Substrate Bioavailability And Biodegradation Of Naphthalene Anthracene And Pyrene On Contaminated Aqueous-Soil Matrix

ABSTRACT

The focus of this research work is the unraveling of the microbial dynamics of the biodegradation of a mixture of polycyclic aromatic hydrocarbons (PAH), naphthalene, anthracene and pyrone in an aqueous- soil matrix. The soil used in these studies was characterized as highly porous with a sandy-clay ratio of 85-14%. The microbial growth study was characterized by an initial lag phase, a rapid and an exponential increase in cell biomass, a stationary phase and finally a death phase. The growth and consumption rates estimated using the Monod kinetics showed that all the microbes (bacteria and fungi isolated from the indigenous soil and used in this study exhibited a high metabolic affinity for naphthalene

Respirometric studies conducted to measure the level of microbial activity and PAH biodegradation rates in the soil microcosm reactor indicated that a reasonable degree of PAH acclimation was achieved in the reactor, with a net cumulative oxygen uptake and carbon (iv) oxide evolution attaining their maximum limit within 60days of exposure. Results on the batch adsorption/desorption kinetics and equilibris depicted that the desorption rate was slower than the adsorption rate. The cumulative extent of desorption for the three PAHs suggested that the desorption step was rate limiting for biodegradation.