Multiobjective Groundwater Remediation Design Using a Coupled MFree Point Collocation Method and Particle Swarm Optimization

Abstract

Pump and treat (PAT) is one of the commonly used techniques for groundwater remediation in which the contaminated groundwater is pumped, treated, and put back to the aquifer system or other sources. For an effective PAT system design, simulation-optimization (S/O) models are very useful; the simulation model helps in predicting the spatial and temporal variation of the contamination plume, and optimization models are used to minimize the cost of pumping. For large-scale groundwater flow and transport simulation, grid-based or mesh-based models such as the finite difference method (FDM) and the FEM have been found to be cumbersome and time consuming. Meshfree (MFree)-based numerical models that use a set of nodes scattered within the problem domain and on the boundaries of the domain regardless of the connectivity information between them are found to be very effective for large-scale field problems. In this study, the MFree point collocation method (PCM) is used for the groundwater flow and transport simulation, and an evolutionary algorithm based on particle swarm optimization (PSO) is proposed for optimization. The S/O model based on PCM and PSO with multiobjective (PCM-PSO-PAT-MO) strategies are developed and applied for remediation of an unconfined aquifer polluted by total dissolved solids (TDS) using PAT. The PCM-PSO–based models are found to be simple and effective in groundwater remediation design using PAT.