Treatment Of Cracking Catalyst Wastewater With Electrocoagulation Partial Nitritation-anammox Process

Petroleum chemical industry is the pillar industries in national economy, cracking catalysts is one of the most important catalyst in petroleum refining process. Wastewater from cracking catalyst production line of petroleum refining industry is difficult to be treated, which got high density of salinity, low C/N, high concentration of SS and big fluctuation of water quality. In the current treatment process, there are many problems existed unstable effluent quality, complex management and high treatment cost.Against the problem of unstable effluent quality, litt le removal of TN, high treatment cost, electrocoagulation partial nitritation-anammox process was used to treat cracking catalyst wastewater. The effects of salinity in cracking catalyst wastewater towards the Anammox process, the treatment performance, stability, effect of temoerature and economic analys is of combined system were investigated in order to find a new way to treat cracking catalyst wastewater.The results showed that: the nitrogen removal effic iency of Anammox reactor which inoculated with Candidatus Jettenia Anammox sludge,was greatly influenced by the salinity. Compared to other genus, Candidatus Jettenia got poor resistance towards salinity, low salinity would inhibit the activity of Anammox sludge. The effect of Anammox genus should be considered when Anammox used to treat wastewater with high salinityIn the construction of electrocoagulation partial nitr itation- anammox process:The electrocoagulation got strong stability used to pretreat cracking catalyst wastewater, 20~30% of COD can be removed and the turbidity of effluent was below 40 N TU. Through the control of aeration time according to the concentration of ammonium nitrogen, partial nitr itatiom can be achieved stably in Sequencing Batch Reactor which got stable shortcut nitrification,and the NO2--N/NH4+-N of effluent kept in 0.9 to 1.4 which can satisfied the need of anammoxhrough the control of aeration time.In the EGSB- Anammox reactor which was started up with synthetic wastewater first, the anammox sludge was domesticated through the nitrification effluent. The anammox process was sucessifully used in cracking catalyst production wastewater, and the nitrogen removal rate can be attained 0.5 kg N/(m3·d).The effluent quality of the electrocoagulation partial nitritation-anammox process remained: turbidity <30 N TU, NH4+-N<10 mg/L, NO2--N<3 mg/L, COD<100 mg/L, NO3--N<40 mg/L. As the temperature would greatly influence the metabolic rate, the effluent quality still can be maintained through the adjustment of aeration time in SBR and the hydraulic retention time(HRT) of EGSB reactor.Compared with coagulation sedimentation+MBBR wastewater treatment process, the electrocoagulation partial nitritation-anammox process could decrease the construction investment cost by 61% and save the running expense 3,275,000￥ annually, in the treatment of cracking catalyst production wastewater(200 m3/h).