Abstract

RAMIREZ-RAMIREZ, Natividad et al. Treatment with Ozone of Wastewater Containing Tannins from Vegetal Tannery. Tecnol. cienc. agua [online]. 2016, vol.7, n.3, pp.53-73. ISSN 2007-2422.

The aim of this work is establishing the ozonation conditions that enable the degradation of tannins contained in the residual liquors of tannery (RLT) originated in vegetal tanning, to achieve a safe disposal. Ozonation at 6.3 initial pH and advanced oxidation, with ozone at alkaline pH, were applied to aqueous solutions of the freeze-dried RLT and quebracho (QS), during 180 min, analyzing total phenols, COD and color. The treatments present the bigger reduction of the parameters within the first hour of ozonation. Pseudo's first order kinetics for the degradation of COD with both processes were observed, obtaining the respective kinetic coefficients, being QS the smaller one. Globally, the process of advanced oxidation achieved efficiencies of elimination between 80 and 100% of total phenols, COD and color, while in the ozonation these values oscillated between 50 and 95%. The two treatments offered good results, but in the advanced oxidation of the RLT all variables measured, at the end of the process, have not detectable values according to the analytical methods used. The volume estimated of a column of treatment (considering the constant surface speed during the process of scaled-up), was 300 l of useful volume, operating on discontinuous regime, for processes of treatment with one hour of contact time. The experimental results obtained in the advanced oxidation of RLT, allow approving this treatment to be scaled-up to pilot level and recognize its application for achieving a safe disposal to the environment and/or evaluating its reuse in the process of tannery itself.

Keywords : Ozone; advanced oxidation; condensed tannins; degradation; kinetic coefficients; scale-up.

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