Study On Degradation Of PPCPs By A Humid O₂ Strong Ionization DBD Method In Aqueous And Its Toxicological Effect And Mechanism

Pharmaceuticals and personal care products（PPCPs）are a variety of chemical substances,which are widely used in family,veterinary,agriculture and aquaculture.As a new organic pollutant,PPCPs concentration is usually ng/L-μg/L,which is difficult to be effectively removed by traditional water treatment technologies.PPCPs can enter the water environment through a variety of ways,which will cause serious impacts on human health and aquatic organisms.Dielectric barrier discharge（DBD）technology has been widely studied and applied in PPCPs wastewater treatment in recent years because of its large amount of oxidation products,high removal efficiency and simple operation.Traditional DBD plasma has the disadvantages of low electron concentration and energy,low concentration of·OH and low output,resulting in low wastewater treatment capacity,which is only suitable for small-scale applications.In order to overcome the above shortcomings of DBD plasma in practical application,a humid O₂ strong ionization DBD technology was proposed to remove PPCPs pollutants in aqueous.In view of the over standard situation of PPCPs and other pollutants in urban sewage treatment plants and natural water bodies,OTC,CBZ,OXA and NP were selected as the target pollutants in PPCPs,and high concentration·OH,O₃ and H₂O₂ were produced by a humid O₂strong ionization DBD to degrade OTC,CBZ,OXA and NP.The degradation mechanism and effect of·OH,O₃ and H₂O₂ on PPCPs were investigated.The water environmental toxicological effect and mechanism of PPCPs and its degradation intermediates were analyzed.The optimal control parameters were determined,which provided a new effective method for the rapid,efficient,zero pollution and zero discharge treatment of PPCPs pollutants in urban sewage treatment plants or drinking water sources.The research contents are as follows:（1）Withα-Al₂O₃,quartz glass and borosilicate glass are used as dielectric materials,the effects of structure,dielectric properties,insulation strength and thermal conductivity of dielectric materials on surface charge deposition in large-scale region were studied.Make sure thatα-Al₂O₃ ceramics can meet the needs of dielectric materials with high insulation and high dielectric constant for strong electric field ionization discharge.A discharge system with high concentration of gaseous active substances such as OH,O₃ and H₂O₂ was constructed for strong ionization DBD.By adjusting the input voltage U,discharge frequency f,carrier gas Q and other physical parameters,the effects of these physical parameters on the production and concentration of active substances such as OH were investigated,and the optimal electric field discharge conditions of HOSIDBD were determined:U=3.8 k V,f=10.8 k Hz,q=5 L/min,the production of OH and O₃ active particles were 0.74 mmol/L and 13.4 mg/L,respectively.And build a set of HOSIDBD water treatment system withα-Al₂O₃ ceramic as medium material and venturi jet as gas-liquid mixing device.The energy consumption of HOSIDBD method is only 0.28 k Wh/m³,which is far lower than the existing wastewater treatment process;Due to the addition of high pressure atomization device,the concentration of active substances produced is much higher than that of ordinary AOPs device;Without adding any catalyst,the cost of treatment and operation is reduced,and it is expected to realize large-scale production and industrial application as soon as possible.（2）The occurrence and distribution of PPCPs in surface water sources and sewage treatment plants of three different Southeast Asian countries were investigated for one year.Eight common PPCPs compounds were detected,and their concentration distribution and water quality were determined.Meanwhile,CBZ,OXA,OTC and NP were selected as different target pollutants to evaluate the effect of water quality on the degradation of four PPCPs in the process of HOSIDBD degradation.The highest removal efficiency were 100.0%,99.8%,99.9%and 100.0%,respectively;The correlation between the degradation efficiency of PPCPs and DOMs in water was studied by Pearson correlation analysis.The results show that the removal efficiency of PPCPs strongly depends on its molecular weight Mw(R_CBZ=0.0608;R_NP=0.0599;R_OTC=0.0492),biopolymer(R_CBZ=-0.506),salinity(R_OTC=-0.691),conductivity(R_OTC=-0.610),TDS(R_OTC=-0.0659;R_OXA=-0.491)and p H(R_CBZ=0.511),the removal efficiency was affected by both inorganic and organic matter.In addition,in order to improve