Effect of increasing inoculum ratio on energy recovery from chicken manure for better use in Egyptian agricultural farms

Background Poultry production is one of the fastest growing agricultural activities in Egypt. This activity is delivering large quantities of chicken manure. This organic waste can have a negative impact on the environment and public health in the vicinity of the Egyptian agricultural farms. In this study, we treated this organic waste by anaerobic digestion for achieving the maximum production of biogas with a high percentage of methane. For this, we investigated the different ratio of bacterial inoculum and manure chicken content. Methods Seven anaerobic mixtures with different inoculums (1:1, 1:2, 1:3, 1:4, 1:5, 1:6 and 1:7) were tested. All digesters are placed in a constant temperature 35 °C. Biogas and methane production during 50 days of incubation. Results The best ratio in terms of biogas produce is the low ratio (1:7) with a production of 73.3 Nml/gVS. But from a qualitative point of view, the largest ratio (1:1) was delivering a biogas with the highest calorific value in terms of methane content with 69.9% of biogas. Conclusions The energy valorization of chicken manure depends on the waste/inoculum ratio. The maximum biogas produced is using the lowest ratio of waste and inoculum (1:7) but the highest methane percentage in the biogas is reached by the highest of ratio (1:1). Thus, from a qualitative point of view, the high percentage of methane is obtained for the highest ratio 1:1, however, from a quantitative point of view, the largest production is obtained from the lowest ratio 1:7.