Combined treatment of ozonation and subsequent
biological degradation with a biofilm, to reduce the
color and COD, was investigated. The experimental part
of the study consisted of two phases. The first phase was
the ozonation process; the results obtained demonstrated
that the ozonation of Remazol Black B dye at pH values
of 3–11, was effective, partially oxidizing and completely
decolorizing the effluent, even at relatively high
concentrations of the dye (500 mg/L). Color removal efficiencies greater than 96% were obtained in all cases.
It was possible to verify that the ozonation process as a
pretreatment increases the dye degradation efficiency. For
the biological treatment, an increase in ozonation time
increased the dye concentration reduction in hydrolyzed
dye synthetic effluent. The toxicological results of the tests
with Daphnia magna showed that there is an increase in
toxicity after ozonization and a decrease after submitting the
ozonized synthetic wastewater to biological treatment with a
biofilm (De Souza et al. 2010).