title: Simultaneous removal of H2S and NH3 in biofilter inoculated with Acidithiobacillus thiooxidans TAS.
abstract: H2S and NH3 gases are toxic, corrosive and malodorous air pollutants. Although there are numerous well-established physicochemical techniques presently available for the treatment of these gases, the growing demand for a more economical and improved process has prompted investigations into biological alternatives. In biological treatment methods, H2S is oxidized to SO4(2-) by sulfur-oxidizing bacteria, and then NH3 is removed by chemical neutralization with SO4(2-) to (NH4)2SO4. Since the accumulated (NH4)2SO4 can inhibit microbial activity, it is important to utilize an effective sulfur-oxidizing bacterium that has tolerance to high concentrations of (NH4)2SO4 for the simultaneous removal of H2S and NH3. In this study, a sulfur-oxidizing bacterium with tolerance to high concentrations of (NH4)2SO4 was isolated from activated sludge and identified as Acidithiobacillus thiooxidans TAS. A. thiooxidans TAS could display its sulfur-oxidizing activity in a medium supplemented with 60 g.l(-1) (NH4)2SO4, even though its growth and sulfur-oxidizing activity were completely inhibited in 80 g.l(-1) (NH4)2SO4. When H2S alone was supplied to a ceramic biofilter inoculated with A. thiooxidans TAS, an almost 100% H2S removal efficiency was maintained until the inlet H2S concentration was increased up to 900 microl.l(-1) and the space velocity up to 500 h(-1), at which the amount of H2S eliminated was 810 g-S.m(-3).h(-1). However, when NH3 (50-500 microl.l(-1)) was simultaneously supplied to the biofilter with H2S, the maximum amount of H2S eliminated decreased to 650 g-S.m(-3).h(-1). The inhibition of H2S removal by low NH3 concentrations (50-200 microl.l(-1)) was similar to that by high NH3 concentrations (300-500 microl.l(-1)). The critical inlet H2S load that resulted in over 99% removal was determined as 400 g-S.m(-3).h(-1) in the presence of NH3.
authors.affiliation: Department of Environmental Science and Engineering, Ewha Womans University, 11-1 Daehyung-dong, Seodaemun-gu, Seoul 120-750, Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Lee
authors.forename: Kyung-Suk
authors.initials: KS
authors.lastname: Cho
authors.forename: Hee Wook
authors.initials: HW
authors.lastname: Ryu
mesh_terms: D013856:Acidithiobacillus thiooxidans / Q000378:metabolism*; D000393:Air Pollutants / Q000302:isolation & purification / Q000378:metabolism; D000397:Air Pollution / Q000517:prevention & control*; D000641:Ammonia / Q000302:isolation & purification* / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006862:Hydrogen Sulfide / Q000302:isolation & purification* / Q000378:metabolism*; D014462:Ultrafiltration / Q000295:instrumentation* / Q000379:methods
chemical_list: D000393:Air Pollutants; D000641:Ammonia; D006862:Hydrogen Sulfide