THE TREATMENT OF WASTE-WATER FROM COKE-OVEN AND CHEMICAL RECOVERY PLANTS BY MEANS OF BIOFERRIC PROCESS - AN INNOVATIVE TECHNIQUE

The treatment of wastewater from coal-derived liquor is considered to be extremely difficult because of large quantities and fluctuating concentrations of toxic chemicals. This paper describes the performance of an innovative technique, - the Bioferric process as it compared to conventional activated sludge during pilot. semiscale and full-scale tests of wastewater treatment coke oven and chemical recovery plants. Bioferric sludge uses the affinity of ferric hydroxide floc for the bacterial surface to create a dense, strong adsorptive and good settling sludge. As a result, the biomass can be operated at 7,000 to 9,000 mg/l, with SVI ranging between 50 to 90 and F/M ratios of 0.1. These levels can be realized without requiring additional oxygen. Due to the low F/M ratio, sludge production is markedly reduced. An additional benefit is iron-rich enhances sludge dewatering. The pilot study showed that the bioferric process maintained average phenol removal at 99.93% even with influent cyanide as high as 40 mg/l. Especially under accidental spills, BOD, COD and cyanide removal were still at 98%, 81.3% and 98% respectively. In contrast, phenol, BOD, COD and cyanide removal were 80.7%, 19.7%, 25.8% and 72% respectively using conventional activated sludge. Full-scale tests confirmed the conclusions of the pilot study under conditions with high fluctuations of influent flow rate and toxic contents. They showed that the bioferric process always maintains a stable operation with effluent phenol, cyanide, BOD far below the required discharge standards and all at negligible increased cost.