Two-Stage Biological Treatment of Coke Plant Wastewater

摘要

The report documents a pilot-plant study of the use of advanced waste treatment methods in upgrading metallurgical cokemaking wastewaters to Best Available Technology (BAT) levels. Mobile treatment units, operable at a flow rate of 191/min, were used. Methods used included two-stage activated sludge treatment for removal of organic carbon compounds and ammonia; filtration and activated carbon were also studied as polishing steps. For each treatment studied, samples (including toxic pollutants) and operational data were obtained for later use in assessing and comparing treatment adequacy. The study showed that high levels of organic pollutant removal were achieved in the 1st stage of biological oxidation. Abnormal operating conditions in the coke plant wastewater pretreatment system during the testing resulted in ammonia levels as high as 2000 mg/l, making it necessary to dilute the 2nd stage feed before nitrification could be achieved. Ammonia reductions of >97% were achieved in the 2nd stage. Activated carbon and filtration effectively removed suspended solids, total organic carbon, color, and thiocyanate.