MillWatch #37 (August 2002): News for People Interested in CLEAN Pulp and Paper Production

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In the August 2001 Pollution Engineering "Industry News" section, there were some brief paragraphs announcing a catalytic process that converts toxic waste streams from Kraft pulp mills into valuable formaldehyde (a building-block chemical that is used for adhesives that find wide application in the plywood industry). The inventor of this environmentally benign process is Israel E. Wachs, professor of chemical engineering at Lehigh University, Bethlehem, PA.

There are roughly 150 kraft pulp mills in North America and they generate waste streams that contain the largest Hazardous Air Pollutants. Methanol is the largest single source of emissions from kraft pulp mills, accounting for 70 to 80 percent of total emissions.

A Kraft process uses sodium sulfites to chew up the wood and make pulp. The problem: Wood contains wood alcohol/methanol precursors and because the process uses sulfites to do the "pulp digesting," some of the sulfur also gets into the wood alcohol precursors and forms methyl mercaptans (CH3SH, CH3SCH3 and CH3SSCH3). The condensable waste stream has previously been disposed of by dumping the stream into rivers.

The US EPA "cluster rule," which went into effect April 15, 2001, places limits on methanol emissions for all pulp mills in the United States. This gave the industry eight years to determine how to best comply. At that time, two alternative technologies were proposed to attain compliance.

First, incineration at 1,500 degrees F, which burns the condensable waste stream and creates CO2 and some SO2, as well as NOX emissions that are associated with global warming gases and acid rain. The other option is bioremediation, to put it in a pond and have specific bacteria digest the methanol and mercaptans. They too will generate CO2 and SO2. Although this is less energy intensive, the waste is still being converted to CO2 and SO2.

In September of 1994, Andrew Gibson, the manager for process improvements for Georgia-Pacific Corp., invited Wachs to lunch to discuss these environmental issues facing the pulp and paper industry and to ask him if he had any other ideas. Presented with this challenge, Wachs grabbed the nearest napkin and started drawing a process scheme that would address the problem.

"My first position was why are you incinerating valuable methanol since it is a major chemical commodity for the paper industry and it can be converted into formaldehyde, which is used to manufacture resins for plywood?" Wachs recalls.

Wachs proceeded to design a catalytic process which recovers formaldehyde and valuable terpenes used to make specialty chemicals such as fragrances and waxes, recycles the SO2 that the mills need to digest the wood, and emits no NOX.

The process was tested for two years at a Georgia-Pacific pilot plant reactor, 5 feet long with a 1-inch tube diameter at a mill in Brunswick, GA.

This is what Wachs defines as "true green engineering and chemistry" since all of the valuable products are produced from renewable resources--trees rather than fossil fuels. The SO2 and NOX emissions are completely eliminated, CO2 emissions are only several percent that of incineration, the methanol and mercaptans are selectively converted to valuable formaldehyde, and the terpenes are recovered as specialty chemicals.

Furthermore, the resulting produced steam from this oxidation can be sent elsewhere in the pulp and paper plant for use as process heat. In addition, this new environmentally benign process produces revenues of approximately $1 million per year (economic analysis performed by Andrew Gibson). Thus, current disposal costs are replaced by significant annual profits.

For the 150 Kraft pulp mill plants in North America, implementation of this novel technology would result in pollution reductions amounting to ~4,200 tons/year of CO2, ~6,500 tons/year of SO2 as well as smaller amounts of NOX.

Once the demonstration unit has been proven at a pulp mill, the new technology will be available for licensing to pulp and paper manufacturers. The final outcome from the demonstration unit will be reported when the commercial tests are successfully completed (expected to be in 2003).

* Excerpted with permission from Pollution Engineering, January 2002, www.pollutionengineering.com

The "Zero AOX" law quietly repealed by the British Columbia Liberals in July would have done much more than eliminate persistent toxins from pulp mill effluent. Achieving the goal of zero organochlorine discharge would have improved environmental health, worker and community safety and pointed towards a value-added future for BC's pulp and paper industry.

A week before the government granted the pulp industry relief from the law's December 2002 deadline, an accidental release of chlorine dioxide gas at the Howe Sound Pulp and Paper mill near Gibsons again raised the alarm of death or serious injury. Then last Thursday, three explosions rocked the bleach plant of a Weyerhaeuser pulp mill in Washington State, releasing a yellow-green cloud of chlorine gas to drift through the town of Cosmopolis and causing the evacuation of residents and mill workers.

Moving to oxygen or hydrogen peroxide bleaching technologies and eliminating chlorine-based processes will make mills and communities safer from the frightening menace of these repeated accidents. In the US, storage of mill gases is now considered a security risk. In addition to eliminating deadly dioxins and furans from mill waste, these changes will make it possible to close the waste loop, reducing the huge amounts of fresh water used by the mills.

The industry was given 10 years to make the changes necessary to convert to safer, cleaner bleaching technology in their mills. This could have built a chlorine-free pulp and paper products sector and spurred diversification in the industry away from low-grade commodity pulp. The vision behind the law was that of a modernized, value-added, environmentally sound pulp industry.

By the late 1980s BC's pulp mills were a filthy disgrace. Their toxic pollution included high levels of dioxins and furans, among the most persistent and poisonous substances known. These chlorine-based compounds concentrate in animal tissue, accumulating in body fat and breast milk of mammals - harbour seals, killer whales and people - and they are conveyed directly to their offspring.

Scientific evidence, backed by overwhelming public pressure, resulted in Social Credit and then New Democratic governments passing progressively more stringent laws to protect the marine environment and protect the food chain. Pulp mills were forced by this appropriate law to clean up. But they only went part way. Chlorine was replaced with chlorine dioxide, reducing but not eliminating the discharge of AOX.

The Liberal government has rescued the industry from any need to make these long-term investments. By tasking its science review panel with absurdly narrow terms of reference, they reversed the onus of proof and turned the precautionary principle inside out. The claim that there was no scientific basis for the previous law is a cynical misuse and misrepresentation of science, and does not serve the public interest.

Despite its constraints, the science panel pointed to several other pollution problems that remain at the mills: toxic black liquor and serious air pollution. The government is silent on these concerns.

BC's pulp industry regularly exceeds the generous pollution permits it is granted and now has a free pass to continue polluting our air and water. We will continue to call for an end to the risk to workers' safety, toxic air and water discharges, inefficient mills, wasted water, dioxin-filled landfills, and energy and pollution subsidies.

* Peter Ronald is marine habitat campaign coordinator with the Georgia Strait Alliance. Delores Broten is senior policy advisor for the Reach for Unbleached! Foundation.

* This article was originally submitted to the Victoria Times-Colonist.