Enhancing Biogas Production: Influence of Mixing Cow and Chicken Manures

The objectives of this study were to enhance the production of biogas through using a mixture of cow and chicken manure and to investigate the effect of digested manure on plant growth. Biogas digester consisted of a plastic polyethylene tank with a volume of 0.25 cubic meters. Cow and chicken manures were collected from certified animal and chicken farms. Mixture of manure was prepared by mixing 5 kg of chicken manure and 5 kg of cow manure together in 100 L plastic tank containing 90 L water free from chlorine. Percentage of manure in all cases was 10% (w/v). The manures were transferred to the digesters and kept in greenhouse to insure warm conditions (30°C - 39°C). Produced biogas was measured each two days and digestate samples were taken every two days for pH, EC, BOD, COD determination. Results showed increased biogas production and reached the highest quantity after 28 days and the amount of biogas produced from the mixture of cow and chicken manures was higher than the amount produced from each manure individually. Decreases in pH values were observed during biogas production followed by BOD, COD reduction. On the other hand, increases on EC values were observed. Application of digested manure in agriculture increased yield of lettuce by 75% comparing with the control sample. The study recommended using cow manure mixed with chicken manure to increase the production of biogas and to use the digested manure in agricultural.