Experimental Study On Start-up And Operational Stability Of BCO Device For Treatment Of Campus Sewage Under Low Temperature

Now in China, water resources are extremely scarce and the sewage pollution is becoming a growing problem. It is of great practical significance to develop domestic sewage reuse programs since it can increase the ratio of reused and decrease wastewater disposal. Some environmental companies have already developed and used different kinds of processing equipment. One part of our sewage reuse programs is the recycle and reuse of the sewage on campus, which features two characteristics that are conducive to sewage recycle and reuse, less pollution and large volume of water. The effluent can be used for campus landscaping, road flushing and dormitory toilet flushing, which not only beautify the campus, but also greatly reduce investment and running cost of school.In the experiment, in case, we have considered the characteristics of campus sewage and studied the campus sewage discharge in Xinjiang Agricultural University, then we collected and treated the sewage using bio-contact oxidation. Our goals in this experiment include making the effluent quality to reach the standard and discussing the factors that may influence the cost of infrastructure construction and operating.Firstly, we have used the method of inoculating sludge to research the start-up period of contact oxidation device. The removal rate of COD will be used as index to determine if the biofilm has succeeded and we also analyzed the biofilm formation time and its removal effect. Under the same conditions of the quality and quantity of raw water, temperature and pH value, we have studied the effect of dissolved oxygen(DO) on wastewater purification to determine the optimum dissolved oxygen. With the optimum DO and some other invariants, we have studied the effect of hydraulic retention time(HRT) on removal effect to determine the optimal hydraulic retention time. Lastly, we studied the operation stability of the device under low temperature with the optimum DO and HRT.The conclusions of this experiment are:(1) in the twelfth day, the removal rate of COD reached 89.75%and tended to be stable. It marks the success of the biofilm with 16 days.(2) The data suggests that, with the increasing of DO and HRT, sewage purification effect is better where the COD, SS and ammonia nitrogen removal rate increased. This experiment concluded that DO=4mg/L and HRT=9h is the best condition.(3) A device in optimum conditions can adapt to continuous low temperature which is typical in Xinjiang area and the effluent quality of the system can meet the requirements in "Miscellaneous Urban Water Quality Standard"(GB/T18920-2002).All these demonstrate its strong adaptability in severe environment and its effective purification of sewage. More over, its integrated buried equipment which occupies a small area will not be an eyesore on campus and its operation is very simple. It provides a great option for the campus sewage reuse projects.