A novel process design for enhanced biogas production from poultry manure using a solar water heating system.

Abstract

This paper analysis the enhancement of biogas production from poultry manure using a small scale anaerobic digester assisted by a solar water heating system in a Palestinian poultry farm. The farm, located in Ramallah district, with a total area of 140 m2 and accommodating around 1800 birds every 50 days produces annually about 6.57 tons (18 kg/day). An anaerobic digester with a design volume of 0.5 m3 and a working capacity of a 0.3 m3 was fed by poultry manure (total solids: 20%, C:N ratio: 32:1) in a continuous mode. A solar water heating system circulated water within the digester to enhance the anaerobic digestion process. The daily biogas yield ranged from 80 to 300 L and the methane content of the biogas ranged between 46% and 66%. As substitute to natural gas, the biogas with heat generated of 777 MJ was directly used for on farm heating purposes during the study period. Digester monitoring during the winter period revealed that biogas production rate increased by 33% and the temperature increased by 50% by using solar system. The fresh anaerobically digested slurry showed a nutrient rich fertilizer (NPK ratio of 1:1.3:1.3). Solar drying tank enhanced the removal of fecal pathogens (F. streptococcus) up to 3 log10. The economic profitability is expected to increase, making the capital investment worthwhile to farmers as of free-cost feed.