title: Kinetics of denitrification using sulphur compounds: effects of S/N ratio, endogenous and exogenous compounds.
abstract: The influence of different sulphur to nitrogen (S/N) ratios on the specific autotrophic denitrification activity was studied in batch experiments using thiosulphate and nitrate as substrates. Transitory accumulations of nitrite were observed for assays with S/N ratios of 3.70 and 6.67 g/g, probably due to the higher specific reduction rate of nitrate compared to that of nitrite. Nitrite was the main end product when S/N ratios of 1.16 and 2.44 g/g were tested. The effects of endogenous (NO(3)(-),NO(2)(-),S(2)O(3)(2-)and SO(4)(2-)) and exogenous compounds (acetate and NaCl) on the specific denitrifying activity of the sludge were tested. Nitrite and sulphate did exert clear inhibitory effects over the process while thiosulphate, acetate and NaCl did not have strong effects at the concentrations tested. Similar experiments also showed that sulphur was not a suitable electron donor for these microorganisms, but sulphide was used successfully.
authors.affiliation: Department of Chemical Engineering, Institute of Technological Research, School of Engineering, University of Santiago de Compostela, Rua Lope Gómez de Marzoa, E-15782 Santiago de Compostela, Spain. eqluis@usc.es
authors.forename: J L
authors.initials: JL
authors.lastname: Campos
authors.forename: S
authors.initials: S
authors.lastname: Carvalho
authors.forename: R
authors.initials: R
authors.lastname: Portela
authors.forename: A
authors.initials: A
authors.lastname: Mosquera-Corral
authors.forename: R
authors.initials: R
authors.lastname: Méndez
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D000693:Anaerobiosis; D018533:Biomass; D019149:Bioreactors; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry* / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry* / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry* / Q000378:metabolism; D017672:Nitrogen Compounds / Q000737:chemistry* / Q000378:metabolism; D013431:Sulfates / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D009566:Nitrates; D009573:Nitrites; D017672:Nitrogen Compounds; D013431:Sulfates; D013455:Sulfur; D009584:Nitrogen; D019342:Acetic Acid