Algae eyed to clean Chesapeake Bay

Scientists say 'scrubbers' can reduce pollution, produce fuel

September 26, 2010|By Timothy B. Wheeler, The Baltimore Sun

DELTA, Pa. — Soft and stringy, a mat of green clings to the bottom of the long metal trough as warm water courses down it to the Susquehanna River.

"There it is — green gold!" says Patrick C. Kangas, as he scoops up a clump of blue-green algae growing in the sluiceway he's set up at the Peach Bottom nuclear power plant, just across the Maryland line.

Kangas, a University of Maryland ecological engineer, sees a bright green future in such lowly pond scum — a solution to the Chesapeake Bay's water-quality woes, and possibly even a clean, renewable energy source to boot.

With the help of Exelon Corp., the Chicago-based power company that owns Peach Bottom and other energy facilities along the lower Susquehanna, Kangas hopes to demonstrate the year-round pollution-scrubbing potential of the algae he's cultivating in heated discharge water from the nuclear plant.

Kangas' Peach Bottom project is one of a small but growing handful of tests around the bay of a technology that's been around for decades, but only lately has drawn interest in this region as a tool for ecological restoration. It also comes, coincidentally, at a time of renewed interest in seeing if algae can be cultivated on an industrial scale to produce some form of renewable energy.

Similar experiments are under way on a farm on Maryland's Eastern Shore and in Virginia. A Baltimore firm is preparing to test the technique in the Inner Harbor, one of the most degraded spots in the bay. NASA scientists, meanwhile, are working on an ambitious project to produce jet fuel from algae used to treat municipal wastewater, and they hope to try it out in the bay, too.

It's ironic, as algae are often seen as a symptom of the bay's pollution. Every spring, massive algae blooms sprout in the Chesapeake, fed by fertilizer washing off lawns and farm fields and pouring (much diluted) out of wastewater treatment plants across the six-state watershed. And when those masses of tiny aquatic plants die and decay on the bottom, they suck life-supporting oxygen from the water, making it hard for fish, crabs and other shellfish to survive.

In this case, however, Kangas and others believe that algae can be transformed into the cure, rather than the cause, for the bay's infamous dead zone — if only the tiny pilot projects they're working on now could be enlarged and replicated at key points around the bay to cover thousands of acres of land or water.

"The nutrients that would otherwise go to [form] the dead zone can be used," says Jonathan Trent, OMEGA project scientist at NASA's Ames Research Laboratory in California. "Let's capture the dead zone from algae with other algae."

Cultivated algae would soak up nutrients in the water before they can get to the bay and cause problems. Like plants on land, the aquatic organisms feed on the nitrogen and phosphorus in the water, reducing the amount left to fuel algae blooms in the wild.

"We can remove nutrients and clean up the bay, if we have enough acreage," Kangas contends. "This location couldn't be better," he adds, gesturing toward the river where his sluiceway empties. "Right there is the Susquehanna, the main source of nutrients to the bay."

Indeed, the Susquehanna, which drains much of Pennsylvania and a portion of New York, supplies half the fresh water entering the bay. It also accounts for 44 percent of the nitrogen and 25 percent of the phosphorus getting into the bay watershed, according to the Environmental Protection Agency.

The trough Kangas has built at Peach Bottom is known as an "algal turf scrubber," a technology developed in the early 1980s by Walter Adey, an ecologist at the Smithsonian Institution. Adey initially devised it to clean aquaria he had at the Museum of Natural History, explains Kangas. It was designed to simulate the rich biological conditions Adey found on the edge of a coral reef, where sea water pulses in shallow waves over the reefs.

Adey, now 76, is convinced his technology can reduce nutrient pollution in the bay more quickly and less expensively than many of the traditional means being pursued.

"I think it's the only technology, or methodology, that's available today that's capable of cleaning the bay of its nutrients in any reasonable period of time — say, the next three to five years," says Adey. The bay states and the federal government, by contrast, are aiming now to take all the steps needed by 2025 to restore the Chesapeake's water quality.

However, Adey says he's had little luck interesting policymakers.

"It seems like a great idea,'' says Beth McGree, a senior scientist at the Chesapeake Bay Foundation. "But I think we need more information on how it's going to work."

The algal scrubber has been tried in Florida as an alternative way of treating wastewater, Adey says, and in Texas to maintain water quality at a commercial fish farm. Those warm, sunny locations were ideal for growing algae, however.

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