A novel strategy for comprehensive utilization of distillers’ grain waste towards energy and resource recovery

Abstract

This study developed a novel strategy for distillers’ grain waste (DGW) management towards energy and resource recovery, i.e. butanol and methane production. DGW was enzymatically hydrolyzed and the liquid phase (DGWEH) was used to produce butanol. A total of 30 potential inhibitors were identified in DGWEH and part of esters were confirmed to be one of the inhibitors affecting butanol production. After the detoxification by overliming, approximately 42.5 % of the identified compounds including 99.2 % of esters were removed. Butanol and isopropanol were significantly increased to 8.19 ± 0.01 and 1.49 ± 0.09 g/L, respectively, with negligible amounts of acetone and ethanol (i.e. 0.18 ± 0.00 and 0.36 ± 0.01 g/L, respectively). The residual solid fraction of DGW and the distillery waste derived from the solvents extraction process after butanol fermentation were used for methane production. The average chemical oxygen demand removal rates were 99.0 ± 0.3 and 97.7 ± 0.5 %, respectively, while the total methane yield approached to 170.6 m3/t DGW. This work verified the technical feasibility of comprehensive utilization of DGW for energy and resource recovery, with benefit to the environment.