the pollution control effect,the effect of physical parameters such as the initial concentration of PPCPs,the concentration of·OH and other active substances,the treatment time,the p H value of reaction solution,inorganic ions(CO₃^2-、HCO₃^-、Cl^-和NO₃^-),hydroxyl inhibitors(TBA、IPA、CO₃^2-和HCO₃^-),NOMs（humic acid（HA）,bovine serum albumin（BAS））were studied on its degradation was studied.The results show that HOSIDBD is suitable for different p H solutions,and the degradation efficiency of four target pollutants is the best under neutral conditions.The order of inhibition intensity of different inhibitors on the removal of PPCPs by HOSIDBD was TBA>IPA>CO₃^2->HCO₃^-had no significant effect on the degradation efficiency of PPCPs.There is competition between NOMs（HA,BSA）and PPCPs.The active particles not only have excellent degradation performance for PPCPs,but also have good degradation effect for HA and BSA.When U is 3.8 k V,f is 10.8 k Hz and Q is 5 L/min,the degradation efficiency and kinetic constant of PPCPs are the highest.The relationship between dose effect and time effect of·OH and other active substances to degrade the target pollutants was determined,which provided the best design and operation parameters for the industrial demonstration test of HOSIDBD method to degrade PPCPs.（3）Under the optimal reaction conditions:U=3.8 k V,f=10.8 k Hz,Q=5 L/min,neutral p H,the chemical process of HOSIDBD degradation of OTC,CBZ,OXA and NP by active substances such as·OH and the difference between the active substances were studied by ESR,UV-Vis,TOC,COD,HPLC and LC-MS,and the intermediate and final products were analyzed,The degradation pathway,migration and transformation pathway were discussed.The results show that the removal efficiency of the above four PPCPs are more than 93%,and the removal rates of TOC and COD are much higher than other DBD degradation methods.At the same time,M/Z 417(C₂₁H₂₃NO₈)and M/Z 426(C₂₂H₂₀NO₈)conversion products of OTC were detected for the first time in the degradation process of HOSIDBD;The main degradation mechanism of CBZ is the conversion of olefin double bonds in the central heterocycle to alcohols,aldehydes,ketones and carboxyls.Fourteen main by-products and seven different conversion pathways were identified.The five by-products of OXA and their transformation pathways include hydroxylation,hydrolysis and decarboxylation;The degradation process of NP includes loss of functional groups,cracking of benzene ring,hydroxylation,demethylation,decarbonylation and dehydration..（4）Taking P.putida and zebrafish as model organisms,the toxicological effects and mechanisms of OTC,CBZ,OXA,NP and their degradation intermediates were studied.The quantitative structure-activity relationship（QSAR）method was used to evaluate the toxicity of four PPCPs and their intermediates by using T.E.S.T..The toxicity of OTC,CBZ and OXA solutions to P.putida at different treatment time showed that both OTC and OXA solutions were toxic except CBZ solution,and the toxicity to P.putida gradually decreased with the reaction time.The toxicity of NP to zebrafish showed that high concentration of NP（NP-20and NP-200）could induce significant changes in early embryonic development（live egg rate（24 hpf）,fetal movement（24 hpf）,body length（72 hpf and 96 hpf）,behavior（96 hpf）and deformity rate）in zebrafish exposed to 24 hpf-96 hpf;After dilution,the growth and development toxicity of NP solution degraded by HOSIDBD method for 30 min（NP-DBD-30）and 60 min（NP-DBD-60）decreased gradually.Zebrafish over 20D old exposed for 70D had no obvious teratogenicity and mortality.The results showed that exposure to NP could induce the increase of E2 and T in both female and male fish,and the increase of T in male fish was significant.NP-DBD-60 could significantly decrease the E2 and T levels in both male and female fish;NP exposure had no significant effect on ovarian development of female zebrafish,but had greater effect on testicular development of male zebrafish,and the higher the concentration of NP,the more significant the effect;Transcriptome analysis showed that the up regulation of Dmrt1,Hsd3b and Cyp19a1a could induce zebrafish to develop towards female,while the up regulation of ESRL and Sox9a and the down regulation of Amh gene were closely related to Testis Damage in male zebrafish.The T.E.S.T.simulation results of four PPCPs and their degradation products showed that the toxicity of PPCPs by-products was sometimes stronger than PPCPs itself,and the toxicity of by-products would be further reduced with the progress of HOSIDBD reaction.