Biodecolorization of the azo dye Reactive Red 2 by a halotolerant enrichment culture.
The decolorization of the azo dye Reactive Red 2 (RR2) under anoxic conditions was investigated using a mesophilic (35 degrees C) halotolerant enrichment culture capable of growth at 100 g/L sodium chloride (NaCl). Batch decolorization assays were conducted with the unacclimated halotolerant culture, and dye decolorization kinetics were determined as a function of the initial dye, biomass, carbon source, and an externally added oxidation-reduction mediator (anthraquinone-2,6-disulphonic acid) concentrations. The maximum biomass-normalized RR2 decolorization rate by the halotolerant enrichment culture under batch, anoxic incubation conditions was 26.8 mg dye/mg VSSxd. Although RR2 decolorization was inhibited at RR2 concentrations equal to and higher than 300 mg/L, the halotolerant culture achieved a 156-fold higher RR2 decolorization rate compared with a previously reported, biomass-normalized RR2 decolorization rate by a mixed mesophilic (35 degrees C) methanogenic culture in the absence of NaCl. Decolorization kinetics at inhibitory RR2 levels were described based on the Haldane model (Haldane, 1965). Five repetitive dyeing/decolorization cycles performed using the halotolerant culture and the same RR2 dyebath solution demonstrated the feasibility of biological renovation and reuse of commercial-strength spent reactive azo dyebaths.
Beydilli
M Inan
MI
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, USA.
Pavlostathis
Spyros G
SG
D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D004396:Coloring Agents / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods; D007700:Kinetics; D009282:Naphthalenesulfonates / Q000378:metabolism*; D014227:Triazines / Q000378:metabolism*; D014876:Water Pollution / Q000032:analysis / Q000517:prevention & control
D004396:Coloring Agents; D009282:Naphthalenesulfonates; D014227:Triazines; C098610:reactive red 2