White paper - with less dioxin.White paper--with less dioxin Last year's finding that chlorine bleaching of wood pulp Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter. The main use of wood pulp is to make paper where whiteness (similar to but not exactly the same as "brightness") is an important generte some 250 different chlorinated chlorinated /chlo·ri·nat·ed/ (klor´i-nat?ed) treated or charged with chlorine. chlorinated charged with chlorine. chlorinated acids some, e.g. contaminants, including the most toxic dioxin, sent paper mills scurrying scur·ry intr.v. scur·ried, scur·ry·ing, scur·ries 1. To go with light running steps; scamper. 2. To flurry or swirl about. n. pl. scur·ries 1. The act of scurrying. to modify or redesign their bleaching operations (SN: 8/5/89, p.94). One new technology promises not only to reduce these toxic residues in pulp and its wastes by more than 90 percent, but also to cut costs and bleaching time, reports I.J. Wilk, a consulting chemist in Menlo Park, Calif. His system passes an electric current through a saltwater bath containing 10 percent wood pulp. As the briny solution decomposes, oxygen, chlorine and ozone are generated at the positive electrode. Wilk observes that this "very potent" bleaching combo takes only 4 to 15 minutes to accomplish the same degree of whitening whit·en·ing n. 1. An agent used to make something white or whiter. 2. The act or process of making white or whiter. Noun 1. obtained after 1 hour or more with conventional pulp-bleaching mixes. Moreover, in 15-minute test runs, his electrolytic e·lec·tro·lyt·ic adj. 1. Of or relating to electrolysis. 2. Produced by electrolysis. 3. Of or relating to electrolytes. e·lec system produced only 0.6 to 0.8 percent as much chlorinated organic pollution as conventional chlorine bleaching and only 8 percent as much as chlorine-dioxide bleaching. "By adjusting ozone levels, we think we might be able to totally eliminate any chlorinated [organic contaminants]," Wilk told SCIENCE NEWS. However, he adds, because the test data show that this system can also destroy chlorinated organic chemicals, any contaminants that do form might be purged by simply recycling the contaminated wastewater -- minus the pulp -- through the electrolytic cell. Though his team has not yet assayed for dioxin in the pulp and waste, Wilk says, "we don't expect to find any dioxin" because the process generates such a low overall level of chlorinated contaminants. Last week the U.S. government added impetus to the search for cleaner pulp-bleaching techniques when EPA EPA eicosapentaenoic acid. EPA abbr. eicosapentaenoic acid EPA, n.pr See acid, eicosapentaenoic. EPA, n. and FDA FDA abbr. Food and Drug Administration FDA, n.pr See Food and Drug Administration. FDA, n.pr the abbreviation for the Food and Drug Administration. announced plans to formally regulate dioxin levels in pulp wastewater, sludges and possibly paper products. Said EPA Deputy Administrator Henry F. Habicht, "Even though dioxin levels in paper products are small enough to be no cause for alarm, our intention is to reduce those levels even more." |
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