Amerikanske forskere tester avanceret algesensor i realtid på vandbehandlingsanlæg

Da fare truer i vandmasser globalt, hvor giftige alger blomstrer, kan et lille plastikopbevaringsbalje i Toledo, der er forseglet for at beskytte mod stænk, edderkopper og fugleafføring, indeholde en spilskiftende teknologi i kampen mod det voksende miljøproblem.

Algeforskere ved University of Toledo tester en optisk realtidssensor på Toledo Water Treatment Plant som en del af dets kildevandsovervågning for at beskytte den offentlige drikkevandsforsyning i den skadelige algeopblomstringssæson.

Hvert 15. minut tager enheden en slurk af Lake Erie-vandet, der kommer ind i anlægget, læser prøven og sætter måledataene online, så forskere og vandforsyningsledere kan få fjernadgang.

Dens største værdi er evnen til at fortælle, om små encellede organismer kendt som cyanobakterier, der udgør skadelige algeopblomstringer i Lake Erie, er skrøbelige og begynder at bryde op. Hvis cellerne går i stykker, frigiver de toksin. Opløst toksin er mere udfordrende for vandbehandlingsanlæg at fjerne, fordi det kan passere gennem filtre og skal fjernes med kemiske midler, før vandet forlader anlægget til vores vandhaner.

Siden juli har UToledo-forskere kontrolleret enhedens ledninger og slanger for at sikre, at den fungerer korrekt. De laver også laboratorieeksperimenter ved UToledo Lake Erie Center, der viser, at teknologien fungerer, som den forventes.

"Vores arbejde denne sommer med PhycoSens-enheden er den første test af dette online algeovervågningssystem på et drikkevandsanlæg i USA," siger Dr. Thomas Bridgeman, professor i økologi og direktør for UToledo Lake Erie Center. "Hvis vi viser succes på Toledo Water Treatment Plant og i hele regionen for straks at opdage og underrette om toksinfrigivelse, så kan det skaleres op i hele landet. Indtil videre er det lovende."

Testimplementeringen af ​​det avancerede overvågningssensorsystem er en del af et UToledo-projekt på 1,4 millioner dollars finansieret af U.S. Army Corps of Engineers, der begyndte for mere end et år siden og fokuserer på tidlig påvisning og håndtering af skadelige algeopblomstringer.

Siden vandkrisen i Toledo i 2014 efterlod en halv million indbyggere uden rent vand fra hanen i tre dage, har forskerne større klarhed over, at det ikke kun er størrelsen og udseendet af algeopblomstringen, der betyder noget, men hvad der sker i cellerne.

Bridgemans enheder lavet af det tyske firma bbe Moldaenke bruger optiske sensorer til at måle i realtid, hvor meget og hvilken slags alger der kommer ind i vandbehandlingsanlægget, herunder cyanobakterier. Endnu vigtigere er det, at sensorerne kan give en advarsel om, at cyanobakteriecellerne bryder op og lækker deres indhold, inklusive eventuelle toksiner, de måtte indeholde, ud i vandet.

"A large release of toxin can happen in a matter of hours, and it is critical for water plant operators to have this information so they can adjust their treatment levels quickly, before dissolved toxin can get through the plant," Bridgeman said. "The data are produced every few minutes, which makes it a useful early warning tool for a potentially rapidly changing algal situation."

Notable for researchers is data collected in late July showing the peak of the bloom and its decline.

"So far we have not detected any of that cell breakage at the water treatment plant or near the water intake out in the lake using the automated sensor, which is good news," Bridgeman said. "However, UToledo crews on our research vessel taking water samples out in the lake throughout Lake Erie's western basin—not near the water intake—have detected cell breakage using the manual version of the same device this season."

Bridgeman said that cell breakage events leading to large releases of dissolved toxin don't happen every year in Lake Erie.

"It happened in 2019 and possibly in 2014 but not to a large extent this summer, at least not near the water treatment plant's water intake out in the lake," Bridgeman said.

The Toledo Water Treatment Plant's laboratory makes the most use of the data.

"The experimental optical sensors being tested at the raw water pump station are a useful source for both the changes and the severity of algae levels coming from the lake," said Jeff Martin, chief chemist at the Toledo Water Treatment Plant. "We didn't have remote access to the data until part of the way through the bloom season due to computer issues, but since then it has been a welcome tool in treatment decisions."

Bridgeman has studied harmful algal blooms for two decades. His laboratory is one of the key locations for tracking and providing early warning of harmful algal blooms in the western basin of Lake Erie.

He said while the new instruments can detect the health, or physiological condition, of the cyanobacteria, they do not provide actual toxin readings, making them a supplemental weapon in a water utility manager's arsenal to efficiently and economically adjust treatment to maintain drinking water safety.

"Measuring toxin still requires a separate, fairly time-consuming test," Bridgeman said. "Therefore, the fast optical measurements will be coordinated with slower chemical toxin measurements to provide a complete picture of what is happening in the lake water that is entering the water plant."

The device will be removed from the water treatment plant for analysis in October and then his team will study the results and potentially put it back in the plant next summer.

Bridgeman's device monitoring tests are one part of a larger, wide-ranging project funded by the U.S. Army Corps of Engineers that also includes faculty in the UToledo College of Engineering.

Dr. Youngwoo Seo, professor of civil and environmental engineering and chemical engineering, leads the three-year project to improve water quality from the source to the tap.

Some of the technology and techniques being tested by UToledo are new to water treatment plants in the western hemisphere.

The project features two different parts working together:

• Advanced monitoring sensors and molecular genetic analyses to enhance early harmful algal bloom detection and real-time condition diagnostic capability; og
• Nature-inspired biological treatment methods coupled with algaecides to attack cyanobacteria and degrade toxins it produces.

Dr. Dae-Wook Kang, assistant professor of civil and environmental engineering, leads a molecular approach to develop a robust detection method, and his analysis will help better understand what triggers the toxin gene production of cyanobacteria.

Seo is focused on mitigation and the treatment method for toxin removal. His laboratory is working on the biological degradation of cyanobacteria and their toxins using the naturally occurring bacteria and viruses from the lake and NSF-approved chemical treatments. + Udforsk yderligere

Skadelig algeopblomstring bliver sporbar langs den vestlige Erie-sø