(169b) Efficient Degradation of Hydrogen Sulfide in Groundwater Using a Chemical-Free Photocatalyst

About 15% of Americans do not have access to public water systems and must use private wells for drinking water.¹ These private wells are unregulated, and the user is responsible for maintaining and treating their water supply. Current treatment options for private water sources, such as UV disinfection or reverse osmosis, can be expensive, complex, or ineffective against certain contaminants. Hydrogen sulfide is one such contaminant that occurs naturally in groundwater and private wells due to the activity of anaerobic sulfur bacteria. The rotten-egg smell of even low concentrations of H₂S is a source of disgust for users of private wells. Photocatalytic advanced oxidation processes (P-AOPs) offer a chemical-free, lower-cost, and complete solution to treating the various contaminants found in private water sources.

In a previous work, we demonstrated that the P-AOP we developed effectively degrades model textile dyes, pharmaceuticals, pathogens, and chloro-hydrocarbons.² In this work, we report our system’s effectiveness at treating H₂S-contaminated water. The photocatalyst consists of commercial titania nanoparticles, P25, that have been immobilized on quartz fibers, resulting in a high surface area photocatalyst on UV-transparent supports. The high photocatalyst surface area is advantageous for the mass-transfer-limited degradation reactions, and the UV-transparent supports maximize photon management in our reactor.

We test the efficacy of our reactor system in degrading H₂S under illumination from a UVC lamp. Our system achieves an electrical energy per order (E_EO) of < 1 for H₂S. We also investigate the effect of hydroxyl radical and hole scavengers, TOC, and pH on photocatalytic performance by performing tests using a synthetic water source prepared with interfering compounds and water from a Baton Rouge wastewater treatment plant. Finally, we propose improvements needed to scale our reactor system for practical application in the treatment of private wells.

(1) DeSimone, L. A. Quality of water from domestic wells in principal aquifers of the United States, 1991–2004. US Geological Survey 2009, 139.

(2) Daniel E. Willis, E. C. S., Madhusudan Kamat, Sarah K. Glass, MaCayla J. Caso, Mary Worbington, Tochukwu Ofoegbuna, Samuel D. Snow, Kevin M. McPeak. Efficient Chemical-Free Degradation of Waterborne Micropollutants with an Immobilized Dual-Porous TiO₂ Photocatalyst. ACS ES&T Engineering Under Review.