When algal blooms occur in lakes, the over-abundant cyanobacteria (blue-green algae) produce a toxin known as microcystin. Now, Ohio-based scientists are using other types of bacteria to neutralize that toxin, in a process that could be cheaper and more eco-friendly than the alternatives.

The University of Toledo's Dr. Jason Huntley was motivated to develop the system, after a 2014 bloom in Lake Erie left half of the city's residents without safe drinking water for three days.

After assessing the various types of bacteria that are native to the lake, Huntley and colleagues identified and isolated 13 that are capable of breaking down MC-LR, which is the most common and toxic type of microcystin. According to the scientists, lab tests indicate that certain combinations of the bacteria are effective enough that they would have been capable of making the lake water safe to drink during the 2014 crisis.

The bacteria aren't known to be harmful to humans, so it's unlikely that there would be any health risks if they were to be used in biofilters at water treatment plants. Additionally, because they're local to the area, the microbes should be both easily obtainable and non-disruptive to the environment. Although previous studies identified microcystin-neutralizing bacteria in other countries, those bacteria weren't native to the Great Lakes region.

Current methods of removing such toxins include chlorination, ozonation, activated carbon adsorption and flocculation (the causing of contaminants to clump together). According to Huntley, however, these all have drawbacks.

"Those techniques are not ideal because of high costs, limited removal efficiencies, and they lead to the production of harmful byproducts or hazardous waste," he says. "Biofilters are a cost-effective and safe alternative to the use of chemicals and other conventional water treatment practices."

The scientists are now in the process of testing the bacteria in some such biofilters, and have patented the technology.