Formation and emission of PCDD/Fs in Chinese non-wood pulp and paper mills.
Chlorine bleaching is still practiced by non-wood pulp and paper mills in China, resulting in considerable formation and emission of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). We investigate the distribution of PCDD/Fs in different papermaking processes and dioxin emissions at six typical Chinese non-wood pulp and paper mills. Raw materials for papermaking included reed, wheat straw, bamboo, and sugar cane bagasse. The formation and emission of PCDD/Fs varied strikingly according to bleaching processes and raw materials. Elemental chlorine bleaching promoted the formation of tetra- to octa-CDDs and 2,3,7,8-TCDF, while hypochlorite bleaching only gave rise to a significant increase of 2,3,7,8-TCDF. Bleaching with elemental chlorine and hypochlorite increased 2,3,7,8-TCDF 0.9-42.5 and 0.3-4.1 times, respectively. Most of the 2,3,7,8-TCDF formed at hypochlorite bleaching stage was partitioned into the effluent, which indicated that hypochlorite bleaching was also an important emission source of dioxins. The removal of PCDD/Fs occurred visibly during alkaline digestion, alkaline extraction, and hydrogen peroxide bleaching. Furthermore, the annual emission of PCDD/Fs from Chinese non-wood pulp and paper mills was evaluated.
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, People's Republic of China.
Xueli
X
Wang
Yuwen
Y
Ni
Haijun
H
Zhang
Xueping
X
Zhang
Jiping
J
Chen
D000393:Air Pollutants / Q000032:analysis*; D001572:Benzofurans / Q000032:analysis*; D002681:China; D002713:Chlorine / Q000737:chemistry; D000072338:Dibenzofurans, Polychlorinated; D004784:Environmental Monitoring; D006861:Hydrogen Peroxide / Q000737:chemistry; D006997:Hypochlorous Acid / Q000737:chemistry; D007220:Industrial Waste; D016877:Oxidants / Q000737:chemistry; D010209:Paper; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis
D000393:Air Pollutants; D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D007220:Industrial Waste; D016877:Oxidants; D000072317:Polychlorinated Dibenzodioxins; D002713:Chlorine; D006997:Hypochlorous Acid; D006861:Hydrogen Peroxide