Comparison Between Ultrafiltration and Membrane Biological Reactor Treatment for Closure of Mechanical Newsprint Mills, 1997 Environmental Conference Proceedings

Ultrafiltration (UF) and aerobic membrane biological reactor (MBR) treatment were compared as potential treatment alternatives to remove dissolved and colloidal substances (DCS) from a synthetic recirculated newsprint whitewater. The parameters considered in this study included resin and fatty acids (RA and FA), COD, solids, cationic demand and color. The same UF unit (molecular weight cut-off = 75 kDaltons) was used for both the UF and the MBR lab scale studies. The MBR is a modification of the activated sludge process whereby UF is used as the solids-liquid separation step.

The MBR system was several-fold more effective at removing compounds contributing to COD than UF, due to bio- oxidation of the degradable organic matter. Excellent removal efficiencies were obtained with both processes for FA removal (>98%), but the MBR was more effective at removing RA, due to rapid sludge adsorption. Pitch deposits encountered during UF of the whitewater were not experienced with the MBR. For both processes, total dissolved solids and color removal efficiencies were modest. Although the MBR resulted in better removal of most contaminants, the use of UF may be a more conservative choice for use as a kidney to purge DCS from a closed mechanical newsprint mill.