Dyeing wastewater treatment by activated sludge process with a polyurethane fluidized bed biofilm

Abstract

In case of the porous polyurethane fluidized bed biofilm-activated sludge process followed by a coagulation process(the FBAS-C process), 75% CODMn was removed by treating with the biological FBAS process in the loading range of 0.16∼0.32 kgCODMn/kgVSS·day. The biomass yield and microbial decay coefficients were 0.42 kg MLSS/kgBOD and 0.11 day−1, respectively. The optimum coagulation conditions for the effluent of the FBAS process were at pH 6 and 600mg/L alum dosage. Consequently, 92% of total CODMn removal efficiency was observed in the FBAS-C process. Meanwhile, in case of a coagulation process followed by the porous polyurethane fluidized bed biofilm-activated sludge process(C-FBAS process). the raw dyeing wastewater was treated at pH 6 in the presence of 1,000 mg/L alum and, continuously, the effluent coagulated wastewater was treated by the FBAS process in the loading range of 0.09∼0.19 kg CODMn/kgVSS·day. Removal efficiency of CODMn in the biological process, FBAS, was 82%. The biomass yield and microbial decay coefficient in the C-FBAS process were similar to those in the FBAS-C process. The final effluent CODMn was about 65 mg/L in both tested processes, the FBAS-C and C-FBAS. However, the FBAS-C process illustrated better treatibility than C-FBAS in terms of the total sludge production, since the former produced about 20% less sludge than the latter.