Modeling biochemically driven mineral precipitation in anaerobic biofilms

Abstract

A numerical model links the build-up of mineral precipitate (primarily CaCO3) and the anaerobic activity of biofilms, which occur in granular material permeated with leachate from a municipal solid waste landfill. The model represents 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 microorganisms carrying out acetogenesis of propionate and methanogenesis of acetate. It also directly links substrate utilization to 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, methanogens, inert biomass, and mineral precipitate. Although substrate utilization by the active microorganisms drives the entire system, mineral precipitate becomes a dominant component in the biofilm.