By George Couch Researchers at the USDA Forest Service Forest Products Laboratory (FPL) have joined with several other federal agencies and the pulp and paper industry in an effort to reduce the economic and environmental costs of paper used by government agencies—while simultaneously improving paper quality. The federal government annually buys 500,000 tons of bleached kraft paper. That includes paper used in computer printers, copiers, and fax machines. It’s the equivalent of using 11 million standard sheets of paper per hour, every hour of the year. (Even so, the federal government uses less than 2 percent of the bleached kraft paper produced in North America each year.) In a “Green Engineering Partnership,” FPL researchers are working with the Office of the Federal Environmental Executive, the Government Printing Office, the Environmental Protection Agency’s Office of Solid Waste, the Government Services Agency, and the Department of Defense Printing Service. The initial task facing the group will be to redefine paper “quality,” that is, to determine what performance criteria for paper are most important to government printers and offices. “One way to improve some paper performance characteristics while simultaneously reducing cost is to reduce the amount of bleaching,” explained Dr. Carl Houtman, a chemical engineer in FPL’s paper research unit. “Eliminating a bleaching stage would conserve energy, wood pulp, water, and chemicals. The resulting paper will likely be stronger and more durable and possess other characteristics that better meet the government’s needs.” Not surprisingly, however, eliminating a bleaching stage would also reduce the paper’s “brightness.” Brightness is defined by the International Standards Organization (ISO) as the percentage of blue light at a particular wave length (457 nanometers) that is reflected by the paper’s surface. Brightness is normally measured on an ISO scale, with standard office printing papers being in the range of 82 to 95 ISO. A brightness index of 90 ISO or above is commonly associated with “high quality” papers. Some manufacturers add fluorescent compounds to the paper’s surface to increase brightness—enabling one major retail chain to advertise paper with a brightness index of 113! Because pulp must be bleached at least 5 points higher than the final paper brightness to compensate for a phenomenon called brightness reversion, paper with an 84 ISO brightness—like much of that used in government agencies—requires actual bleaching to 89 ISO. The Green Engineering Partnership is challenging the assumption that high brightness is important for most applications. “Depending on how the paper is being used, high brightness might not be desirable,” Houtman said. “For example, it might create glare that could interfere with readability. And the amount of bleaching needed to achieve a high brightness will have a negative impact on qualities such as durability or printability.” And, of course, achieving high brightness ratings requires more energy, more chemicals, and more wood pulp. A shorter process could reduce energy consumption by one-third and similarly reduce handling and consumption of potentially hazardous chemicals such as hydrogen peroxide, chlorine dioxide, and alkali. Pulp yield could be increased by as much as 1 percent, significantly reducing wood consumption. Eliminating a bleaching step could reduce the cost of paper by $34 per ton, saving the federal government $17 million a year. A typical pulp plant processing 1,000 tons per day would save more than $11 million per year, and 70 such plants operate in the United States. Eventually, the big savings—economically and environmentally—will come when less bright paper becomes more widely accepted. In North America, some 40 million tons of bleached kraft paper are produced each year, and 98 percent of this paper is used by businesses, state and local governments, and consumers. *This article first appeared in the Summer ‘05 issue of the Forest Products Laboratory’s quarterly newsletter, NewsLine.
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