You can hear the passion in Dan Peterson’s voice when he speaks about his product. As superintendent of the Durham (N.H.) Wastewater Treatment Plant, he gets excited about testing technologies, making the highest-quality effluent possible, and meeting the challenges of nitrogen limits for the Great Bay, a unique salt marsh and estuary.

He likes to compare influent and effluent quality in glass jars in front of college students who tour the plant. Occasionally, he adds a glass of tap water. “A lot of times, they have trouble telling the difference,” he says. “The product we produce keeps me interested in this job. There is magic here; I just get excited about it.”

For his dedication and outstanding work in the Durham plant, Peterson received the U.S. EPA 2012 Regional Wastewater Treatment Plant Operator Excellence Award. His nomination came from the New Hampshire Department of Environmental Services Wastewater Engineering Bureau.

Learning process

Durham is home to the University of New Hampshire. The 2.5 mgd activated sludge treatment plant serves the student body and about 12,000 residents. “Throughout the year, the college population can make it a very difficult treatment system to operate,” Peterson says. “When the kids are in, it’s great, everything’s online, but if they go away, especially on Christmas break, it’s like someone turns off the light switch. You lose half your flow and half your loading, but you’re still trying to keep the system at 100 percent because of the cold weather. Over summer break, we’re running great on half the tanks. Then the students come back all at once. We have to think ahead of time and slowly bring systems online.”

Peterson and his team of four have adapted their system through this and other obstacles. The team includes Daniel “Max” Driscoll, chief operator; Nick Shonka, laboratory technician; Lloyd Gifford, process operator; and Steven Goodwin, lead mechanic. Driscoll and Gifford each have more than 24 years’ experience, Goodwin has nine and Shonka has two. Peterson, who has worked in wastewater since he enlisted in the U.S. Air Force after high school, has been at Durham for six years.

The Durham team is responsible for 20 miles of sewers, three pump stations and the treatment plant, which uses the modified Ludzak-Ettinger (MLE) process. The system includes two rectangular primary clarifiers, four aeration basins, two secondary clarifiers with Envirex Tow Bro solids collectors (Siemens Water Technologies) and two chlorine contact tanks.

Flow is mixed and moved by a mixer and recycle pump (Flygt, a Xylem brand), four pumps (Netzsch Pumps North America), four new blowers (APG-Neuros), two return activated sludge pumps (Hayward Gordon) and one wasting pump. For basic analytics, the team uses DO probes (Hach), an ORP probe (GLI) and an iFix SCADA system (GE Intelligent Platforms). Disinfection is achieved with hypochlorite and sodium bisulfite, with caustic soda for pH adjustment. Effluent discharges to the Oyster River, which feeds the Great Bay estuary.

Team solution

The team controls solids processing in two primary tanks and one secondary storage tank, using three primary feed pumps (Penn Valley Pump Co.), a secondary sludge pump, a gravity belt thickener and belt filter press (Ashbrook Simon-Hartley) and a dry polymer feeder (Acrison).

In 2008, the plant’s biosolids contractor required the team to fill larger containers (60 cubic yards on 18-wheel trailers instead of 30 cubic yards) to maximize efficiency in transporting material to a composting facility. “Before, all we had was the single discharge chute off of our belt filter press,” says Peterson. “When it dumped into the roll-off containers, we pushed them forward and moved them back to level it off, but now that we were going with a trailer, we had no way to distribute any of the material without actually moving the trailer itself.”

So the team and Dave Cedarholm, town engineer, debated ideas. “We tossed around the cost of commercial levelers, and everything was way out of our budget, so we and especially Steve Goodwin came up with a design. We installed a reversing conveyor over the container that moves on a track, supported by beams inside the garage bay in the solids processing building.”

Peterson estimates the home-grown device saved $20,000 over a commercial solution.

Pushing the limits

That innovation aside, Peterson calls the plant’s treatment system the team’s biggest achievement. Before he was superintendent, the plant at times had trouble meeting its permit pH requirement. The Wright-Pierce engineering firm designed the MLE system in 2006 to recoup alkalinity and lower ammonia to less than 0.5 mg/L. Even then, discussions were beginning about nitrogen levels in the Great Bay.

Peterson wanted to know what the system could do about the nitrates. “We had the tools that the engineers already put in place, so let’s push the plant to the limit,” he recalls thinking. “Let’s really see what we can make this plant do.”

