Between 130,000 to 425,000 brownfield sites nationwide 9.4% market growth in microbe blends

1. 6 soils were tested under 91-day, 182-day, 270-day and 354-day bioreactor runs. Then a mass transfer test, abiotic release assay and Microtox™ test were run to evaluate bioavailability of BTEX & PAH. Concentration plateaus following soil tox and abiotic assay gives new information to base regulatory action. A new concentration ratio test shows lack of microbial factors such as missing hydrocarbon PAH degraders or co-metabolic substrates in later stages of remediation are the limiting factor in remediation. If limiting factor for aged soil remediation is reduced or eliminated site closures can be speeded up thus reducing costs which presently run $230-$270/ton using slurry phase bioreactors and produce harmless byproducts which reduces liability. Brownfields Act authorizes $250 MM for brownfield remediation & limits liability. FEW 229594 Development of Innovative & Cost Effective Methods-Assessment of Bioavailability Limitations During Bioremediation of Aged Petroleum Hydrocarbon Contaminated Soils • Between 130,000 to 425,000 brownfield sites • nationwide • 9.4% market growth in microbe blends • Growth from present microbe market $47.61 MM to $74.55 MM by 2006. • IRS memo of understanding (TAM 199952075) allows current year deduction for cleanup of petroleum contaminated sites when in prep for new construction. • HUD will provide $25 million in grants to local gov’ts under Section 108 for brownfields redevelopment projects.

2. Hydrocarbon biodegradation in aged soils generally occurs in 2 stages - Initially high uptake and metabolism by soil bacteria - As bioremediation proceeds and all readily available hydrocarbons have metabolized, the rate of biodegradation slows and is controlled by the rate of hydrocarbon desorption from soil or dissolution for NAPLs If contaminants are released from soil particles and are bioavailable but not metabolized they may pose a risk to ecological receptors If bacteria populations are weakened or not present at all, it may be possible to stimulate them more effectively during bioremediation treatment PAHs which remain in the soil/sediments after intensive bioremediation are generally not bioavailable to microbes Diagnostic concentration ratio test should give quick, inexpensive indicator of potential bioavailability limitation during bioremediation Conceptual Model of the species and processes involved in biodegradation Dispersed Bacteria Dissolved Hydrocarbon Attached bacteria Molecule Soil Particle Soil Pore Sorbed Hydrocarbon Molecule NAPL- Phase Hydrocarbons FEW 229594 Development of Innovative & Cost Effective Methods-Assessment of Biavailability Limitations During Bioremediation of Aged Petroleum Hydrocarbon Contaminated Soils