Grantee Research Project Results

Final Report: Advanced Mixed Oxidation and Inclusion Technology

EPA Contract Number: EPD10024
Title: Advanced Mixed Oxidation and Inclusion Technology
Investigators: Ball, Raymond G.
Small Business: Enchem Engineering, Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2010 through August 31, 2010
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2010) RFA Text |  Recipients Lists
Research Category: SBIR - Waste , Small Business Innovation Research (SBIR)

Description:

Coal tar contaminants such as polycyclic aromatic hydrocarbons (PAH) are difficult to treat in a timely and cost-efficient manner. The generally poor performance of conventional PAH treatment schemes, such as soil flushing or bioremediation, has led to research application of innovative in situ remediation methods. This project focuses on the in situ destruction of recalcitrant coal tar PAH in soil and groundwater. EnChem Engineering, Inc., has an  innovative treatment approach based on simultaneous:  (1) desorption from soil or sediment; and (2) oxidation via radical formation. A proprietary reactive agent (OxyZone-C®) developed by EnChem’s team combines highly effective cyclodextrin-facilitated PAH desorption with the targeted delivery of a combination of powerful oxidants (ozone, buffered sodium persulfate, and hydrogen peroxide) in the treatment zone. The specific objectives of this study are to evaluate:  (1) the parameters (such as reagent concentration and contact times) that have the greatest effect on enhanced ozone solubility and stability in the presence of cyclodextrin; (2) the parameters that have the greatest effect on PAH degradation with respect to oxidation rate with ozone alone, ozone combined with hydrogen peroxide, and ozone, hydrogen peroxide, and persulfate, either buffered or unbuffered, of select target PAH compounds and mixtures leading to mineralization; (3) the parameters that have the greatest effect on desorption rate of select target PAH compounds and mixtures such as cyclodextrin type and concentration; and (4) the fate of cyclodextrin in the presence of the proposed oxidants and vice versa.

The anticipated results of this study will provide an understanding of these objectives using batch and semi-batch experiments followed by column experiments to generate quantitative data needed to assess the performance of Enchem’s treatment technology under a variety of test conditions, including varying PAH concentrations. The demand for this technology as a method of PAH soil remediation is rated in billions of dollars for manufactured gas plant sites owned by the utility industry. There are many other types of sites that require remediation of PAHs such as fuel oils, jet fuels, and others at military bases and other Department of Defense and Department of Energy installations as well as National Priority List sites. Enchem also expects that this technology will prove useful for remediation of chlorinated organic sites containing dense nonaqueous phase liquids (DNAPLs) and for polychlorinated biphenyl (PCB) sites.

Summary/Accomplishments (Outputs/Outcomes):

This Phase I investigation demonstrates that recalcitrant coal tar composed of PAH compounds in soil and groundwater can be destroyed effectively with Enchem's innovative, U.S. and foreign patents-pending, OxyZone^®-C treatment approach.  Both an artificially PAH-contaminated sandy soil and a "real-world" former manufactured gas plant (MGP) soil as well as contaminated water were investigated under static (batch) and dynamic (column) test conditions.  The results of these tests indicate that:  (1) the addition of a relatively small concentration of cyclodextrin (CD) to the treatment solution increased the PAH solubility many times over; (2) treatment with OxyZone-C resulted in complete PAH destruction; (3) the treatment is most efficient during the initial hours after injection of OxyZone-C solution; (4) rates of destruction vary for individual PAH compounds; (5) a fraction of the CD is destroyed during the treatment; (6) the presence of CD stabilizes ozone, which is an integral part of the OxyZone-C formulation. Ozone released slowly from the CD complex extended the reactivity of the treatment solution; (7) treating soils with high organic carbon content resulted in preferential degradation of the total organic carbon (TOC) rather than the CD; (8) higher CD concentrations in the OxyZone-C formulation resulted in higher PAH removal rates; and (9) there is no evidence for the formation of any undesirable by-products of PAH soil treatment with OxyZone-C.

Conclusions:

Based on batch and column studies, OxyZone-C completely destroyed PAH compounds, and either ex situ or in situ treatment of PAH-containing soil and water at the field scale likely can be implemented. In regards to in situ treatment, the results of the Phase I study indicate that the OxyZone-C technology can be implemented in the field by using either EnChem's already proven treatment scheme, which relies on single or multiple injections of conventional, patented OxyZone treatment solution and/or the OxyZone-C treatment solution discussed here into the contaminated soil zone for in situ treatment; or by applying a "push-pull" in situ treatment scheme.  In the first approach, OxyZone or OxyZone-C is injected into the ground and allowed to solubilize and react with PAH for a short period, and if necessary a second injection of OxyZone-C is provided and allowed to solubilize and react with PAH. In the second approach, a slug of OxyZone-C is injected into a well to remain in the ground for a relatively short period of time. The solution then is pulled out of the same well and the process is repeated after reconditioning the flushing solution.  For ex situ treatment of soil and water, an appropriate reactor vessel is used. EnChem intends to submit a Phase II SBIR proposal to demonstrate either ex situ or in situ treatment approaches at a field site.

• EnChem Engineering has been contracted to implement the OxyZone and OxyZone-C technologies for in situ clean-up of a private sector No. 2 fuel oil release site in late 2010 or early 2011. 
• EnChem Engineering also has been contracted to perform bench-scale testing on PAH-contaminated sediment.

Supplemental Keywords:

small business, SBIR, EPA, waste management, monitoring, coal tar contaminants, polycyclic aromatic hydrocarbons, PAH degradation, PAH concentrations, bioremediation, ozone, environment, pollutants,soil remediation, oxidation rate, PCB, DNAPL, in situ treatment, NPL, Superfund, groundwater treatment, soil treatment