title: Effect of S/N ratio on sulfide removal by autotrophic denitrification.
abstract: In this study a completely stirred tank reactor was used to study the effect of sulfide to nitrate (S/N) ratio on sulfide removal while nitrate was used as electron acceptor. Several S/N ratios were studied for this purpose ranging from 0.3 to 2.4 mol/mol. The complete sulfide removal was achieved when S/N ratio 0.85 mol/mol was used with the autotrophic denitrification efficiency up to 80 %. No nitrite accumulation was observed, and the main product of sulfide oxidation was sulfate. Dissimilatory nitrogen reduction to ammonia occurred and subsequently, elemental sulfur accumulated while S/N ratio was higher than 1.3 mol/mol. The specific autotrophic denitrification rates under S/N ratios 0.8 and 1.2 were 5 and 26 mg g(-1) h(-1) (N-NO3 (-), VSS), respectively. Thiobacillus denitrificans and Thiomicrospira denitrificans were detected in the reactor by fluorescent in situ hybridization, but their overall representation was not more than 5 % of the entire microbial populations.
authors.affiliation: Department of Water Technology and Environmental Engineering, Faculty of Environmental Technology, Institute of Chemical Technology, Technická 5, 166 28, Prague 6, The Czech Republic, petr.dolejs@vscht.cz.
authors.forename: Petr
authors.initials: P
authors.lastname: Dolejs
authors.forename: Ladislav
authors.initials: L
authors.lastname: Paclík
authors.forename: Josef
authors.initials: J
authors.lastname: Maca
authors.forename: Dana
authors.initials: D
authors.lastname: Pokorna
authors.forename: Jana
authors.initials: J
authors.lastname: Zabranska
authors.forename: Jan
authors.initials: J
authors.lastname: Bartacek
mesh_terms: D000641:Ammonia / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology*; D058440:Denitrification; D020565:Epsilonproteobacteria / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis*; D010084:Oxidation-Reduction; D013431:Sulfates / Q000378:metabolism; D013440:Sulfides / Q000378:metabolism*; D013455:Sulfur / Q000032:analysis*; D013855:Thiobacillus / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D009566:Nitrates; D013431:Sulfates; D013440:Sulfides; D013455:Sulfur; D000641:Ammonia; D009584:Nitrogen