Study On Treatment Of Coking Wastewater Characteristic Pollutants By Simultaneous Denitrification And Methanogenesis Process In Upflow Blanket Filter

Coking wastewater is a typical high C / N ratio of refractory organic wastewater,the COD_cr concentration is generally 1000 4000 mg / L,NH₃-N concentration between 200 400 mg / L,C / N in 10 or so.Coking wastewater contains a large number of phenols,nitrogen heterocyclic and other difficult degradation of organic pollutants,BOD₅ / COD_cr ratio is low,less than 0.3.Coking wastewater treatment process commonly used A / O?hypoxia / aerobic?,A² / O?anaerobic / anoxic / aerobic?and so on,which are enhanced through anaerobic hydrolysis of wastewater biodegradability.Then,the organic matter is oxidized to CO₂ by anaerobic tank,and the organic matter is removed.At the same time,NH₃-N is oxidized to NO_x^--N in the aerobic tank and returned to anoxic tank?A pool?,NO_x^--N is finally reduced to N2,the total nitrogen in waste water achieves discharge standards in the final.In the common process of coking wastewater treatment,the removal of organic matter mainly by the aerobic pool,not only increased the aerobic tank energy consumption,and a large number of aerobic micro-organisms also inhibit the growth of autotrophic nitrification so that the wastewater nitrification efficiency is decreased,thus affecting the total nitrogen removal rate.In order to achieve the removal rate of COD_cr,total nitrogen,on the basis of A / O and A² / O processes,a lot of pretreatment measures to strengthen the hydrolysis of organic matter and post-treatment measures such as coagulation and filtration are applied so that coking wastewater treatment process will become more complex,higher processing costs.The simultaneous denitrification and methanogenesis in the reactor?UBF?is a simultaneous denitrification and methanogenesis in a reactor.The denitrification,methanogenesis and other anaerobic flora synergistic effect can be exerted simultaneously by the simultaneous denitrification and methanogenesis in the reactor to treat the coking wastewater,and the removal of organic matter and NO_x^--N in the same reactor can be realized and the treatment is simplified at the same time.But also enhancing the COD anaerobic removal efficiency and reducing the COD concentration in the subsequent aerobic stage,thereby reducing aerobic COD removal aeration energy consumption,while alleviating the aerobic microorganisms on the inhibition of nitrifying bacteria,improving the efficiency of nitrification,and bioenergy produced by anaerobic methanogens degrading organic matter can also be obtained.In this study,coke plant wastewater was simulated with phenol,quinoline,pyridine and indole water.The start conditions,influencing factors and stable operation characteristics of The simultaneous denitrification and methanogenesis in the reactor were studied.The process of treating characteristic pollutants in coking wastewater was established.The main conclusions are as follows:?1?By constructing the sludge load model,determining the initial sludge load of 0.10 kgCOD /?kgVSS·d?,the load increment rate of 20%.The initial efficiency,environment and microbial characteristics of The plan1,after the culture of methanogenic bacteria,denitrifying bacteria were cultured,and the plan2,while denitrifying bacteria and methanogenic bacteria were cultured were compared and analyzed.The total COD removal rate was 85% and NO₃^--N removal rate was 99% after 14 weeks in plan1,while the same removal efficiency was achieved after 11 weeks,and the reactor operating parameters were more stable in plan2.So plan 2 is more efficient.?2?Adjusting the HRT of the inlet water,influent C / N ratio and rising rate of sludge bed,The effects of the above factors on the treatment efficiency of UBF reactor were analyzed.The optimum working conditions were as follows: HRT was 6h,C / N ratio was 10,the sludge bed rising velocity was 1.0 m / h 3.0m / h.?3?The effects of organic loading on the UBF reactor were studied.The results showed that the total removal rate of COD and NO₃^--N was almost unaffected when the organic load was 6.012 kgCOD /?m₃·d? 10.045 kgCOD /?m₃·d?.When the load increases to 12.260 