Mulch biofilm barriers for PAH- and surfactant-contaminated groundwater remediation

Organic mulch was considered as a new supporting material for preventing migration of PAH and nonionic surfactants and was also used as a medium for biofilm growth. To facilitate the mass balance analysis, batch sorption experiments were performed with a model PAH (naphthalene) and a nonionic surfactant (Triton X-100). To monitor the fate and transport of the PAH and nonionic surfactant, laboratory scale mulch-biofilm column reactors were used to simulate a subsurface permeable reactive barrier under aerobic conditions. Four 3.8 cm ID glass column were constructed with a 30 cm length. To obtain naphthalene degrading biomass, activated sludge was acclimated with naphthalene and biomass was inoculated into the mulch reactors. The total amount of mulch used for each column was 110 g. A mineral salts solution tank was connected to a saturated naphthalene tank (200 mg/L), and the combined solution was pumped to the bottom of the column at a constant flow rate of 2.55 mL/min which simulated 5 m/day linear velocity. This is an abstract of a paper presented at the 8th International In Situ and On-Site Bioremediation Symposium (Baltimore, MD 6/6-9/2005).