Application of Membrane Filtration for Reuse of Bleaching Plant Effluent in the Process

摘要

Membrane filtration technology is being adopted increasingly in the paper mills for closing of process water streams. E- Stage bleaching effluent is very well suited for ultrafiltration process because of its comparatively small volume and high molecular -weight -substances in it. In the present study extraction stage (E- stage) bleach plant effluent of an integrated paper mill employing CEH bleaching sequence for bleaching of hardwood pulp was treated in the Ultrafiltration (UF), Nanofiltration (NF) and Reverse osmosis (RO) in series. Concentrate of each stage is recycled back and permeate of ultrafiltration is fed to nanofiltration, and permeate of nanofiltration is fed to RO. Molecular weight cut-of (MWCO) were 1000, 300 and 50 Dalton, for UF, NF and RO respectively. Initial inlet pressure was 6.8 bar for UF, NF and 10.3 bar for RO. All membranes performed well as per expectation and water recovery was 86.4%, 95.28% and 95.95% for UF, NF and RO membrane respectively.