Pulp & Paper Production Chapter V

INTERNETINTERNET EDITIONEDITION PULP & PAPER PRODUCTION CHAPTER V ZEROING OUT DIOXIN IN THE GREAT LAKES: WITHIN OUR REACH June 1996 CBNS CENTER FOR THE BIOLOGY OF NATURAL SYSTEMS QUEENS COLLEGE, CUNY FLUSHING, NEW YORK http://www.qc.edu/CBNS PULP & PAPER PRODUCTION CHAPTER V ZEROING OUT DIOXIN IN THE GREAT LAKES: WITHIN OUR REACH Barry Commoner Mark Cohen Paul Woods Bartlett Alan Dickar Holger Eisl Catherine Hill Joyce Rosenthal June 1996 This report is the result of the second year’s work on a two-year project, “Economically Constructive Conversion of the Sources Contributing to the Chemical Pollution of the Great Lakes,” supported by The Joyce Foundation. Printed on 100% post-consumer recycled paper processed without chlorine. TABLE OF CONTENTS I. Introduction II. Strategic Approach References III. Medical Waste Incineration A. Introduction B. Technical Background C. Economic Analysis of the Alternative Means of Medical Waste Disposal D. Conclusions References IV. Municipal Solid Waste (MSW) Incinerators A. Introduction B. The Regulatory Situation C. Implementation of An Intensive Recycling System In the Great Lakes Region D. Direct Economic Impact of the Intensive Recycling Programs E. Other Economic Impacts of Implementing the Intensive Recycling Programs F. Conclusions and Recommendations References Appendix V. Paper and Pulp A. Introduction B. Technical Background C. The Environmental Effects of Chlorine Dioxide-ECF and TCF Technology D. Economic Analysis E. Product Marketing and Demand References Appendix VI. Iron Sintering A. Introduction B. Technical Background C. Economic Analysis D. Conclusions and Recommendations References VII. Cement Kilns Burning Hazardous Waste A. Introduction B. The Regulatory Situation C. Technical Background D. The Economic Consequences of Preventing Dioxin Emissions E. Conclusions and Recommendations References VIII. Conclusions References V-1 V. PULP & PAPER PRODUCTION A. Introduction: The paper and pulp mills that dispose of their effluent into the Great Lakes and their tributary rivers contribute a relatively small part of the total amount of dioxin1 that enters the lakes. Nevertheless, even this effect is important, for however dilute dioxin may be, it becomes concentrated in its passage through the food chain. Moreover, in pulp mill effluent dioxin is accompanied by a large group of other chlorinated organic compounds, lumped together under the term “AOX”. Although in recent years the industry has made a successful effort to reduce the levels of dioxin in pulp mill effluent and the pulp itself, the levels of AOX and other pollutants remain relatively high. Even the most modern low effluent mills have toxic effects on aquatic organisms. Because of the multiplicity of pollutants produced by paper and pulp production, and the high cost of removing them once they are produced, there is a growing recognition that pulp and paper mills must move toward a design in which effluents, instead of being released, are recycled in a closed loop. As it happens, the technical possibility of achieving such a “Totally Effluent Free” (TEF) pulp mill is facilitated by the design changes that produce a “Totally Chlorine Free” (TCF) system -- which realizes the goal of completely preventing the formation of dioxin to begin with. For these reasons, despite the considerable reduction in the pulp and paper industry’s environmental impact on the Great Lakes, it remains important to consider what can be done to completely eliminate the production of dioxin and other chlorinated pollutants that are now generated by pulp and paper mills. The response of industry and the regulatory agencies to the problem of waterborne dioxin created by pulp mills contrasts sharply with their response to the airborne sources that we have analyzed. The remedial approach to the airborne sources has relied on tacked-on control devices. In contrast, in the last decade the pulp and paper industry, faced with the issue of dioxin pollution, has made changes in the production process itself, applying the strategy of pollution prevention rather than control. And, like the most familiar successes of pollution prevention -- the more than 95% reduction in airborne lead emissions largely achieved by removing lead from the production of gasoline -- the strategy has worked equally well to reduce the dioxin content of pulp mill effluents. To this extent, the recent effort of the industry to deal with the dioxin problem can be regarded as a salutary example to other industries -- many of which regard pollution prevention as moreof a slogan than a principle of action. 