| Dye industry wastewater is one of the most difficult chemical wastewater to be treated because of its complex components,poor biodegradability and high organic matter content,faced with the gradually tightened emission standards,the traditional biological nitrogen removal process has a poor effect on the removal of CODCr and TN.In this paper,the up-flow hydrolysis denitrification and aerobic process was proposed to conduct a pilot study on the actual dye wastewater from a dye manufacturer in tianjin,compared with the pilot study of the traditional A/O process,the stable operating condition of the up-flow hydrolysis denitrification and aerobic process and the pollutant removal effect of the synergetic action of hydrolysis and denitrification were investigated,the removal effect and pollutants degradation mechanism of this new process were studied through the analysis of pollutant degradation rule and microbial community change,finally realize the engineering application of the new process.The conclusions of the study are as follows:when the traditional A/O process is used to treat the first-level aerobic biochemical tail water(2018.4?2018.10),its necessary to add a large amount of additional carbon sources to the influent to ensure complete denitrification,The average removal rates of pollutants such as CODcr,NH4+-N,TN,formaldehyde and aniline in the system were 68.6%,86.3%,58.8%,29.6%and 41.5%respectively,a number of effluent pollutant indicators do not meet the indirect discharge standard of tianjin municipal standards(DB12/3 56-2018),the operation effect is easily affected by the influent toxicity and impact load,resulting in poor stability,and the average removal rate of organic nitrogen is only 11.2%,the average concentration of CODcr was 509.6mg/L.when the up-flow hydrolysis denitrification and aerobic process is used to treat the first-level aerobic biochemical effluent(2019.3?2019.7),which added vertical suspended filler in the anoxic section to achieve hydrolysis and acidification,and the sludge in the anoxic section and the aerobic section was cultured independently,provide a suitable living environment for microorganisms with different functions,and further enhance the system's denitrification efficiency on the basis of the newly added function of hydrolysis and acidification in the anoxic section,it has a good treatment effect on a variety of pollutants,especially organic nitrogen and COD which are difficult to degrade.the sludge concentration in the anoxic section increases to about 9mg/L,and the sludge concentration in the aerobic section is controlled between 4.0-5.Omg/L,The average removal rates of pollutants such as CODCr,NH4+-N,TN,formaldehyde and aniline in the system were 66.4%,95.1%,61.7%,63.2%and 61.3%respectively,and the treatment effect significantly improved compared with the traditional A/O process,the effluent pollutant indicators of CODCr,NH4+-N,TN,formaldehyde and aniline are superior to the indirect discharge standard of tianjin municipal standards(DB12/356-2018),the pollutant removal effect is unaffected by influent toxicity and impact load during the stable operation.The synergism of hydrolysis acidification and denitrification significantly increased the removal effect of organic nitrogen and COD which are difficult to degrade,with the average removal rate of organic nitrogen reaching 45.4%,the average concentration of CODCr was 509.6mg/L.Using GC-MS to analyze the organic components of the influent and the effluent of each section,The main organic compounds of influent were aromatic amines,alcohols and aliphatic carboxylate esters,under the synergistic action of hydrolysis acidification and denitrification,organic species increased from 34 to 65,aromatic amine was reduced to ketones,esters,phenols and hydrocarbons,and the organic amine content decreased by 30.6%.Amines,alcohols,phenols and ketones are easily biodegradable in aerobic stage.At the same time,the newly added hydrolytic acidification function can effectively destroy the chromogenic group in sewage,so that the chroma removal rate can reach 30.8%.when the up-flow hydrolysis denitrification and aerobic process is used to treat the raw water after the physicalization(2019.8?2019.11),The sludge concentration in the system gradually increased,enhance the water load by gradually reducing HRT and when the sludge load in the anaerobic reactor is about 0.45kgCOD/(kgVSS*d)and the hydraulic load is 0.6-0.7m3/(m2*h),granular sludge with an average particle size of 145.3um appeared in the anaerobic section,The coexistence of floc sludge,granular sludge and biofilms on fillers was realized in the anaerobic section and the sludge concentration could reach 18g/L in the stabilization stage,the sludge concentration in the aerobic section was controlled between 6.0-9.0 g/L.The average removal rates of pollutants such as CODCr,NH4'-N,TN,formaldehyde and aniline in the system were 84.6%,97.6%,67.9%,87.5%and 86%respectively,the effluent pollutant indicators of CODCr,NH4+-N,TN,formaldehyde and aniline are superior to the indirect discharge standard of tianjin municipal standards(DB12/356-2018).The emergence of hydrolyzed denitrifying granular sludge further improved the synergistic action of hydrolysis and denitrification in the anaerobic section.The average removal efficiency of the system for organic nitrogen reached 49.7%,the average concentration of CODCr was 509.6mg/L.The analysis of microbial flora in sludge samples was carried out by Miseq sequencing technology,the diversity and abundance of the microbial community in the anoxic or anaerobic section of the up-flow hydrolysis denitrification and aerobic process were significantly higher than that in the anoxic section of the traditional A/O process.As the hydrolysis acidification function gradually improved,the bacteria with the function of degrading organic metter and acidification such as Arenimonas,Synergistaceae and Syner-01 were concentrated on the fillers.However,due to different requirements on available organic carbon sources,the content and distribution of denitrifying bacteria,such as Rhizobiaceae,Thauera,and Azoarcus,were significantly different in fillers and floc sludge.In granular sludge,there are several hydrolytic acidification bacteria and denitrifying bacteria as well as Methanolobus.Large molecules of organic matter in sewage were decomposed into small molecules of organic matter by hydrolytic acidifying bacteria,some of them are used by denitrifying bacteria as electron donors to participate in the denitrification process,and some of them are converted into VFA,which are completely decomposed into CH4 and CO2 by methanogens.According to the results of pilot study,the up-flow hydrolysis denitrification and aerobic process was designed to treat the first grade aerobic biochemical effluent,The average removal rates of pollutants such as CODCr,NH4+-N and TN in the system were 73.9%,88.2%,60.5%respectively,the effluent pollutant indicators of CODCr,NH4+-N and TN are superior to the indirect discharge standard of tianjin municipal standards(DB12/356-2018),The average removal efficiency of the system for organic nitrogen reached 49.7%,the average concentration of CODCr was 410mg/L,and increase the anti-shock loading capability and mithridatism of the original process,the aging phenomenon and settling performance of sludge in terminal aerobic tank are greatly improved. |
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