A study of enhancing the biogas production in anaerobic digestion

Anaerobic digestion is one of the main strategies for waste management that eliminates waste and produces biogas simultaneously. Biogas is an alternative source of renewable energy consisting mainly of methane and carbon dioxide. This is suitable for transport applications, energy production and cooking. The present study provides a comprehensive overview on biogas production enhancement techniques in anaerobic digestion from various biomass wastes. Co-digestion, two phase digestion, recirculation of slurry, thermal pretreatment, alkaline pretreatment, acid pretreatment, ultrasound pretreatment, hydrothermal pretreatment and milling pretreatment are some of the techniques used to improve the biogas production. Comparatively co-digestion significantly improves the biogas production than the other processes which gives the biogas production of 531 Lkg−1VS with 52% cow manure and 48% food wastes in a 30-day hydraulic retention period. Pre-treatment before anaerobic digestion increases the biogas yield, especially hydrothermal pretreatment of rice straw increases the yield of biogas from 140 to 315.9 Lkg−1VS. In addition, thermal and mechanical pretreatment of barley straw increases the biogas production by 40.8% and 50.2% respectively. Information on different biomass waste components is important for the efficient implementation of anaerobic digestion and maintaining the key parameters within the desired range will also boost the biogas production.