ENHANCED BIODEGRADABILITY OF AZO DYES THROUGH PRETREATMENT WITH ELEMENTAL IRON

The objective of this research is to evaluate an integrated system coupling zero-valent iron (Fe0) and aerobic biological oxidation for treatment of azo dye wastewater. Zerovalent iron can be used to reduce the azo bond, cleaving dye molecules into products that are more amenable for mineralization by bacteria in aerobic biological treatment processes. Azo dye reduction products, including aniline and sulfanilic acid, have been shown to be readily biodegradable at concentrations up to approximately 25 mg/L. This batch reduction and biodegradation data has been used to support an integrated iron pretreatment/activated sludge process for the treatment of the azo dyes orange G and orange I. The integrated system was able to decolorize dye solutions and yield effluents with lower total organic carbon concentrations than control systems without iron pretreatment. The success of the bench-scale integrated system demonstrates that iron pretreatment technology is a feasible option for treatment of dye-containing wastewaters.