Hydrogen Sulfide Generation Suppression by Nitrate Addition �C Application to Solid Waste Landfill Site

Abstract

In Japan, three deaths were reported at an inert solid waste landfill site after exposure to hydrogen sulfide (H2S) generated at the site. H2S gas is produced when sulfate-reducing bacteria (SRB) convert sulfate derived from waste gypsum board under anaerobic conditions. The recommended countermeasure is to supply oxygen by installing gas venting pipes. However, a large cost is necessary for pipe installation and the pipes are not applicable to coastal landfill sites. On the other hand, H2S generation suppression by nitrate (NO3) addition has been reported in sewage systems. In this study, in order to develop a method to suppress H2S generation by NO3 addition at a landfill site, the extent of suppression was quantitatively estimated. When NO3 reagent was added at the rate of 0.46 mmol-NO3/(L•d) into a liquid from which H2S gas was generated at the rate of 0.21 ± 0.05 mmol-H2S/(L•d), H2S generation rate was decreased to approximately 1/4 of the original rate. Although it was difficult to maintain the concentration of NO3 because it tended to disappear rapidly, the frequent addition of NO3 reagent to maintain the concentration of approximately 430 mg-NO3/L enabled us to control H2S concentration to below 1000 ppmv for one month and H2S generation rate to below 1/20 of the original rate.