Removal of contaminants from recirculated white water by ultrafiltration and/or biological treatment

This study investigated the potential of ultrafiltration technology and/or biological treatment to remove contaminants such as total dissolved solids (TDS), chemical oxygen demand (GOD), total organic carbon (TOC), and resin and fatty acids (RFAs) from recirculated white water. Batch ultrafiltration experiments indicated that TDS, soluble GOD, and TOC removal efficiencies were affected by membrane molecular weight (molar mass) cut-off, but were independent of the operating temperature, in the 20 to 60 degrees C range. Except for fatty acids, where average removals exceeded 90%, the separation efficiency of the process for all other parameters (TDS, soluble GOD, TOC, and resin acids) was moderate, ranging from 10 to 41%. Biological treatment using a sequencing batch reactor (SBR) unit was very effective in removing RFAs, TOC, total and soluble GOD. Furthermore, ultrafiltration of the biologically treated process water resulted in significant additional TDS, soluble GOD, and TOC removal.