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Sustainable Manufacturing: Au Naturel

Sustainable Manufacturing: Au Naturel

Alcoa is using plants, soil and microbes to reduce pollutants and cut water discharge.

When Alcoa's new smelter in Iceland becomes operational, most likely in the second or third quarter of 2007, it will benefit from natural sustainable technologies previously employed at the company's smelting operations in Mount Holly, S.C.

It's part of an initiative that Pittsburgh-based Alcoa Inc. developed six years ago and is known as the 2020 Strategic Framework for Sustainability. "What the corporation is doing is allowing me and others in my group to look at innovative ways to move toward water sustainability," explains John Smith, manager of sustainable production technology at the Alcoa Technical Center near Pittsburgh. "We have targets of reducing water use significantly over the next five to 10 years, as well as moving toward zero water discharge."

The keyword is natural. Alcoa is using plants, soil and microbes -- rather than tanks, pumps and mechanical systems -- to reduce the volume of water it discharges as well as to lower the level of pollutants in the discharged water. Alcoa is working with Roux Associates Inc., an Islandia, N.Y.-based environmental management and consulting firm, on natural systems at three locations: Mount Holly, Iceland and Lafayette, Ind.

Natural media filtration cell at Alcoa's Lafayette, Ind., facility.
The natural approach at Mount Holly, which is still a work in progress, involves "greening" the smelter's production area with runoff-reducing plants, constructing treatment wetlands to remove contaminants from water and using spray irrigation on grass and a grove of polar trees in an application of phytoremediation technology. Phytoremediation is a passive technology that uses fast-growing trees and plants to deal with environmental contaminants, according to Roux Associates. Even in its pilot stage, the natural approach at Mount Holly has cut process water discharges to the locally owned public water treatment works by 60% to 70%, at a cost "at least" 50% less than conventional technology, says Alcoa.

Meanwhile, at Alcoa's engineered-products plant in Lafayette, Ind., commercially available mushroom compost is being used to remove low levels of PCBs (polychlorinated biphenyl), aluminum, suspended solids, and oil and grease from process and storm water. This natural media filtration system reduced PCB levels to less than 100 parts per trillion from one part per million during its pilot stage, says Alcoa. Now the facility is achieving "non-detect levels" of PCBs as measured by U.S. Environmental Protection Agency methods, the company claims.

Alcoa figures when its natural approach at Lafayette is operating full scale, it will have saved $10 million in up-front capital costs compared with conventional engineered methods, and will save $800,000 to $1 million a year in operating and maintenance costs.

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