Co-digestion of poultry droppings with maize cob for bioenergy and bio-fertilizer production

Co-digestion of biodegradable wastes is a viable option to utilize multiple biogenic wastes and overcome energy shortages. However, bioenergy and biofertilizers produced during the co-digestion of different wastes can be reliable options for achieving circular bio-economy systems and Sustainable Development Goal 7 (Affordable and Clean Energy). Thus, a batch study of poultry droppings (PD) and maize cob (MC) was conducted at seven different (100:0, 90:10, 70:30, 50:50, 30:70, 10:90, and 0:100) mixing ratios to select the optimum ratio for codigestion. This laboratory scale study was conducted in a control condition (35 degrees C temperature) to investigate the biogas production potential of each test group. The 30:70 ratio of PD and MC showed the highest biogas (315.4 +/- 15.8 mL/gVS) and methane (162.67 +/- 7.37 mL/gVS) yield. Biogas production was 4.8 and 1.16 times higher compared to mono-digestion of PD and MC, respectively. Hydrogen sulphide content of biogas at 30:70 ratio was reduced by 99.50 % and 92.58 % compared to mono-digestion of PD and MC, respectively. Potassium and phosphorus content of digestate at 30:70 ratio was increased by 97.91 % and 75.17 % compared to feedstock. Kinetic simulation of experimental methane yield showed that the Logistic model was well-fitted and reliable for determining the kinetic process parameters, and forecasting methane yield. Further study on suitable pretreatment and the addition of additives during co-digestion might increase yields.