title: Mass transfer limitation of sulfate in methanogenic aggregates.
abstract: The role of mass transfer limitation of sulfate as a factor governing the competition between sulfate reducing and methane producing bacteria in methanogenic aggregates was theoretically evaluated by the calculation of steady-state sulfate microprofiles using a reference set of parameters obtained from the literature. The shooting method was used as a numerical technique for solving the mathematical model. The effect of the parameters on mass transport limitation was tested by varying each reference value of the parameters with a factor of 3. Sulfate limitation within granules prevailed at moderate (0.1 kg m(-3)) and low sulfate concentrations in the bulk liquid, at high maximum sulfate utilization rates (3.73 x 10(-5) kg SO(4) (2-) kg(-1) VSS S(-1) or biomass concentrations (40 KG VSS m(-3)), and in large aggregates (radius of 7.5 10(-4) m). The effective diffusion coefficient of sulfate and the affinity constant were less determinative for the penetration depth of sulfate within a granule.
authors.affiliation: Centre of Environmental Sanitation, University Gent, Coupure L 653, 9000 Gent, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Overmeire
authors.forename: P
authors.initials: P
authors.lastname: Lens
authors.forename: W
authors.initials: W
authors.lastname: Verstraete