Evaluating the effect of biochar dosage on biogas production during the anaerobic digestion of biochar-infused abattoir effluent

The study evaluated the influence of biochar dosage on biogas and methane (CH 4 ) generation and organics removal during anaerobic digestion (AD) of abattoir effluent. Batch samples were prepared with cow dung inoculum and biochar doses of 0 - 70 g L -1 and filled up to 800 mL with abattoir effluent. The experiment was monitored for 40 days using an Automated Methane Potential System (AMPTS III). Biochar markedly affected gas production, with a 2 g L -1 dosage yielding the highest cumulative biogas of 3864.9 ± 158.9 mL, which exceeded the control (2701.0 ± 53.9 mL). This resulted in cumulative CH 4 of 2371.9 ± 59.0 mL, which was 30% higher than the control experiment. Excessive biochar doses yielded lower biogas yields, such as the 30 and 70 g/L, which yielded 2703 ± 55.4 mL and 2611.3 ± 41.6 mL of biogas. CH 4 content ranged from 61 to 69%. Soluble Chemical oxygen demand (sCOD) removal mirrored the gas trends, wherein the digestate sCODs were 1.12 ± 0.03 - 2.62 ± 0.30 g L -1 for 2, 4, 8, 30, and 70 g L -1 , corresponding to up to 73.14 ± 1.05% reduction. Thus, low–moderate dosing (2–8 g L -1 ) enhances energy recovery and organics removal, whereas excessive dosing (≥30 g L -1 ) reduces performance; possibly due to sorption/occlusion or hydraulic effects that limit substrate accessibility.