Mitigating Toxicity To Permit Bioremediation of Constituents of Nonaqueous-Phase Liquids

A study was undertaken to find means by which bacteria may degrade phenanthrene initially dissolved in toxic nonaqueous-phase liquids (NAPLs). In shaken cultures containing 5% NAPLs, bacteria readily mineralized phenanthrene initially present in di- n -butyl phthalate or 2,2,4,4,6,8,8-heptamethylnonane but not in 1,2-dichlorobenzene, toluene, 2-chlorotoluene, or 1,2,4-trichlorobenzene. Attempts to acclimate bacteria to tolerate higher concentrations of the first two NAPLs were unsuccessful. However, bacteria sensitive to 1,2-dichlorobenzene and toluene extensively degraded phenanthrene initially present in these toxic NAPLs in a system containing the toxic NAPL, a water phase, and a separate nontoxic NAPL to lower the toxicant concentration in the aqueous phase.