The Detection Of Typical PPCPs In Water Body And Its Removal In Electrolysis-integrated Constructed Wetland

Recharging of reclaimed water to groundwater will introduce trace toxic and hazardous substances that can pose potential risks to groundwater.It is important to understand the pollution conditions of pharmaceutical and personal care products（PPCPs）and antibiotic resistance genes（ARGs）during the groundwater recharge process.Moreover,in order to prevent further expansion of PPCPs,seeking cost-efficient techniques of PPCPs removal is crucial.An analytical method was developed for the determination of 26 PPCPs by solid-phase extraction（SPE）followed liquid chromatography-tandem mass spectrometry（HPLC-MS/MS）.The limits of detection and quantitation for the 26 PPCPs were 0.007-1.78 ng/L and 0.02-5.68 ng/L.The recoveries for the 26 PPCPs were in the range of52.28%-115.24%.The method was successfully applied to investigate occurrences of persistent PPCPs in surface water and groundwater.A survey was conducted across Chaobai River in Beijing for the analysis of the presence of 26 PPCPs and 5 ARGs.The PPCPs were detected at concentration of ND-602.45ng/L in surface water and ND-95.08 ng/L in groundwater.All type of ARGs were detected at the relative abundance of 2.31×10^-5-9.95×10^-1 in surface water.Except quinolone resistance genes（qnr S）,other ARGs were detected at the relative abundance of ND-4.42×10^-1.Ibuprofen and carbamazepine were the predominant PPCPs in the surface water and groundwater.The relative abundance of sulfonamide resistance（sul1）were highest among all ARGs.The relative abundance of the ARGs has significant correlation with the concentration of antibiotics and class I integron.It illustrates the transmission of target genes strongly relies to the transfer of the presence of antibiotics and the transfer of integron.The level of PPCPs and ARGs in groundwater were generally lower than in surface water.During the recharge of reclaimed water,PPCPs and ARGs decay to a certain degree along the flow direction,the increase of groundwater depths and of the distance from the river.Ibuprofen,carbamazepine,sulfamethazine and diclofenac were selected as model PPCPs in this project.In electrolysis-integrated tidal flow constructed wetland system（E-TFCW）,the remove of PPCPs,the degradation pathway and microbial communities were studied.The PPCPs removal E-TFCWs have the highest removal efficiency for the four investigated PPCPs when the electrodes are arranged at the bottom of the E-TFCWs.The removal efficiency of four PPCPs increases from 4.41%-11.71%to28.83%-68.32%when using electrolysis combined with tidal flow constructed wetlands.The synergy effect for the degradation of PPCPs between electrolysis and constructed wetlands on the degradation of PPCPs in E-TFCWs were significant（enhancement factor>1）,while the removal efficiency of PPCPs after the electrolysis（10 h,accounting for 14.98%-44.41%）is higher than that before electrolysis（10 h,accounting for 9.62%-27.14%）and electrolysis process（4 h）accounting for 42.81%-68.47%.Electrolysis can enhance the removal of PPCPs through direct oxidation.Moreover,the increase in intermediate oxidation compounds in the E-TFCWs may imply the enhanced biodegradability of PPCPs during the electrolysis process since the by-products of PPCPs were identified.The contents of Thermomonas,Microbacterium,Cloacibacterium and Acidovorax at the bottom of the E-TFCWs were significantly higher than those of other bacteria,which contributed to the removal of PPCPs.Electrolysis can enhance the biodegradability of PPCPs and the formation of anoxic/aerobic conditions for the growth of predominant bacteria,which contributes to the degradation of PPCPs in the E-TFCWs.