| Multiphase Fenton advanced oxidation technology is an important drinking water treatment technology at the current stage of water treatment technology development.This technology has many advantages such as simple and mild reaction conditions,no generation of various by-products,and narrow response range to PH.This article is based on a pilot scale experiment to test the effectiveness of multi-phase Fenton advanced oxidation technology to remove natural organics,trace pollutants and microorganisms.Taking the mixed water source of Miyun Reservoir flowing into the water plant as the research object,the main research process in the pilot experiment is coagulation-precipitation-sand filtration-multiphase Fenton advanced oxidation-bioactive carbon;the control process is coagulation-precipitation-sand Filtration-ozone sterilization-biological activated carbon.The specific experimental research results are as follows:1)The pilot-scale ozone-activated carbon process was compared with the multi-phase Fenton-activated carbon process to investigate the control effect of the multi-phase Fenton-activated carbon process on microorganisms Opportunistic Pathogens).The pilot scale test analyzed the content and properties of dissolved organic carbon DOC),three-dimensional fluorescence,real-time quantitative polymerase reaction QPCR),extracellular polymeric EPS)and gene sequencing in effluent,and also disinfected part of the effluent.To determine the control effect of microorganisms after disinfection of different processes.The results show that the multiphase Fenton-activated carbon process can control the DOC concentration at 1.29±0.3 mg·L-1,and remove most of the microbial metabolites,fulvic acids and tryptophanes.However,Fenton activated carbon has limited control effect on microorganisms Opportunistic Pathogens),ozone activated carbon has the best effect after disinfection,and sand filtration has the worst effect.The Fenton effluent polysaccharide increased by 12.5%,the protein decreased by 5%,and the ratio of protein/polysaccharide PN/PS)in EPS was reduced,and the cohesiveness was significantly reduced.Because of the increase in microorganisms,the ATP concentration increased to 0.16 nmol·L-1,and decreased to 0.1 nmol·L-1 after disinfection.Microbial sequencing to some extent characterizes the changes in microbial community structure.Activated carbon can effectively remove the content of microorganisms Opportunistic Pathogens),but it will increase the diversity of microbial species.The Fenton process does not significantly affect the structure of the microbial community.In order to better explain the mechanism of the effects of multiphase Fenton-activated carbon on microorganisms and organic matter,microbes Opportunistic Pathogens),ATP,extracellular polymeric substances EPS),infrared spectroscopy and gene sequencing on the surface of activated carbon were examined.Compared to the microorganisms in the effluent,more pathogenic bacteria were detected on the surface of the activated carbon.The total bacteria increased by 3.1 logarithmic magnitude,and it can be seen that some pathogenic bacteria such as Ma)are not detected in the effluent,but can be detected in large quantities on the surface of activated carbon.It shows that activated carbon has a strong adsorption effect on some pathogenic bacteria.Fenton activated carbon is reduced by about 0.5 logarithmic magnitude of microbes compared to ozone activated carbon.The concentration of ATP on Fenton activated carbon is 0.0047 nmol·g-1 higher than that of ozone activated carbon,which is consistent with the fact that Fenton activated carbon can adsorb more microorganisms Opportunistic Pathogens).Fenton activated carbon biofilm can remove 12%-15%of polysaccharides,because Fenton activated carbon biofilm has strong cohesiveness,thus reducing the microbial content and cohesion in the effluent.The peak value of Fourier transform infrared spectroscopy on ozone activated carbon was significantly lower than that of Fenton activated carbon.Fenton activated carbon is enriched with more microorganisms.In summary,the sand filter-Fenton activated carbon process is capable of more efficiently degrading dissolved organic matter DOC)in water by enriching microorganisms.Significantly reduce the protein content of EPS,so that the cohesiveness of microorganisms in Fenton activated carbon effluent is worse,and the disinfection effect is better.This process reinforces the conventional drinking water treatment process.2)In order to investigate the biofilms communities on the surface of heterogeneous Fenton catalyst and their effects on the removal of bisphenol A,firstly,the heterogeneous Fenton was studied in a pilot scale to test its effect on the removal of natural organic matter NOM).It showed great roles on the removal of NOM.Then,the biofilms bacterial community structure,bacterial biomass,bacterial metabolism,and the composition of extracellular polymeric substances EPS)were analyzed.Lastly,the effect of biofilms on the rmoval of bisphenol A was studied using bench scale test.The results indicated that the biomass and the relative abundance of Reyranella and Hyphomicrobium increased in the biofilms of catalyst from top to bottom.Moreover,the function of bacterial metabolism increased,and the bacteria can produce more EPS.This maybe the main reason for the more removal of bisphenol A by biofilms adsorption. |
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