Pulp and Paper Industry Strives to Reduce Its Water Impact

July 29, 2013

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Pulp and paper mill in Canada. Credit: Alex Vye, CC BY-SA 3.0

Pulp and paper mill in Canada. Credit: Alex Vye, CC BY-SA 3.0

As with many industries, water stress is pushing the pulp and paper industry to improve its water and wastewater treatment processes. According to a 2013 market study by research firm Frost and Sullivan, the industry's high reliance on water makes it vulnerable to water risks. “Pulp and paper manufacturing is characterized by a high water footprint,” says the study, which adds, “water stress in particular regions may increase the cost of water as well as result in supply limitations.”

The industry “has high volume and concentration of chemicals in wastewater streams,” resulting in regulatory and reputational risks for firms in this sector, as well as financial risks around fines and cleanup costs in case of polluted discharge.

High Volumes of Water Needed for Papermaking

Michelle Hamm, environmental manager at Monadnock Paper Mills in Bennington, N.H., acknowledged in an interview that “papermaking is very water-intense,” so an in-house wastewater treatment plant “is common for our type of facility... For a municipal facility to be able to handle the discharge would be very difficult.”

Monadnock Paper Mills has to discharge its treated wastewater into the Contoocook River, meeting strict New Hampshire environmental standards.

Monadnock Paper Mills has to discharge its treated wastewater into the Contoocook River, meeting strict New Hampshire environmental standards. Courtesy of Monadnock Paper Mills.

Water scarcity is not really an issue for Monadnock. “New Hampshire is a very water-rich state,” Hamm said. “We bring all of our water in from the ground. We're sitting on an amazing aquifer that gives us an abundant supply of groundwater.” All the same, she said, “we still believe in conservation,” so the company continually works on reducing its water consumption per ton. The company has “instituted some very intense water recycling efforts inside our facility. We use water over and over again.”

“The pulp and paper industry uses large volumes of water as a fiber carrier and as a solvent,” writes Frost and Sullivan. Much water is lost to evaporation during production -- between 0.5 to 2 m3 per tonne -- resulting in high demand for fresh water. The industry has made steady progress over the past three decades in reducing its relative water footprint, says the firm, dropping from 300 cu m per tonne to about 50 cu m per tonne, a reduction of 80 percent.

Frost and Sullivan sees a growing market for equipment and services in pulp and paper water and wastewater treatment, especially in disinfection and filtration systems. According to the group's study, the global market should grow at 6.0 percent compound annual growth rate (CAGR), from $984 million in 2012 to about $1.57 billion in 2020. North America and Europe each represent about a third of the market, the Asia-Pacific region about a quarter with high growth expected.

Treating Paper Mill Wastewater

As I explained in last week, the three standard steps in industrial wastewater treatment are referred to as primary, secondary, and tertiary treatment. Primary treatment uses sedimentation to remove suspended solids from wastewater, forming sludge. Secondary treatment removes organic matter using biological processes. Tertiary treatment provides final polishing to remove any other contaminants required before discharge into the receiving environment. In industrial wastewater, those three standard steps will be altered or augmented depending on the nature of the facility and its processes.

Frost and Sullivan analyst Eric Meliton recently wrote, “Sludge represents the largest volume of waste stream generated by the industry... mainly composed of boiler and furnace ash, scrubber sludge, lime mud, wood processing residuals, and various effluent solids,” such as sediments, absorbable organic halides (AOX), chlorinated organic compounds, chemical oxygen demand (COD), and biological oxygen demand (BOD).

Monadnock employs an intentionally-oversized 8-million-gallon capacity lagoon system. Courtesy of Monadnock Paper Mills.

Monadnock employs an intentionally-oversized 8-million-gallon capacity lagoon system. Courtesy of Monadnock Paper Mills.

Monadnock employs an “extremely efficient system,” Hamm told me. The system is based on a clariflocculator, which is a combination clarifier and flocculator that causes suspended solids to clump together so they can settle to the bottom to form sludge. The clarified water is transferred out to an 8-million-gallon capacity lagoon system for secondary treatment. Monadnock's sludge is clean enough to pass New Hampshire's tough environmental standards and to be used for such purposes as topsoil at area farms.

It's normal for paper mills to operate their own wastewater treatment plants, said Hamm. “What's not the norm is for 100 percent of the byproduct to be beneficially used in the agricultural industry. One-hundred percent of ours gets reused. None is landfilled.” Monadnock is able to provide such an environmentally-friendly byproduct by “eliminating hazardous materials in the facility itself,” Hamm told me. The company has fine-tuned its manufacturing processes to avoid contaminants on the front end. “The sustainability of that byproduct is because hazardous materials don't get introduced into the system in the first place.”

Monadnock boasts that it is “the only premium uncoated text and cover paper mill with a Certified ISO 14001:2004 Environmental Management System,” which requires continuous environmental improvement across its operations. The company is acknowledged by the EPA as a Climate Leader, a Green Power Partner, and a Wastewise Partner. It is also a Forest Stewardship Council (FSC) Certified Mill. Monadnock's manufacturing facility is carbon neutral and uses 100-percent renewable energy, half of which is generated using its own hydroelectric plant.

A Technology Roadmap for the Forest Products Industry

A comprehensive solution for wastewater treatment in the forest products industry is under development through a research project called Agenda 2020, a partnership supported by the U.S. Dept. of Energy, the Georgia Institute of Technology, the American Forest & Paper Association (AF&PA), and a number of companies interested in improving the sustainability of the industry.

Monadnock's sludge is clean enough to be used for topsoil by local agriculture. Courtesy of Monadnock Paper Mills.

Monadnock's sludge is clean enough to be used for topsoil by local agriculture. Courtesy of Monadnock Paper Mills.

The purpose of Agenda 2020 is “to transform the forest products industry through innovation in its manufacturing processes and products.” The group has developed a Technology Roadmap centered on the four “platform areas” of sustainable manufacturing, extraction of value from biomass, use of novel materials, and sustainable forest productivity. Agenda 2020 urges a new R&D effort to advance the forest-products industry in all of these areas.

The roadmap includes certain efforts especially relevant to wastewater treatment. For example, it calls for reducing freshwater use in mills and plants by 50 percent, reducing energy intensity in manufacturing by 25 percent, and developing new value-added products from woody biomass.

Making paper consumes a lot of energy, and the wastewater treatment process contributes significantly. Agenda 2020 says its member companies of the AF&PA decreased greenhouse gas (GHG) emissions between 2000 and 2006 from 0.738 to 0.637 tons of CO2 equivalent, a reduction of 13.6 percent. The group acknowledges that more progress is needed in this area. Energy is the third largest cost area in the industry, and the industry is the third most energy-intensive, behind petroleum and chemicals.

As I mentioned before, Monadnock Paper Mills uses 100-percent renewable energy. Even so, Hamm told me the company continues to work on reducing its energy intensity. For example, the company's secondary treatment system includes “a new energy-efficient aeration system.” The company is installing sensor-activated shutoffs that can automatically turn off the system's aerators when dissolved oxygen (DO) reaches a high enough level.

The Agenda 2020 roadmap calls for technologies that can reduce water consumption in pulping and papermaking, remove contaminants, and enable closed-loop systems with the objective of “100-percent recovery, treatment and reuse of water.”

 

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