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Over 85%of COD in CSC coke-oven wastewater is removed by the conventional activated sludge system.In order to prevent the exceed quantity of incoming coke-oven wastewater that caused system upset,CSC has built a membrane bioreactor(MBR)to increase the capacity of the wastewater treatment system.The MBR is able to adapt unexpected high influent quantity and/or contaminant concentrations.The overall COD removal efficiency of coke oven wastewater treatment plant has been increased from 88%to 93%.In addition,CSC is planning to revamp the existing aeration tanks into a MBBR nitrogen removal process to meet the future ammonia standard of 20mg/L.The R&D department has established the start-up strategies and the upset recovery plans based on the pilot study in the field.Preliminary pilot results show that phenolics,thiocyanate and cyanate will certainly inhibit nitrification.Moreover,the overall ratio of ammonia to alkalinity(as CaCO3)in the start-up period of shall be 1:9,which is higher than the theoretical value of 1:4.This suggests that autotrophic bacteria such as thiocyanate-degrading bacteria existing in the activated sludge would consume the alkalinity as a carbon source for growth.Furthermore,with the application of carriers in the nitrification tank,the biofilm on the carriers can increase 20%of ammonia conversion rate.