BIOSLURRY TREATMENT OF A SOIL CONTAMINATED WITH LOW CONCENTRATIONS OFTOTAL PETROLEUM-HYDROCARBONS

The objective of this study was to investigate the degradation pattern s of petroleum hydrocarbons during bioremediation of soils containing low levels of contaminants. The study was conducted in pilot-scale bio slurry reactors (701) under aerobic conditions. The reactors were ,qui pped with a process-gas-recirculation system to ensure complete contai nment and eventually complete degradation of all contaminants. The con centrations of benzene, toluene, ethyl benzene, and xylenes (BTEX-comp ounds) and of naphthalene, anthracene, and phenanthrene were found to decrease rapidly. But, polyaromatic hydrocarbons (PAHs) containing >3 aromatic rings did not show significant biodegradation. Addition of ra pidly metabolizing substrates such as sodium acetate and/or phenanthre ne did not enhance the degradation of PAHs containing >3 aromatic ring s. However, the augmented phenanthrene was rapidly metabolized.