSTRACT Pakistan, being an agro-livestock based economy; has massive amount of biomass in the form of crop residues, dung, poultry litter etc. In addition, urban areas produce 55,000 tons of municipal solid waste every day, but due to lack of proper waste management system, a large quantity of solid waste is openly dumped without any treatment. On the other hand, our country is seriously facing energy crisis at an alarming rate. There is a need for exploring and exploiting renewable sources of energy. This study was conducted to investigate the effect of alkali pre-treatment on corn cobs and to evaluate the potential of co-digestion of poultry waste and corn cobs in the presence of cow dung and leachate for biogas production at mesophilic temperature (37°C) range. For this reason, NaOH loadings (1%, 2%, 5%, 25% and 45% (w/w)) were applied for various time periods (1.5 h, 24 h and 72 h) to reduce the lignin content of corn cobs. Optimized treated corn cobs were further used in batch digestion in 1.2 L digesters made from water filter jugs. Digesters were filled with untreated/treated corn cobs, poultry manure, cow dung and leachate with 8%, 12 % and 16% of TS content. In the 2nd setup, the effect of leachate addition on biogas production was investigated. The results showed that NaOH loading of 5% (w/w) for 72 h at room temperature is effective, as it removes 26.5% lignin from corn cobs. pH adjustment was achieved by adding buffer (NaHCO3) and found that digesters fed with treated corn cobs with lower TS content (8%) performed well and produced greater volume of biogas (591.2 ml/gVS), higher COD reduction (62.5%) and greater TS & VS reduction (46% and 56.9% resp.) as compared to digesters fed with untreated cobs. Similarly, digesters fed with leachate and cow dung with 8% TS content produce greater volume of biogas (300 ml/gVS), higher COD reduction (61.9%), maximum TS reduction (36.7%) and VS reduction (41.92%), as compared to others.