Occurrence Characteristics And Ecological Risk Assessment Of Perfluorinated Compounds And Microplastic Fibers In Textile Dyeing And Finishing Industry

Perfluorinated compounds(PFCs)and Microplastics(MPs)fibers are a class of novel pollutants that have stable chemical properties and can remain in the environment for a long time.As one of the most important industrial products,microplastic fibers are released in the whole life cycle of the product.Meanwhile,PFCs are often used as a triple-proof finishing agent in the finishing process to improve the performance of the product.These two kinds of pollutants enter sewage treatment facilities through a large number of textile dyeing and finishing wastewater and are put into natural water bodies or urban pipelines after treatment,but they are still one of the important pollution sources of PFCs and MPs fiber in the environment.The Yangtze River Delta is the largest economic zone in China,where printing and dyeing industries are highly concentrated,and the terminal discharge point pollution from enterprises or centralized sewage treatment plants is densely distributed.These two new types of pollutants are discharged and stored in the nearby surface water and adjacent sea,making this region a highly sensitive area for ecological risks.Therefore,this study is of certain significance to comprehensively explore the residual levels and ecological risks of PFCs and MPs fiber in textile industrial wastewater in the Yangtze River Delta region.In this study,a typical textile dyeing and finishing industrial park in the Yangtze River Delta was selected as the research object.Raw water and effluent water after treatment were collected from 58 printing and dyeing enterprises in Zhejiang province and Jiangsu Province,and the emission characteristics and environmental behavior trend of PFCs and MPs fibers were investigated in large scale and deep level.At the same time,the adsorption of PFCs by different MPs was explored under laboratory conditions,the co-pollution characteristics of the industry were revealed,and the potential exposure risks were investigated,which provided a scientific basis for the terminal treatment of new pollutants in the printing and dyeing industry and the cleaner production of enterprises.The main results are as follows:(1)Research on PFCs.Eight kinds of short medium chain(C4?C8)PFCs in printing and dyeing wastewater were analyzed by solid phase extraction(SPE)-ULTRA high performance liquid chromatography-mass spectrometry(UPLC-MS/MS).The results showed that the detection rates of eight PFCs were 38.9%?100%and 46.3%?100%,respectively,and the concentration of?PFCs ranged from 29.37 to 4518.27 ng/L and 8.82 to 3995.76 ng/L.The primary pollutant in both raw water and tail water is PFOA,with an average concentration of 233.77 ng/L and 248.12 ng/L,respectively.The average concentration of most PFCs was reduced,and the highest removal rates were PFBA(79.9%),PFPe A(67.4%)and PFHx S(63.2%),respectively.Of concern is that the average concentration of PFOA in the tail water increased by 6.1%,which may be due to decomposition of precursor materials.In addition,Kruskal-Wallis test showed that the residues of PFOA,PFHp A and PFHx A in chemical fiber were significantly higher than those in other materials(P<0.05),which may be related to the selection of three prevention finishing agents and the existence of fluorine additives in chemical fiber materials.Spearman correlation coefficient analysis showed that there were significant positive correlations between PFHx A and PFHp A,PFHx A and PFOA,PFHp A and PFOA,PFHp A and PFHx S,PFOA and PFHx S in raw water(P<0.01).PFOA in tail water was positively correlated with PFPe A,PFHx A,PFHp A and PFOS(P<0.01).Principal component analysis showed that PFOA,PFHp A,PFHx A,PFPe A and PFBA in raw water had high loading on the first and second components,PFOS and PFHx S had high loading on the third component,and PFHp A,PFHx A,PFPe A and PFBA in tail water had high loading on the first and second components.PFOS,PFHx S and PFBS have high load on the third component.This indicates that the degradation of precursor substances and some properties of PFCs,including carbon chain length and functional group structure,may be the main factors affecting the source of PFCs.The results showed that the risk quotients of PFOA and PFOS were far less than 1,which did not reach the level of risk to the ecological environment.However,the compound environmental effects of multiple PFCs could not be ignored.