BIOREMEDIATION OF SOILS CONTAMINATED WITH BIS-(2-ETHYLHEXYL) PHTHALATE (BEHP) IN A SOIL SLURRY-SEQUENCING BATCH REACTOR

A bench-scale study was conducted to assess the feasibility of bioremediating phthalate contaminated soil from a polyvinyl chloride manufacturing operation in New Jersey. A bench-scale slurry reactor study which utilized C-14-labeled (bis-2-ethylhexyl) phthalate (BEHP) demonstrated that approximately 50 to 60% of the carbon in BEHP was mineralized directly to CO2 by indigenous microbial flora, while the remaining 40 to 50% was converted into cell mass. Additional bench-scale studies were conducted in Soil Slurry-Sequencing Batch Reactors (SS-SBR to evaluate the impact of basic biotreatability parameters (e.g., nutrient requirements and seed acclimation) on the bioremediation of soil contaminated with high levels of BEHP and total petroleum hydrocarbons (TPH). Treatment efficiencies of greater than 96% for both BEHP and TPH were observed in slurry reactors supplemented with nutrients (e.g., 1.4 to 2.0 g N per kg dry soil and 0.16 to 0.4 g P per kg dry soil). BEHP concentrations were reduced from initial levels as high as 24,000 mg/kg to less than 230 mg/kg and TPH concentrations, from 8,000 mg/kg to 160 mg/kg.