Study On The Formation Of By-products And The Variation Of Progesterone Concentration In Hospital Wastewater Under Different

In recent years,hospital wastewater?HWW?has gradually become a research hotspot in the field of water treatment due to its high content of pathogenic microorganisms and drugs.Progesterone is enriched in HWW,as a steroid hormone,its consumption is much greater than estrogen and androgens,so it has gradually received widespread attention from scholars.Besides that,as an indispensable unit for HWW treatment,disinfection often has different treatment effects and impacts on HWW due to different processes selected,and the disinfection process is often accompanied by the generation of disinfection by-products?DBPs?.DBPs and progesterone enter the water body with the effluent discharge,which will adversely affect the aquatic ecology and human health.In this study,the primary filtration treatment effluent?FPTE?and secondary biological treatment effluent?SBTE??i.e.,HWW after primary physical treatment and secondary biological treatment?were selected as the research water,and the chlorine disinfection?Cl₂?,chlorine dioxide disinfection?Cl O₂?,ultraviolet disinfection?UV?,ozone disinfection?O₃?,and ultraviolet/chlorine combined disinfection?UV/Cl₂?were respectively performed.These above five disinfection processes were investigated to study the changes of DBPs formation,formation potential,acute toxicity of effluents and progesterone in the water.The results showed that the amounts of total DBPs in different disinfection processes under the optimal disinfectants dosage followed the order of Cl₂>UV/Cl₂>Cl O₂>UV?O₃,and the concentration was 10.28?170.76?g/L,which demonstrated that the amount of DBPs formation was closely related to the dosage of chlorine.Meanwhile,the amounts of total disinfection by-products formation potential?DBPFP?under the optimal disinfectants dosage followed the order of UV/Cl₂>UV?Cl₂>O₃>Cl O₂,and the concentration range was 1.05?1297.94?g/L.Besides that,it was found that with the reduction of chlorine dosage,the formed DBPs in UV/Cl₂disinfection process decreased.However,UV/Cl₂disinfection process might degrade organic compounds into more DBPs precursors,leading to higher DBPFP than that in Cl₂disinfection process.Significantly,some specific DBPFPs such as haloketones-FP?HKFP?,chloral hydrate-FP?CHFP?and trichloronitromethane-FP?TCNMFP?in O₃disinfection process were found higher than that in Cl₂disinfection process,which could be attributed to the formation of O₃oxidation by-products,for instance aldehydes,methyl ketones and trivalent nitrogen compounds.Additionally,apart from O₃,the growth inhibition rate of Chlorella vulgaris increased in all the other disinfection processes and the order of the acute toxicity in each disinfected effluent were consistent with that of DBPs formation.Progestins test results found that 61 types of natural and synthetic progestins in HWW were detected,the total concentration was 1126.18 ng/L,and the concentrations of natural progestins were the main ingredients,which were 845.51 ng/L.The primary treatment process had almost no effect on the progesterone concentration,but the secondary biological treatment process can effectively reduce the progesterone content through the metabolism and degradation of activated sludge.The concentration of total progesteroneon FPTE and SBTE treated with the optimal parameters of each disinfection process,from low to high was:UV/Cl₂<Cl₂<O₃<Cl O₂<UV,and the removal order was UV/Cl₂>Cl₂>O₃>Cl O₂>UV.Besides that,their removal effect on natural progestins was better than the other three types of progestins.Itwas worth mentioning that O₃could effectively reduce the progesterone content in the effluent,and the removal effect of most progestins?except 5?-DHP and 5?-DHP?was better than Cl₂.It was recommended that ozone was the best choice for the disinfection process of hospital wastewater.The best dosage for the first and second effluent was 30 mg/L?FPTE?and 10 mg/L?SBTE?,respectively.Not only did it produce less DBPs,but it could effectively reduce the DBPFP of the effluent,and its effluent had the lowest acute toxicity,and it also had a good effect on removing most progestins.