Design of Permeable Adsorptive Barriers (PABs) for groundwater remediation by COMSOL Multi-physics simulations

Abstract

A B S T R A C TThis work deals with an innovative approach to design a permeable reactive barrier (PRB) filled with activated carbon, namely a permeable adsorptive barrier (PAB). A 2D numerical model, solved using a finite element approach via COMSOL Multi-physics, was used to describe the pollutant transport within groundwater and the pollutant adsorption onto the barrier. The PAB design procedure was applied to a benzene-contaminated aquifer situated in the metropolitan area of North Naples (Italy), lately hit the headlines as "Gomorra's land". Model results showed that PAB is an effective tool for the remediation of the aquifer under analysis, since the pollutant concentration downstream the barrier resulted everywhere lower than the regulatory limit set for groundwater. A sensitivity analysis was carried out to evaluate the influence of some site parameters on the PAB design, i.e. hydraulic conductivity and dispersivity. Finally, the simulation results allow estimating the long-term efficiency of the treatment system and the time required to achieve a complete restoration of the aquifer.

An optimized configuration of adsorptive wells for the remediation of an aquifer contaminated by multiple aromatic hydrocarbon pollutants

“…PRBs made of adsorbing materials are usually referred as Permeable Adsorptive Barriers (PABs) (Bortone et al, 2015;Erto et al, 2014;Powell et al 1998).…”

“…The design and optimization of a PAB-D consists mainly in: i) the definition of the well grid (i.e. number and position of wells), ii) optimization of its geometrical parameters such as the well diameter, the well-to-well distance, the number of well columns in the grid and the column-to-column distance (Santonastaso et al, 2018a;2018b;Bortone et al, 2015) The optimal PAB-D design was carried out by using a numerical 2D model developed in COMSOL Multiphysics ® environment, in which a finite element approach is used (Tabatabain, 2014;Prior, 2011). Numerical simulations predicted the pollutants fate and transport within the aquifer and the adsorption phenomena occurring onto the material of the wells.…”

“…Ex-situ technologies generally embrace pump and treat methods (P&T), which can be combined with a physical containment of the polluted water by installing slurry walls or some other permanent structure (Brauner and Killingstad, 1996). However, in some cases, being BTEX contamination very persistent through the soil and groundwater, ex-situ treatments can be financially impracticable, and replaced by in-situ methods, which can offer lower costs, less disruption to the surface, and more effective treatment (Bortone et al, 2015;Cole, 1994). In this contest, Permeable Reactive Barriers (PRBs) are a well-regarded passive technique for groundwater remediation, on behalf of their high efficiency, low operating and maintenance costs, especially when dealing with high volume aquifers and low pollutant concentrations (Luo et al, 2016;Bortone et al, 2013a;Powell et al, 1998).…”

Effects of calcium ion and pH on the adsorption/regeneration process by activated carbon permeable reactive barriers

“…10 To better utilize the AC-PRBs, differently designed structures of the PRBs were investigated and applied in groundwater remediation. 11 PRB offers the potential for low-cost remediation, taking advantage of the passive groundwater ow to bring the contaminants in contact with the reactive materials in the barrier. 12,13 However, AC-PRBs are limited by AC's adsorption capacity.…”