MEMBRANE TECHNOLOGIES FOR PULP AND PAPER APPLICATIONS

Membrane technologies for three different pulp and paper applications are currently under investigation at the Pulp and Paper Research Insti tute of Canada. These are: Ultrafiltration and reverse osmosis for the treatment of mechanical pulp mill effluents and for water reuse; Elec trolysis of a portion of weak black liquor in kraft mills for providin g incremental kraft recovery capacity, low sodium and sulphur lignin a nd pure caustic soda; Bipolar membrane electrodialysis for the product ion of bleaching chemicals (e.g., caustic soda and chloric acid) while , at the same time, addressing the sodium and sulphur imbalance proble ms at kraft mills. This paper reviews the investigation of these three technologies in terms of technical feasibility, process integration a nd economics.