UF/NF TREATMENT OF ORGANIC LADEN WASTEWATER IN INDUSTRIAL PULP AND PAPER WASTEWATER

摘要

The pulp and paper industry converts massive amounts of wood pulp into bright whitepaper. During the chemical processing of the pulp, bleaching and caustic extraction areused to remove the lignin molecules which give a brownish color to the paper. As aresult, though, the process generates large quantities of wastewater which have high pH,high temperature, and high organic load. A unique sulfonated polyethersulfone NFmembrane was chosen for this application since it was suitable for high pH operation andcould reject the organic material, while passing much of the inorganic ions. This wouldallow the membrane process to operate at high recovery.Initial lab trials with this color removal NF membrane and plant wastewater proved thatthe color could be removed at high recoveries, but when trialed at the plant, it was foundthat the NF elements readily fouled. Further experiments proved that very fine colloidalmaterial was the cause of the fouling. A capillary UF pretreatment system was institutedprior to the NF membrane, and resolved the fouling problem. Operating data from the testare reported and show stable operation and the ability to clean and recover performance.The NF was run at up to 90% recovery and was able to reduce color from 12,000 PCU to20 PCU, while only rejecting about 50% of the inorganic ions. Evaluations wereunderway to consider the feasibility of reusing the permeate and the concentrate in thepapermaking process.