How exothermic characteristics of rice straw during anaerobic digestion affects net energy production

The self-heating of lignocellulosic biomass, when degraded under anaerobic conditions, has been reportedly observed. Such a phenomenon would cause substrate to show exothermic characteristics which are in contrast to the current thermodynamic or microbiological knowledge. Rice straw (RS), when undergone anaerobic digestion, is prone to self-heating which can increase the reactor temperature according to heat-releasing characteristics, thus improve the net energy production. In the present study, the relationship of biogas production and self-heating release as well as the synergistic effects of two energy production pathways was investigated. Moreover, the optimal process for maximizing the biogas production under self-heating phenomenon was scrutinized. Compared to control assays, a 0.48 degrees C increase in average temperature was noticed among experimental trials due to RS self-heating phenomenon. The results showed that the self-heating was even improved simultaneous with increased methane production rate. Hydrolysis rate and total solid content were found to be possible promising options to control the self-heating release. (C) 2020 Elsevier Ltd. All rights reserved.