Anaerobic co-digestion of linen, sugar beet pulp, and wheat straw with cow manure: effects of mixing ratio and transient change of co-substrate
Mahmoud Elsayed, Yves Andrès, Walid Blel
Abstract
Abstract This study concerns the improvement and sustainability of producing methane (CH 4 ) from the co-digestion of cow manure (CM), sugar beet pulp (SBP), linen (Ln), and wheat straw (WS). The first step involved co-digesting CM, Ln, and WS at various mixing ratios (CM/Ln/WS) in batch reactors to ascertain the best gas production. Biochemical methane potential (BMP) tests were carried out under mesophilic conditions using sludge from a wastewater treatment plant as an inoculum. The highest CH 4 production (351 mL/g VS add ) and volatile solids removal rate (72.87%) were observed at the mixing ratio 50/25/25 and the lowest CH 4 production (187 mL/g VS add ) was recorded at the ratio 25/25/50. A kinetic analysis was carried out to suggest the best strategy for methane production based on the ratio of substrates in the mix. The second step involved co-digesting CM, SBP, Ln, and WS in a semi-continuous stirred tank reactor to study the influence of a transient change in co-substrate on gas production and reactor performance. The rate of biogas production doubled with the transient change of co-substrate from WS to SBP, which may be due to the SBP being more easily biodegradable than WS.