Study On Start-up Of Simultaneous Denitrification And Imethanogenesis UBF Reactor In Coking Wastewater Treatment

Seed sludge in this experiment derived from coking plant biological treatment section and municipal wastewater treatment plant anoxic stage separately. Up-flow sludge bed filter (UBF) for treating simulated coking wastewater was developed by aerobic sludge and denitrification sludge as seed sludge at an ambient temperature of33±1℃. While nitric oxide dosing ratio was C/NOx-N=10, UBF achieved simultaneous denitrification methanogenesis (SDM) process.Comparing with different UBF start-up experiments, the effect level for SDM-UBF by by two different seed sludge was investigated, different start-up order, such as"denitrification and methanogenesis at the same time" and "methanogenesis firstly, denitrification secondly", was researched, aiming at obtaining quick start-up method of SDM-UBF.Three influence factors were observed and determined about optimum dosage, such as ammonia nitrogen、 NOx-N、alkalinity, which is be related nitrogen cycle closely. According to operating condition of reactor already started, dynamics analysis about SDM-UBF was carried on the basis of monod model、second order dynamic model and Stover-Kincannon model. The experiment specific conclusions as follows:1、aerobic precoating of the biomedium combined with batch addition of aerobic sludge and denitrifying sludge was available, which was employed as a method for a short start-up period of SDM-UBF.2、Aerobic sludge growth rate in SDM process was faster than same type sludge in methanogenesis process and denitrification sludge in SDM process. SDM-UBF seeded aerobic sludge achieved start-up about30days in advance, COD removal rate about70%.3、Comparing with UBF start-up experiments, SDM-UBF seeded aerobic sludge in different start-up order always start quckly, run stably,and treatment result was efficient.4、SDM with two different start-up order, such as"denitrification and methanogenesis at the same time"and"methanogenesis firstly, denitrification secondly", could startup after110d. When volume loading rate was3kgCOD/(m3·d), COD removal rate reached above65%, NO3-N and NO2-N concentration in effluent were all lower than5mg/L5、When NO3-N or NO2-N impact load concentration were150mg/L COD removal rate of methanogenesis sludge were nearly same. NO2-N concentration reached maximum12.8mg/L, as denitrification middle product, rate of accumulation was30.77%in1.5h after dosing NO3-N in methanogenesis sludge. Its COD removal process had similar trend as methanogenesis process. There was not NOx-N removal postpone after dosing NO2-N in methanogenesis sludge.6、Appropriate proportion of carbon and nitrogen for best COD removal rate was C/N=30:1during SDM process. Appropriate proportion of COD and alkalinity for economic efficient operation was COD/Alk=5:1during methanogenesis process, alkalinity dosage was0.20gCaCO3/gCOD; Appropriate proportion of COD and alkalinity for economic efficient operation was COD/Alk=7:1during SDM process, alkalinity dosage was0.14g CaCO3/gCOD.7、The related coefficient of first order dynamics model, second order dynamics model, modified Stover-Kincannon model for SDM-UBF were0.17,0.98and0.99separately. Second order substrate removal rate constant was10.81d-1, modified Stover-Kincannon model maximum removal rate constant and Saturation constant were83.3g/(L·d) and186.23g/(L·d) separately. Therefore, second order dynamics model, modified Stover-Kincannon model are available to SDM-UBF design.