There’s already a lot of activity going on in the aftermath of the 2014 harmful algal bloom (HAB) in Lake Erie, which left residents in the city of Toledo without drinking water. Water treatment plants have added additional testing for the algal toxin microcystin that caused Toledo’s water shutdown, scientists are monitoring HABs as they develop, and backup intakes let larger plants avoid pulling in potentially contaminated water altogether.
A University of Toledo team led by Dr. Glenn Lipscomb is taking that activity one step further by showing that reverse osmosis (RO) membranes, an essential component of drinking water purification systems installed under kitchen sinks in many homes, can remove algal toxins from drinking water.
Reverse osmosis occurs when water is pushed through a semipermeable membrane with “holes“ that are too small for anything but the water molecules themselves. The process removes minerals and particles that can cause undesirable flavors, but to the scientists, the removal of algal toxins was an obvious additional benefit that needed to be explored further.
Partnering with NSF International (formerly the National Sanitation Foundation) and funded by Ohio Department of Higher Education, the research focuses on the reverse osmosis systems commonly sold at home improvement stores at a relatively low cost of $250-300. The goal is to develop a certification process for these home membrane systems that shows that they remove microcystin from drinking water, with the final certification protocol complete in early 2018.
One of the challenges the researchers face is the chlorine that’s added to drinking water to help disinfect it: the chemical attacks the filter membrane and can reduce its longevity and its ability to filter out toxins. So they developed “accelerated aging“ protocols based on previous research that shows that higher chlorine concentrations over a short time can age filters the same as low concentrations over a longer time.
What they have found over the last year is with those “accelerated aging“ protocols in place, microcystin is removed with chlorine in the water.
“Our most recent results indicate that chlorine in the water does not affect microcystin removal. Chlorine is added to our drinking water to help control microbes. The reverse osmosis units still removed microcystin to safe levels after we accelerated testing to mimic exposure to the chlorine levels present in Toledo drinking water for six months,“ says Lipscomb.
For more about this ODHE-funded HABRI project, contact Dr. Glenn Lipscomb at Glenn.Lipscomb@utoledo.edu. This work is thanks to the collaborative efforts of The University of Toledo’s research team of Chemical Engineering chair Dr. Glenn Lipscomb; Post-Doctoral Research Associate Dr. Youngwoo Seo; Masters student Neelam Jagani; and undergraduate student Xavier Johnson.