Water Management Association of Ohio
The only organization dedicated to all of Ohio's water resources.
Presenter: Natalie Hull,
Assistant Professor: Civil, Environmental, and Geodetic Engineering
Core Faculty Member: Sustainability Institute
The Ohio State University
Abstract: Managing microorganisms and their biomolecules in water is still one of the greatest global challenges threatening public health. Cyanobacteria and their toxins produced during harmful algal blooms must be managed comprehensively during and after drinking water treatment to protect public and environmental health. To examine impacts on harmful algal blooms during drinking water treatment processes, we investigated impacts of various UV wavelengths on cyanotoxin degradation and cyanobacteria disinfection. To examine impacts of harmful algal blooms after treatment processes, we investigated various extraction and quantification methods for a variety of residuals from different unit processes and different drinking water treatment plants throughout Ohio and the US.
For the cyanotoxin degradation studies, we found that in spiked lab water and in natural water samples, lower wavelength UV-C (222 nm) more efficiently and completely degraded the cyanotoxin microcystin-LR, resulting in lower concentrations and better reductions in toxicity than traditional higher wavelength UV-C (254 nm). For the cyanobacteria disinfection studies, we disinfected a cyanobacterial population presumed to be Planktothrix spp. that was isolated from Deer Creek Reservoir near Akron, OH and found that 254 nm disinfected the bacteria and caused damage to the genome of the bacteria in a dose dependent manner. Impacts of 222 nm on the cyanobacteria are still under investigation. For the studies of cyanotoxins in drinking water treatment residuals, we demonstrated for the first time the widespread prevalence of microcystins in residuals from conventional settling processes, storage lagoons, and dissolved air flotation. We demonstrated the impact that cell lysis method, extraction solvent (especially methanol), and quantification method can have on measured concentrations. We also quantified biological and other physiochemical processes during storage that can reduce residuals microcystins concentrations. Together, these studies provide quantitative mechanistic information to support management of cyanobacteria and cyanotoxins during and after drinking water treatment.
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