Matt Seib goes to work each day focused not just on the quality of effluent leaving the Nine Springs Wastewater Treatment Plant, but on how the plant can do even better in the future.

As a process and research engineer with the Madison (Wisconsin) Metropolitan Sewerage District, Seib works with colleagues on projects to enhance sustainability, recover resources, boost energy production and efficiency, and improve overall treatment performance.

In three and a half years with the district, he has worked to improve an innovative nutrient recovery process, increase activated sludge treatment efficiency, investigate co-digestion of food waste to boost biogas production, explore elevating biosolids from Class B liquid to a more versatile Class A product, and more.

He came to the position well equipped, with a Ph.D. in civil engineering. The following fall, he received his Professional Engineer credential. His industry peers have noticed his contributions: He was recognized in 2018 as the Outstanding Young Professional of the Year by the Central States Water Environment Association and as Newcomer of the Year by the Wisconsin Wastewater Operators’ Association.

Alan Grooms, operations manager and Seib’s predecessor as process and research engineer, observes, “The district has supported research for three or four decades at least. Not all projects pay off, but even some that do not can save you from making high-dollar mistakes down the road. Matt is certainly meeting expectations. He’s been very valuable with the research work we’re doing to evaluate future processes.”

Changing course

Seib, a native of Waukesha in southeastern Wisconsin, enrolled at the University of Wisconsin-Platteville to study structural engineering. “It became clear after a few classes that structural engineering was not my strength or my interest,” he recalls. “Environmental engineering and wastewater were much more my thing.

“What really drew me to that area was the double idea of helping to protect the environment and public health while also being able to do things like apply anaerobic digestion to recover resources from waste and use them beneficially. I liked the idea that I could take something that had no value and make value out of it.”

After earning his civil engineering degree at UW-Platteville, he went on to complete a master’s in environmental engineering at Michigan Technological University, in the process spending two years in the Peace Corps in Mali in West Africa, as a water and sanitation engineer under the Master’s International program.

While completing his Ph.D. in civil engineering at Marquette University, he worked as a research assistant with the university’s Water Quality Center, investigating low-energy alternatives to activated sludge, evaluating different fixed-film anaerobic bioreactor configurations and performing energy audits to compare the energy demands of wastewater process equipment.

On completing his degree, he was drawn to his current position with Madison Metropolitan Sewerage District: “It was a way to be engaged in the higher-level aspects of engineering with research but also be involved in day-to-day problem-solving. It was a chance to take my knowledge and use it.”

He works closely with operations group team members including Aaron Dose, operations supervisor; Matt Allen, assistant operations engineer; Matt Erbs, process control system programmer; Drew Suesse, regulatory and process engineer; and Eric Dundee, director of wastewater operations and reliability.

Progressive facility

The Nine Springs plant (57 mgd design, 42 mgd average) has 30 aeration basins and uses an enhanced biological phosphorus removal system with two process configurations.

The plant’s activated sludge facilities consist of two complexes. The east complex includes 18 aeration basins configured as six three-pass aeration trains with 11 secondary clarifiers. The west complex includes 12 aeration basins configured as four three-pass aeration trains with eight secondary clarifiers.

Both complexes operate an enhanced bio-P process. Most of the plant, except for two treatment trains in the east complex, use the modified University of Cape Town process. In this configuration, wastewater enters an anaerobic zone where it is combined with mixed liquor from the downstream anoxic zone.

Return activated sludge is pumped to the anoxic zone, where nitrate is reduced to nitrogen gas before a portion of the mixed liquor is pumped to the upstream anaerobic zone. Flow from the anoxic zone that is not returned goes to the aerated zone for BOD removal and nitrification. The modified UCT configuration maintains the integrity of the anaerobic zone by denitrifying the RAS in the anoxic zone before it enters the anaerobic zone, and so improves phosphorus removal.

Two treatment units in the east complex use the anaerobic/aerobic process, which includes an anaerobic zone upstream of an aerated zone and does not have a nitrified mixed liquor recycle.

Tackling a problem

The Nine Springs plant was among the first in the world to deploy the Ostara Nutrient Recovery Technologies nutrient recovery process, which captures phosphorus from waste activated sludge before thickening and from biosolids dewatering filtrate and converts it to pellets that can be marketed as a phosphorus-rich struvite fertilizer. Working with a first-generation technology, plant staff encountered several challenges with achieving the desired struvite yields as they gained familiarity with the process. Seib and colleagues went to work troubleshooting and fine-tuning the process to optimize the struvite yield.

“One thing I worked on was finding a way to minimize scale in the system,” Seib says. “We produce struvite as pellets, but we also get struvite scale in the process that needs to be cleaned out.” That means soaking the reactors overnight in a low-pH solution to redissolve the scale.

“We had been using powdered citric acid, taking 10 to 12 sacks up to the tops of the reactors — about three stories off the ground — and pouring it in,” Seib says. “There were issues with material handling and safety that we weren’t particularly comfortable with.”

Testing determined that the same amount of acetic acid would dissolve more scale, and at a lower cost. The next step was to find a safe way to introduce the acid to the reactors. The answer was a pumping system that lets operators deliver the acid without climbing the reactors and with minimal risk of spilling or spraying.

