Co-digestion of euryhaline microalgae Scenedesmus sp. MKB. with paddy straw for biogas production

Abstract

Biogas is a clean and renewable biofuel source produced by anaerobic digestion of organic matter and can replace conventional sources of energy such as fossil fuels. The present study was undertaken to assess biogas production from microalgae Scenedesmus sp. MKB. (MN796425) which was isolated from the saline water collected from the waterlogged area of Southwest Punjab. The biogas production for different concentrations of microalgal biomass, microalgal filtrate, and paddy straw was observed in laboratory conditions and the performance of microalgae was also studied in field conditions. The co-digestion of microalgal biomass and paddy straw under laboratory conditions revealed maximum production of 60.18 L when both were co-digested as compared to 48.56 L during the digestion of paddy straw alone. Kinetics of biogas production studied by modified Gompertz equation revealed that the highest biogas production potential (P) of 68.58 mLg-1 volatile solids at the biogas production rate (Rm) of 1.34 mLg-1d-1 with lag phase (λ) of 0.66 days. Microalgae biomass production under field conditions was carried out in an open raceway pond of 200 L capacity and later biomass was digested in 1 m3 digester that showed cumulative biogas production of 2,407 L and it was 20.44% more than control.