1 As is the general case throughout this report, and noted earlier, we use the term “dioxin” here as it has become commonly used to denote the entire class of toxic polychlorinated dioxins and furans. When discussing empirical measurements or chemical mechanisms however, we will occasionally specify particular dioxin and furan congeners. V-2 B. Technical Background: 1. The basic process: Wood is chiefly composed of two major substances; both are organic, that is, their molecules are built around chains and rings of carbon atoms. Cellulose, which occurs in the walls of the plant cells, is the fibrous material that is used to make paper. Lignin is a large, complex molecule; it acts as a kind of glue that holds the cellulose fibers together and stiffens the cell walls, giving wood its mechanical strength. In order to convert wood into pulp suitable for making paper, the cellulose fibers must be freed from the lignin. In mechanical pulping this is done by tearing the wood fibers apart physically to create groundwood pulp, leaving most of the lignin intact in the pulp. The high lignin content of groundwood pulp leaves the paper products weak and prone to degradation (e.g. yellowing) over time. Mechanical pulp is used principally to manufacture newsprint and some magazines. In most pulp production -- for example, the kraft (German for strong) process -- lignin is separated from the fibers chemically: wood chips are heated (“cooked”) in a solution of sodium hydroxide and sodium sulfide.2 The lignin is broken down into smaller segments and dissolves into the solution. In the next step, “brownstock washing,” the breakdown products and chemicals are washed out of the pulp and sent to the recovery boiler.3 Kraft unbleached pulp has a distinctive dark brown color, due to darkened residual lignin,4 but is nevertheless exceptionally strong and suitable for packaging, tissue and toweling. For brighter and more durable products the pulp must be bleached: the color in the residual lignin is either neutralized (by destroying the chromophoric groups5 ) or removed with the lignin. This process traditionally has been accomplished for kraft pulp by chlorine bleaching, usually followed by washing and extraction of the chemicals and breakdown products. This process is not much different than washing clothes: the stains imbedded in cloth fibers are either neutralized by bleach, or broken down and washed out. Thus, the basic steps in pulp production are: delignification; brownstock washing; 2The kraft pulping process is the dominant chemical process in the United States as a whole and in the Great Lakes region. In another chemical process, the sulfite process, pulp is produced by cooking wood chips in an acidic or neutral solution of bisulfides. 3The processing chemicals are recovered for reuse in this process, but not completely: the air emission of sulfur compounds produce the distinctive aroma of the kraft pulp mill. 4The traditional kraft cooking process removes 80% of the lignin. (Smook, 1992, pg 77). 5Chromophoric groups are particular chemical structures which absorb specific wave lengths of light, giving the substance color. Bleaching agents either restructure or break up the chromophoric groups by oxidation or chlorination reactions, thereby eliminating the color in the pulp. V-3 bleaching; and extraction. Additional bleaching and extraction stages are added to achieve the desired brightness. As the industry has developed, these basic steps have been refined and additional chemicals and sequences introduced. (See Figure V-A in Appendix.) 2. The pollution problem: Long before the dioxin problem arose, pulp mills were notorious sources of environmental pollution. Although their most obvious environmental effect was foul sulfur odors, the more serious impact was on local rivers and lakes. The spent chemicals and waste products were dumped into the waters. In the 1930's, the industry developed a radical pollution prevention innovation: the brownstock washing was recirculated to a recovery boiler where the pulping chemicals were recovered for reuse and the lignin was used to generate energy. The cost savings made kraft mills more competitive. In the 70's and 80's end-of-pipe treatment dominated pollution reduction efforts in North America. In the Nordic countries the application of the principle of pollution prevention has led to a complex and flexible array of production processes, among them ones that have a crucial impact on the dioxin problem. The most serious pollution problems have arisen from the use of chlorine in bleaching.6 Emitted into local bodies of water, these pollutants have rendered water unfit for drinking, made fish unsuitable for consumption and seriously harmed aquatic life. Chlorine, in the elemental form of chlorine gas, readily reacts with organic molecules. As a result, when chlorine enters the pulping process it reacts with lignin, its breakdown products, other organic plant components, and chemical contaminants to form numerous chlorinated organic chemicals, many of them toxic. These are referred to, collectively, as “AOX.” By 1993, more than 300 chlorinated organic compounds had been reported in pulp mill bleach plant effluents; but these were estimated to account for no more than 10% of the effluent components (Suntio et al., 1988; USEPA, August 1993, p. 2-10-11). As of 1994, 415 organic substances had been identified (Paper Task Force, 1995c, p. 34). The bulk of the chlorinated organics (75-90%) are high molecular weight compounds (HMWC’s molecular weight > 1,000), which are difficult to characterize due to their large size and variable structures.

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