Wheat straw pretreatment with KOH for enhancing biomethane production and fertilizer value in anaerobic digestion

Wheat straw biodegradability during anaerobic digestion was improved by treatment with potassium hydroxide (KOH) to decrease digestion time and enhance biomethane production and fertility value. KOH concentrations of 1% (K1), 3% (K2), 6% (K3) and 9% (K4) were tested for wheat straw pretreatment at ambient temperature with a C:N ratio of 25:1. 86% of total solids (TS), 89% of volatile solids (VS) and 22% of lignocellulose, cellulose and hemicellulose (LCH) (22%) were decomposed effectively with the wheat straw pretreated by 6% KOH. Enhanced biogas production and cumulative biomethane yield of 258 ml·(g VS)− 1 were obtained increased by 45% and 41% respectively, compared with untreated wheat straw. Pretreated wheat straw digestion also yielded a digestate with higher fertilizer values potassium (138%), calcium (22%) and magnesium (16%). These results show that TS, VS and LCH can be effectively removed from wheat straw pretreated with KOH, improving biodegradability biomethane production and fertilizer value.

Graphical abstractImprovement on wheat straw biodegradability during AD was investigated by using potassium hydroxide (KOH) to decrease digestion time and enhanced biomethane yield and fertility value. 86% of TS, 89% of VS and 22% of LCH were decomposed effectively in wheat straw pretreated with 6% KOH. The total biogas production and cumulative biomethane yield was enhanced by 45% and 41% respectively, compared with untreated wheat straw. Digestion of pretreated wheat straw also yielded a digestate with higher fertilizer value, potassium (138%), calcium (22%) and magnesium (16%).Figure optionsDownload full-size imageDownload as PowerPoint slide