| As a substitute for bromine flame retardant,phosphorous flame retardant is widely used as flame retardant and plasticizer.Sewage water,enfluent of secondary sedimentation tank,final enfluent,sludge of biolgical pool and dewatered excess sludge samples in 9wastewater treatment plants(WWPTs)in Suzhou,including 7 A~2/O process and 1 oxidation ditch process were collected in 2017,in order to study the pollution characteristics of organophosphorus flame retardants(OPFRs)in WWPTs.Accelerated solvent extraction(ASE)combined with solid-phase extraction method was used for sample pretreatment,while GC-MS was used to detect the concentration of 7 kinds of OPFRs in sewage and sludge,the removal efficiency of OPFRs in two different processes within each process was compared.The content and components of OPFRs in the WWPTs were verified by seasonal variation,and the samples of sewage and sludge in summer and winter were collected,and the measurement and data comparison were conducted.By measuring the effluent collected from the sewage treatment plant and the sample of residual sludge,the average daily discharge of the final discharge environment was estimated,and the risk of the sewage plant to the ecolgical environment was evaluated.For Ti BP,TBP,TCEP,TCPP,TDCPP,TBEP,TPhP,good recovery and repeatability were achieved.The environmental behavior of OPFRs is influenced by its physical and chemical properties,and the physical and chemical properties of OPFRs vary greatly,which caused the migration and transformation in the environment can be very different.Seven kinds of target objects were all detected,the content of TDCPP in WWPTs water uses A~2/O process was the highest,average concentration is 56.09?g/L.The concentration of TDCPP in final enfluent was also the maximum,and the mean value was59.43?g/L.The average total amount of 7 kinds of OPFRs in the WWPTs using oxidation ditch process was 9.70?g/L and the average total amount in final enfluent was 0.79?g/L.The removal rate of TBP of both process is over 90%,and the removal rate of TBEP is over 70%.OPFRs like TCPP,TCEP and TDCPP were affected by the steric effect,which made them difficult to be degraded in the sewage plant.The average removal rate of 7kinds of OPFRs uses A~2/O process was 33.78%,while the average removal rate of oxidation ditch process was 83.15%,which was significantly higher than other WWPTs use A~2/O process.Maybe it's because the oxidation ditch process has long hydraulic retention time,low organic loading and longer sludge age,so compared with traditional activated sludge method,oxidation ditch technolgy can guarantee good processing effect.Concentration of OPFRs in final enfluent in summer is significantly lower than in the winter.OPFRs concentration in waste sludge in summer was significantly higher than that in winter.The total daily emission of OPFRs in 9 WWPTs in Suzhou was calculated as36.69 g/d~31561.18 g/d in winter and 8.4 g/d~59.40 g/d in summer.The total daily emission of the waste sludge OPFRs was as follows:the minimum range in winter is 7.85g/d~15.71 g/d,the maximum range is 57.13 g/d~114.25 g/d;The minimum range in summer is 11.79 g/d~23.59 g/d,the maximum is 214.68 g/d~429.37 g/d.Higher concentration of emissions output will pollution aquatic environment and soil environment,which can enter organism through breathing,food intake and skin contact way such as penetration and cause a harm to people's health. |
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