The Comparative Study On The Treatment Of Petrochemical Wastewater By Tidal Biological Contact Oxidation Process And Activated Sludge Process

With the increasing concern of environmental protection,China’s research on petrochemical wastewater has increased the biological treatment of petrochemical wastewater.It has been widely used due to its low operating cost,high treatment effect and no secondary pollution.However,the complex composition of petrochemical wastewater and the large amount of refractory organic matter and toxic and harmful substances have become the biggest limiting factors of biological treatment.Many researchers have improved the biological treatment process to adapt to more complex petrochemical wastewater.Compared with the activated sludge method,the biological contact oxidation reactor biofilm can retain microorganisms with longer epoch cycles,richer biological phases,longer food chain,stable ecosystem,high concentration of active biomass,and strong anti-shock load capacity.The experiment improves the biological contact oxidation process,and adopts the urban sludge regeneration filler for secondary utilization of resources to produce a“tidal-type”operation mode,which overcomes the problem that the traditional biological contact oxidation process is not easy to be uniform in water distribution,and the partial dead angle is caused.At the same time,the cost of the aeration system is saved.In order to verify the ability of tidal biological contact oxidation process to treat petrochemical wastewater,the ability of tidal biological contact oxidation process and activated sludge process to treat petrochemical wastewater was compared,which provided a reference for the treatment of petrochemical wastewater.The specific research content of the paper is as follows:（1）The tidal biological contact oxidation process starts the domestication stage of the domestic sewage filming phase and gradually increases the amount of petrochemical wastewater.Since the temperature is between 22°C and 28°C in July and August of Lanzhou,the domestic sewage is used for 8 days.Left and right,the effluent is stable,and then enters the domestication stage.After 60 days of treatment,the effluent of the petrochemical wastewater is stable,indicating that the start-up is completed;the activated sludge process is directly taken from the aerobic tank activated sludge of the Lanzhou Sewage Treatment Plant,and after about 7 days of operation,The effluent from the petrochemical wastewater is stable and the activated sludge process is completed.（2）By comparing the degradation of COD_Cr by two sets of devices,it can be found that the removal rate of BOD₅ in the tidal biological contact oxidation process is 60%in the first hour,and the removal rate of BOD₅ in the activated sludge process is 47%in the first hour.After 4 hours of treatment,the B/C value decreased,the removal rate of BOD₅ in the tidal process was 82%,and the removal rate of BOD5 in the activated sludge process was 59%.The tidal biological contact oxidation process removes COD_Cr by about 20-30 mg/L higher than the activated sludge process.The tidal biological contact oxidation process is superior to the activated sludge process in degrading COD_Cr.（3）By comparing the nitrogen removal of the two sets of devices,it can be found that the removal rate of NH₃-N in the first hour is 74%,the growth rate of NO₃^--N is 111%,and the removal rate of TN is 9%.The sludge process is in the first No degradation of NH₃-N occurred within one hour,the NO₃^--N removal rate was 60%,and the TN removal rate was8%.After 4h treatment,the removal rate of NH₃-N in the tidal process was 91%,the cumulative rate of NH₃-N was 120%,and the removal rate of TN was 47%.The sludge process NH₃-N did not degrade,and the removal rate of NO₃^--N was 80%.The TN removal rate is 80%.The difference in total nitrogen degradation capacity between the two sets was not obvious,but the sludge process was affected by water quality,NH₃-N did not undergo oxidation reaction,and the sludge process did not undergo nitrification reaction.（4）By comparing the ultraviolet-visible absorption spectra of the inlet and outlet water of the two sets of devices,it can be found that the tidal process exhibits strong absorption in the wavelength range of 200-230 nm.Compared with the ultraviolet spectrum of the effluent in each stage,the effluent peak of the tidal process shows a blue shift,indicating The degree of conjugation may be damaged to some extent,and the benzene ring may be opened,so it moves in the short wave direction.The phenomenon of effluent from sludge process is not obvious.Compared with the ultraviolet spectrum of the tidal process water inlet and outlet,the absorption peak has been changing and migrating with the treatment time,but the above phenomenon of the sludge process is not obvious,which indicates that the tidal process is more complicated in the process of degrading petrochemical wastewater.Physical and chemical effects.The tidal process has a conversion rate of 41%for UV₂₅₄ at 5h,and the conversion rate of UV₂₅₄ is 28%at 5h.The tidal process is superior to the sludge process.The tidal process partially degrades the UV₂₅₄ substance to better conversion between substances.Sludge process.These phenomena indicate that the tidal process has better processing capacity for petrochemical wastewater than the activated sludge process.（5）By comparing the microbial characteristics of the two sets of devices,it can be found that the biofilm on the surface of the tidal process filler is smooth and there is an adherent water layer;the activated sludge of the sludge process is yellow-brown floc,with large flocs and good sedimentation..The presence of surface insects,phosphorus worms,bell worms,worms,rotifers,nematodes,pipeworms,and caterpillars was observed on the tidal process biofilm.Case bacteria,bell worms,and worms were observed in the activated sludge.The presence of rotifers and nematodes.This shows that the tidal process has a richer biological phase than the sludge process.（6）By comparing the differences between the tidal biological contact oxidation process and the activated sludge process in the treatment of petrochemical wastewater,it is found that the tidal biological contact oxidation process is superior to the activated sludge process in the treatment of petrochemical wastewater.Therefore,it is recommended to select"hydrolysis acidification tank and tidal biological contact oxidation process"to treat this type of petrochemical wastewater.