Pilot Study On The CSTR-IC-SBR Combined System For Treatment Of Cellulosic Ethanol Wastewater

At present, it is booming in using the straw as raw material for cellulosic ethanol production, a lot of pilot plant for the production of practice have been set up and established a demonstration plant in some areas.With the expansion of cellulosic fuel ethanol production industry, the problem of wastewater treatment is becoming more urgent. According to the literature, each producing 1t cellulosic fuel ethanol will generate about 13-15 t of industrial wastewater. The treatment and recycling of high concentrated organic wastewater the lignocellulose fuel ethanol production is demanding prompt solution. Research methods to treat such wastewater and develop economic and practical wastewater treatment process are extremely important to accelerate the pace of industrialization of cellulosic etha nol.The wastewater from a group’s corn straw cellulosic ethanol plant was the subject of this study. Based on the analysis of the sources, the features and present treatment process of cellulosic ethanol wastewater, two-series anaerobic- short nitrification and denitrification process was proposed. Pilot-scale wastewater treatment was designed and including continuous stirred tank reactor(CSTR), internal circulation(IC) and sequencing batch reactor(SBR). According to the point of microbial ecology and biochemical, the acclimation, startup, process parameters and factors of CSTR, IC, SBR were systematically studied, meanwhile, the controlling factors to achieve short nitrification and denitrification process were analyzed.The low concentration wastewater was used to start biological wastewater treatment reactors, which lasted 100 days. The acclimatization stage has run over a period of 70 days after the successfully started of three reactors. With the acclimation of five stages step by step, the reactors could run steadily for the cellulosic ethanol wastewater and anaerobic effluent reflux, which is mixed by the 1: 6 for volume ratio and the total COD removal rate can reach to 85%, ammonia removal efficiency is above 90%.The organics, ammonia nitrogen, BOD5, alkalinity and sulfate during the mixed wastewater treatment process were also detected, and then the B/C of every treatment section were calculated and analyzed. The results of all the aspects above shown that the mixed wastewater can be treated effectively. Under the condition of sufficient alkalinity, the p H value of short nitrification and denitrification system showed certain regularity. The appearance of "Ammonia valley" may indicate the end of the nitration reaction. At the same time, in differen t ways for different aeration affect water sulfate levels. In addition, different operation modes and denitrification adding different carbon sources can affect short nitrification and denitrification performance.Analysis the economics of amplifying combined process engineering. The results show that the set of combined treatment of wastewater cellulosic ethanol has a good economy. Wastewater treatment price per ton for 6.15 yuan, equipment operating costs of 4.492 million yuan a year. At the same time, technological process can also produce the energy type gas-methane. By calculate the theoretical value of the methane heat producing electricity, it shows that creates value of 2.429 million yuan.