EFFECT OF ALIPHATIC NONAQUEOUS PHASE LIQUIDS ON NAPHTHALENE BIODEGRADATION IN MULTIPHASE SYSTEMS

Biodegradation of naphthalene by a Coryneform bacterium was examined i n multiphase aqueous slurry systems containing a nonaqueous phase liqu id (NAPL), The evolution of (CO2)-C-14 provided an index of biodegrada tion under aerobic conditions, The effect of NAPL hydrophobicity was e valuated by considering a homologous series of n-alkanes (C6-C16), Exp eriments were conducted in NAPL-water and soil-NAPE-water systems wher e the inoculum was pre-incubated with a sandy aquifer material, Relati ve to aqueous systems, conversion to CO2 increased in the presence of decane, dodecane, and hexadecane, Biodegradation was apparent, but dec reased in the presence of octane, and was negligible in the presence o f hexane. Thus biodegradation was sustained in multiphase systems wher e log K-ow of the NAPL was >5, and was inhibited in systems where the log K-ow of the NAPL was <4, Naphthalene partitioning between water an d each of the NAPLs was similar, indicating that the observed differen ces in biodegradation among the homologous series were not due to diff erences in naphthalene distribution, Naphthalene sorption to the sandy aquifer material was minimal and the aquifer material did not signifi cantly modify biodegradation. Mineralization rates were reduced in mul tiphase systems when compared with aqueous systems; CO2 production cur ves were described with a first-order kinetic model, Reduced mineraliz ation rates in soil-NAPL-water systems can be explained by the lower a queous phase concentration, This was not the case in the NAPL-water sy stem, suggesting a direct effect of the NAPL on the bacteria.