Textile wastewaters are rated among the most polluting in all industrial sectors, including high organic
loads and dyes that are generally resistant to aerobic biotreatment. Alternative, staged anaerobic/aerobic
regimes have been tested, with clear success in the biodecolorization of the widely used azo dyes.
The novel aerobic granular sludge (AGS) technology has excellent potential in this context, due to the
anoxic/anaerobic zones within granules and their increased tolerance to toxicity.
In this study the performance
of anaerobic/aerobic, flocculent and AGS sequencing batch reactors (SBR) was compared in the
treatment of a simulated textile wastewater. Similar color removal yields (75–80%) of an azo dye were
attained in both systems but with higher anaerobic and overall COD removal yields in the AGS SBR, thus
demonstrating the latter’s good potential.
Comparison of the toxicity of samples collected from both
SBR using yeast-based assays highlighted the better performance of the AGS SBR as compared with the
flocculent SBR, with respect to detoxification potential.