Design of a two-phase digester system to optimize biogasification of rice straw

Abstract

The two-phase bench scale digester system to optimize the bio gasification process was successfully fabricated. The system comprised two main reactors, namely, hydrolysis (acidification) and methanation reactors. The reactor performance was evaluated in terms o f its efficiency for biogas production using rice straw for about two months and it was found that biogas production increased by -10% over the conventional dry batch reactor system. The maximum biogas production was 2.6 L/kg on the 30th day in the two-phase reactor system. Total gas production over 62 days was 81 L/kg and 74 L/kg, for two-phase reactor system and the dry batch reactor system, respectively. Further optimization o f gas production in terms o f gas quality (with increased methane) and quantity could easily be achieved by controlling the operating parameters o f the system since the three processes involved in the anaerobic process are separated to two anaerobic chambers. The nutritive value o f the digested material (anaerobically digested straw) was evaluated and N, P and K percentages were increased in digested straw. However, no significant increase in yield was observed in the field trial conducted with okra for the evaluation o f digested material as organic manure