Electrodialysis reversal applied to tertiary treatment of Kraft pulp mill effluent

Abstract

The electrodialysis reversal (EDR) technology was applied as tertiary treatment for final effluent from a Kraft pulp mill industry located in Bahia, Brazil. Two samples were evaluated: first, the final effluent treated by conventional processes (FE); the second one was additionally filtered by sand and activated carbon (FEAC). The tests in a pilot plant were carried out in batch mode, with electrode’s polarity reversion. Temperature, pH and electrical conductivity measurements were performed during EDR treatment. Solutions before and after the EDR treatment were submitted to physicochemical characterization in order to determine the system efficiency. Chloride and sulfide concentrations have been reduced by up to 98.6 and 100% respectively. Only for FE treatment it was observed fouling and scaling occurrence, due to high organic and inorganic ions concentrations. In addition, the evaluated ions were satisfactorily removed by EDR for both effluents, giving to them the suitable quality for disposal or reuse in industrial processes. The study presents a mitigating solution to environmental and technological problems, itself as a viable alternative in the tertiary treatment of effluents from the Kraft process in the pulp industry.