Delignification of paddy straw by sodium sulphite-microwave pretreatment for enhancing biogas production

Paddy straw, pretreated with 4 per cent sodium sulphite (soaked and microwave irradiated) was analyzed for change in its chemical composition and biogas production from paddy straw. The lignin content decreased by 41.7 per cent and 48.3 per cent when microwave irradiations were supplemented to the sodium sulphite pretreatment for a time period of 30 and 60 min, respectively. Maximum reduction of 15.4 per cent in silica content was observed in case of Na₂SO₃-60 min microwave pretreatment. These two factors resulted in 47.2 per cent increase in biogas production in case of Na₂SO₃-60 min microwave paddy straw pretreatment than that of the control.