M12 PM Remediation
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 345-346

(IQB-1117-701564) Managing bioremediation at extreme creosote-contaminated Superfund site by optimizing temperature and moisture using polyethylene heat-entrapment.

Iqbal, J¹, Portier, R, ¹ Louisiana State University Agriculture Center, Baton Rouge, LA, USA

ABSTRACT- Temperature and moisture was managed within a biopile using polyethylene sheet and spray sprinklers during an ex situ bioremediation of heavy creosote contaminated Superfund Site at Georgia, USA. The effect of heat entrapment was evaluated for 300d to determine the efficiency of Immobilized Microbe Bioreactors (IMBR) installed in contaminated soil excavated from creosote wastes ditch at a former wood preservation facility. Bioremediation/bioplugs units inoculated with PAH/phenol specific microbes showed significant reduction in TPAHs mass (35%; from 13054±1408mg/kg to 8468±1012mg/kg; p<0.05) in harsh cold winter when biopile temperature and moisture parameters were optimized. Efficiency of IMBR system at higher ambient temperature during hot summer on the other hand was -25% without optimizing the temperature and moisture (from 6814±499mg/kg to 8547±619mg/kg; p<0.05). First order kinetic rates (KR) of TPAHs mass also increased four times (400%) from -0.0023 to 0.006 k(d^-1). Although high molecular weight PAHs (4, 5 and 6-rings) are less soluble with much slower desorption kinetics, it was revealed that their KR significantly increased from 0.005k(d^-1) to 0.425k(d^-1). Bioremediation of 2-ring PAHs accelerated significantly from 39% to 57%. Remediation of carcinogenic PAHs was also accelerated significantly. Fluoranthene, a 4-ring carcinogenic PAH, was most abundant in the soil had highest KR with management measures. KR in deeper part of the biopile, fairly stable initially before applying corrective/management measures, increased significantly. KR in shallow parts of the biopile also increased significantly. Total benzo(a)pyrene toxicity equivalent mass (BaP_equiv) significantly reduced with a KR of 0.01 k(d^-1) (48% removal) as compared to 0.003 k(d^-1) (22% removal). Average soil moistures increased from 15.7% to 41.4%. Phenol compounds significantly reduced by 98%. Results indicated enhanced efficiency of IMBR with temperature and moisture management in cold winter. This study shows that optimizing temperature and moisture in in situ bioremediation technologies at Superfund Sites may reduce time required for successful mineralization of hazardous wastes even in cold regions and cold weather.

Key words: bioremediation, immobilized microbe bioreactors, kinetic rates, benzo(a)pyrene toxicity equivalent