The Effect And Mechanism Of UV/H₂O₂/O₃ Advanced Oxidation To Remove Odor And Organic Matter From Algae

With the rapid development of economy and society,water pollution has become more and more serious,and water eutrophication has become more and more common,causing algae growth,which not only harms the water environment,but also seriously affects people's production and life,In particular,it brings serious hidden dangers to the safety of drinking water supply.The algae-derived organic matter released during the metabolism of algae is a complex mixture composed of proteins,fatty amines,polysaccharides and other components.These algae-derived organic matter is an important precursor of some toxic disinfection by-products(such as trihalomethane,NDMA,etc.);the algae toxins and odorants produced by algae have a great impact on water quality.In particular,the presence of algae source odors will directly affect the sensory properties of drinking water and reduce the quality of water,causing widespread concern.Therefore,the removal of algae-derived organic matter and odorous substances is an important issue concerning the safety of drinking water.In this study,the organic matter and odor of algae and its control issues were studied.The organic matter and odor characteristics of algae were studied.UV/H₂O₂/O₃ process was selected as the control technology and the parameters were optimized.Finally,UV/H₂O₂/O₃ was used to remove algae-derived organic matter and the mechanism of the process was studied.The growth of Anabaena,Microcystis aeruginosa,Oscillatoria,and Chlorella was studied,and the odor and organic components in the intracellular and extracellular organic matter were detected and analyzed.Citral is the most abundant odorant among the four types of algae,the composition of intracellular organic matter(IOM)and extracellular organic matter(EOM)of algae is different.IOM mainly contains microbial metabolites,tryptophan,tyrosine and other substances,and EOM mainly contains humus Acid and fulvic acid;the changes in the intracellular and extracellular organic matter of Anabaena at different growth stages have been studied.At different growth stages,the odor and organic composition of Anabaena algae inside and outside the cell are basically the same,but the content has changed.In the logarithmic phase IOM contains more odorants,and the fluorescence intensity of organic matter is relatively strong.At the end of growth,due to the fragmentation of a large number of algae cells,the odor and organic matter in IOM are released into EOM,resulting in Changes in odor and organic content.The oxidation of UV,H₂O₂,and O₃ alone cannot effectively remove the2-methylisocamphanol(2-MIB)and geosmin(GSM),which are the Algae-derived odor.The four combined advanced oxidation methods,UV/H₂O₂,UV/O₃,O₃/H₂O₂,UV/H₂O₂/O_3,can increase the removal rate of 2-MIB and GSM,and the UV/H₂O₂/O₃ oxidation system has the highest removal rate.The BBD response surface method was used to optimize the experiment of UV/H₂O₂/O₃ to remove the four targets of 2-MIB,GSM,TOC and trihalomethane,respectively,and under specific working conditions(UV intensity 150W,H₂O₂ dosage 5mg/L,O₃ dosage 2mg/L,residence time 5 minutes)was verified by experiments,2-MIB removal rate was 83.9%,GSM removal rate was 79%,TOC removal rate was 23.3%,and the simulation effect was good.There is a big gap between the model effect of methyl halide and the actual result.The results of 29 sets of experiments show that UV/H₂O₂/O₃ has a better removal effect on 2-MIB and GSM,and a lower removal rate of TOC,it shows that its thorough mineralization rate of organic matter is not high.The removal effect of trihalomethane formation potential is not good,and it will even increase the generation capacity of trihalomethane.Under acidic conditions,the UV/H₂O₂/O₃ technology has the best oxidation effect on 2-MIB and GSM;as the initial concentration increases,the removal rate of 2-MIB,GSM and TOC increases.In the experiment where UV/H₂O₂/O₃ degrades algae-derived organic matter(AOM,IOM,EOM),most of the odorants were not effectively detected before the reaction,The content of citral is the highest,and after the reaction,citral has also been largely removed.The removal effect of trihalomethane formation potential in algae-derived organic matter is not good.The changes of the organic matter before and after the reaction were characterized and analyzed by molecular weight distribution,fluorescence analysis,and LC-OCD-OND.The results show that UV/H₂O₂/O₃ can remove all components of algae-derived organic matter in the filtered water.It has an obvious degradation effect on macromolecular organic matter,and improves the biodegradability of algae-derived organic matter.