Parallel treatment of a minimum effluent TMP-newsprint whitewater by aerobic membrane biological treatment and ultrafiltration at 55oC

• Main Author: Ragona, Christina S. F.
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/7987

A lab scale membrane biological reactor (MBR) consisting of an aerobic biological reactor coupled to a lab scale ceramic ultrafiltration membrane (pore size 500 Angstroms) was operated in parallel with an ultrafiltration treatment system consisting of a non-inoculated mixing tank and the identical ultrafiltration membrane to treat a simulated minimum effluent TMP-newsprint Whitewater at 55°C. The MBR system was operated at hydraulic residence times (HRTs) of 1 day, 0.5 days and 0.33 days with a constant solids retention time (SRT) of 20 days, corresponding to water recovery fractions of 0.95, 0.975, and 0.983, while the UF system was operated at water recovery fractions of 0.9, 0.95, 0.983. The filters were operated at a flow through velocity of 4 m/s and a transmembrane pressure of 138 kPa (20 psi). The MBR performed optimally at a water recovery fraction of 0.983, achieving removal of total and dissolved solids of 29% and 22%, and total and dissolved chemical oxygen demand of 48%) and 34%. Removal of resin and fatty acids were 66% and 99% respectively, cationic demand removal was 48% and removal of UV-Lignin, 8%. The maximum flux through the filter was 162 L7(m2»hr) and the time for a 20% loss of flux was 110 hours. The UF system performed best at a water recovery fraction of 0.95, achieving lower removal of total solids (23%), dissolved solids (18%), total COD (31%), dissolved COD (4%) than the MBR. Removal of resin and fatty acids were 95% and 98% respectively, and removal of cationic demand was 74%. UV-Lignin was not removed at all by the UF system. Maximum flux through the filter was 162 L/(m²∙hr) and the time for a 20% loss of flux was 170 hours. The reduced fouling potential and improved removal of certain contaminants coupled with the lower cost of operation and fewer operational upsets would suggest the ultrafiltration treatment system operated at a water recovery fraction of 0.95 (or volume reduction factor of 20) has higher potential for treating minimum effluent TMP-newsprint Whitewater at 55°C than aerobic membrane biological treatment.