Decreasing effluent loads through bleaching modification
Autor: | Ai Van Tran |
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Rok vydání: | 2005 |
Předmět: |
Paper
Environmental Engineering Bleach chemistry.chemical_element Industrial Waste engineering.material Kappa number Waste Disposal Fluid chemistry.chemical_compound polycyclic compounds Chlorine Coloring Agents Waste Management and Disposal Effluent Water Science and Technology Civil and Structural Engineering Chlorine dioxide Waste management Viscosity Ecological Modeling Pulp (paper) Oxides Hydrogen Peroxide Pulp and paper industry Oxidants Pollution Oxygen chemistry Kraft process engineering Chlorine Compounds Waste disposal |
Zdroj: | Water research. 40(3) |
ISSN: | 0043-1354 |
Popis: | Almost all of the kraft pulp bleach plants worldwide are now practicing elemental chlorine-free (ECF) process to comply with environmental regulations in different countries. Usually, these conventional ECF bleaching sequences contain one or two alkaline extraction stages of which the first one is often the principal source of color and chemical oxygen demand (COD) in the resulting effluent. However, the results of this study showed that the ECF sequences which did not include any alkaline extraction stage and contained solely chlorine dioxide decreased both the color and COD loads of the effluent. On the other hand, the ECF sequences containing both chlorine dioxide and hydrogen peroxide but excluding the alkaline extraction stage could lower only the color but not the COD load. It is suggested that the total kappa factor (the ratio of the total active chlorine to the kappa number) affected the COD load and that the content of hexeneuronic acid groups influenced the color of the bleach effluent. Compared to the reference pulp, the viscosity of the pulp from the exclusively chlorine-dioxide-based ECF sequence without the alkaline extraction stage was lower but the tear index and sheet density at a given tensile index were similar. |
Databáze: | OpenAIRE |
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