Pulp Mills and White Paper: Bringing Down the Environmental Price

October 5, 1994

Jeffery Kahn, JBKahn@LBL.gov

BERKELEY -- Lawrence Berkeley Laboratory researchers led by chemist Shih-Ger (Ted) Chang have developed a new process that could help U.S. paper manufacturers meet proposed new EPA standards. Called the POZONE process, this new technology could cut in half the cost of producing ozone, a form of oxygen used in an environmentally benign method of bleaching pulp.

Paper products are a $125-billion business in the U.S, making it the nation's eighth largest industry. Currently, all but one U.S. mill rely on chlorine-based chemicals to bleach pulp for the production of white paper. Chlorine bleaching creates wastewater containing hazardous organic compounds such as dioxin.

In response to concerns about water pollution and declining fisheries, the EPA has proposed rules that would require U.S. mills to reduce or eliminate chlorine. In Europe, manufacturers already have begun phasing over to a substitute bleaching process that uses a combination of oxygen-based chemicals including ozone. While environmentally friendly, oxygen bleaching processes also are most costly.

The POZONE technique, developed by Chang and his colleagues in LBL's Energy and Environment Division's Flue Gas Chemistry Group, can substantially reduce the costs of generating ozone for the paper industry. U.S. paper mills produced about 14 million tons of pulp in 1993. With about 15 pounds of ozone required to bleach each ton of pulp, the savings from their process, which has been patented and is available for licensing, could total some $105 million/year in the U.S. alone.

In the conventional process, ozone is generated electrically. The POZONE process -- useful in both pulp bleaching and effluent treatment -- generates ozone by chemical means through the reaction of yellow phosphorus with the oxygen in air.

The paper making process starts by feeding wood chips into a digester, which cooks the wood down into pulp. Pulp looks and feels like bread dough, the brown, whole-wheat variety. It consists of cellulose fibers, from which paper will be made, and about five percent lignin, a natural resinous adhesive which gives the pulp a brownish color. To create white paper from brown pulp, paper makers use a series of treatments with bleaching agents.

Both chlorine and oxygen-based bleaching processes can be effective. Both work by breaking down and destroying the lignin. The difference is that chlorine bleaching has environmental consequences and that it has been cheaper.

The POZONE process originally was conceived in order to deal with a different problem. In recent years, Chang and his group have focused on devising new approaches for removing the airborne pollutants emitted by plants that burn fossil fuels, patenting three separate processes. One technology, called PhoSNOX, allows existing power plant scrubbers to perform double duty, not only removing sulfur dioxide but also capturing nitrogen oxides. Part of this multi-stage PhoSNOX process is a new and cheaper means to generate ozone. This creates the basis for POZONE, and what may be a better way to bleach pulp.

The American Public Health Association strongly advocates a phase-out of chlorine-based bleaching in the pulp and paper industry. In 1993, the APHA which represents 50,000 public health professionals, issued an unusual resolution that said the following: "Because chlorinated organic compounds have subtle and widespread effects on human and wildlife health," exposure to organochlorides must be presumed to pose a health problem. For that reason, "policies to protect public health should be directed toward eventually achieving no exposure to chlorinated organic chemicals as a class."

To accomplish this phase-out, changes must occur in a number of industries. Cost-effective and environmentally-friendly, POZONE can help expedite the change to environmentally-friendly processes.

Says Chang, "The potential for POZONE extends well beyond the pulp industry. The semiconductor industry could benefit as could the national effort to cleanup groundwater contaminated with solvents. In both cases, activated carbon often is used to adsorb volatile organic compounds. POZONE can be used to regenerate (recycle) the carbon, reducing costs."

Members of Chang's group include Shu-Mei Wang, who has worked on POZONE for the past three years, David Littlejohn, and Loc Lee.

LBL is a national laboratory that conducts unclassified scientific research for the U.S. Department of Energy. It is located in Berkeley, California, and is managed by the University of California.

For further information, contact:

The POZONE process which has been patented, is available for licensing. For information about licensing, contact Viviana Wolinsky in LBL's Technology Transfer Department at [510] 486-6463.