Treatment of Actual Coking Wastewater by Two-stage EGSB System with Self Recirculation and Crossed Recirculation

摘要

To investigate the possibility of simultaneous high efficient removal of COD and NH_3-N in the actual coking wastewater through micro-aerobic granular bio-film reactor, two-stage granular bio-film reactor system (EGSB I + EGSB II) were continuously operated through two effluent recirculation ways for about 5 months: ERWl(24L.h~(-1) self recirculation) and ERW2(15 L.hf1 self recirculation +15 L.h~(-1) crossed recirculation). Compared with ERW1, through using ERW2, the two-stage EGSB reactor system could attain high COD and NH3-N removal efficiencies (86.7%-96.9% and 48.6%-80.4%) and low effluent NOf and NO_3~- concentrations (0-25mg.L_1 and 7-71mg.L~(-1)). Using ERW1, the two-stage EGSB reactor system melt with difficult of NO_2" accumulation in the EGSB II (accompanied with low NH_3-N removal of only 41.4%). Using ERW2, the difficult of accumulation in the EGSB II was solved and simultaneously high efficient removal of NH3-N and NO_2~-in the EGSB I was achieved.