Highly efficient method for oxidation of dissolved hydrogen sulfide in water, utilizing a combination of UVC light and dissolved oxygen

Hydrogen sulfide is a hazardous contaminant that may appear in well-water and in sewage streams. Here we present a very efficient way for the removal of H2S from well-water, based on combining UVC light and oxygen. The method was tested with H2S-enriched tap water as well as with natural well water, both of which containing up to 20 mg/L of H2S. A conversion of up to 90% was obtained within a residence time of no more than a few minutes. The quantum efficiency, defined as the ratio between the number of removed H2S molecules to the number of impinging photons, was found to be as high as 70%, depending on conditions. The main product was found to be sulfate, without the appearance of elemental sulfur, i.e. with no major change in turbidity. The absence of sulfur in the outlet stream in of large importance when treating H2S-containing well-water, since it omits the need for posttreatment removal of particles. Results are explained by the excitation of HS− species, following by formation of polysulfide anions that readily react with any formed elemental sulfur, eventually yielding sulfate ions.