Various pretreatments of canola straw with hydrogen peroxide, calcium hydroxide, silica, and Pleurotus ostreatus to improve methane yield through anaerobic co-digestion

Canola straw (CS) is the lignocellulosic biomass and is often managed by burning in Pakistan. Pretreatment is a well-established technique for partially disintegrating the crop residue to use in anaerobic digestion. The present study efforts were made to evaluate the effect of optimal pretreatment through comparison. CS was subjected to various pretreatments using H2O2, Ca(OH)(2) (concentrations), SiO2 (nanoparticles), and P. ostreatus (incubation times) that were used as acidic, alkaline, catalyst, and biological pretreatments to enhance methane yield by anaerobic co-digestion. On the basis of 5 g volatile solids (VS), CS was mixed with buffalo dung (BD) at a ratio of 40:60. The batch was carried out in Semi-Automatic Methane Potential Test System (SAMPTS) under mesophilic conditions. Experimental findings observed that all pretreatments effectively improve methane production. Maximum methane yields of 417.3, 386.1, 381.0, and 238.6 mlCH(4)/gVS were obtained at 0.4% Ca(OH)(2), 0.2% H2O2, 0.5 mg SiO2, and 30th day P. ostreatus respectively. However, the highest biodegradability (about 27.1%) was observed in the pretreatment of H2O2. In addition, optimal results were statistically analyzed (P < 0.05) and S-Gompertz model (SGM) was applied to the highest methane yields. Kinetics parameters indicated that the applied model was best fitted. Based on economic valuation and favorable for methanogens, Ca(OH)(2) pretreatment is recommended.