Modeling biochemically driven mineral precipitation in anaerobic biofilms

A numerical model links the build-up of mineral precipitate (primarily CaCO 3) and the anaerobic activity of biofilms, which occur in granular material permeated with leachate from a municipal solid waste landfill. The model r epresents the porous-media flow system as a collection of elements in which each element acts as a separate, fixed-film reactor. The model represents biofilm growth for microorganism carrying out acetogenesis of propionate an d methanogenesis of acetate. It also directly links substrate utilization t o mineral precipitation and accounts for the accumulation of inert biomass on the porous media at any time or position along the length of the column. Thus, the model describes the ecological interactions among fermenters, me thanogens, inert biomass, and mineral precipitate. Although substrate utili zation by the active microorganisms drives the entire system mineral precip itate becomes a dominant component in the biofilm. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.