Operation Strategies And Activated Sludge Characteristics Of Nitrogen And Phosphorus Removal In Campus Sewage Treatment System

Campus sewage has the characteristics of large changes in influent quantity,unstable water quality and pollutant loading.How to maintain the sewage treatment system operating in a normal and stable way is the key to the campus sewage treatment system operation.The treatment capacity of activated sludge would have changed during this periodic water volume change process,which will have a fluctuate effluent quality.However,compared with the treatment effect of the campus sewage treatment station during normal operation,the change in influent quantity before and after the holiday has a remarkable impact on the performance of activated sludge.Therefore,it is of great significance to maintain efficient and stable sewage treatment capacity in sewage treatment stations by studying and analyzing the changes of activated sludge in the sewage treatment system before and after holidays,proposing corresponding operating strategies for the change of influent quantity before and after holidays to reduce the attenuation of activated sludge,accelerating the recovery of sludge performance after the holidays.The article took a campus sewage treatment station as a research object,evaluate the processing capacity of the sewage treatment station during normal operation,then put forward holiday operation strategies when the sewage treatment station should taken during the holidays,to adjust the?anaerobic+anoxic?:aerobic time of sewage treatment station to 2:1 during the holiday,the effect of the strategy on the performance of activated sludge during the holiday was also studied.The operation status of the sewage treatment station is evaluated by measuring the water quality index of the influent and effluent,the biofacies of the activated sludge is observed to evaluate the floc status,the nitrification activity of the sludge is measured to evaluate the nitrogen removal performance,and the phosphorus release rate,phosphorus absorption rate,and acetic acid absorption rate are measured,which are used to evaluate the performance of phosphorus removal.The FISH technology was used to measure and analyze the microbial community structure in activated sludge.The comprehensive measurement and analysis results above obtained the following main conclusions:?1?The campus sewage treatment system operates stably,and the effluent water quality can stably reach national 1A discharge standard.The activated sludge in the system has good phosphorus removal ability,and its phosphorus release activity and the phosphorus absorption activity is 20 mgP·gVSS^-1·h^-11 and 15 mgP·gVSS^-1·h^-1,respectively.PAOs accounted for 25%of the total bacteria in FISH analysis.At the same time,the AOB activity in the activated sludge was 2.5 mgNH₄⁺-N·gVSS^-1·h^-1,and the NOB activity was 0.8 mgNO₂^--N·gVSS^-1·h^-1.?2?The influent water quantity of the campus sewage treatment station during the holiday operation is only 5%-10%of the influent quantity during the normal operation phase.The holiday operation strategy can be used to keep the activated sludge in an anaerobic decay state to maintain the activity and quantity of functional microorganisms.At this time,the sludge concentration has dropped from 4500 mg·L^-1to 3200 mg·L^-1.The phosphorus release and absorption activities of the sludge decreased to 5 mgP·gVSS^-1·h^-1and 2 mgP·gVSS^-1·h^-1,which only were 20%and13.3%before the strategy adjustment,respectively;the AOB activity and NOB activity decreased to 0.55 mgN·gVSS^-1·h^-1and 0.5 mgN·gVSS^-1·h^-1,which were 22%and 63%of the conventional strategy,respectively.?3?Implementing the holiday operation strategy for the campus sewage treatment station can significantly reduce the decay rate of functional microorganisms in activated sludge.The reduction of AOB and NOB in both proportion and activity was lower than that of PAO.That is to say,holiday operation strategy can provide a certain degree of protection for slow-growing nitrifying bacteria and reduce their decay during the holiday.When holidays are over,the influent quantity of the sewage treatment station restore rapidly,and the nitrification activity of the activated sludge can also recover to the level before the holiday strategy operated in a short time.The implementation of the holiday operation strategy can make the nitrifying bacteria decay at a lower rate than PAO and other bacteria,which is more conducive to the restart of the activated sludge system.