Simultaneous removal of COD, thiocyanate, cyanide and nitrogen from coal process wastewater using fluidized biofilm process

Simultaneous removal of chemical oxygen demand (COD), thiocyanate (SCN), cyanide (CN), ammonia (NH4+-N) and total nitrogen (TN) from coal process wastewater was investigated using fluidized biofilm process at a laboratory scale and commercial scale. In the laboratory scale tests, the removal efficiencies of COD, SCN, CN, ammonia and TN were 97, 99, 99, 99 and 93%, respectively, at 1.0 day of hydraulic retention time (HRT) and 3.4 kg m−3 day−1 of COD loading. A commercial wastewater treatment plant with 3.4 day of HRT was revised to the fluidized biofilm process with anoxic–oxic–anoxic–oxic (AOAO) reactors arrangement. The results in the revised commercial plant were similar to those in the laboratory test.