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Public Radio's Environmental News Magazine (follow us on Google News)

Sludge-Eating Fish

Air Date: Week of

Eric Westervelt of New Hampshire Public Radio profiles Terry Welch, a man with a dirty job and a unique idea. Welch uses bottom-feeding fish to break down huge quantities of sludge at his sewage treatment plant. Other sewage managers scoff, but federal sewage experts are taking interest in the process.


NUNLEY: Just add fish. That's Terry Welch's recipe for turning the effluent and sewage settling ponds into clean water with no leftover sludge. Sludge is a big problem for sewage treatment plants: it's expensive and difficult to dispose of in an environmentally-friendly way. But Welch, who runs several small treatment facilities in northern New Hampshire, thinks he's found a safe, cheap, and remarkably simple way to deal with his sludge problem. He's released thousands of bottom-feeding fish from local rivers and lakes into his settling ponds, and he says his sludge problem has virtually disappeared. Now, Federal officials are trying to find out if Welch really is on to something. From New Hampshire Public Radio, Eric Westerveldt has our report.

(Footsteps on gravel or sand)

WESTERVELDT: Few people truly love their jobs, especially those who work with human excrement.

WELCH: I love this plant. This is like my baby. I started this when I was, from day one. I was here since the first day it started up, and I don't ever want to leave.

WESTERVELDT: Meet Terry Welch, who runs sewage treatment plants in the north country of New Hampshire: facilities he affectionately calls his little Gardens of Eden. His Breton Woods operation north of Crawford Notch overlooks the local ski resort and the snow-dusted Presidential Range of the White Mountain National Forest. The heart of the plant is 2 large swimming pool-size lagoons 10 feet deep that hold and process the domestic waste from more than 60 ski resort condominiums.

(Inside plant: blower)

WESTERVELDT: This time of year it's shrouded in deep snow and ice, quiet except for a massive blower that constantly pumps air into the sewage, which helps separate the solids from the liquids and adds oxygen which aids bacteria breakdown of the sewage. From here, the water is then filtered twice and drained into the nearby Ammonoosuc River.

WELCH: I swim in these rivers. I fish in the rivers. And I raft in them. And I don't want to pollute them. And now I have a direct hand on what goes to the river. So that's why I'm constantly trying to make it, my end-product, better.

WESTERVELDT: The end-product is supposed to be clean water from wastewater. But to get clean water, many plants have to deal with a number of problems, including sludge: the solids left behind when cleaning wastewater.

(Entering the plant office)

WESTERVELDT: Inside the plant's small office, Terry Welch explains that dredging, pumping, and shipping the sludge waste out of the ponds is a big, nasty, and expensive process: one that can cost towns tens and sometimes hundreds of thousands of dollars.

WELCH: The first time I did it my wheels were turning. There's gotta be a better way. (Laughs)

WESTERVELDT: Now Welch thinks he's found a better way to get rid of the sludge. New high-tech equipment? No. Perch, bluegills, hornpout, large mouth and small mouth bass: tens of thousands of them. Using these fish, Welch claims he has dramatically reduced the amount of sludge.

WELCH: We have actual data from other consultants that took the sludge depths before I put the fish in, and I had a state official this year take sludge depths four years later. And there's nothing out there. It's all gone.

WESTERVELDT: Welch got the idea to enlist fish in his operation almost by accident. An avid scuba-diver and fisherman in his spare time, Welch watched these kinds of fish in local ponds poking around the bottom and stirring up sediments, and the idea was born. Welch isn't really sure, but he speculates that the fish reduce the sludge in his sewage lagoons two ways. They burrow and swim through the excrement, stirring it up, aerating it, and allowing millions of microorganisms and bacteria to naturally break it down. He's also found evidence that these fish actually eat the sludge. Welch's creative solution to an old problem has caught the eye of state, regional, and Federal environmental officials. Paul Olander is an engineer with Vermont's Department of Environmental Conservation.

OLANDER: I'm very optimistic. I think that, boy, if we could get the fish to do this work for us, at least to some degree, it could save a lot of communities quite a bit of money.

WESTERVELDT: And Welch has actually saved towns money, thousands of dollars in the avoided costs of dredging and chemicals. And Welch says his treated water meets Federal clean water standards. The New Hampshire and Vermont Departments of Environmental Services have formed an ad hoc committee with Federal officials to study Welch's seemingly crazy idea. Welch is more than willing to help. In fact, he plans to dive into the excrement lagoons next summer to photograph his Eden in action and help prove his case. Dr. James Martell, an environmental engineer with the US Army Corps of Engineers, who's involved in the research, says he'll reserve judgment on the experiment. But he says there is a precedent for using fish to help treat sewage.

MARTELL: In Asia, they use this technology all the time. They grow fish in their lagoons and they actually catch the fish and eat them.

WESTERVELDT: So far, Welch's fish haven't been deemed safe to eat. Tissue analysis is being done on the fish to see if they're consuming any heavy metals from the domestic sludge. Terry Welch welcomes the cooperation and attention of state and federal officials, but he quickly dismisses other non-believers, especially fellow wastewater plant operators, some of whom view his sludge-eating fish with mirthful skepticism.

WELCH: If they don't believe it and don't want to try it, well, good for them. In another five or ten years they're going to be wading in it getting rid of it, and I'll be here laughing, catching fish. (Laughs)

WESTERVELDT: For Living on Earth, I'm Eric Westerveldt in Breton Woods, New Hampshire.



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