(2)Research on MPs.The MPs fiber in printing and dyeing wastewater was analyzed by filtration-digestion-stereoscope selection-microscopic infrared identification.The results showed that the average abundance of microplastic fiber in raw water and tail water of printing and dyeing enterprises was 7504.8±5685.9 and 1272.7±782.2 n/L,Polyethylene terephthalate(PET)accounted for 77.2%,the main contributor.The rest included Polypropylene(PP),Polyethylene(PE)and Polyamide(PA),accounting for 9.47%,7.27%and 6.06%respectively.The fabric raw materials in the investigation mainly included chemical fiber,proembryonic cloth,wool fabric,cotton,knitted fabric and silk.Kruskal-wallis test showed no significant effect of raw materials on polymer composition(P>0.05).In terms of microplastic fiber size,the proportion of 100?300?m in raw water was the highest(40.47%),followed by 300?500(19.59%)and 500?1000?m(15.47%).After treatment,the proportion of microplastic fiber>100?m in the tail water decreased,and the proportion of 100?300,300?500,500?1000 and>1000?m decreased to 35.36%,12.31%,10.4%and 4.8%,respectively.However,the proportion of<50?m and 50-100?m increased to 7.5%and29.63%,indicating that the end treatment technology can remove large size fiber(>100?m)well,but has limited removal effect on small size fiber.There were 10 colors of microplastic fiber in raw water,among which colorless and transparent fiber was dominant,accounting for 54.7%,while colorless and transparent fiber in tail water was reduced to 44.3%.Although the average removal rate of microplastic fiber by the end treatment can reach 78.3±10.2%,and the removal rate increases with the increase of the size,the discharge of microplastic fiber through the tail water of printing and dyeing is up to(3.88±5.75)×10~9 n/L,and the ecological risk brought by this is continuous and accumulated.(3)Study on adsorption behavior of pollutants.To investigate the adsorption of 16 PFCs on four kinds of microplastics with particle sizes of 30?m,Including polyethylene terephthalate(PET),polypropylene(PP),high-density polyethylene(HDPE),and low-density polyethylene(LDPE),the adsorption capacity was determined at day 0,1,7,56,respectively.The results showed that the adsorption rate of PET to PFCs was the lowest,and the maximum adsorption rate of all targets was not more than 40%.The maximum adsorption rate of PFDS(C10),PFNS(C9)and PFOA(C8)were 35.5%,34.6%and 34.2%,respectively.The maximum adsorption rates of PP to PFDS(C10)and PFNS(C9)were 67.6%and 62.1%,respectively.The adsorption rates of PFCs by HDPE did not exceed 60%,while the adsorption rates of PFTe DA(C14),PFDS(C10)and PFOA(C8)were58.8%,42.6%and 41.3%,respectively.The maximum adsorption rates of LDPE to PFTe DA(C14)and PFDS(C10)were 67.5%and 66.6%,respectively.Due to the same size,the four MPs showed similar adsorption process for PFCs.After 1 day,the adsorption rate increased rapidly,and after 7days,all the adsorption rates decreased except HDPE.By calculating the K_dvalues of PFCs that reached the adsorption equilibrium,it was found that the K_d values of both PFCs and PFCs increased with the increase of carbon chain length,and hydrophobicity may be an important factor affecting the adsorption.The adsorption rate data at 7 days were selected to explore the influence of functional groups.The research results of PET,PP and HDPE did not show significant influence,but the common point was that the adsorption rate of PFOA was much higher than that of PFOS.LDPE has a better adsorption ability for sulfonates,followed by carboxylic acids and sulfonamides.PFCs of LDPE are more than those of the other three MPs in the adsorption process,indicating the influence of functional groups.At the end of the experiment,MPs did not show the highest adsorption rate for the longest carbon chain compounds of the same functional group.Self-aggregation of micelles may be another key factor affecting the adsorption.