German-made device gives plant operators real-time algae data
Tests appear promising on a new German-made device designed to help water-treatment plant operators learn almost instantly when algal toxins are being released into Lake Erie.
“I think it’s been doing really well,” said Tom Bridgeman, director of the University of Toledo’s Lake Erie Center. “It’s lived up to the expectations we had for it.”
Now, the city of Toledo has to decide if it’s worth buying a copy of the device, said Andy Mcclure, the Collins Park Water Treatment Plant’s administrator.
The decision isn’t just about the device, which costs about $50,000. Other considerations include manpower and the amount of regular cleaning and maintenance needed to keep it functioning, the plant’s chief chemist, Jeff Martin, said.
But he and Mcclure said they found it a useful addition during the summertime trial run.
UT owns the device and headed up the experiment. It hasn’t ruled out using it in the Toledo water-treatment network again, but wants the flexibility of potentially trying it out elsewhere too, Bridgeman said.
“We have other studies in other locations where we would like to use it,” he said.
Martin said data generated by that device complemented the early-detection capabilities of hightech buoys that have been deployed en masse across the Great Lakes region since the first weekend of August 2014, when Toledo’s tap water was fouled by an algal toxin.
In that case, the toxin was detected too late to prevent a temporary crisis for the metro region’s homes and businesses.
“It’s like the next generation of tools created since 2014,” Martin said.
The device is a real-time sensor developed by a German company called bbe Moldaenke Gmbh.
UT began working with that company in early 2021 to set up this summer’s experiment, part of a $1.4 million research project funded by the U.S. Army Corps of Engineers. Each aspect of the project focuses on early detection and management of harmful algal blooms.
Unlike the buoys, which provide data on general water quality, temperature, wind speed, organic material, acidity, and other environmental factors from various parts of the lake, this particular sensor can show when cyanobacteria — the scientific word for harmful blue-green algae — are present. Equally as important, it shows when algal cells are releasing toxins.
Not all algal blooms carry toxins, and larger blooms don’t necessarily mean higher toxicity.
Algae that produce toxins, though, carry it in their cells. Scientists don’t know precisely when, why, or how the toxins get released, although the prevailing theory is that most of that release occurs as algal cells age and start to break down.
The 2014 water crisis was different, in part because a virus in the lake caused algal cells to break open early and release toxins into the water during the early stages of that summer’s bloom.
The real-time sensor was installed in a fixed location inside Toledo’s low-service pump station near Reno Beach earlier this year, and will likely stay there until deep into October, once the annual bloom appears gone, Bridgeman said.
Then, like the buoys, it will be taken out, cleaned, and recalibrated during the off-season.
The low-service pump station is where raw Lake Erie water is piped after it is drawn into the city’s intake out in the lake. He and others said they wanted it there to run tests without inference from chemicals used during the treatment process at Collins Park, to which the water is pumped next.
“This summer was the first time we were able to do this deployment at the low-service pump station,” Bridgeman said.
Limno Tech, an Ann Arbor-based company that installs many of the Great Lakes buoys, hooked up the sensor in a way that allowed readings to be loaded online every 15 minutes, he said.
Plant operators like it when they get to algal cells before they’ve cracked open because that makes it easier to bind them together with treatment chemicals. The clumps fall out of the water column before they’re screened out by plant filters.
But it’s kind of like chasing a rabbit when the cells crack open and release toxins inside the plant.
The toxins can still be removed, but there’s a greater reliance on filters.
Early detection is the key, and it helps plant operators when devices such as this German-made sensor can tip them off that a problem might be brewing, Bridgeman said.
“You have to know when it’s happening,” he said. “If you have a big event overnight, you have to respond pretty quickly.”
The device doesn’t show actual toxin being released, but researchers can tell by changes in fluorescent light and pigments transmitted to their computer screens, Bridgeman said.
“We are measuring a signal,” he said.
This year also was Toledo’s first full year of having its new ozone treatment process operating, Martin said.
“We saw it does a very good job of taking on the algae,” he said. “It’s been a very good barrier.”