Decolorization of Orange Ⅱ using an anaerobic sequencing batch reactor with and without co-substrates

We investigated the decolorization of Orange Ⅱ with and without the addition of co-substrates and nutrients under an anaerobic sequencing batch reactor（ASBR）.The increase in COD concentrations from 900 to 1750 to 3730 mg/L in the system treating 100 mg/L of Orange Ⅱ-containing wastewater enhanced color removal from 27% to 81% to 89%,respectively.In the absence of co-substrates and nutrients,more than 95% of decolorization was achieved by the acclimatized anaerobic microbes in the bioreactor treating 600 mg/L of Orange Ⅱ.The decrease in mixed liquor suspended solids concentration by endogenous lysis of biomass preserved a high reducing environment in the ASBR,which was important for the reduction of the Orange Ⅱ azo bond that caused decolorization.The maximum decolorization rate in the ASBR was approximately 0.17 g/hr in the absence of co-substrates and nutrients.

Screening and Identification of a Highly Effective Azo Dye-degrading Strain

In this study, strain tsl-2, which could effectively degrade azo dye amaranth, was isolated from activated sludge in the sewage treatment pool of a print- ing and dyeing mill in Liaocheng City, Shandong Province. Based on morphological characteristics, physiological and biochemical properties and 16S rDNA se- quence analysis, the isolated strain was identified preliminarily as Leucobacter komagatae. The decolorization of strain tsl-2 was investigated under static culture conditions. The results showed that strain tsl-2 exhibited the highest decolorization rate when initial concentration of amaranth was 50 rag/L, and the maximum de- colorization concentration was 1 250 mg/L. After decolorization under optimal conditions for 14 h, the decolorization rate of amaranth reached above 95%. This study provided the basis for further optimization of azoreductase production conditions.

Rapid decolorization of Acid Orange Ⅱ aqueous solution by amorphous zero-valent iron

Some problems including low treatment capacity,agglomeration and clogging phenomena,and short working life,limit the application of pre-treatment methods involving zero-valent iron （ZVI）.In this article,ZVI was frozen in an amorphous state through a melt-spinning technique,and the decolorization effect of amorphous ZVI on Acid Orange II solution was investigated under varied conditions of experimental variables such as reaction temperature,ribbon dosage,and initial pH.Batch experiments suggested that the decolorization rate was enhanced with the increase of reaction temperature and ribbon dosage,but decreased with increasing initial solution pH.Kinetic analyses indicated that the decolorization process followed a first order exponential kinetic model,and the surface-normalized decolorization rate could reach 2.09 L/（m^2 ·min） at room temperature,which was about ten times larger than any previously reported under similar conditions.Recycling experiments also proved that the ribbons could be reused at least four times without obvious decay of decolorization rate and efficiency.This study suggests a tremendous application potential for amorphous ZVI in remediation of groundwater or wastewater contaminated with azo dyes.