Effective Chemical Delivery Through Multi‐Screen Wells to Enhance Mixing and Reaction of Solute Plumes in Porous Media

Abstract

AbstractIn‐situ groundwater remediation is usually limited by the incomplete mixing of reactive species due to creeping flow characteristics and limited dispersion in porous media. In this study, we propose a novel approach to deliver chemicals through a multi‐screen well (MSW) to enhance the in‐situ remediation efficiency without extra energy or labor costs. The basic idea is to separate the injected solution into several plumes to enlarge the contact area between injected chemical compounds and ambient contaminants and enhance the mass exchange flux and reactive mixing. We perform laboratory experiments and numerical simulations of steady‐state instantaneous reactive transport in two‐dimensional porous media. We consider three separate screens in an MSW for the injection of treatment solutions and compare its plume distributions with a classical single‐screen well system. The experimental results confirm our conjecture and demonstrate the reliability of the numerical model. Furthermore, we derive an optimal injection interval of the MSW system by comparing analytical and numerical methods and demonstrate its capability to achieve effective transverse mixing and reaction enhancement. An interval that is smaller than the optimal injection interval leads to the exhaustion of contaminants between the injected plumes and the coalescence of the separate injected plumes at the downgradient portion along the travel distance, which reduces the effectiveness of the MSW system. We also investigate the sensitivity of the injected concentration, individual screen length, transverse dispersivity, and seepage rate on the determination of the optimal injection interval and provide suggestions about the design of an MSW system.