Performance of laboratory adsorbent-based permeable reactive barrier for treating MTBE-contaminated groundwater

To evaluate the performances of adsorbent-based permeable reactive barriers (PRBs) for the treatment of methyl tert-butyl ether (MTBE)-contaminated groundwater, rapid small scale column tests were conducted and evaluated. Two granular activated carbons (GACs), F600 and F300, were used as the adsorbents. MTBE of between 80-891 g L^-1 were tested in deionized water and three natural waters in the column tests. Steeper breakthrough curves (BTCs) and smaller integrated column capacities in groundwater and river water were found compared with those in deionized water. Based on the experimental observation, it is interpreted that the natural organic matters in the natural waters competed with MTBE for the adsorption sites within GACs and suppressed the surface loading of MTBE of the adsorbents. The influent MTBE concentrations have great influences on the integrated column capacities as well as the spreading of BTCs under different empty bed contact times (EBCTs). A model approach, fixed-bed surface diffusion model incorporated with the simplified competitive adsorption model (SCAM)/equivalent background compound (EBC), successfully described the MTBE profiles under different influent concentrations and EBCTs in natural waters. The model predictions agreed well with the experimental data and no adjustable parameters were used during the calculations of the model. The SCAM-EBC approach was successfully applied to predict the BTCs in column studies as well as the equilibrium and kinetics adsorption conducted in batch experiments. The results may provide a means to more efficiently design PRBs and to better predict the performances of adsorbent-based PRBs under different conditions in groundwater remediation.