Dyes removal from simulated and industrial textile effluents by dissolved-air and dispersed-air flotation techniques

In this study, which complements the previously published work of this team on dyes removal, dispersedand dissolved-air flotation were employed in order to remove dyestuffs from simulated and industrial textile effluents, originating either from the dyeing mill or from the equalization tank of a dye-house. The influence of initial dyes, sodium chloride, and surfactant and polyelectrolyte content was investigated. A first-order kinetic model could adequately describe dispersed-air flotation time profiles. The results show that both flotation techniques are realistic methods for the treatment of effluents originating from the equalization tank by employing 100 mg/L cetyltrimethylammonium bromide (CTAB). Dissolved-air flotation can be used for effluents originating from the dyeing mill with the addition of polyelectrolyte, flocculant, dodecyl hydrogen sulfate sodium salt (SDS), and CTAB. Dye removal was higher than 97%, and the residual dye content could be lower than the limit of 300 American Dyestuff Manufacturer's Institute units. Furthermore, the possibility for reuse of the decolorized water was evaluated in dyeing experiments. However, the results should be confirmed in full-scale experiments.