Influence of Supplemental Acetate on Bioremediation for Dissolved Polycyclic Aromatic Hydrocarbons

Abstract

The influence of supplemental acetate on in situ bioremediation for the removal of dissolved polycyclic aromatic hydrocarbons (PAHs) in groundwater was evaluated in laboratory sand columns. Sand columns, inoculated with a soil enrichment culture, were fed with dissolved PAHs (9 mg/L naphthalene, 0.8 mg/L phenanthrene, 0.09 mg/L pyrene), nutrients, and hydrogen peroxide to sustain aerobic microbial growth. Pore water PAH concentration profiles were obtained during the study. Determinations of viable biomass, carbohydrate, and PAH sorption capacity were obtained at the conclusion of the experimental runs. Pore water profiles indicated that PAH biodegradation capability became more quickly established after 45 days in sand columns amended with acetate versus the unamended control. The endpoint pore water PAH concentration profiles were similar for both acetate-amended and unamended columns. Higher biomass in acetate-amended columns increased the overall sorption capacity of the sand medium for PAHs by 24–47%. Supplemental acetate resulted in minimal biofouling of the sand medium as the final hydraulic conductivity of the acetate-amended treatments was 36–72% of the clean sand value.