EFFECT OF NITROGEN LOAD ON NOB INHIBITION IN PARTIAL NITROSATED ACTIVATED SLUDGE SYSTEM UNDER MAINSTREAM CONDITIONS
Partial nitrification(PN)is an important way for anaerobic ammonium oxidation(ANAMMOX)to obtain nitrite(NO2-N)as a substrate.However,the concentration of ammonia nitrogen(NH4-N)in municipal sewage is usually low and fluctuates frequently,making it difficult to achieve a stable PN.In this study,the two reactors were started by shortening the hydraulic retention time(HRT),and the changes in nitrogen transformation and microbial community structure in the PN system were compared under different nitrogen loads(NLR).The results showed that the NLR of R1 increased from 0.15 kg/(m3·d)to 0.5 kg/(m3·d),and the ammonia nitrogen conversion rate(ACR)increased from 45％to 65％,in a hypoxic environment,the nitrous nitrogen accumulation rate(NAR)increased from 0 to 95％,indicating that the rapid start-up of PN could be achieved,but PN became unstable after 60 days of stable operation.However,under the condition of high NLR[0.8～1.2 kg/(m3·d)],ACR and NAR could reach 68％and 85％,and could achieve stable operation,indicating that it was easier to obtain stable and effective NOB inhibition.The microbial community structure further showed that with the increase of NLR,the relative abundance of NOB in R2 was much lower than that in R1;at the same time,the dominant bacteria of NOB in R2 gradually changed from Nitrospira to Nitrolancea.It showed that under high load operation,the type of NOB bacteria changed.This provided a new method for solving the bottleneck problem of the application of the PN-Anammox process under mainstream conditions,which had important research significance and application value.
partial nitrosationcommon conditionnitrogen loadNOB inhibitionmicrobial community structure
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