Research On The Application Of Ozone Activated Carbon Fluidized Bed In Water Pretreatmen

As an advanced treatment technology in water treatment,ozone activated carbon can effectively remove soluble substances from nature and artificial synthesis through physicochemical adsorption and biodegradation.This study focuses on the water source of the Yellow River in Shandong Province,a complete set of pilot-scale water purification process of“O₃-BAC with Conventional Treatment”was constructed.The research contents included the exploration of the suitable working parameters of the pretreatment unit,water purification effect of the combined process,strengthening mechanism of the ozone activated carbon fluidized bed and characteristics of the fluidized bed activated carbon biofilm,etc.The results show that:During the biofilm formation of fluidized activated carbon,the removal rate of COD_Mn and the physicochemical properties（iodine value and methylene blue value）of activated carbon showed a rapid downward trend,and the removal rate of ammonia nitrogen gradually increased and gradually stabilized after 65 days.According to the raw water quality and influent load,the suitable ozone activated carbon fluidized bed parameter was selected to add 2.5～3 mg/L ozone with 1:1,and the activated carbon filtration rate was 7.96 m/h;long-term operation of the fluidized bed found that low temperature conditions have a slight effect on the removal of COD_Mn and ammonia nitrogen,and had a greater impact on the removal of BDOC.The changes of iodine value and methylene blue value indicated that The microporous structure of activated carbon was covered by biofilm firstly.The pilot test of ozone activated carbon fluidized bed-conventional treatment combined process showed that the overall removal rates of COD_Mn,BDOC,UV₂₅₄ and turbidity were 72.1%,57.9%,80.0%and 96.2%.The ozone activated carbon fluidized bed pre-removed most humic acids,fulvic acids and tyrosine proteins,and improves coagulation conditions by reducing colloid stability and increasing flocculation cores.The coagulation sedimentation unit exhibited the highest removal rate of organic matter and turbidity in the combined process;After secondary biodegradation by activated carbon and sand filter,ammonia nitrogen by ozone oxidation removed significantly,the total ammonia nitrogen concentration in the effluent was less than 0.02 mg/L;The combined process had a removal rate of 83.8%and 90.2%for bacteria and algae respectively.Coagulation effectively alleviated the problem of bacterial surge in effluent after BAC,and the removal rate of bacteria for BAC effluent reached 81.1%.In addition,the O₃-BAC fluidized bed removed odorant substances and oxidation by-products significantly.Through various characterization methods,the results showed that the visible pores of activated carbon were only micron sized large pores,and the surface of activated carbon was completely covered by biomembrane.The biofilm structure of activated carbon was composed of various microorganisms,which grew and adhered to the activated carbon in the form of zoogloea;In the early stage of growth,the biomass of the influent section was relatively high,while in the later stage,the biomass of middle section was the highest.Low temperature affected the biomass of the carbon layer;The distribution characteristics of SOUR in the carbon layer are the same as that of biomass,the oxygen consumption rate of unit biomass in the middle section was slightly lower than that in the influent section,indicated that although the biomass of the activated carbon in the middle section was higher,the SOUR of per unit microorganism was slightly lower than that in the influent section;For different bacteria,the final performance was that SOUR of heterotrophic bacteria was significantly higher than that of autotrophic bacteria,and the oxygen consumption rate of autotrophic bacteria nitrite bacteria was significantly higher than that of nitrate bacteria;Amplifiers sequencing showed that under similar external conditions,pre fluidized activated carbon and post filter activated carbon had similar community structures,but the abundance and evenness of the former were higher.