title: Unexpected promotion of PCDD/F formation by enzyme-aided Cl2bleaching in non-wood pulp and paper mill.
abstract: Enzyme-aided Cl2bleaching is widely considered as promising replacements for conventional Cl2bleaching in wood pulp and paper mills. However, the effects of using enzyme-aided bleaching on the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the non-wood pulp and paper mills are unclear. A field study was performed to investigate PCDD/F formation when enzyme-aided Cl2bleaching was used to replace conventional Cl2bleaching in non-wood pulp and paper mills. Unexpectedly, the PCDD/F toxic equivalents (TEQs) in solid samples were higher when using enzyme-aided bleaching (0.49-5.4 pg TEQ/g) than that using conventional Cl2bleaching (0.15-2.44 pg TEQ/g). Large amounts of octachlorodibenzo-p-dioxin were formed during the enzyme-aided bleaching process. This could have been because enzyme strongly promoted the release of organic molecules bound to lignin and thus accelerated the formation of octachlorodibenzo-p-dioxin through organic molecular precursors. Although enzyme-aided Cl2bleaching was previously considered to be efficient for reducing PCDD/F releases and to be the best available technologies and best environmental practices for wood pulp and paper mills, the results obtained in this study suggested the necessity and urgency to evaluate the suitability of enzyme-aided Cl2bleaching for non-wood pulp and paper mills that intensively practiced in developing countries.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China; Institute for Environmental Reference Materials of Ministry of Environmental Protection of the People's Republic of China, Beijing, 100029, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China.
authors.forename: Minghui
authors.initials: M
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China. Electronic address: grliu@rcees.ac.cn.
authors.forename: Guorui
authors.initials: G
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China.
authors.forename: Yuyang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Liu
authors.affiliation: Institute for Environmental Reference Materials of Ministry of Environmental Protection of the People's Republic of China, Beijing, 100029, China.
authors.forename: Linyan
authors.initials: L
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China.
authors.forename: Li
authors.initials: L
authors.lastname: Guo
mesh_terms: D057886:Bleaching Agents / Q000737:chemistry*; D002681:China; D002713:Chlorine / Q000737:chemistry; D000072338:Dibenzofurans, Polychlorinated / Q000032:analysis*; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007220:Industrial Waste / Q000032:analysis; D010209:Paper; D000072317:Polychlorinated Dibenzodioxins / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D057886:Bleaching Agents; D000072338:Dibenzofurans, Polychlorinated; D007220:Industrial Waste; D000072317:Polychlorinated Dibenzodioxins; D014874:Water Pollutants, Chemical; D002713:Chlorine
keywords: Bleaching; Dioxins; Non-wood fiber; Pulp and paper making; Xylanase