The team did a lot experimenting for a couple of years. To reclaim the carbon source lost when the university students moved out, the system bypasses the primary clarifier during those times. “We have a very good step screen [Huber] that removes 90 percent of the rags, and a good grit system,” Peterson says. “We put an ORP probe in our selector, and we tied that in with our recycle pump. When we had low ORP numbers, our recycle pump would speed up and return much more of the solids to break down those nitrates.”

Over time, the process has improved: “Last year we had it dialed in really good. It was a 6.3 mg/L rolling average total nitrogen April through September. It’s been fun to see how close to the edge we can push the plant to get to the numbers without blowing permit. It’s a real fine balance there. The treatment plant is not really set up for nitrogen removal.” 

To help get the plant equipped for nitrification, the town approved a four-stage pilot Bardenpho aeration system. Peterson notes that regulatory authorities are issuing permits for nitrogen at 8 mg/L and that they may decide that is not low enough. “I can do 8 mg/L but the plant is not really designed for that,” he says. “The permit could be lowered to 5 or even 3 mg/L.”

Community support

“A nitrification pilot was already pretty much budgeted because we knew this was coming a few years ago. The town wants to be proactive, to be ahead of the game.” The planning team included Peterson; Todd Selig, town administrator; Michael Lynch, Public Works director; Cedarholm; and the Wright-Pierce engineering firm. The consultants designed the pilot, which was to begin last summer.

Peterson notes that Durham’s college town status means the plant at most can take down only one tank to nitrify. “We’re looking to have a four-stage system with two trains,” he says. “When students are out, we’ll just have to run a single train. It will give us much more flexibility and hopefully denitrify and come up with really low nitrogen numbers. Regardless what permit numbers we do get, we’ll build it and design it for the lowest possible number, which is 3 mg/L.”

In service

Peterson’s background in the water sector goes back to his days in the military. In 1983, fresh out of high school in Cumberland, Wis., he was uncertain of his career path. He trusted his local Air Force recruiter: “He told me, ‘I’ve got the perfect job for you — you can be an environmental support specialist.’”

The work included water and wastewater treatment and the promise of travel. He was initially assigned to Pease Air Force Base in Portsmouth, N.H. Over seven-and-a-half years, he ran the base’s trickling filter plant with digesters and sand beds. When the base closed, he left the Air Force and kept working at the plant under a government contract.

“I had to keep the wells and water treatment plant going even though it was a ghost town. It was very eerie. You could lie down in the middle of the road and not worry about getting hit by any vehicles.” Eventually the city of Portsmouth took the plant over, and Peterson was involved in decision-making for an upgrade of the plant to activated sludge with a sequencing batch reactor to serve a brewery.

“That was my first real experience being an operator, sitting in on the process with the engineers who got that contract,” he says. “I really learned a lot.” He mastered the new process quickly and worked for Portsmouth from 1993 to 2007. “It was a great place; I loved working for the city,” he says. “If the job hadn’t come open in Durham, I’d probably still be there.”

A purposeful team

Once onboard in Durham, Peterson encouraged all the operators to become licensed. “I pushed for that to get them that extra education,” he says. “If they want to advance on anything, it’s always out there for them.” In the daily routine, he doesn’t micromanage — they all know their jobs and “most of them are older than me.”

Peterson relies especially on Driscoll, chief operator: “Without him I would be lost around here because he really takes care of the day-to-day operations. Driscoll competed on a Water Environment Federation Operations Challenge Division 1 team last year.”

As superintendent, Peterson is responsible for substantial paperwork, but he’s not fond of sitting at a desk: “To be honest, I like going out there and doing anything in the yard, like cleaning tanks or processing solids or whatever needs to be done. During the summer I might go out on the truck and jet a line or two. I was brought up in a home where you don’t ask somebody to do something you’re not willing to do yourself. We’re all here as one team. Regardless of your job title, we’re all here for one purpose: to make the best possible effluent that we can.”

Peterson maintains a link to the military, serving in the New Hampshire Air National Guard for the last 17 years. He receives regular training on technology, such as mobile reverse osmosis water purification systems, and he deploys to various locations so that he finally gets to travel.

“A couple of years ago, I did two weeks in El Salvador,” he recalls. “We were working for the National Guard on a clinic out in the middle of nowhere, doing some plumbing. It was eye-opening. You really don’t know what you’ve got until you see something like that first-hand.”