ACTIVATION OF AN INDIGENOUS MICROBIAL CONSORTIUM FOR BIOAUGMENTATION OF PENTACHLOROPHENOL CREOSOTE CONTAMINATED SOILS/

Soil activation, a concept based on the cultivation of biomass from a fraction of a contaminated soil for subsequent use as an inoculum for bioaugmentation of the same soil, was studied as a method for the aero bic biodegradation of pentachlorophenol (PCP) and polycyclic aromatic hydrocarbons (PAH) in contaminated soils. A microbial consortium able to degrade PCP and PAH in contaminated soil from wood-preserving facil ities was isolated and characterized for PCP degradation and resistanc e. To obtain an active consortium from the contaminated soil in a fed- batch bioreactor, the presence of soil as a support or source of nutri ents was found to be essential. During the 35 days of bioreactor opera tion, residual PCP in solution remained near zero up to a loading rate of 700 mg/l per day. The PCP mineralization rate increased from 70 mg /l per day when no PCP was added to the bioreactor to 700 mg/l per day at the maximum loading rate. The consortium tolerated a PCP concentra tion of 400 mg/l in batch experiments. Production of a PCP-degrading c onsortium in a fed-batch slurry bioreactor enhanced the activity of PC P biodegradation by a factor of ten. PAH biodegradation increased, dur ing the same time period, by a factor of 30 and 81 for phenanthrene an d pyrene, respectively. Preliminary laboratory-scale results indicated that a significant reduction in the time required for degradation of PCP and PAH in contaminated soil could be achieved using activated soi l as an inoculum.