Enhancing biogas production by anaerobic digestion of animal manure

The objective of this work is to investigate enhancing biogas production by anaerobic digestion of three different animal droppings namely; cow, camel, and chicken. The investigation showed that biogas production can be enhanced by mixing equal mass of the above three animal manures and diluting by tap water at 37°C. The amount of biogas produced was increased by 12, 28 and 5 folds compared to that produced from digesting only cow, camel, or chicken manure, respectively. The digestion process was carried under batch mode condition in plastic bottles of 1.5 L volume. The bottles were immersed in a water bath to control its temperature at the desired values. The amount of biogas produced was determined via a syringe tightly connected to the bottle exit. The effect of dry solid mass fraction, pH, and temperature on the amount of biogas produced by digesting certain types of manure alone was studied. The results showed that the amount of biogas produced versus dry solid mass fraction goes through a maximum. The maximum value of the biogas produced occurred at solid mass fraction of 0.11, 0.1, and 0.16 for cow, camel, and chicken manure, respectively. Digestion of cow, camel, and chicken manure at 37°C increased the production by 2.2, 2.1, and 1.3 folds, respectively, compared to that obtained at 25°C.