Research On The Treatment Of Cellulosic Ethanol Wastewater By Physicochemical Technology And Pilot Test

Cellulosic ethanol wastewater has the characteristic of high concentration, high salinity, strong acidity, pungent odor, high chroma, high turbidity. The wastewater usually contains lignin that is hard to biodegrade. Cellulose ethanol wastewater is a typical high concentration organic industrial wastewater. Currently, cellulosic ethanol wastewater has become the main factor restricting the development of cellulosic ethanol production industry. It is needed to solve this problem economically and effectivly.Organic pollutants that are difficult to degrade still exist in the secondary biochemical effluent after biological anaerobic treatment and aerobic treatment, and the effluent can not meet the national emission requirements for cellulosic ethanol wastewater. Therefore, the physico-chemical methods are employed in the treatment to strongthen the biochemical treatment and in the advanced treatment of cellulose ethanol wastewater after biochemical degradation.In this study, the anaerobic effluent was treated in the strengthening process by coagulation, Fenton oxidation and ozone oxidation. The most appropriate approach was selected in terms of economic feasibility and treatment effect. The factors which affect the treatment effect was studyed to determine the optimum reaction conditions. The secondary biological effluent was treated in the advanced treatment by ozone oxidation and fluidized bed-Fenton oxidation. The influence of factors in the best method on the treatment efficiency were studied to determine the optimum reaction conditions. Enhancement treatment section was expanded to pilot scale to determine the optimum process parameters, and economic analysis was carried based on the optimum reactions conditions.Ozone oxidation was a more appropriate method to treat the anaerobic effluent. The research showed that initial p H, ozone dosage, reaction temperature, and reaction time influenced the pollutants removal efficiency in different degrees. Under the optimum reaction conditions(initial p H value of 10, ozone dosage of 5 g/L, reaction temperature of 30 ℃, and reaction time of 80 min), the COD removal efficiency was up to 35%, the ammonia removal efficiency was up to 45%, and BOD/COD can be increased to 0.325. In the pilot scale, the effluent biodegradability was significantly increased with BOD / COD value increased from 0.11 up to about 0.26 when HRT was 140 min and ozone dosage was 6 g/h.Fenton oxidation method was the most appropriate method for the advanced treatment. The research showed that initial p H, Fe2+/H2O2, H2O2/COD, reaction temperature and reaction time influenced the COD, ammonia and turbidity removal efficiency in different degrees. Under the optimum reaction conditions(initial p H value of 3.0, Fe2+/H2O2 of 0.67, H2O2/COD of 2.8, room temperature and reaction time of 3 h), the effluent COD was less than 100 mg/L, the effluent ammonia was less that 4 mg/L and the effluent has almost no turbidity, which measured up to the state standards of cellulose ethanol wastewater.About 2111 t/d wastewater was produced in the proposed project. The cost of the enhancement treatment by ozone oxidation was low, including the equipment investment of about 630,000 yuan, the annual running cost of about 309,000 yuan. The equipment investment of advanced treatment by fluidized bed-Fenton oxidation was about 200,000 yuan, and the running cost was about 69.96 yuan per ton.