Some chemical and toxicological aspects about paper mill effluent treatment with ozone

The paper mill industry produces high effluent volumes that normally cause a high environmental impact. In this work, Kraft E-1 effluent was treated w ith ozone and some chemical parameters (total organic carbon, molecular mas s distribution and total phenols) were analysed at different ozonization ti mes. The toxicity of the effluent was determinated during the ozonization p rocess, using the bacterium Escherichia coli, by a respirometric test. Afte r sixty minutes of ozonization, total organic carbon decreased to around 12 %, total phenols to 70% and effluent colour to 35%. The effluent molecular mass was significantly reduced during the process and the toxicity to E. co li decreased with effluent ozonization.