RESUMO
The present study investigated the synergistic characteristics between abiotic and biotic transformation with a view to improving the methane production efficiency of thermophilic and mesophilic sequencing batch dry anaerobic digestion (SBD-AD). The pilot scale experiment consisted of a lignocellulosic material based on a mixture of corn straw and cow dung. A leachate bed reactor was used for an AD cycle of 40 days. Several distinct differences are reflected in biogas (methane) production and VFA concentration and composition. A combination of first-order hydrolysis and a modified Gompertz model determined that the holocellulose (cellulose + hemicellulose) and maximum methanogenic efficiency at thermophilic temperatures were increased by 112.03 % and 90.09 %, respectively. Additionally, the methane production peak was extended by 3-5 days in comparison with that at mesophilic temperatures. The microbial community exhibited vastly different functional network relationships under the two temperature conditions (P < 0.05). The data indicate that Clostridales and Methanobacteria had preferable synergistic effects and that the metabolism of hydrophilic methanogens is necessary for the conversion of VFA to methane during thermophilic SBD-AD. The effect of mesophilic conditions on Clostridales was relative weakened, and acetophilic methanogens were mainly present. Moreover, simulation of the full-chain and operational strategy of SBD-AD engineering resulted in a decrease in heat energy consumption of 21.4-64.3 % at thermophilic temperatures and 30.0-90.0 % at mesophilic temperatures from winter to summer. Furthermore, the total net energy production of thermophilic SBD-AD was increased by 105.2 % in comparison with that at mesophilic temperatures, demonstrating strengthened energy recovery. Overall, raising the SBD-AD temperature to thermophilic levels has considerable application value for improving the treatment capacity of agricultural lignocellulosic waste.
