Fate Of Artificial Sweeteners Through Wastewater Treatment Plants And Water Treatment Processes

Artificial sweeteners(ASs)are sugar substitutes widely used in food,beverages,pharmaceuticals and personal care products,which were listed as emerging contaminants due to their persistence and widely occurrence in aquatic environment.Wastewater treatment plants(WWTPs)was the main gathering location for ASs spread into the environment.ASs fate within the WWTPs,their removal methods and ecology risk have been the research hotspot but few researches have focused on it.Four ASs(acesulfame(ACE),sucralose(SUC),cyclamate(CYC)and saccharin(SAC))were chosen as typical ASs.Based on the analytic method to quantify ASs in environment,the fate of four ASs through wastewater treatment processes was assessd in this study Also,adsorption and advanced oxidation process were evaluated to remove ASs.Furthermore,the chronic toxicy of ACE and its UV irradiation products to Carassius auratus were assessed.The main results are as follows:1.The occurrence of ASs were investigated in 5 WWTPs(characteristic biodegradation process(SBR,oxidation ditch,A2/O and BAF)and physico-chemical process(UV,CIO2))was as followed:ASs concentration in influent were in the order of CYC>ACE ? SAC>SUC,with mean concentration of ASs detected of 3.15?13.47?g/L in autumn and winter and 0.66?2.69 ?g/L in spring and summer.CYC and SAC were easily biodegraded with removal of 93.49?99.61%and 89.71?99.28%ACE removal was of-3%?30.5%and SUC was induced along the process.ACE could be partly removed by 15.54 to 32.88%through biodegradation and especially through the denitrifying process.The A2/O process was more efficient to biodegrade ASs than others.The removal of ACE and SUC was all below 8%in BAF.UV irradiation was only effective to degrade ASs with the removal rate between 1.23?11.89%,in contrast ClO2 disinfection was useless to remove ASs.2.The inhibition rate of 100 mg/L ASs to Vibrio fisher was of 7.8?10.2%,indicating a low toxicity of ASs to Vibrio fisher.The oxidative stress in liver of Carassius auratus exposed to ACE and its UV irradiation products was studied with exposure of 0.1 and 10 mg/L ACE(ACE group)and ACE after 5 min UV irradiance(ACE-UV group).The oxidative stress in fish liver exposed to ACE group had no distinct change after 7 d exposure.However,in the ACE-UV group,the quantity of ·OH was induced by 17.96?55%and the MDA content increased by 16.28?68.28%compared to control.Time-effect exposure in the ACE-UV group showed that in the first 3 d the quantity of ·OH reached its peak,causing SOD inhibition of 64.57%and GPx induction of 58.28%.GSH decreased significantly by 22.55?30.38%(p<0.05)after 3 d.Eight irradiation products of ACE were identified in HPLC-MS.An increased toxicity of ACE after UV irradiance was observed and its irradiation products may have bigger environmental risk.3.The saturated adsorption amounts of resin were 3.33?21.08 times more than that of GAC except for SUC with the same amount.The adsorption ability of ASs using resin decreased in the order of SAC>ACE>CYC>SUC in accordance with the pKa.The adsorption ability of ASs using GAC decreased in the order of SAC>SUC>CYC>ACE in accordance with the log Kow.Degradation of ASs followed pseudo-first-order kinetics in UV/sodium persulfate(PDS)and UV/H2O2 process,and the rate constant k was in positive relationship with oxidant dosage.The rate constant k in UV/PDS was 2-4 times higher than that of UV/H2O2.ACE and CYC were more likely to react with ·OH or·SO4-.While applying to the secondary effluent,UV/PDS was more efficient with ASs degraded by 30.87?99.93%in 30 min.Considering the electrical and oxidant cost per removal order,UV/PDS is considered as the more economical and efficient way to remove ASs.