The Study On Biological Treatment And Resource Utilization Of Bioethanol Wastewater With Functional Bacteria Analysis

With the development of bioethanol based on lignocellulosic materials, technologies for purification and resource utilization of bioethanol wastewater can increase the environmental benefits and economy of bioethanol industry. And these technologies are the basic processes for rapid development of bioethanol industry.In this study, purification of the wastewater from corn stover and corncob-based bioethanol production process with simultaneous biogas production was investigated in a combined system, which was based on thermophilic anaerobic digestion in a fluidized bed reactor (AFBR), an aerobic airlift loop reactor (ALR), and a biological aerated filter (BAF). High strength distillery wastewater and high ammonia nitrogen content pretreatment wastewater were used as the influents. In the thermophilic anaerobic process (53~55℃), the methane yield of 280mL/g-COD removed was obtained at organic loading rate (OLR) of 14.1g-COD/L·d and hydraulic retention time (HRT) of 48 h in the AFBR. Then co-digestion of anaerobic effluent and pretreatment wastewater was carried out in the ALR. COD and NH4+-N average removal rate of 88.5% and 96.7% were obtained at HRT of 10h, temperature of 30~33oC and superficial gas velocity (μg) of 12mm/s. The aerobic effluent was finally purified in the BAF operated at ambient temperature and HRT of 5h with simultaneous removal of COD, NH4+-N and chroma. Final effluent with COD and NH4+-N concentrations of 65.1mg/L and 3.9mg/L was obtained with other main indexes satisfying the primary discharge standards for ethanol industry in China. Clone library analyses show that methanogen were dominated by Methanoculleus and Methanosarcina in thermophilic anaerobic sludge and with other species related to Clostridia. While bacteria in aerobic activated sludge were dominated by species related to Sphingobacteria and Alphaproteobacteria.Extreme-thermophilic biohydrogen production from distillery wastewater was investigated in batch and continuous-mode operation. Hydrogen-producing mixed culture was enriched by repeated batch cultivations. Effect of temperature and pH on biohydrogen yield was investigated in batch experiments. The highest hydrogen yield of 196.4 mL/g-volatile solidsaddded (VSadded) was obtained at 70℃and pH 7.0 in batch culture. Continuous biohydrogen production was performed in CSTR reactor with yield of 172.0mL/g-VSadded at HRT of 4 days. The main metabolic products were acetate, lactate, and ethanol. Community structure of hydrogen-producing microflora was investigated by 16S rRNA gene clone library analyses. The microorganisms involved in both batch and continuous-mode were similar and hydrogen production was carried out by a group of extreme-thermophilic bacterial species related to Thermotoga, Coprothermobacter.