COLUMBUS , Ohio -- A water filtration technique that normally cleans up agricultural chemicals is also effective at removing a toxin secreted by algae found in lakes and rivers, an Ohio State University study has found.

Engineers here determined that the technique greatly outperformed other methods by removing at least 95 percent of a toxin secreted by Microcystis, a blue-green algae.

Some water filtration plants around the country already use the technique, which couples activated carbon with membrane filters, said Hal Walker, associate professor of civil and environmental engineering and geodetic science at Ohio State .

Microcystis is native to freshwater lakes and rivers around the country, and secretes toxins that can cause liver damage in animals including humans. Worsening environmental pollution in Lake Erie during the last decade has caused algal blooms, the most recent of which began this August.

Some 13 million people rely on Lake Erie for their water supply, so Microcystis is a growing concern there, Walker said. But dangerous algal blooms have occurred across the country this summer, from Massachusetts to California .

And while many water filtration plants are beginning to use high-tech ultrafiltration membranes with very fine holes to filter water, Microcystin toxins are small enough to slip through. For example, the toxin used in this study was microcystin-lr, a tiny molecule made up of only seven amino acids.

The study will appear in the journal Environmental Science & Technology, and has been published in advance on the journal's Web site.

Rather than invent a new technology for filtering microcystin-lr, Walker and his colleagues decided to test whether combining activated carbon with membrane filters would do the trick. That technology has already proven effective for removing herbicides and pesticides from drinking water.

"This toxin is an organic molecule, and we kn
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Contact: Hal Walker
Walker.455@osu.edu
614-292-8263
Ohio State University
23-Aug-2006