title: Effect of oxygen dosing point and mixing on the microaerobic removal of hydrogen sulphide in sludge digesters.
abstract: Limited oxygen supply to anaerobic sludge digesters to remove hydrogen sulphide from biogas was studied. Micro-oxygenation showed competitive performance to reduce considerably the additional equipment necessary to perform biogas desulphurization. Two pilot-plant digesters with an HRT of ∼ 20 d were micro-oxygenated at a rate of 0.25 NL per L of feed sludge with a removal efficiency higher than 98%. The way of mixing (sludge or biogas recirculation) and the point of oxygen supply (headspace or liquid phase) played an important role on hydrogen sulphide oxidation. While micro-oxygenation with sludge recirculation removed only hydrogen sulphide from the biogas, dissolved sulphide was removed if micro-oxygenation was performed with biogas recirculation. Dosage in the headspace resulted in a more stable operation. The result of the hydrogen sulphide oxidation was mostly elemental sulphur, partially accumulated in the headspace of the digester, where different sulphide-oxidising bacteria were found.
authors.affiliation: Department of Chemical Engineering and Environmental Technology, Escuela de Ingenierías Industriales, Sede Dr. Mergelina, University of Valladolid, Dr. Mergelina s/n, 47011 Valladolid, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Díaz
authors.forename: S I
authors.initials: SI
authors.lastname: Pérez
authors.forename: E M
authors.initials: EM
authors.lastname: Ferrero
authors.forename: M
authors.initials: M
authors.lastname: Fdz-Polanco
mesh_terms: D000693:Anaerobiosis; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004867:Equipment Design; D005740:Gases; D006862:Hydrogen Sulfide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000737:chemistry*; D012722:Sewage; D013440:Sulfides / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D005740:Gases; D012722:Sewage; D013440:Sulfides; D010100:Oxygen; D006862:Hydrogen Sulfide