Removal of Benzene, MTBE and Toluene from Contaminated Waters Using Biochar-Based Liquid Activated Carbon

Abstract

Fuel compounds (BTEX) and fuel additives (MTBE) are pollutants frequently detected in groundwater resources. They may cause serious environmental and health issues and have to be removed from water before use. Ex-situ technologies such as air stripping, advanced oxidation and column adsoroption have been in use for years with different success rates. Recently, more attention has been given to the in-situ remediation methods using liquid/colloidal carbon adsorbents. However, limited studies were found on the use of these adsorbents for the removal of BTEX and MTBE from contaminated waters.Therefore, this study investigates the capacityof using raw biochar-based liquid activated carbon (LAC) and iron-modified biochar-based liquid activated carbon (LAC-Fe) in removing these pollutants. The LAC and Fe-LAC were coated on different host materials (i.e. sand, limestone, 1:1 mixutre of sand and limestone) and granular activated carbon (GAC) under lab-scale batch suspension-adsorption experiment. Results of the study revealed that coating LAC or LAC-Fe on subsurface materials has marginally improved the removal efficiency of MTBE, benzene and toluene but still below that of GAC which reached a removal of 80% for MTBE and more than 90% for BTEX. Results also showed that benzene and toluene were better removed by LAC and LAC-Fe (∼40%) than MTBE (∼20%). There were marginal effects of water chemistry (i.e. salinity and pH) on the removal efficiency of pollutants under the study conditions. The results indicate that more research work is needed to improve the capacity of biochar-based liquidactivated carbonin removing MTBE and BTEX compounds.