Analysis Of The Effect Of Removing Perfluorooctanoic Acid From Typical Domestic Sewage Treatment Process And Its Influencing Factors

Perfluorooctanoic acid(PFOA),as a non-degradable typical perfluorinated compound,has a high level in landfill leachate.It has a good removal effect after treatment with reverse osmosis membrane when treated separately.Generally,there is no treatment process for high-pressure membranes such as reverse osmosis membranes in the typical domestic sewage treatment process,and the removal efficiency of PFOA may be low,resulting in a large pollution load on the environment caused by the effluent.This study aimed at the level of PFOA in domestic sewage,combined with the typical domestic sewage treatment process principle to investigate the removal effect of PFOA at all level of treatment units,and discussed the main processing units that significantly affected the level of PFOA.At the same time,the disinfection unit was selected to analyze the influence of different disinfection treatment processes on PFOA,and the disinfection treatment process with lower PFOA emission in the effluent was obtained.This study has the following conclusions:(1)The level of PFOA in domestic sewage collected from two places were155.28~376.54ng/L and 114.12~298.14ng/L,respectively.Although the sampling locations are different,the difference is not significant.After the treatment of sewage,the overall removal rate of PFOA was 14.81%~18.76% and-21.99%~-38.71%,respectively.The sewage treatment system has no significant effect on the removal of PFOA,and there is a phenomenon that the level of PFOA in the effluent is higher than that of the influent.(2)In the domestic sewage treatment system,the pretreatment stage shows a certain removal effect on PFOA,and the fluctuation level of PFOA in the biochemical treatment stage increases or decreases.The specific biochemical treatment unit and disinfection treatment unit are the main processing units that result in an increased level of PFOA.(3)The disinfection unit will affect the presence of PFOA by degrading the precursor.After chlorine disinfection,ozone disinfection and UV disinfection treatment,the formation rate of PFOA in the effluent is similar,and it is impossible to judge which kind of disinfection treatment process will increase the level of PFOA in the effluent.However,the degradation rate of the precursor material 8:2 FTOH is significantly lower than that of ozone disinfection and UV disinfection,and the 8:2 FTOH emission after disinfection treatment is larger.(4)Different water quality conditions will not affect the degradation of precursor materials under different disinfection treatment processes to produce PFOA,but the effects of reaction promotion or inhibition according to specific water quality are different.When controlling the level of PFOA in sewage effluent by selecting different disinfection processes,it is necessary to consider the actual sewage water quality.