Non‐homogeneous biofilm modeling applied to bioleaching processes

Abstract

A two-dimensional non-homogeneous biofilm model is proposed for the first time to study chemical and biochemical reactions at the microorganism scale applied to biological metal leaching from mineral ores. The spatial and temporal relation between these reactions, microorganism growth and the morphological changes of the biofilm caused by solid inorganic precipitate formation were studied using this model. The model considers diffusion limitations due to accumulation of inorganic particles over the mineral substratum, and allows the study of the effect of discrete phases on chemical and microbiological mineral solubilization. The particle-based modeling strategy allowed representation of contact reactions between the microorganisms and the insoluble precipitates, such as those required for sulfur attack and solubilization. Time-dependent simulations of chemical chalcopyrite leaching showed that chalcopyrite passivation occurs only when an impervious solid layer is formed on the mineral surface. This mineral layer hinders the diffusion of one kinetically determinant mineral-attacking chemical species through a nearly irreversible chemical mechanism. Simulations with iron and sulfur oxidizing microorganisms revealed that chemolithoautotrophic biofilms are able to delay passivation onset by formation of corrosion pits and increase of the solid layer porosity through sulfur dissolution. The model results also show that the observed flat morphology of bioleaching biofilms is favored preferentially at low iron concentrations due to preferential growth at the biofilm edge on the surface of sulfur-forming minerals. Flat biofilms can also be advantageous for chalcopyrite bioleaching because they tend to favor sulfur dissolution over iron oxidation. The adopted modeling strategy is of great interest for the numerical representation of heterogeneous biofilm systems including abiotic solid particles.

The Atacama Desert: Technical Resources and the Growing Importance of Novel Microbial Diversity

“…Metabolic models have been constructed for several of the key bioleaching bacteria. These include bioleaching flux analysis of A. ferrooxidans (71); ferrous iron oxidation and nitrogen and CO assimilation by Leptospirillum ferrooxidans (84); metabolic reconstruction of mixed populations of dominant leaching bacteria in Chilean operations (85); and modeling of the bacterial biomass at the mineral surface (96).…”

Challenges for Complex Microbial Ecosystems: Combination of Experimental Approaches with Mathematical Modeling

“…They focus on various aims, for example, the analysis of detachment (6), the effect of EPS production on the community structure (69), the biofilm formed in membrane-aerated bioreactors (41), granular aggregate formations (42, 68) and biofouling (52) in the wastewater treatment process, the biofilm formed in microbial fuel cells (50), and biofilm development in the bioleaching process (47). Although there are various types of experimental techniques, which enable direct measurement of the microbial community, there have been limited numbers of studies on the experimental verification of multi-dimensional biofilm model predictions (41, 66).…”

The effect of biofilm permeability on bio‐clogging of porous media

“…A variety of 2D and 3D biofilm growth models have been developed and reported in the literature [a relatively recent overview is given by Wanner et al (2006)]. These have been successfully applied to a range of industrial scenarios ranging from biofouling of reverse osmosis membranes (Radu et al, 2010) to mineral ore bioleaching (Olivera‐Nappa et al, 2010). In terms of their application to bio‐barriers, or more generally porous media, Clement et al, (1997) and Taylor et al (2002) considered a bio‐barrier simulation model assuming homogeneous biofilm growth on soil particles.…”