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Treatment of thermomechanical (TMP) white water with organically-tailored synthetic zeolites

University of British Columbia

In an effort to reduce fresh water usage and wastewater discharge, white water process streams in pulp and paper mills can be targeted for recycling. However, accumulations of dissolved and colloidal substances (DCS) in a closed white water system are detrimental to mill operations, machine runnability, and product quality. This study determined the technical feasibility of using organically-tailored synthetic zeolites, whose cation exchange capacities (CEC) and external CEC (ECEC) values ranged from approximately 80 to 240 meq/lOOg and 20 to 160 meq/lOOg, respectively, for treatments of synthetic process water (SPW) and thermomechanical (TMP) white water (WW) samples. The SPW contained only dehydroabietic acid (DHA) at a concentration of approximately 30 mg/L. Treatment of SPW with untailored synthetic zeolites at 20 g/L mineral dose resulted in removal of 19-45% of DHA. Complete uptakes of DHA were also achieved when water-soluble organic cations (C15 and C17) were used to tailor the zeolites. Lower DHA uptake capacities (9-71% removal efficiencies) were observed when alcohol- (methanol and ethanol) soluble organic surfactants (C20-C40) were used for tailoring the zeolites. Mineral doses of TDTMA-tailored synthetic zeolite as low as 5 g/L removed 90% of the DHA from SPW, and complete DHA removal was obtained at doses of 10 g/L and higher. Also, the uptake of DHA from SPW by TDTMA-tailored synthetic zeolite occurred within minutes of contact, where the maximum removal efficiency was achieved after 3 minutes of treatment. DHA removals at low pH (4-7.25) values ranged from 40 to 100%, as compared to the 20-27% removals observed at pH 10-12. In addition, the removal of DHA from SPW was not affected by the nature of the buffering system used (unbuffered, acetate, and phosphate). Treatment of white waters (pH 7.25) using TDTMA-tailored zeolites at 1 g/L mineral dose resulted in 51% reduction of resin and fatty acids (RFA), 10% removals of soluble biochemical and chemical oxygen demands, 85% removal of acute toxicity, and 24% uptake of sterols. Higher (20 g/L) mineral doses resulted in more complete removals of the compounds of concern: RFA (100%), soluble biochemical oxygen demand (SBOD) (36%), soluble chemical oxygen demand (SCOD) (38%), acute toxicity (91%), and sterols (100%).

Thesis/Dissertation

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2009-08-13

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http://hdl.handle.net/2429/12184

Chemical and Biological Engineering

University of British Columbia

UBCV

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