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A mathematical model to simulate the three-dimensional growth of multispecies anaerobic biofilms is developed and tested with a two-species biofilm composed of sulfate-reducing bacteria and methanogens. The numerical approach is based on the separation of biological, physical, and chemical phenomena so that quasi-steady-state conditions can be used in the solution. Simulations with Desulfovibrio vulgaris and Methanobacterium formicicum result in the formation of a biofilm heterogeneous in structure and composition. The model predicts different biofilm structures in the absence of sulfate, when a syntrophic association between the two organisms develops, and in the presence of sulfate, when the two organisms compete for the available hydrogen.

Abstract:Corrosion of copper pipes may release high amounts of copper into the water, exceeding the maximum concentration of copper for drinking water standards. Typically, the events with the highest release of copper into drinking water are related to the presence of biofilms. This article reviews this phenomenon, focusing on copper ingestion and its health impacts, the physicochemical mechanisms and the microbial involvement on copper release, the techniques used to describe and understand this phenomenon, and the hydrodynamic effects. A conceptual model is proposed and the mathematical models are reviewed.