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Evaluation of Ecological Risks Associated with the Use of Chlorine Dioxide for the Bleaching of Pulp

Scientific Progress Since 1993.

Doug Bright, Royal Roads University, 2005 Sooke Road, Victoria, BC, V9B 5Y2
Peter Hodson, School of Environmental Studies, Queen's University, Kingston, ON, K7L 3N6
Karl-Johan Lehtinen,
Finnish Environmental Research Group, Techniikantie, 12, Espoo, Finland, SF-02150
Bruce McKague,
CanSyn Chem. Corp, 200 College Street, Toronto, Ont., M5S 1A4, CANADA.
John Rodgers,
Department of Biology, University of Mississippi, University, MS 38677
Keith Solomon,
Centre for Toxicology, University of Guelph, Guelph, Ontario, N1G 2W1, CANADA (Chair).





Table of Content

 

Executive Sumary


    1. INTRODUCTION 2. CHARACTERIZATION OF POTENTIALLY HAZARDOUS SUBSTANCES

    3. ENVIRONMENTAL FATE PROCESSES

    4. EFFECTS CHARACTERIZATION

    5. CHARACTERIZATION OF RISK

    6. ECOLOGICAL RELEVANCE

    7. UNCERTAINTIES

    8. LITERATURE CITED

    LIST OF TABLES

    Table 3.1 Compound previously detected in pulp mill final effluents (before and after
    treatment) and expected environmental behavior
    Table 4-1 Compounds, effluents, and process streams from pulp mills that are associated
    with specific physiological responses of fish
    Table 4-2 Results of chronic toxicity tests using effluents from mills with ECF bleaching
    Table 5.1 Toxicity criteria and hazard quotients for chlorinated compounds in mill effluents
    produced from bleaching processes with 100% chlorine dioxide substitution
    Table 5.2 Probabilistic assessment of chlorophenol TEQs exceeding the EPA FW criteria


    LIST OF FIGURES

    Figure 1 The risk assessment process as proposed for use under CEPA (Environment Canada,
    1997)
    Figure 2 The process of pulp production under bleaching.
    Figure 3 Chlorinated aromatic compounds identified from samples of degraded fulvic acid from
    both natural and bleached kraft mill effluents.
    Figure 4 A reaction of lignin with chlorine dioxide.
    Figure 5 New organic substances identified in effluent from ECF bleaching.
    Figure 6 The reaction of lignin with ozone.
    Figure 7 Diagrammatic representation of exposure pathways in pulp mill effluents.
    Figure 8 Sterols and triterpenoids found in pulp mill effluents.
    Figure 9 Biotransformation reactions in pulp mill effuents.
    Figure 10 Temporal trends in total TCDD/TCDF loads from pulp mill in BC, Canada.
    Figure 11 Temporal trends in concentration of TCDD/TCDF reported in mill effluents from BC,
    Canada.
    Figure 12 Changes in liver tissue EROD activity in rainbow trout exposed to 1/400 dilution of
    effluents from pulp mills and other sources.
    Figure 13 Illustration of the tiers of risk assessment.
    Figure 14 Distributions of concentration of tetrachloroguaiacol and tetrachlorocatechol from
    mills using 100% chlorine dioxide substitution compared to the most sensitive toxicity
    enpoint.
    Figure 15 Distribution of concentrations of all chlorinated phenols from mills using 100%
    chlorine dioxide substitution expressed as pentachlorophenol TEQs and compared to
    assessment criteria for pentachlorophenol.
    APPENDIX 1 Compounds identified since 1993 in effluent from mills employing ECF bleaching


    Continue to Section 1