Improving aeration

Lately, Seib devotes most of his attention to a pair of pilot treatment plants being used to explore energy-saving low-dissolved-oxygen options in the activated sludge process. “One option is basically to mimic our current setup and see how low we can turn the air down and still get good treatment,” he says. The other is an innovative process called nitrite shunt, recommended by a consultant as part of facility planning for future upgrades.

Grooms notes, “Matt has been heavily involved in laying out and working that case. His work will basically determine whether we go with the nitrite shunt or another low-DO process.”

Seib states, “Nitrite shunt is a process that only has one full-scale example in service right now, and that’s in Florida. We’re concerned that in the colder Wisconsin climate the process may not be able to perform reliably. We’ve been piloting that for about two years in different iterations to see how effective it is.”

The traditional nitrification-denitrification process converts ammonia in the wastewater to nitrite, then to nitrate and finally to nitrogen gas. “The nitrite shunt process is designed to achieve higher total nitrogen removal,” Seib says. “Instead of taking ammonia first to nitrite and then to nitrate, you’re going from nitrite directly to nitrogen gas, shunting out the biological step that creates nitrate.

“In essence it’s a simultaneous nitrification-denitrification process that relies on fostering anammox bacteria and other heterotrophic organisms in a single tank under specific conditions. It’s a sensitive process that may be very challenging to operate effectively. We’re trying to see if we can get it to work and how well.

“The primary benefit is even greater energy savings by being able to operate the aeration basins at a lower DO. In addition, we believe that somewhere down the road, this facility will get a total nitrogen limit, and nitrite shunt would help us get ahead of that.

“What’s also interesting about the process is that it uses much more sophisticated controls and sensors than we currently use. A practical benefit of the pilot project is that we will gain experience and insight with more sophisticated instruments that we are likely to use in the future, regardless of what type of activated sludge process we continue with.”

Boosting gas production

Another of Seib’s projects ties in with the district’s long-term goal to achieve energy neutral operation, mainly through co-digestion of hauled organic waste to increase biogas production. One option studied is to form a partnership with the City of Madison to take household organic waste from curbside collection, process it into a slurry and feed it to the digesters.

“There are a lot of questions in terms of how to collect the material, how to process it, how to remove contamination, where to put it into our digestion process, how much gas we can get out of it, how it affects biosolids production and to what extent it increases sidestream loading for nitrogen and phosphorus,” Seib says.

Seib produced an internal white paper that laid out all those issues. He also used reports from the city to estimate the tipping fees needed to receive and preprocess food waste on a break-even basis. “We also collected some curbside organic material from the city and used it to run bench-scale digesters in our lab. This is all preliminary exploration to help point us toward what we might be able to do in the future.”

The results of that study will help inform an energy master plan for Nine Springs, looking at priorities to rehabilitate or replace the facility’s energy infrastructure over the next 10 years. Another component of that plan will examine the potential for a change in biogas utilization — from using it as an energy source on site to processing it for sale to the gas utility grid to generate renewable energy credits.

On the process side, Seib and colleagues are conducting a digester tracer study to help optimize maintenance practices, including how frequently or aggressively to take digesters out of service for cleaning.

Active in the industry

Outside his day-to-day duties, Seib is active in professional organizations at the state, regional and national levels. “It’s really important to be involved,” he says. “There’s always somebody doing something a little bit better or a little bit greater.”

“Historically, wastewater has been a very collaborative industry. People from different plants are always happy to share stories. When a plant is having trouble, it’s very common to call the people around you and say, ‘Have you seen this issue as well? What have you done about it?’ Professional organizations give you more people to talk to when you’re trying to work through challenges.”

Looking back, Seib is happy with the change of career direction he made early in college: “The work I do impacts a lot of people, much more so than if I were a structural engineer designing an office building. Working in wastewater helps bring benefits to the people in my community and to everybody else downstream. It touches the lives of a lot of people, and that’s very rewarding.”

Toward Better Biosolids

The Madison (Wisconsin) Metropolitan Sewerage District has one of the nation’s oldest and most successful biosolids recycling programs, but there’s no reason it can’t be better. Matt Seib, process and research engineer, and colleagues are looking at enhancements.

For many years, the district has applied its liquid Class B biosolids, called Metrogro, to cropland. “But it’s becoming more challenging every year because we’re having to haul it longer distances, our equipment is starting to age and there are issues with phosphorus application on fields,” Seib observes.

The team has pilot-tested dewatering to produce a Class A cake product, but so far it hasn’t lent itself well to spreading on land. “We’re exploring how we can turn that into something people will really want,” Seib says. “Because we do bio-P here, our biosolids have a pretty high phosphorus content, and that could be a problem for farmers, who would be overapplying phosphorus if they used our cake.

“We’ve looked at composting it with wood chips, bedding straw or crop residues to see if we can create a material that has the right handling properties and the right nutrient balance. If we can compost it with other material and balance the carbon, nitrogen and phosphorus ratio, then we’ll have a final product that’s easier to use and has wider applications.”