In middle school, Elisabeth Werth did science experiments and built rockets.

Science was a natural fit: “I’ve always been curious and scientific,” says Werth, laboratory support supervisor at Metro Wastewater Reclamation District in Denver, Colorado. “I like to gather my own evidence and dig into the details, to learn things all the time.

“I was always on a technical career path. It was always where I was headed. I excelled in math and science more than in other areas.” With a bit of tongue-in-cheek and a twinkle in her eye, she says she was “really cool in middle school.” Now she takes pride in having earned the 2019 Water Environment Federation Laboratory Analyst Award for the Rocky Mountain Water Environment Association.

Getting to goals

Werth heads the laboratory support group for the Metro District, which treats the wastewater for most of metropolitan Denver. She oversees sampling and analysis for nonroutine and one-of-a-kind projects. These often require her to develop or validate new treatment technologies the district is considering or has installed.

“You can’t just use any old analysis on any sample and expect good results,” she says. “What we do really well is work with the person requesting an analysis. We dig into their data quality objectives. We ask: What are you going to use this data for? What are your goals?” That helps her group know what to sample, when, and where, and what type of analyses to perform.

“Any bias in the sample from collection will be amplified throughout the analysis,” she observes. “Small changes in the mixed liquor or suspended solids number can have huge effects on wasting calculations and treatment efficiencies.”

One example she cites is the relatively new MagPrex phosphorus-recovery technology (Centrisys/CNP) the district has adopted: “It’s an aerobic tank that comes after anaerobic digestion in the process train. We want to get struvite to form there, in the tank, and not in our piping. Then we can recover it.”

It took exacting analysis to determine how to get the struvite to form its crystals in the tank, and not elsewhere in the treatment process. All the analytes had to be precisely measured and accounted for. Then the struvite crystalizes, precipitates and drops to the cone at the bottom of the tank for removal.

Weighing options

Werth earned her bachelor’s degree in chemistry at Colorado School of Mines, one of the premier technical universities in the West. She did a recruiting trip to the school during October when the leaves were changing to gold, the weather was perfect and the mountains were beautiful. She was also interested in playing soccer. “They said come on and practice with us. It all really appealed to me.”

She began college thinking about a degree in chemical engineering, but “after taking thermodynamics four different times, I realized I didn’t want to do that my whole life. So I followed the why and the how.” She also took a couple of biology classes, and her microbiology course has paid big dividends in her current career.

She came to work at the Denver district after a friend brought her to the wastewater treatment plant in fall of 2012 and showed her around. Tanya Bayha, now her boss, took her through the lab, and she learned that a laboratory analyst job was open: “I thought it sounded interesting, and I applied and got it. I worked my way up, and now I’m in Tanya’s group.”

Making connections

The largest group in the lab is analytical services, which does all the compliance and process control sampling and analysis. That includes including analyzing loadings that determine, along with flows, how much the connectors to the Denver Metro system pay for treatment.

The group also analyzes samples in support of the district’s retreatment program. Biological oxygen demand, TSS and TKN are the loading constituents of interest. When flow is factored in, the concentration and amount of each measured constituent helps the district determine how much it costs to treat the wastewater for the city or sanitation district where it originated.

The analytical services group also has an organic chemistry team, a quality assurance/quality control group, and several supervisors who oversee the production work. In addition, an inline instrumentation group installs and maintains analytical tools. “This group has grown a lot recently, and operations can see the trends in the process in real time,” Werth says.

The lab support group where Werth works “fills in the gaps. We’re the liaison among all the different groups at the plant like strategy and innovation, regulatory affairs, pretreatment and operations. We do capacity planning for the lab and balance the workload.”

Protecting the watershed

One of the biggest jobs is supporting developmental work. “We evaluate new technologies and work on process optimizations,” Werth says. “We adapt already-developed methods for different, weird matrix types that we’re trying to evaluate. We also work on potential new regulations, looking at things like whether we can reduce the detection limits of our analyses to meet them.”

The team also works with the water quality group. These scientists collect watershed monitoring data that help the district assess the overall health of the South Platte River, the stream to which the treatment plant discharges 130 mgd of effluent. 

The data collected goes to stream modelers. “We use the output from the model to talk with Colorado Department of Public Health and the Environment,” Werth says. “We look both upstream and downstream from our outfall, so we know what’s coming into the plant, what our treatment capacities are, what kind of efficiencies we can get, and how that will impact the watershed.

“I think Metro does a good job of discussing proposed regulation changes with the state and engaging in a balancing act. We can show the ideal treatment and what’s practical without being a financial burden on our customers. We might show that we get 90% of the benefit for this much money using this treatment, and it costs that amount again to get the remaining 10% of the benefit.”

Optimum dosing

Werth has been deeply involved in full-scale studies evaluating peracetic acid as an alternative disinfectant. “Peracetic acid is a really powerful oxidant, and it’s a very effective disinfectant,” she says. “We’re evaluating and optimizing it here.”

The project started with a small-scale pilot demonstration in 2016 and moved to full-scale evaluation in January 2018. The group is looking at optimum dosing and effects due to seasonal changes, and there’s a hidden benefit, too: “What’s really beneficial about peracetic acid is you’re not adding additional salt to the river.”

Werth clearly enjoys her work. She calls the Lab Analyst Award a nice surprise, but, “It’s not why I come in every day. My work changes every day, and that’s exciting. Every day is something different.”