Study On Treatment Of Refinery Catalyst Wastewater By Partial Nitrification-Anammox Process

Partial nitrification-anammox process was used to treat refinery catalyst wastewater.Firstly,coagulation experiments were carried out to deal with the possible problems of suspended solids and colloids in wastewater.Secondly,partial nitrification reactor was started by sequencing batch and dynamic influent modes to investigate the formation of nitrite nitrogen in wastewater.Finally,the activity recovery of anaerobic ammonia oxidizing bacteria(AnAOB)was examed,and the effects of hydraulic shock on denitrification performance were studied.The conclusions are as follows:(1)The turbidity of untreated catalyst wastewater can be reduced to 50～600 NTU after natural sedimentation for half an hour.When 400 mg/L polyaluminium chloride(PAC)coupled with 2 mg/L polyacrylamide(PAM)coagulant was used,the turbidity of effluent was below 5 NTU.(2)When the partial nitrification reactor was started by sequencing batch mode,the starting speed was slow with a long cycle time,while the obvious partial nitrification reaction could be observed within only 19 cycles under the dynamic influent mode.The accumulation rate of nitrite nitrogen was stabilized at 100%after the partial nitrification reactor was operated steadily.The average ratio of nitrite nitrogen to ammonia nitrogen of the effluent was 0.92,which providing the basic substrate for the subsequent anammox process.(3)Under the condition of low concentration substrate,the biological activity of AnAOB undergoes three stages including lag stage,increasing stage and stable denitrification stage.At the stable denitrification stage,the biological activity decreased temporarily before continuously increasing when doubling the substrate concentration,Finally,the long-term stable biological denitrification was achieved,and the removal efficiencies of ammonia nitrogen and nitrite nitrogen were stabilized at more than 85%.The maximum volumetric removal loadings of ammonia nitrogen and nitrite nitrogen were 0.547 kg N/(m~3·d)and 0.589 kg N/(m~3·d),respectively.(4)Hydraulic shock to AnAOB at the stable stage was examed by altering influent flow and internal recirculation flow of anammox bio-filter.The increase of hydraulic shock can promote the denitrification performance of the filter to a certain extent.The maximum volumetric loadings of ammonia nitrogen,nitrite nitrogen and total nitrogen reach 1.846,2.979 and 4.605 kg N/(m~3·d),respectively.