Treatability Studies and Toxicity Reduction in Pulp and Paper Mill Effluents

A study of the liquid effluents of various production process stages and of the final effluent of the RIPASA S/A Celulose e Papel plant, by means of conventional parameters and toxicity, was undertaken. Using these parameters, the performances of the current treatment system (an aerated pond) and of pilot-scale experimental systems (using aerobic biological processes with one or two stages) were compared. The two-stage system yields better results in the improvement of final effluent quality. Biological degradation rates were also determined. It is thought that these discharges will not have an impact on the receiving water, as far as toxicity is concerned.