This SBIR Phase I project will develop and demonstrate the feasibility of X-ray with or without UV-C treatment for inactivating, destroying, or otherwise reducing major wastewater contaminants. The investigators will also make preliminary determinations as to the effectiveness and comparative advantages of X-ray and UV-C against estrogen, a broad spectrum of fluid stream contaminants, and ascaris (worm) eggs to determine priorities for Phase II prototyping and market entry. Tests will also be run using both fluxes simultaneously or in sequence, as hardware permits, to determine if synergistic effects are present.
The broader/commercial impact of the project will be creation of X-Ray sources for the water and wastewater environment that can be installed as a flat broad-area source, or installed within a round pipe. Successful demonstrations of the objectives of this project will lead to new solutions and major commercial opportunities not only in municipal wastewater treatment, but in fresh water treatment, industrial wastewater, marine, and residential water treatment markets.
We investigated the development of cost-effective wastewater treatment technologies using UV-C for effluent and x-ray irradiation for sludge. We demonstrated the feasibility of UV-C radiation sources in panel form factors by successfully constructing prototypes and obtaining initial test data. X-ray disinfection studies show promise for the treatment of total coliforms, E. coli, and Salmonella, demonstrating the potential application of x-ray ionizing radiation, with its greater penetration compared to UV-C, as a means for treating sludge in wastewater applications. Low energy x-ray was also found to significantly reduce the concentration of estrogens in effluent, offering an approach to a growing problem in the industry. We developed two types of prototypes: one using cold cathodes and a second prototype using hot filament cathodes. Both approaches show promise and offer different benefits: hot filaments offer potentially higher performance through greater intensity, while cold cathodes offer potentially greater energy efficiency. The disinfection properties of UV-C are widely known and there is an established user base in the wastewater industry. Therefore, we focused our hardware development efforts on producing prototypes for UV-C. As our technology can be readily adapted for x-ray use, we performed disinfection studies using low energy x-rays in sludge to evaluate the potential of x-ray sterilization for wastewater applications. We hypothesized that the greater penetration of x-rays would provide a benefit for sludge sterilization. Our results show a 99% reduction of total coliforms, E. coli, and Salmonella in anaerobically digested sludge samples. X-ray sterilization was shown to kill total coliforms and E. coli at lower doses than gamma ray irradiation, which is an indication of greater relative biological effectiveness. We successfully demonstrated a 20-30% reduction in estrogens in effluent under low energy x-ray irradiation. The results suggest a method that may be employed in municipal water treatment facilities to breakdown estrogenic compounds generated in industrial and agricultural processes that accumulate in the water.
