Nanofiltration as Pretreatment to Reverse Osmosis for Paper and Pulp Mill Effluent

Abstract

The paper and pulp industry produces effluent which is high in organic content and salinity, typically making is difficult to treat. For reclamation of this wastewater, the process should be designed such that the water is ‘fit for purpose’. Agricultural reuse of this waste stream is a potential option as the treatment requirements are less intense than for other reuse opportunities. This papers forms part of a larger project for developing an integrated UF-NF-RO system for reclaiming the biologically treated effluent from a thermo-mechanical pulp and paper mill in rural Australia. The current work has characterised the waste water and investigated a suite of commercially available NF membranes as a pre-treatment method for RO. Dead-end stirred cell filtration has been used to evaluate the selective removal of multivalent ions and low molecular weight organics in the NF stage. The result demonstrate the importance of the NF stage to the reclaimed water and show a SAR reduction of between 30-60% is achievable in this system. Of the commercially available membranes tested the membrane which performed the best was the NTR-7450 membrane from Hydranautics.