Bioremediation of PCP‐contaminated soil: Bench to full‐scale implementation

Pentachlorophenol (PCP) is a widely used wood treatment agent and pesticide that is often listed among the contaminants at hazardous waste sites. Bench‐scale studies were performed to develop a microbial culture and biodegradative process that could treat PCP at higher concentrations than previously reported. Several substrate formulations and culture techniques were evaluated. Ultimately a “self‐feeding” (pH auxostat) continuous culture system (pH auxostat) was used to select for biodegradative activity with PCP as the carbon and energy source. After a period of 50 days, influent PCP concentrations reached 3,500 mg/liter at a dilution rate of 0.066 H −1 . Of the total theoretical chloride that could be released from PCP, 99% was detected as free chloride in the reactor effluent. PCP analysis of the effluent verified complete degradation by the microbial consortium. The reactor was converted to a constant PCP feed. At steady state conditions, the dilution rate was 0.05 H −1 with an influent PCP concentration of 2,560 mg/liter and a biomass yield of 018 mg (dry weight) per mg of PCP. Mineralization studies performed with the microbial consortium using [U‐14C1]‐PCP indicated that 36.5% of the label was released as 14C‐carbon dioxide.