Study On The Contamination Profile Of Per-and Polyfluoroalkyl Substances (PFASs) In Drinking Water And The Removal Efficiency Of Water Treatment Process

Per-and polyfluoroalkyl substances(PFASs)are a class of emerging persistent organic pollutants(POPs)which have been manufactured and used for more than 60 years.Due to their Long-range migration capability,persistent,and bioaccumulated properties,PFASs have been widely detected in a vatiety of media.It was widely reported that consumption of food,drinking water,and inhalation are the main pathways for PFASs exposure to general population,Exposure from drinking water is a serious concerned because of the high water solubility of many PFAAs,which increases blood serum levels with the low levels in drinking water.Therefore,the comprehensive investigation of PFASs in drinking water can provide basic information for the human health assessment.In addition,trace the contamination source of PFASs in drinking water would be helpful for its control work.Overall,first,this study investigated and analyzed the pollution levels of 17 types of perfluoroalkyl acids(PFAAs)in drinking water of 79 cities in China;Secondly,taking Tianjin as an example,the contamination levels and changes of 21 types of PFASs from source water to drinking water treatment plants were detected,and analyzed the influencing of rainfall on the concentration and compositions of PFASs;Finally,the removal efficiency and influencing factors of coagulation to remove novel PFASs was studied by laboratory simulation.The specific conclusions are as follows:(1)The PFAAs were ubiquitous present in drinking water across China.The ∑17PFAAs was in the range of 4.49 to 174.93 ng/L with a mean concentration of 35.13 ng/L,and PFBA was the typically prominent PFAAs;The distribution of PFAAs in drinking water was unevenly,according to different classifications,the average concentrations of PFAAs was: Southwest area > Eastern Coast area > Northwest area > Northeast area,Medium city > Big city > Town;The difference of discharge of PFAAs by industrial and human acitiveties are the main factors affecting the region distribution of PFAAs in drinking water.(2)In Tianjin,PFASs were detected in source water,and the processes effluent of drinking water treatment plant,the concentration range of ∑PFASs in two source water,and drinking water treatment plant were 6.24~28.00 ng/L,80.00~119.86 ng/L,and 15.20~19.83 ng/L,respectively,as for the novel PFASs,6:2 Cl-PFESA were found in all samples,indicating that the novel PFASs have been widely used in Tianjin.(3)Different rainfall affects the ∑PFASs in the aquatic environment,but has little effect on the composition characteristics of PFASs.Specifically,the increase in precipitation increased the concentration of PFASs in Beidagang Reservior,which locates in a densely populated area,but has a certain dilution effect on PFASs in Yuqiao Reservior(4)The results of simulated coagulation experiments show that the coagulation process mainly removes PFASs by surface adsorption and electrostatic action.The amount of coagulant,pH value,initial concentration of PFASs,flocculation time and so on have an influence on the PFASs.