PERMEABLE BARRIERS - COMBINED AIR STRIPPING AND BIODEGRADATION OF AROMATIC-HYDROCARBONS

Physical barriers constructed in a contaminated groundwater system tha t intercept and degrade or remove soluble pollutants from solution, ye t allow groundwater to flow through are called permeable barriers. The y may be constructed as trenches placed down gradient from a leak or s pill, and the trench backfilled with media capable of interacting with the solutes. This project investigated the technical feasibility of u sing trench-based air stripping to remove volatile aromatic hydrocarbo ns commonly associated with gasoline contaminated soils, specifically benzene, toluene, and o-xylene (BTX). The project first experimentally validated a previously developed mathematical air stripping model. Ba sed on air-to-liquid flow ratios, trench-based air stripping was found to be competitive with packed tower air stripping up to approximately 95% removal; for higher removals packed tower stripping is more effic ient. The project next investigated combined air stripping and biologi cal degradation of the hydrocarbons. Removals in excess of 95% were ac hieved at very low air-to-liquid flow ratios. These results suggest th at combined trench-based air stripping and biodegradation of BTX may b e a feasible alternative to conventional technologies.