Abstract

Ozonation of pulp bleaching effluents of Pinus radiata from the sequences C:D(90:10)/E, C:D(70:30)/E and Eucalyptus globulus from the sequences C:D(80:20)/E and D/E(p)/D, was studied. The influence on the reduction of color, AOX, COD and pH, of the variables pH (2-10), temperature (10-40°C), ozone flow (0.9-5.0 g h -1) and time (2-10 min), were evaluated using a factorial design. The results showed that for the alkaline extraction effluents, the pH is not an important parameter in the organic matter degradation by ozone. On the other hand, for the chlorine dioxide stage effluent, the efficiency of the treatment was pH dependent, obtaining the best results at alkaline pH. In all the effluents, color was removed faster and more efficiently than COD and AOX. Multivariate analysis was used to find equations that estimate the efficiency of the treatment, depending on the initial color, AOX, COD and of the ozone charge.