| Reducing the concentration of phosphorus in municipal sewage plant is the key measure and method to prevent eutrophication.Post-endogenous denitrification（i.e.,under starvation stress）can improve phosphorus release,phosphorus removal efficiency and reduce sludge production in anaerobic zone,but the probability of secondary phosphorus release in pre-deficient zone increases significantly,which increases the blindness of process regulation.The effects of anaerobic conditions on the amount of phosphorus released by PAOs and the effect of systematic phosphorus removal,but the mechanism of secondary phosphorus release and the effect on the system phosphorus removal under the starvation stress of pre-deficient zone or secondary settling tank are not studied in depth.As to the causes of secondary phosphorus release in A~2O、MUCT、MSBR、JHB、AOA and other enhanced phosphorus removal processes and the effect of ineffective phosphorus release on microbial population structure in the system,no reports have been reported.A SBR reactor（anaerobic/aerobic/anoxic/reaerobic/pre-anoxic operation mode called double post-denitrification process）was used to study the relationship between pre-anoxic time and phosphorus removal effect in pre-anoxic process and macro genome sequencing of activated sludge in different operating stages of the system.To explore the relationship between microbial community structure and system phosphorus removal effect.This study concludes as follows:The pre-deoxygenation time in the first post-denitrification process is controlled at 2h/2.5h/3h and 0,which will not affect the removal efficiency of COD in the reactor.However,because the aeration stage is DO sufficient,ammonia nitrogen is almost completely removed.The pre-deoxygenation time has a great influence on the removal of nitrate nitrogen,and the longer the pre-deoxygenation time,the lower the denitrification efficiency of the system.That is,too long pre-deoxygenation time is not conducive to the realization of system denitrification function.With regard to phosphorus removal,the pre-deletion time has a significant effect on biological phosphorus removal.When the pre-deletion time of the system is not higher than 120 min,the phosphorus removal function of the system is destroyed and gradually lost when the pre-deletion time of the system is higher than 120 min.And in the system pre-deletion period appeared invalid phosphorus release phenomenon,the system pre-deletion time is too long is not conducive to biological phosphorus removal.in the pre-deoxygenation period of 5 h and 3 h,the ineffective phosphorus release occurred:the higher the ineffective phosphorus release,the lower the anaerobic phosphorus release and TP removal rate,which showed a negative correlation.The microbial diversity and relative abundance in the initial sludge,domesticated and active biological samples of the post-denitrification SBR system were analyzed 3.at three classification levels:gate,class and genus.A succession rule of the key functional flora with the change of pre-deficient time was obtained:the pre-deficient time of the key functional genera related to the denitrification process was positively correlated with the total An AOB content.The main DNB genera were detected in each stage of the system,and the total content of DNB flora was maintained at about 1%,which was not the main functional flora of the system.Therefore,it can be inferred that the denitrification and phosphorus removal effect of the system is generally consistent with the pollutant removal results.Typical DPAOs genera and typical P of P-related functional genera... |
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