A Copper-Clean Trout Stream

Nancy Marie Brown
September 01, 1994

The city of Saint Marys lies in a small white spot on the Pennsylvania map, amid a cluster of orange State Game Lands, flanked by the varied greens of the Allegheny National Forest and the Elk and Moshannon State Forests. Elk Creek, which winds along the edge of town, is a designated trout stream.

"It's a beautiful place, backed up to the forest," said Fred Cannon, a Penn State professor of environmental engineering. "But go down the right road, and you'll see a huge factory nestled up by all those oak trees. It's what the true American Yankee spirit is all about. Saint Marys is considered the powdered metal industry capital of the world."

It's the trout stream that's the problem. Saint Marys' treated wastewater flows into Elk Creek, carrying with it, from the factories and the town, roughly 50 parts per billion of copper.

"Fish don't like copper," said Cannon. "They run from it." (He knows. On his resume, beneath "Bureau of Land Reclamation," "Stanford University," and "Consulting Engineer," is "Commercial Fisherman . . . caught 40,000 salmon with seine net.") To preserve the trout stream, the Pennsylvania Department of Environmental Resources plans to restrict the copper content of Saint Marys' treated water to as low as 6 parts per billion, a standard Cannon described as follows: "The population of the entire world is 5 billion. Take 30 of them. In comparison, the drinking water standard is 1,300 parts per billion of copper." The city has until 1995 to come up with a plan.

"That's where we come in," said Cannon. With funding from the state's Ben Franklin Partnership, he and graduate students Tzung-Yuh Yeh and K.G. Karthikeyan are attempting to keep the copper out of the creek.

In St. Marys' powdered metal factories, bits and shavings of metal are formed and melded to make, for example, an auto part. "You have this big machine," explained Cannon. "The powdered metal flows in, the machine goes ka-chung, the powder ends up in the form of an auto part. It's fairly fragile. It's a bunch of powder in the shape of a part, but a conveyer belt takes the form, passes it through a furnace, all those little flakes melt into each other, and it's an auto part. The ka-chunging occurs about every 30 seconds."

The process is not necessarily copper-intensive; little can be done, at any individual factory, to reduce the copper content of Elk Creek. Which is why Cannon took his graduate students directly to the sewage treatment plant: rather than limiting input to the wastewater, they would clean it of copper before it hit Elk Creek.

Cannon and his students collected sewage samples last January. "These guys are from the tropics," Cannon noted; Yeh from Taiwan, Karthikeyan from Tamil in India. "We're up in Saint Marys and it's minus-40 degrees. It was bitter cold -- even for a guy from Alaska. I asked them what they thought of America, and Karthikeyan said, 'I never knew people could survive in such cold.' We couldn't use gloves. Rubber gloves were cold -- worse than nothing."

The samples are stored in the refrigerators of the pristine new Environmental Engineering labs in the sub-basement of Sackett Building. Yeh swivelled off a top, sniffed, and proffered it like perfume: eau de pig farm. He grinned. "When you smell that, you know the activated sludge is viable. It's good. If you don't smell that, you know you're in trouble."

"It may be sewage to you," Cannon quipped, "but it's my bread and butter."

"What you do," he continued more seriously, "is mix iron, in the form of ferric chloride, or alum, as aluminum sulfate, with the wastewater in an activated sludge basin. You can't destroy the copper, but you can make it so it's not going out into the stream.

"The process is called flocculation. It's used all the time in water treatment -- that's upstream of the intestines. We're using it in wastewater treatment -- downstream of the intestines.

"The reason it works is actually quite complicated. In an activated sludge basin, you have a lot of bacteria. Bacteria have a negative charge. Alum, iron, and copper all have a positive charge. The alum and iron draw the bacteria to themselves to form a floc, then the negative charge of the bacteria will attract the copper."

Copper does attract bacteria by itself, but at the parts per billion level, there isn't much effect. "You're dealing with parts per million of iron or alum." As these metals are not toxic to fish, they are allowed into Elk Creek in much higher quantities.

Over the next year, Cannon, Yeh, and Karthikeyan will pinpoint the required amount of iron and/or alum and the best acidity and temperature in "mayonnaise-jar" tests, then set up a pilot test in the sewage treatment plant used by the University. "The plant in State College is about the same size as St. Marys', and has the unit process we're chasing up there, called trickling filters. We'll narrow in on the right spot here, then take it to Saint Marys and make sure it works there."

In jar tests so far, Yeh has reduced the copper content between 55 and 80 percent using iron; Karthikeyan, with alum, has reached 60 to 80 percent. "At this point, we look at them separately, but they might work well together," noted Yeh.

Cannon hopes such a reduction will satisfy the DER. Saint Marys' other alternatives are to extend its effluent pipe to the Clarion River, which has a different copper standard than Elk Creek, or to reduce the output of some its factories: Not an option. Nearly 3,000 of Saint Marys' 14,000 residents work in the powdered metal industry.

"And," said Cannon, "commerce is booming." He grinned at his graduate students, muttered ka-chung, ka-chung. "We want to make sure the progress of Saint Marys isn't limited by something as arbitrary as a copper standard. Applying fundamental principles to solving practical problems is what engineering research is all about, in my opinion."

Fred S. Cannon, Ph.D., is assistant professor in the College of Engineering, 215 Sackett, University Park, PA 16802; 814-863-3854. Tzung-Yuh Yeh and K.G. Karthikeyan are doctoral students in environmental engineering. This project is supported by the Ben Franklin Partnership, with contributions from the City of Saint Marys, Keystone Carbon, OSRAM Sylvania, Carbide/Graphite Group, Windfall Products, St. Marys Carbon, Stackpole Corp., Straub Brewery, Contact Technologies, and St. Marys Metal Finishing.

Last Updated September 01, 1994