The influence of nitrified supernate’s recycle ratio on the removal of coking wastewater

摘要

The influence of the recycle ratio on the removal of coking wastewater has been researched using the anaerobic-anoxic-aerobic (A/A/O) biofilm process.The research indicates that the concentrations of chemical oxygen demand (COD) and NO3-N in the water are the lowest when the recycle ratio is 3∶1,but the removal efficiency of total cyanide (TCN) is the highest when the recycle ratio is 1∶1.The removal efficiency of NH+4-N is more than 99% at all three different recycle ratios.Compared with Grade A of the National Discharge Standard (GB 8978—1996),the effluent NH+4-N is standard,but COD and TCN can not meet the requirements and further treatment processes are needed.