Study On Anaerobic Treatment Of Molasses Alcohol Wastewater At Different Temperatures And Associated Microorganisms

Molasses alcohol wastewater is produced in the process of producing alcohol by molasses fermentation.The large emissions,high difficulty and cost of harmless treatment of molasses alcohol wastewater cause huge environmental protection and economic pressure to enterprises.As a kind of wastewater treatment method with high efficiency,low operating cost and by-product energy,biological anaerobic treatment technology has been widely used in the treatment of industrial organic wastewater.Temperature has an important effect on the anaerobic treatment of wastewater and is considered to be one of the important factors affecting the anaerobic digestion process.At present,there are few reports on the biological anaerobic treatment of molasses alcohol wastewater,especially the influence mechanism of temperature on the anaerobic digestion process and its associated microorganisms.In this study,the biological anaerobic treatment of molasses alcohol wastewater under two different temperature conditions of variable temperature and constant temperature was studied,and the temperature change was combined with the traditional sludge acclimation technology(the influent OLR gradually increased).The influence of different temperature conditions on the performance of the reactor and the diversity of associated microorganisms was deeply analyzed,which has important reference value for the selection of anaerobic treatment process for alcohol wastewater and other industrial wastewater,the operation and management of the reactor.In the tolerance of activated sludge to temperature and organic loading changes study,it was found that the activity of anaerobic activated sludge decreased greatly under the condition of 40 ~oC and above,the treatment efficiency of molasses alcohol wastewater was extremely low,and the anaerobic digestion system could not operate stably,which was related to the fact that the anaerobic activated sludge used in this study was mesophilic sludge(acclimation at 35 ~oC).In the thermostatic anaerobic digestion system,additional insulation equipment is needed to maintain a constant temperature.A non-thermostatic anaerobic reaction system does not require insulation equipment.Therefore,based on simplified process and cost reduction considerations,this study focuses on the anaerobic treatment of alcohol wastewater under lab-scal by means of 35~oC(constant temperature)and room temperature(variable temperature)combined with gradual enhancement of organic load acclimation.After the stable operation of the anaerobic digestion system,the study was carried out on the anaerobic treatment of alcohol wastewater,including the analysis of treatment efficiency,substrate conversion efficiency and associated microbial response.The main results are as follows:(1)In terms of the efficiency of anaerobic digestion,the soluble chemical oxygen demand(SCOD)removal rate at 35 ~oC was slightly higher than that at room temperature,especially when the OLR of influent was higher,the maximum difference between the two was 6%.The average decolorization rate of wastewater under 35?is slightly higher than that under room temperature.(2)In terms of the anaerobic digestion process,the volatile fatty acid(VFA)accumulated in the anaerobic digestion system at 35?was lower than that at room temperature,and the proportion of acetic acid in the VFA was higher overall.However,there was no significant difference in the alkalinity and the electrical conductivity of wastewater in the anaerobic digestion system at the two temperature conditions.(3)In terms of the effluent quality of the anaerobic digestion system,the effluent p H of the digestion system under the two temperature conditions maintained at the ideal state of 6.7-7.8.There was no significant difference in the effluent p H and ammonia nitrogen concentration of the anaerobic digestion system under two temperature conditions.The protein concentration of anaerobic digestion system in 35?was slightly lower than that in room temperature.The results show that the anaerobic treatment of molasses alcohol wastewater at 35 o C is better than that at room temperature in terms of treatment efficiency,system process stability,effluent quality.(4)The number of bacterial species in activated sludge at room temperature was more than that at 35 ~oC,while the number of archaea species was the opposite.The diversity of bacteria and archaea was higher in activated sludge at room temperature.The microbial community structure in the activated sludge was similar under the two temperature conditions,but the relative abundance of organic-degrading bacteria Anaerolineaceae and Lachnospiraceae,as well as Methanobacteriaceae and Methanosarcinaceae in the activated sludge under 35~oC condition was higher than that under room temperature condition.The abundance of organic-degrading bacteria and methanogens was slightly higher than that under room temperature,indicating that the ability of degrading organics and producing methane was stronger.When the room temperature was above 25 ~oC,there was little difference in the anaerobic treatment effect between the two conditions.The research results can provide reference for the improvement and optimization of anaerobic wastewater treatment process.