Mesophilic anaerobic digestion of corn thin stillage: A technical and energetic assessment of the corn-to-ethanol industry integrated with anaerobic digestion

摘要

The purpose of this study was to reduce the VS (volatile solid) and recover energy (methane) from thin stillage through mesophilic anaerobic digestion in corn-ethanol plants. The performance of a continuously stirred tank reactor (CSTR) with different hydraulic retention times (HRTs) was evaluated in this study. Results: The results show no differences in volatile solid (VS) destruction (82-83%) in the reactor with HRTs ranging from 25 to 40 days. The maximum volumetric methane production rate of 1.41 L L~(-1) day~(-1) was produced at 25-day HRT, whereas the maximum methane yield of approximately 0.63 L CH_4 g~(-1) VS_(fed) (0.77 L g~(-1) VS_(removed)) was achieved with HRTs between 30 and 40 days. Simulation results using a kinetic model indicate that the reactor needs to be operated for longer than 23 days in order to achieve 80% of maximum methane yield. The techno-economic potential of a corn-ethanol facility to produce an estimated 57% energy recovery using mesophilic anaerobic digestion has long been overlooked. A corn-ethanol plant integrated with mesophilic anaerobic digestion increases the net energy balance ratio from 1.26 to 1.80. Conclusion: Mesophilic anaerobic digestion complements the corn-ethanol business so that the sustainable energy obtained from corn recovery is made more lucrative and renewable.