Dr. Mao and Dr. Hershcovitch receive the 2019 SBU/BNL Seed Grant to develop a small-scale plasma device to clean water
They are researching how to apply a small-scale plasma device for removal of contaminants (1,4-dioxane and PFAS) and pathogens from water/wastewater at low cost. The ultimate purpose of the project is to develop a power efficient water treatment technique that can remove polyfluoroalkyl substances (PFASs), 1,4 Dioxane from the water supply and has the potential for deactivating all pathogens, degrading all pharmaceuticals and other chemical contaminates, by in-water plasma generation, at unprecedented rate, which no existing technique can do. The plasma is an in-water, vortex-stabilized water plasma. This is a novel technology that is being employed to prevent electrode erosion. It is essentially a blow torch in the water that should disintegrate all contaminants by brute force, since plasma particles, UV and advance oxidation process (AOP) chemicals can break contaminants’ bonds. However, unlike presently utilized or proposed electron beams and plasmas, which are not stabilized, the proposed plasma is stabilized, providing confinement to electrons and ions driving the electric arc, and are therefore power efficient. Sterilization rates extrapolated from existing electron beam or plasma treatment setups show that a 20 KW prototype wastewater treatment plant should be capable of disinfecting 2,690 liters/sec of pathogens and degrade 216 liter/sec of antibiotics, if the technique works as expected. These rates per unit power of wastewater recovery are orders of magnitude more efficient than currently utilized disinfection methods or water desalination.
The project entails developing a small-scale in water vortex stabilized large diameter arc (an order of magnitude larger than previously achieved). Once the desired plasma is established, the experimental process is straight-forward: known concentrations of PFASs and 1,4 Dioxane are introduced upstream from the plasma arc, and the samples of resultant concentrations downstream from the arc are collected and analyzed. Additionally, UV radiation emitted from the plasma will be measured and quantified to show the plasma potential for deactivating pathogens and degrading pharmaceuticals, since experimental data showing pathogens deactivation and some pharmaceuticals degradation by UV exists.