Algae eyed to clean Chesapeake Bay

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.

"It's a big jump to the Chesapeake Bay," Adey acknowledges. "It's a different environment."

It gets cold here, for one thing, and algae stop growing when it gets chilly enough. Kangas originally tried scrubbers at an Exelon hydroelectric pumping station a little upriver from Peach Bottom, and algae grew in abundance in warm months. But he shut the operation down in winter.

If algae can only be used to clean water in warm months, that's a problem, says Walter R. Boynton, an ecologist at the University of Maryland's Chesapeake Biological Laboratory. "Much of the nitrogen, phosphorus and sediment getting into the bay comes in the cold period of the year," Boynton points out, flushed off the land by snow melt and early spring rains, when the water's still too chilly for algae to grow. "It's a tough nut to crack," he says.

Kangas believes tapping the nuclear plant's "cooling water" may overcome the weather hurdle. Peach Bottom draws water from the Susquehanna to soak up heat generated by its reactors. The water is then diverted into a long canal to cool off before it flows back into the river.

Kangas is drawing heated water — 95 degrees Fahrenheit — from that canal, letting it spill down a sloping metal trough a foot wide and a football field long before emptying into the river. It washes over a mat of blue-green algae covering a black plastic mesh on the bottom of the sluiceway. Every 30 seconds or so, an extra pulse of water pours in, simulating wave action, which Kangas says helps stimulate photosynthetic activity.

(Blue-green algae are really a form of bacteria rather than true algae, though they also perform photosynthesis, using sunlight to convert nutrients into energy.)

In summer, Kangas figures the trough produces about 20 grams of blue-green algae daily per square meter of surface. The harvested material is 3 percent to 5 percent nitrogen, and about a tenth as much phosphorus.

That may not sound like much, but Kangas said one of his colleagues at the University of Maryland calculated that an acre of algae grown under such conditions soaked up as many nutrients as did 50 acres of farmland planted in "cover crops," one of the most efficient land-based practices known for preventing nitrogen and phosphorus from getting in the water.

Others are testing algae in different settings. Timothy R. Goertemiller, an environmental engineering consultant based in Easton, has set up a set of shallow "flow-ways" beside a ditch that drains farmland in Caroline County. His project is being underwritten by the state Department of Agriculture, he said, to test the effectiveness of algae scrubbers at preventing excess nutrients from fertilizer from getting into water ways.

In Baltimore, the staff of Biohabitats, an ecological restoration consulting firm, hopes to set up a scrubber prototype on the reclaimed chrome plant site in Fells Point. The firm designed one of the floating wetlands being tested in the Inner Harbor off the World Trade Center, but Biohabitats' Chris Streb says this method may be even more efficient than wetlands at removing pollutants.

"We're hoping we can demonstrate to people just what the technology is, get some data and then scale up," Streb says.

To really make a dent in the bay's pollution, though, it's going to take a massive effort. Adey calculates that to reduce nutrient pollution in the Susquehanna to acceptable levels, there'd need to be enough algae water scrubbers set up to cover roughly 3,000 acres of land — or water, if they're of the floating type. To deal with the whole bay, he estimates needing about 10,000 acres — not all in one place, but strategically positioned in the main rivers feeding into the estuary.

"The fact of the matter is if we're going to clean up the bay, then we're going to have to make some sacrifices," Kangas says.

Besides cleaning water, the algae harvested from such scrubbers has uses, proponents say. Researchers at the University of Arkansas and at Western Michigan University have figured out how to convert it into butanol, a form of alcohol that could be burned in engines in lieu of gasoline, Adey says.

Large-scale production of energy from algae, however, has yet to prove feasible, in part because of the massive amounts of land and water needed to make meaningful quantities of fuel.

That hasn't stopped some from trying to solve that problem. Trent, the NASA scientist, briefed the Chesapeake Bay Commission recently on the $10.8 million federal effort to develop a system of floating plastic algae "bioreactors" that would feed on nutrients in wastewater from municipal treatment plants.

Government scientists have tested the technology in the lab and in small-scale field trials, said Trent. NASA is negotiating for a larger demonstration with a wastewater plant in the San Francisco Bay area, while also talking with the Navy about trying its technology out in the Chesapeake. The algae would then be collected and processed into biofuel – something the Navy is deeply interested in, as it seeks to wean itself from dependence on foreign oil to fuel its planes and ships.

For his part, Kangas says he's ready to graduate from tiny pilot projects to a larger facility, either on land or floating in the Susquehanna, covering perhaps 100 acres.

"We're ready to scale this thing up. We've done enough experiments. We're ready to move ahead," he said.

tim.wheeler@baltsun.com

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