University of Toledo researchers showed that rice husks can effectively eliminate microcystin from water. They published their findings in the journal Science of the Total Environment.
Previous researches have shown that rice husks, a cheap yet abundant agricultural byproduct, act as water purification solution. This current research is the first in demonstrating the ability of rice husks in eliminating microcystin which is a toxin released by harmful algal blooms.
"Delivering safe water is critical, and finding an economically viable solution to deliver safe water to people all over the world is going to be really important. The ability of this simple material to be powerful enough to address this issue is impressive," said Dr. Jon Kirchhoff, Distinguished University Professor and chair of the Chemistry and Biochemistry Department.
Kirchhoff and Dr. Dragan Isailovic are the team leaders who used organic rice husks in the research. These substances were subjected with hydrochloric acid and heated to 250 degrees Celsius.
Water samples from Lake Erie during the 2017 toxic algal bloom were treated with the rice husks to determine the amount of the toxin that could be absorbed.
"Researchers found the rice husks removed more than 95 percent of microcystin MC-LR -- the most common type found in Lake Erie -- in concentrations of up to 596 parts-per-billion (ppb). Even in concentrations approaching 3,000 ppb, more than 70 percent of the MC-LR was removed, and other types of MCs were removed as well," according to Eureka Alert.
"We looked at the removal of microcystins from real environmental samples and the material has performed really well," Isailovic said. "We are talking about extremely high concentrations of microcystins originating from cyanobacterial cells. Normally during summer, we have much, much lower concentrations in Lake Erie."
Guidelines set by the United States Environmental Protection Agency recommend that young children should not drink water that has more than 0.3 ppb of microcystin and school-age children and adults should not drink water that has more than 1.6 ppb of microcystin.
There are many advantages when it comes to using rice husks. They are inexpensive at $14.50 per half a cubic foot. Rice husks heated to 560 degrees Celsius can also destroy toxins and result to silica particles.
The researchers desire that this innovation can be used in developing more environmentally friendly techniques in water treatment that have been contaminated by harmful algal blooms.
"We could potentially use this readily available material to purify water before it even gets into Lake Erie," Isailovic said. "There are engineering solutions that need to be done, but one of our dreams is to apply what we develop in our labs to provide safe drinking water."
