Evaluation of biogas production and bacterial load from co‐digestion of chicken manure with different types of household waste

Background The aim of this study was to evaluate the biogas production of chicken manure (CM) co‐digestion with different types of household waste (soft organic [SO] and food waste [FW]), as well as to evaluate the bacterial load of feeding stock and digested slurry samples before and after anaerobic digestion (AD). The experiment was carried out using lab‐based prototype digesters for co‐digestion of CM with different household wastes (5%). Three experimental groups (T1, T2, and T3) were designed using mixing ratios of SO:CM:H 2 O:inoculum (5:22.5:22.5:50), FW:CM:H 2 O:inoculum (5:22.5:22.5:50), and (SO + FW):CM:H 2 O:inoculum (2.5 + 2.5:22.5:22.5:50). The digesters were set at 28–34°C for 30 days for hydraulic retention time (HRT). Total viable count (TVC), Escherichia coli , and Salmonella spp. counts were determined using the spread plate technique. Results The study revealed that the highest average cumulative biogas yield was achieved from T1 > T3 > T2, but the concentration of CH 4 was found in T3 > T2 > T1. The biogas production between the three groups was statistically nonsignificant ( p > 0.05) but the daily concentration of CH 4 was found statistically significant ( p < 0.05). The average concentration of CH 4 and CO 2 in biogas was found to be 30% and 68% for T1, 60% and 37% for T2, and 69% and 27% for T3. However, the H 2 S content was within the acceptable range. The bacterial load was decreased by 2–3 logs before and after AD, and this reduction was statistically significant ( p < 0.05). Conclusion The research found that the co‐digestion of CM with combined household wastes increased the methane concentration in biogas.