Evaluation and Optimization of Methane Production from Different Manure Types
Animal manure represents an important biomass source for the production of renewable energy. In Jordan, thousands of tons of animal manure are produced annually from cows, sheep and chickens. This study aims at studying the production of methane from cow, sheep, and chicken manure to determine which type of manure gives the highest yield of methane. This study is also aimed at evaluating the effects of incubation temperature, initial pH, and trace-element supplementation (nickel, iron, zinc, copper, cobalt, manganese and boron) on the production of methane. Finally, the methane yield under optimal growth conditions will be evaluated. Methane was successfully produced from cow manure in tightly-closed stainless steel digesters that yielded the highest methane production (10%) after thirty-five days of incubation compared to other types of manure. No methane was detected in the case of chicken manure, and only 0.1% was detected in the case of sheep manure. The production of Methane from cow manure was then optimized using the one-factor-at-a-time method. The Methane yield increased to 47% when incubation was done at 40 C compared to the room temperature incubation (22.9%) and 30 C (26%). It was also found that methanogenesis was high at acidic pH (pH 4; 42%) when compared to other pH values (pH 5 or 6). In other experiments, the effect of trace-element supplementation was positive with the methane yield being three times greater in the presence of trace-element supplementation than that without supplementation. Finally, methane was produced under optimized conditions (40 C, pH 4, with trace-element ?