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GeoInsighter Fall / Winter 2000 Newsletter
Volume 5 Number 3

Innovative Remediation Technologies

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From the remediation front, new twists on existing technologies hold the promise of faster remediation of petroleum and chlorinated compounds:

  • non-pathogen enzyme agents have come onto the commercial market that, in combination with air injection, significantly accelerate biodegradation of hydrocarbons and, reportedly, chlorinated hydrocarbons;

  • bioaugmentation of zero-valent iron permeable reaction walls holds the promise of increasing the speed of chlorinated compound mineralization and, for nitrate impacts, prevention of ammonia compounds; and

  • compost technology and biodegradation are increasingly being combined to inexpensively speed mineralization of compounds such as waste oil, pesticides, polychlorinated biphenyls (PCBs), and chlorinated hydrocarbons.

In a three week pilot test, which used the enzyme agent HczymeTM on soil contaminated with diesel from apipeline break, a decrease from 1,543 parts per million (ppm) to 280 ppm of total petroleum hydrocarbon (TPH) concentrations in soil was achieved. In ground water, free product TPH concentrations fell to 40,600 ppm from 1,028,000 ppm (a reduction of 80%).

Successful use of HczymeTM on multiple field projects has led the USEPA to approve its use in surface water, ground water, and soil remediation. The non-toxic compound consists of a blend of enzymes produced through a biofermentation process using 26 bacteria and fungi known to digest hydrocarbon compounds. The enzymes activate oxygen and convert it to a form in which the oxygen breaks the long-chain hydrocarbon bonds, eventually changing the hydrocarbon into alcohol, aldehyde, and fatty acids that are assimilated by indigenous bacterial populations. Its cost is approximately $7 per cubic meter, with total treatment costs ranging from $15 to $50 per cubic meter.

In a different application not yet commercialized, recent experiments by the University of Iowa indicate that bioaugmenting permeable reactive barriers composed of zero-valent iron (Feo) with anaerobic bacteria enhances the rate and extent of transformation of chlorinated compounds and minimizes the production of ammonia derived from nitrates. Permeable reactive barriers are being used to treat ground water containing chlorinated solvents, nitrate, chromium, and pesticides.

Finally, remediation composting is gaining popularity as a bioremediation technique because it is quick and inexpensive, significantly reduces the length of time required to remediate contaminated soil, and allows the composted soil to be redeposited on-site, removing the potential liability associated with off-site transport and disposal. Remediation composting occurs when impacted soil or waste is added to the conventional compost mix of carbonaceous and nitrogenous plant matter, oxygen, and water. In the oxygenated compost pile, microbial activity roughly doubles with every 10o C rise in temperature. Limitations to the methodology include metal compounds and 

Shelley F. Bobowski, P.E.
sfbobowski@geoinc.com

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