Degradation Of Emerging Micropollutants In Water By Permangante And UV-based Oxidations

With the evolution of analysis and testing techniques and public awareness of environmental protection,the emerging micropollutants in aquatic environment are becoming a new concern.There is an extensive array and varied property of emerging micropollutants,which have been frequently detected in natural environment and wasterwater treatment plants,and their adverse effect to aquatic ecosystem.The conventional wasterwater treatment plants are difficult to efficiently remove the emerging micropollutants in aquatic environment,hence the development of new strategies to deal with this concern is desired.Permanganate Mn(VII)and UV-based advanced oxidation processes(AOPs)are attractive and promising technologies to destruct organic pollutants.This study investigated the degradation of acesulfame by Mn(VII).The influence factor,identification of transformation products and proposed mechanism,evaluation the acute toxicity for Vibrio fisheri and the degradation efficiency in the actual water bodies were performed.The results showed that the reaction of acesulfame with Mn(VII)followed the second-order kinetic law.The impact of p H on acesulfame oxidation with Mn(VII)was negligible,while the higher temperature was favored for acesulfame oxidation.Except for pyrophosphate,oxalic acid,EDTA and humic acid exhibited a concentration-dependent inhibition on acesulfame oxidation by Mn(VII).The mechanism was involved in the 3+2 electrophilic ring addition reaction of Mn(VII)to the double bond and attacking of rich electron N moiety.Meanwhile,generated transformantion byproducts have a higher acute toxicity for Vibrio fisheri than acesulfame itself.During in real water environment,the removal efficiency of acesulfame was depended on the content and species of natural organic matter(Chapter 2).The degradation of halogenated antibiotics(florfenicol-FLO,chlorampheincol-CAP,and thiamphenicol-THA)was investigated by UV and UV/H2O2.Constitutes of simulated wastewater including fulvic acid,alkalinity,chlolide and nitrate were separately examined.Compared to UV alone,UV/H2O2 treatment can accelerate the degradation of halogenated antibiotics in ultrapure water and sim ulated wastewater,due to the contribution of hydroxyl radical – HO·.The indirect degradation of radical species played a dominant role in ultrapure water,while direct UV photolysis did in simulated wastewater.Fulvic acid and alkalinity exhibited an inh ibitiory effect on the degradation of halogenated antibiotics,while chloride and nitrate on it was negligible.Meanwhile,the established kinetic model based on pseudo-steady-state hypothesis successfully predicted the degradation behavior of the target compounds(Chapter 3).Transformation product identification and proposed mechanism were performed for halogenated antibiotics by UV/H2O2.The study further evaluated the comprehensive toxicity(including antibacterial property,acute toxicity and ecotoxicity),and investigated the trichloromethane(TCM)formation potential by UV and UV/H2O2 pretreatment following chlorination.The results show that hydroxyl substituted products were found in the generated byproducts of all halogenated antibiotics,which involving the addition and single electro transfer of HO·.Low antimicrobial property was detected for transformation products of all investigated halogenated antibiotics against a tested strain identified as a Escherichia coliorganism.Acute toxicity applying luminescent bacterium Vibrio fisheri indicated higher inhibitory effect of FLO and THA after UV/H2O2 treatment.TP-276 and TP-354 of FLO exhibited higher acute and chronic toxity to fish,daphnid and green algae than FLO itselt.UV and UV/H2O2 pretreatment with 30 minutes following chlorination could improve the TCM yield.Prolonging the irradiation to 90 minutes can 't reduce the TCM yield for UV alone,while significantly low it for UV/H 2O2.This was mainly due to the oxidation effect of HO· tawards dissolved organic carbon(DOC),which recuding the precursors of generated TCM(Chapter 4).The degradation behavior and kinetic simulation of UV filters(BP1,BP3 and BP8)degradation in synthetic matrices by UV/H2O2 and UV/PDS was performed in this study.The results showed that UV filters could react with HO·,sulfate radical-SO4·-and carbonate radical-CO3·-.As for the similuated water matrices,UV filter degradation was inhibited,which resulting from the decreasing of HO· and SO4·-concentration.The radical quenching effect of natural organic matter(NOM)and bicarbonate,as well as the light shielding effect of NOM,leads to the reduction of UV filters degradation in the wasterwater.Based on the determination of amination and nitration byproducts in the hydrolysis urine,reactive nitrogen species could destruct the target compounds.Besides,the degradation of BP3 was extremely inhibited during the mixed system.In seawater,chloride is the sink of HO ·,and the coexistence of chloride and bromide is the sink of SO4·-,which were supported by the simulation results of reactive species concentration.Low reactive halogen species generation could account for the reduction of UV filters degradation.The kinetic behavior was non-first order for BP3 and BP8 when UV filters coexist by UV/PDS treatment,and the kinetic phase was consisted of the lag and fast degradation period.Meanwhile,the EE/O value was calculated for UV filters degradation by UV/H2O2 and UV/PDS in different matrices(Chapter 5).