Hydro-geochemical model for treating acidic groundwater using a permeable reactive barrier
This study couples geochemistry with geo-hydraulics to enable time-dependent modelling for the treatment of acidic groundwater using an alkaline permeable reactive barrier (PRB). This is the first such model developed for acidic groundwater generated from acid sulfate soil which is useful to address the adverse effects such as massive fish kills, corrosion of concrete and steel structures and unfavourable conditions for vegetation. The remediation process has been successful to date with a slight decrease in efficiency caused due to chemical clogging by secondary mineral precipitates, which reduces the porosity and hydraulic conductivity of the reactive medium. To predict these changes numerically, governing equations were incorporated into finite different codes, MODFLOW and RT3D. An original geochemical algorithm was developed for RT3D to simulate chemical reactions occurring in the PRB. The results and the model predictions are in agreement, confirming the hydraulic conductivity reduction due to mineral precipitation was only 3% at the entrance phase of PRB.