Mass transfer and bioavailability of PAH compounds in coal tar NAPL- slurry systems. 2. Experimental evaluations

This paper develops experimental protocols for evaluating the impact of physicochemical mass transfer phenomena on bioavailability and biotreatment rates in slurry systems containing multi-component non-aqueous-phase liquids (NA-PLs). The experiments are conducted with two coal tar NAPL samples obtained from field sites. Experimental evaluations consist of abiotic mass transfer tests and independent biomineralization studies. The mass transfer tests measure equilibrium partitioning, dynamic changes in equilibrium partitioning, and dissolution kinetics for two polynuclear aromatic hydrocarbon (PAH) compounds, naphthalene and phenanthrene, released from coal tar NAPL in solid-slurry and liquid-liquid dispersion systems. Companion bimineralization tests assess initial rates of mineralization of naphthalene from coal tar NAPL. The results are used to evaluate the performance of a dissolution-degradation model, developed in the preceding paper, that addresses mass transfer and initial biodegradation rates of PAH compounds in multi-component coal tar (NAPL)-slurry systems. It is shown that independent equilibrium and kinetic dissolution tests aid in quantifying PAH bioavailability and potential initial biotransformation rates.