Degradation of 1-amino-4-bromoanthraquinone-2-sulfonic acid using combined airlift bioreactor and TiO2-photocatalytic ozonation.

BACKGROUND: Traditional treatment systems failed to achieve efficient degradation of anthraquinone dye intermediates at high loading. Thus, an airlift internal loop reactor ( AILR) in combination with the TiO₂-photocatalytic ozonation ( TiO₂/ UV/ O₃) process was investigated for the degradaton of 1-amino- 4-bromoanthraquinone-2- sulfonic acid ( ABAS). RESULTS: The AILR using Sphingomonas xenophaga as inoculum and granular activated carbon ( GAC) as biocarrier, could run steadily for 4 months at 1000 mg L⁻¹ of the influent ABAS. The efficiencies of ABAS decolorization and chemical oxygen demand ( COD) removal in AILR reached about 90% and 50% in 12 h, respectively. However, when the influent ABAS concentration was further increased, a yellow intermediate with maximum absorbance at 447 nm appeared in AILR, resulting in the decrease of the decolorization and COD removal efficiencies. Advanced treatment of AILR effluent indicated that TiO₂/ UV/ O₃ process more significantly improved the mineralization rate of ABAS bio-decolorization products with over 90% TOC removal efficiency, compared with O₃, TiO₂/ UV and UV/ O₃ processes. Furthermore, the release efficiencies of Br⁻ and SO₄²⁻ could reach 84.5% and 80.2% during TiO₂/ UV/ O₃ treatment, respectively, when 91.5% TOC removal was achieved in 2 h. CONCLUSION: The combination of AILR and TiO₂/ UV/ O₃ was an economic and efficient system for the treatment of ABAS wastewater. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]