Study On Simultaneous Intensification Of Ibuprofen Degradation And Nitrogen Removal In Intermittent Aeration Process

The conventional biological treatment process of urban sewage treatment plants is often only aimed at the removal of chemical oxygen demand（Chemical Oxygen Demand,COD）,ammonia nitrogen,nitrogen nitrogen and other conventional indicators,often ignoring the treatment of complex and difficult degradable organic trace pollutants（Organic micro-pollutants,OMPs）,leading to frequent detection of OMPs in the water environment,and ammonia nitrogen is often difficult to meet the discharge.Once these substances are discharged into the water body,they will indirectly or directly affect and endanger the environmental and ecological system,and ultimately endanger human health through the ecological cycle.Conventional sewage biological treatment technology has low degradation efficiency for OMPs,and advanced physical and chemical treatment technology has high energy consumption and is prone to secondary pollution.Therefore,the search for economical and efficient biological treatment measures to enhance the degradation of OMPs and simultaneous denitrification in urban sewage has become an urgent problem to be solved.Based on this,this study uses Ibuprofen（IBP）as a representative of typical OMPs to strengthen the intermittent aeration process for IBP degradation and simultaneous denitrification by adding green synthetic iron oxides,and to explore the relevant mechanism of action.The main research contents and conclusions are as follows:First,optimize the conditions for different iron oxides to enhance the degradation and denitrification of ibuprofen.The results show that green synthetic iron oxide（gFeOx）and activated sludge（AS）are added to the intermittent aeration system with a mass dosing ratio of0.3 and a particle size of 0.05-0.15 mm.The best removal effects on COD,IBP and TN were90%,57%and 85%,which were 22%,73%and 47%higher than the blank control group respectively.The addition of gFeOx showed significant strengthening performance.Secondly,research on the performance of gFeOx to enhance the degradation and denitrification of ibuprofen.The results showed that the R2 system with gFeOx added to the activated sludge system significantly enhanced the removal effect of COD,IBP and NH₄⁺-N in the stable operation stage,and the removal rate was increased by 14%,95%and 40%respectively compared with the blank group R1.The hydraulic retention time is shortened from 12h to 8h,and the R2 system has stronger impact load resistance.During the 90d operation of the continuous flow intermittent aeration process reactor,the Fe²⁺effluent concentration of the R2 reactor was always maintained below 0.5 mg/L,and gFeOx did not show a large amount of dissolution.The results show that gFeOx has significant advantages in enhancing IBP degradation and denitrification performance,and has a continuous and stable strengthening effect.In order to explore the stability of the pollutant effluent during the stable period,the effluent concentration of COD,IBP and NH₄⁺-N was monitored during the8h aeration cycle.The results show that the R2 system has a stable enhanced removal efficiency and can achieve continuous discharge of the effluent.Finally,studies on the mechanism of gFeOx enhancing the degradation and denitrification of ibuprofen were carried out.According to the results of scanning electron microscopy,the addition of gFeOx shortens the distance between activated sludge microorganisms and creates powerful space conditions for the potential electron transfer of different strains.The analysis of the related enzyme activities of activated sludge in the two reactors found that the total DHA,Heme c,NR and NIR activities in the sludge of the R2reactor were 1.6,2,2.5 and 4.2 times that of R1,respectively;the total of the sludge EPS was The activities of Heme c,NR and NIR are 1.1,3.5 and 5.3 times that of R1,respectively.Under aeration conditions,the addition of gFeOx enhances the activity of intracellular and extracellular enzymes in the system,thereby enhancing the performance of IBP degradation and simultaneous denitrification;under the conditions of stopping the exposure,the addition of gFeOx promotes the electron transfer between the reactants on the one hand.The growth of the required enzymes,on the other hand,can increase the electron transfer rate between different microorganisms,thereby improving the system’s denitrification and carbon removal performance.At the same time,the addition of gFeOx significantly enhanced the community diversity and richness of the activated sludge system,making Sphaerotilus and Nitrospirae more concentrated in the system,which are related to denitrification,degradation of aromatic organics,and interspecific electron transfer;XRD spectrum results show that after 90 days of continuous operation under intermittent aeration conditions,most of the gFeOx in the R2sludge still exists in the form of tetraferric oxide,and part of the gFeOx is transformed into goethite,which together act as a carrier for electron transfer to promote Removal of organic matter by microorganisms in the system and denitrification performance.To sum up,this project reveals its internal mechanism by studying the performance of gFeOx synchronously enhanced intermittent aeration process for IBP degradation and denitrification,and verifies that gFeOx is stable and efficient in enhancing the effect of degrading pollutants,which is a synchronously enhanced intermittent aeration process for gFeOx.The research on degradation and denitrification of OMPs（represented by IBP）provides new ideas.