Start-up By Mixing Fliter And NOB Inhibition Of Lable-scale CANON Process In Wastewater Treatment Plant

The completely autotrophic nitrogen removal over nitrite(CANON)is a new biological nitrogen removal process.Compared to traditional nitrogen removal process,CANON process needsno external carbon source,saves aeration and produces less sludge.But current CANON process was operated indoors and only few paper were reported on CANON process which operated in Waste Water TreatmentPlant(WWTP).The difficulties of CANONprocessin WWTP lie inlargeamountofinoculation seedsand effective measures to inhibit activity of nitrite oxidizing bacteria(NOB)in normal atmospheric temperature and low ammonia concentration condition.Lab-scaleCANONprocesswasoperatedinMunicipal WWTPtodealwiththetwoissues.Sewage effluent treated by A/O process which operated in WWTP was served as substance and nitrite bacteria and anaerobic ammonium oxidation bacteria was inoculated to start up lab-scale reactors.The tests leading to two started strategies of CANON filter,R1 was filled with filler with matured ANAMMOX bacteria and inoculated nitrite flocculent sludge,R2started with mixing nitrification filter and anaerobic ammonium oxidation filter with weight ratio of 2:1.The inlet water of R1 and R2 was domestic sewerage after the A/O phosphorus removal treatment and keeping the temperature between 15~21 degree and ammonia nitrogen concentration within 35~55mg/L.The R1 and R2 made use of37d and 19d to keep ammonia removal rate stable at 95%and total removal rate above 70%.After operated 100d,the effluent of reactor almost did not contain ammonia and the maximum effluent total nitrogen concentrationof R1 and R2 was15.8mg/L and 12.1mg/Lbecause of excessive proliferation of NOB.Specially the more worse of R1 and total nitrogen concentration in effluent of R2 metthe first level A emission standards.The start-up strategy of mixed media reduced two thirds of the amount used ininoculatinganaerobic ammonium oxidation bacteria,accelerated the start-up of the reactor,inhibited the activity of nitrite oxidation better,and achieved the long-term ammonia and total nitrogen emission standards.Concentration of total nitrogen in effluent increased substantially due to NOB excessed proliferation after successful start-up CANON filter and concentration of total nitrogen in effluentof R1 excessed the first level A emission standards.It is clamant to inhibition activity of NOB to maintain CANON process operate stablely.Aimed at the problem that nitrite oxidizing bacteria excesses proliferation in CANON process and causes the effluent nitrogen concentration to exceed the first level A discharge standard of pollutants for municipal wastewater treatment plant,to experiment and investigate the effect of high ammonia loading rate,back washing and anaerobic operation on the NOB in the filter column.The results show that the NOB had adaptability to the high ammonia loading rate,when the influent ammonia nitrogen loading rate was 0.60kg/(m~3?d),after the continuous operation of 80d,the total nitrogen removal rate was stable at 65%or so,the maximum total nitrogen concentration in effluent was 15.8mg/L,exceeding the first level A emission standards;NOB was eluted in CANON process by the means of reverse washing,after the back washing the total nitrogen concentration of the continuous 40d effluent was less than10.5mg/L;the inhibitory effect of anaerobic operation on NOB was larger but its inhibitory effect on AOB was smaller,from after anaerobic operation recovers low DO stable operation,the total nitrogen removal rate above continuous 40d was greater than 80%,and the maximum effluent total nitrogen concentration was 9.5mg/L.Due to limited effect of high ammonia loading rate and high price of nitrite,high ammonia loading rate and anaerobic operation would not be utilized in engineering.Because of low enpensive and high efficiency,backwash could be use in WWTP for inhibiting NOB theoretically.In order to investigate the effect of backwash periodically,backwash was implemented in 129th,169th and 213th days.Nitrogen removal rate was more than70%for long time and total nitrogen concentration in effluent was below 12.0 mg/L.Nitrogen concentration in effluent fitted the first level A discharge standard and nitrite oxidizing bacteria was inhibited effectively.The results show:Backwash nearly had no effect on the structureoffilter.Theimpactofbackwashonthicknessof bio-membrane and function bacteria was relatively small but backwash could inhibit activity of nitrite oxidizing bacteria effectively.It is possible that backwash periodically is utilized in engineering to maintain CANON process operate stably.