Comparative evaluation of different pretreatment methods on biogas production from paddy straw

Abstract

The present investigations observed the effect of chemical, enzymatic, biological and micro-wave pretreatment on paddy straw for enhancement of biogas production. Chopped and soaked paddy straw was subjected to chemicals Na2CO3 (1%) and NaOH (2%) concentrations, microwave irradiation (720 watt, 30 min), fungal (spawn impregnated, 7 days) and crude silicase (24 hrs) pretreatment. The proximate and chemical analysis showed 16.0% and 12.1% reduction in lignin and silica content in the case of Na2CO3 pretreated paddy straw whereas 23.0% and 46.8% reduction was observed in enzymatic pretreatment with 43.7% and 31.1% enhancement in biogas production respectively. This clearly indi-cates that Pleurotus ostreatus MTCC 142 is silicolytic as well as ligninolytic in nature. Enzymatic pre-treatment was also compared with, microwave (30 min) and fungal pretreatment which showed 31.2% and 32.8% reduction in silica content enhancing biogas production by 19.7% and 42.6% respectively. NaOH pretreatment showed a maximum increase in biogas production i.e. 49.7% as compared to 1% pretreated sample which showed 28.5% enhancement. The results indicated that the NaOH pretreatment was one of the potential methods to increase biogas production of paddy straw.