Study On The Efficacy And Mechanism Of UV/H₂O₂-BAC Combined Process To Degrade Typical Odorants In Drinking Water

Among many water pollutants,odor is the most common and difficult problem in drinking water treatment at home and abroad.China's"drinking water health standard"(GB5749-2006)has listed the smell and smell as the items that need to be detected in the factory water and pipe network water.The content of GSM and 2-MIB in drinking water should not exceed 10 ng/L.Ozone combined with activated carbon technology needs higher oxidant dosage and longer contact reaction time;in Ti O₂ photocatalytic method,Ti O₂ is expensive,some nano-Ti O₂particles can not be completely recovered,and its residue in water has potential harm to human health;and UV/H₂O₂ combined with activated carbon can make full use of the strong oxidation of advanced oxidation,biological and adsorption of activated carbon,It can effectively control bromate and chlorination disinfection by-products without secondary pollution.This paper selects a reservoir in Shandong Province as the research object of water quality;and compares the removal effect of different UV AOPs on odor substances with small test equipment,and optimizes the parameters of UV/H₂O₂ process;taking the filtered water of a water plant as the pilot water,the paper explores the removal effect of the combination process of UV/H₂O₂-BAC on the odor and organic matter,and probes into the removal effect of the combined process on odor and organic matter The mechanism of division.The results show that:The water quality of the reservoir is gradually getting better from 2018 to 2020,and the water quality of the reservoir is generally class III water standard.From April to may in 2018and from November to December in 2018 to 2019,the concentration of GSM reaches the peak;from July in 2020 and from October to November in 2018 to 2020,the concentration of 2-MIB reaches the peak.According to the water temperature,the change of odorants was analyzed.Except for the lower water temperature in winter and spring,the concentration of odorants may increase in summer and autumn.Among the three different UV-AOPs,UV and UV/Cl,UV/H₂O₂ has the best removal effect on GSM and 2-MIB.The effect of the UV AOPs process on removing GSM and 2-MIB is affected by the dosage of oxidant,light intensity,reaction time,initial concentration of target pollutant,p H value,inorganic anion and humic acid.Moreover,the addition of oxidant increases,the illumination intensity increases and the reaction time is prolonged.The removal rate of GSM and 2-MIB by three UV-AOPs processes will also increase;the initial concentration of target pollutants increases and the p H value increases The removal rate of GSM and 2-MIB by UV-AOPs process decreased with the increase of humic acid concentration.BBD response surface method was used to determine the optimal conditions for the removal of GSM and 2-MIB by UV/H₂O₂ Technology:H₂O₂ concentration of 13 mg/L,UV dosage of 750 m J/cm²,GSM concentration of 100 ng/L,2-MIB concentration of 80 ng/L;the order of influence degree of four factors on the experimental results was:UV dosage>H₂O₂ concentration>2-MIB concentration>GSM concentration.When the experimental parameters of the pilot plant are UV dose of 750 m J/cm²,H₂O₂concentration of 13 mg/L,UVT=95%,influent flow rate of 1.5 m³/h,the concentrations of GSM and 2-MIB are below 5 ng/L,and UV₂₅₄,DOC,SUVA,H₂O₂ and the precursors of disinfection by-products are also effectively removed.Therefore,UV/H₂O₂-BAC combined process can effectively remove odor and organic compounds,which also lays a foundation for practical application.The intermediate products of GSM and 2-MIB removal by UV/H₂O₂ were identified by molecular frontier orbital theory.According to the electron cloud density and contribution analysis,C atom(3)and hydroxyl C atom(4)of GSM were easily oxidized by·OH.For 2-MIB,dehydration reaction is easy to occur.The results of GC-MS were consistent with those of molecular frontier orbital analysis of GSM and 2-MIB.The composition of organic matter in actual water treated by UV/H₂O₂-BAC process was analyzed.The peak areas of the effluent from UV/H₂O₂ process and activated carbon tank were mostly smaller.The results showed that biofilms were formed on the upper,middle and lower layers of activated carbon,and the biomass of the lower layer was more.The diversity,richness and evenness of microorganisms in the lower layer of activated carbon were higher than those in the middle and lower layer of activated carbon.