Research On Typical PPCPs Oxtetracycline Processing Technology Based On IFAS-MBR Process

Oxytetracycline,as one of the four most widely used tetracyclic antibiotics,has been detected in urban sewage,rivers,groundwater and soil.Although the content of antibiotics in the environment is very low,they have sustainable pollution in many aspects such as environmental diversity and biological toxicity.Their residues in the environment can inhibit the growth of animals and plants and endanger human health.For the low-content and difficult-to-degrade oxytetracycline,the traditional sewage treatment process has low removal efficiency.It is urgent to explore the effectiveness of the existing sewage treatment plant in removing conventional pollutants from urban domestic sewage,by optimizing the reaction process parameters or improving the process and other treatment methods to achieve the feasibility of intensifying the removal of antibiotics,and finally establish a set of economically feasible and complete wastewater treatment technologies.Therefore,in this study,the IFAS-MBR reactor was used as the biochemical reactor to explore the performance changes of the reactor when the synthetic wastewater and the oxytetracycline-containing wastewater were treated separately under different operating conditions,with the filler filling ratio?10%,25%,50%?,hydraulic retention time?4h,8h,12h?and sludge retention time?20d,40d,60d?on the removal of COD and ammonia nitrogen compounds in oxytetracycline-free wastewater,and on COD in wastewater containing oxytetracycline,including the removal effect of ammonia nitrogen compounds and oxytetracycline and the influence of membrane fouling.The main research contents and conclusions were as follows:?1?Using oxytetracycline-free organic wastewater as feed water,the sludge retention time in the reactor is 60d,and the hydraulic retention time is 4h.When the filler filling ratio is 10%,25%,and 50%,the removal rate of COD and NH₄⁺-N.increased first and then decreased.When the filler filling ratio was 25%,the removal rate of COD and NH₄⁺-N was the highest,which were 90.26%and 86.45%,respectively;changing the hydraulic retention time to 8h,the removal rate of COD and NH₄⁺-N was higher than that of 4h,all above 90.00%;the residence time was 12h compared with 8h without significant change.When the hydraulic retention time is 8h and the filler filling ratio is 25%,it is the best condition for the removal of COD and NH₄⁺-N in the IFAS-MBR reactor.The average removal efficiency of COD and NH₄⁺-N is as high as95.46%and 98.53%.On this basis,the sludge retention time was increased from 40d to60d,and the removal efficiency of COD and NH₄⁺-N increased from about 80.00%to more than 90.00%.?2?The organic wastewater containing antibiotic oxytetracycline is used as the feed water,and the filling ratio of the filler is controlled to be 25%.When the sludge retention time is 40d,the hydraulic retention time is 8h and 12h,the removal efficiency of the IFAS-MBR reactor is ug/L oxytetracycline is 58.86%and 69.71%;the control hydraulic retention time is 12h,when the sludge with a retention time of 60d is used,the removal efficiency of oxytetracycline reaches 72.30%.With the extension of sludge retention time and hydraulic retention time,the removal efficiency of IFAS-MBR on COD and NH₄⁺-N in organic wastewater gradually increases,but at the same time,the presence of oxytetracycline will inhibit the types and numbers of microorganisms in the IFAS-MBR reactor.Furthermore,the removal of COD and NH₄⁺-N is suppressed.When the hydraulic retention time is 12h and the sludge retention time is 60d,the presence of oxytetracycline will reduce the removal efficiency of COD and NH₄⁺-N by about 5.00%and 3.00%.?3?Taking organic wastewater containing antibiotic oxytetracycline as feed water,the retention time of sludge is controlled to 60d,and the hydraulic retention time is increased from 4h to 12h.The content of protein,polysaccharide,DNA and total organic carbon in EPS and SMP in MBBR and MBR are all Significant decline.When the hydraulic retention time is 12h,the sludge retention time increases from 20d to 60d,and the components in EPS and SMP also decrease significantly,which indicates the reduction of membrane surface pollution.In addition,the choice of carrier has an important impact on membrane fouling.Sponge modified biological carrier or adding resin particles have a certain effect on reducing membrane pollution.Backwashing and on-line maintenance cleaning can prevent and control membrane pollution.