Improving biodegradability and biogas production of wheat straw substrates using sodium hydroxide and hydrothermal pretreatments

This paper presents the results of an experimental methane fermentation study on untreated, NaOH and hydrothermal pretreated substrates of wheat straw. Experiments were conducted at 37 °C (mesophilic temperature). Substrates concentration were maintained at 4.45% VS (44.5 g VS/L). Untreated wheat straw substrate had resulted into specific methane and biogas production yields of 78.4 L/kg VSa and 188.4 L/kg VSa, respectively. The specific methane and biogas production yield of NaOH pretreated wheat straw substrate had resulted into 165.9 L/kg VSa and 353.2 L/kg VSa, respectively. Hydrothermal pretreated wheat straw substrate had resulted to yield specific methane and biogas production of 94.1 L/kg VSa and 205.7 L/kg VSa, respectively. NaOH pretreated substrate produced 87.5% higher biogas production and 111.6% higher methane production compared to the untreated wheat straw substrate. Hydrothermal pretreated substrate had resulted into an increase of 9.2% in biogas production and 20.0% in methane production compared to that of untreated wheat straw substrate.

► NaOH, hydrothermal pretreated substrates of wheat straw were studied for Methane fermentation.
► Minimum 5% NaOH addition is required for hydrothermal substrate to maintain a suitable pH.
► Biogas and methane production were increased by 87.5% and 111.6% for 4% NaOH pretreated substrate.
► Wheat straw NaOH pretreatment found a potential method to enhance biogas and methane production.