Modeling of the clogging in a MgO column used to treat a Ni- and Co-contaminated water and performance prediction for a centripetal radial column

Abstract

A geochemical model was established to predict the chemical and hydraulic performances of MgO columns used to treat a nickel- and cobalt-contaminated groundwater. Using the PHREEQC software, an advection-reaction simulation was carried out to re-create the outlet concentrations observed during a previous axial column laboratory test. Reaction kinetics were introduced to calculate the rates of brucite dissolution as well as iron and manganese oxidation. Pore volume diminution during the test was also predicted using the volume of goethite precipitates generated. The floating-sphere model was applied to calculate the equivalent hydraulic conductivity (K_eq) of the column. The geometry of the model's cells was then adjusted to represent a radial centripetal filter containing the same amount of reactive MgO. The K_eq predictions for the centripetal filter showed that the loss of permeability in the filter could be significantly delayed by changing the filter's flow configuration. While those results are promising, further testing is necessary to provide additional experimental results for radial filters.

Keywords: Contaminated groundwater; Geochemical modeling; Heavy metals; Permeable reactive barrier.