Coupled Flow Modelling for a Geothermally Facilitated Bioreactor

Abstract

Abandoned mines across the world leak contaminated waters into precious water resources, threatening human populations and natural environments alike. The primary demand from the industry for addressing the contamination is a passive system that utilizes locally available and cheap material, with little energy or maintenance requirement. Passive treatment systems can operate in remote regions, using diverse, inexpensive, and locally available material with low waste production, but are subject to ambient conditions and are often space intensive. The geothermal gradient available at abandoned mines is a viable heat energy source that can provide advantageous temperature conditions for established remediation techniques, namely bioremediation.Currently, the primary models used for testing new passive designs are either largely empirically based, or limit the scope of modelling parameters, making it difficult to incorporate innovative design aspects into the existing modelling framework. The following paper presents a model, based on kinetic parameters from a column experiment, which couples mechanics, thermodynamics, hydrodynamics, and microbial kinetics. The modelling results show the effect of an imposed temperature gradient on the permeability and microbially driven reactions of a bioreactor. The model reflects evolving thermal and mass transfer in the multiphase system. The addition of geothermal energy to a bioreactor is shown to improve long-term permeability, enhance reactions and precipitation kinetics, and decrease the necessary spatial expanse of designed bioreactor systems.