Treatment of whitewater from pulp and paper industry using membrane filtrations

Abstract

This work investigated the feasibility of membrane filtrations such as reverse osmosis (RO) in treating whitewater from a pulp and paper mill due to thermo-mechanical pulping. The effects of pH and removal mechanisms of silicon by the membranes during treatment were discussed. Their individual performance in removing target compound was critically evaluated and compared to those of previous studies. It is found that membrane treatment could remove SiO2 from the wastewater samples. With 200 mg/L of initial concentration at pH 11 and 10 bar of pressure, 80% and 85% of silicon could be removed when applying ultrafiltration (UF) or nanofiltration (NF) membrane for 12 h. RO achieved an almost complete removal of target pollutant at 10 bar under identical conditions. Treated effluents, resulting from the membrane filtration, could comply with the maximum effluent limit of lower than 50 mg/L imposed by local legislation. Hence, further treatments are unnecessary.