Bioaugmentation of spent reactive dye-baths via O₃ and O₃/H₂O₂

The effect of ozonation on the decolourization and bioaugmentation of three spent reactive dye-bath analogues was comparatively investigated. For this purpose, respective colour removal efficiencies, pseudofirst order decolourization rate constants, ozone absorption rates and BOD₅ values before and after ozonation were determined for each exhausted dye-bath simulation. In addition, electrical energy consumption rates based on a simple figure-of-merit (i.e. the Electrical Energy requirement per Order of colour removal or EEO values) have been established to assess the overall feasibility of ozonation for the above-mentioned purposes. Results have clearly revealed that ozone not only effectively decolourizes reactive dye-bath effluents over a wide range of dyestuff concentrations, but also improves the biodegradability of these effluents considerably at acceptable electrical energy requirements.