Study on microbial transport and biodegradation in fracture contaminated sites
In-situ bioremediation,as a low-cost and environmentally friendly technique for the remediation of contaminated sites,has garnered significant attention.Current research on bioremediation techniques largely focuses on biostimulation techniques that enhance the inherent degradation capabilities of indigenous microorganisms.Limited research exists on bioaugmentation techniques involving the introduction of exogenous microorganisms.While dominant seepage such as natural and artificial fissures within a contaminated site can affect the transport of injected microorganisms and their degradation reactions.A mathematical model was proposed to stimulate the migration of microorganisms,solutes,and contaminant degradation processes within fractured aquifers.The model accounts for processes including advection,diffusion,adsorption,growth,death,and microbial metabolic reactions.It further integrates the interrelationships among microorganisms,electron acceptors,and substrate,and in good agreement with experimental results.The results show that sustaining optimal contact between microorganisms and contaminants,while providing ample nutrients,constitutes a critical factor in enhancing bioremediation efficiency.Due to biodegradation accelerating the reverse diffusion of contaminants within the matrix to the region surrounding the fracture,the impact scope of bioremediation extending beyond microbial transport zones.Simultaneously,the diffusion coefficient of the extracellular matrix in fractures exhibits the most significant influence on bioremediation efficacy,followed by microbial adsorption coefficients and injection rates.The mathematical model presented herein stands as a vital tool for assessing the effectiveness of bioaugmentation strategies within fractured geological formations,thereby aiding the design and optimization of pertinent bioremediation approaches.
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