Enhanced biodegradation of azo dyes using an integrated elemental iron-activated sludge system: II. Effects of physical-chemical parameters.

As part of a study to evaluate an integrated zero-valent iron (Fe(0))-biological oxidation process for treating azo dye wastewaters, we conducted batch and column experiments with the azo dye orange G to assess the effects of solution conditions on the performance of iron pretreatment. The influence of iron type and surface area, solution pH, dissolved inorganic salts, and phosphate ion on the reduction (decolorization) of orange G solution were examined. In batch experiments, increased iron surface area, decreased pH, and chloride and sulfate salts enhanced dye decolorization, whereas high pH (9.

Enhanced biodegradation of azo dyes using an integrated elemental iron-activated sludge system: I. Evaluation of system performance.

The objective of this research is to evaluate an integrated system coupling zero-valent iron (Fe(0)) and aerobic biological oxidation for the treatment of azo dye wastewater. Zero-valent (elemental) iron can reduce the azo bond, cleaving dye molecules into products that are more amenable to aerobic biological treatment processes. Azo dye reduction products, including aniline and sulfanilic acid, were shown to be readily biodegradable at concentrations up to approximately 25 mg/L.