title: Biofilm development during the start-up of a sulfate-reducing down-flow fluidized bed reactor at different COD/SO4(2-) ratios and HRT.
abstract: In sulfate-reducing reactors, it has been reported that the sulfate removal efficiency increases when the COD/SO4(2-) ratio is increased. The start-up of a down-flow fluidized bed reactor constitutes an important step to establish a microbial community in the biofilm able to survive under the operational bioreactor conditions in order to achieve effective removal of both sulfate and organic matter. In this work the influence of COD/SO4(2-) ratio and HRT in the development of a biofilm during reactor start-up (35 days) was studied. The reactor was inoculated with 1.6 g VSS/L of granular sludge, ground low density polyethylene was used as support material; the feed consisted of mineral medium at pH 5.5 containing 1 g COD/L (acetate:lactate, 70:30) and sodium sulfate. Four experiments were conducted at HRT of 1 or 2 days and COD/SO4(2-) ratio of 0.67 or 2.5. The results obtained indicated that a COD/SO4(2-) ratio of 2.5 and HRT 2 days allowed high sulfate and COD removal (66.1 and 69.8%, respectively), whereas maximum amount of attached biomass (1.9 g SVI/L support) and highest sulfate reducing biofilm activity (10.1 g COD-H2S/g VSS-d) was achieved at HRT of 1 day and at COD/sulfate ratios of 0.67 and 2.5, respectively, which suggests that suspended biomass also played a key role in the performance of the reactors.
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científicas y Tecnológica, Camino a a Presa San José 2055, Lomas 4a., 78216 San Luis Potosi (S.L.P.), México.
authors.forename: E Z
authors.initials: EZ
authors.lastname: Piña-Salazar
authors.forename: F J
authors.initials: FJ
authors.lastname: Cervantes
authors.forename: M
authors.initials: M
authors.lastname: Meraz
authors.forename: L B
authors.initials: LB
authors.lastname: Celis
mesh_terms: D018441:Biofilms; D019149:Bioreactors; D010100:Oxygen / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*
chemical_list: D013431:Sulfates; D010100:Oxygen