kgCOD /?m₃·d?,the total COD and NO₃^--N removal rates begin to decrease.However,the removal rates of COD and NO₃^--N can be recovered quickly after the load recovery.NH₃-N had a certain effect on the activity of methanogens,so when the concentration of NH₃-N was 800 mg / L,the methanogenic bacteria was inhibited obviously,the removal efficiency of COD was decreased and the denitrification efficiency was almost unaffected.?4?The total removal rates of COD and NO₃^--N were 89.12% and 99.87% when the reactor was operated stably under the optimum conditions.COD removal rate of sludge area was 60.63%,and the removal rate of packing area was only 28.49%.NO₃^--N was almost completely removed in the sludge area,the denitrification ratio carbon consumption rate was 5.6 g NO₃^--N / gCOD,and the sludge cell yield was 0.18 gVSS / gCOD.The yield of biogas was 5.582 L / d,of which CH₄,N₂,CO₂ and H₂ accounted for 59.33%,16.34%,21.10% and 2.56% of the total gaseous components respectively.The effluent VFA accounted for COD ratio is the range of 1.67 15.57%,ORP values is in-156 mV ^-302 mV between the reactor height along the direction of decline.The pH value ranged from 6.8 to 7.0,and the pH value in the sludge area was high,while the p H value in the middle of the packing area was the lowest?5?Based on the GC / MS results of different samples,the degradation pathways of phenol,quinoline,pyridine and indole in the simultaneous denitrification and methanogenesis reactor were deduced.The degradation pathway of phenol is 4-hydroxybenzoic acid pathway,quinoline degradation pathway is 2,8-dihydroxyquinoline pathway,pyridine degradation pathway is dihydroxypyridine pathway,and indole degradation pathway is indomethyldione open-loop pathway.?6?The microbial population in the sludge area and the packing area was analyzed by PCR-DGGE,and the dominant bacteria were Bacteroides and Proteobacteria,among them,Bacteroides sp.,Pseudomonas baetica,Stenotrophomonas sp.,Alicycliphilus denitrificans are denitrifying functional bacteria.Ignavibacterium sp,Petrimonas sulfuriphila are common bacteria in the anaerobic degradation organic system,which has the function of degrading PAHs.The predominant microbial dominant species in the packing area are Ignavibacterium sp,Petrimonas sulfuriphila,Uncultured Bellilinea sp.,Mainly Bifidobacterium,and Uncultured Bellilinea sp.Is a methanogenic bacterium.?7?The monod model was modified by introducing refractory coefficient,and the kinetic model of the simultaneous denitrification and methanogenesis in the reactor was established to deal with the characteristic degradation of coking wastewater.The Monod model was used to simulate the degradation kinetics of NO₃^--N in the reactor.The two models fitted well.The main innovations of this study are as follows: Aiming at the drawbacks of the traditional biotechnology of high C / N coking wastewater,while the simultaneous denitrification methanogenesis system combined with the degradation of COD removal process was proposed.A simultaneous denitrification and methanogenesis reactor was constructed to realize functional division of denitrification process and methanogenic process,and the synergistic effect of denitrification and methanogenic bacteriums was used to improve the efficiency of anaerobic biological treatment unit.The characteristics,influencing factors and operating characteristics of simulated coking wastewater treatment by the simultaneous denitrification and methanogenesis in the reactor were studied systematically and comprehensively.The degradation pathways of phenol,quinoline,pyridine and indole were deduced.The microbial flora structure in the sludge and packed areas of the reactor was determined,and the degradation model of organic matter and the degradation model of NO₃^--N was established respectively.This study provides a new perspective for the biochemical treatment of coking wastewater,which has a wide application value in improving anaerobic removal rate of COD in coking wastewater,saving engineering investment and reducing running cost.The establishment of the process theory and technology development,in the field of industrial organic wastewater treatment,has a wide range of applications.