Biological Fluidized-Bed Treatment of Wastewater from Byproduct Coking Operations: Full-Scale Case History

摘要

The Algoma Steel byproduct coke plant consists of three coke-oven batteries capable of producing approximately 3 000 t/d of coke. The source of the primary process wastewater from the coke plant is the excess flushing liquor or weak ammonia liquor pro- duced during initial cooling of coke-oven gases. This raw liquor stream is directed to an ammonia still where ammonia is recovered through steam stripping. Wastewater is then directed to a biological treatment plant designed for phenolics removal. The biological treatment scheme used at Algoma is a fluidized-bed reactor (FBR) system. Design of the system anticipated a median phenolic load of l 1l7 kg/d (2 463 lb/d), consisting of a phenolics concentration of l 0l2 mg/L in the wastewater and a flow of 46.1 m3/h (203 gpm). Nine days after start-up, the FBRs were receiving more than 40 m3/h of wastewater containing l 000 mg/L of phenolics and an approximately equal amount of clean mill water, added as dilution water for tempera- ture control. Effluent from the system contained less than 5 mg/L pheno- lics. During a 6-week performance assessment of the system, which began approximately 2 weeks after process start-up, FBRs achieved more than 99 phenolics reduction based on diluted wastewater feed concentration. Approximately 5 weeks after process start-up, thiocya- nate in the effluent was reduced to less than 5 mg/L, representing approx- imately 95 removal based on diluted wastewater feed concentration. At this time the biomass concentration, measured as volatile solids, in the FBRs was greater than 15 g/L. Water Environ. Res.,