Methane Production and Digestate from the Co-digestion of Rice Straw and Sewage Sludge through Various Pre-treatments: A Review

Abstract

Agriculture residues have the potential to supply a significant amount of sustainable energy. Rice straw can play an important role in development of energy consumption as a source for producing renewable energy. Thailand produces a large amount of rice straw (29 million tons/year). The common practice is to dispose of rice straw, most of which is burned resulting in greenhouse gases being harmful to human health. Anaerobic co-digestion (AcoD) is widely used for the degradation of rice straw and production of methane. The potential of enhancing methane production from rice straw using various pre-treatment ranged between approximately 190-605 mL/gVS, whereas untreated rice straw produces ranging from 92 to 302 mL/gVS. In addition, to assess the effect of digestate from AcoD on the digestate composition, the digestate was characterised by the lignocellulosic fractions (cellulose. Hemicellulose, lignin and water soluble). The digestate can be employed as fertilizer offering a possibility to recycle nutrient into the land.