The Effects of In-Situ Oxidation of Organic Contaminants on Metals Mobility in Sediments
Deborah L. Cussen, Frontier Geosciences, Seattle, WA

Successful Application of Activated Persulfate Chemical Oxidation Followed by Bioremediation in a Tight Soil Matrix
Richard Cartwright, MECX, Amherst, NY

Persulfate Decomposition Kinetics in Presence of Aquifer Materials
Kanwertej S. Sra, University of Waterloo, Waterloo, ON, Canada

Cyclodextrin Enhanced Iron Activated Persulfate Oxidation of TCE
Chenju Liang, National Chung Hsing University, Taichung, Taiwan

Case Study: Bench, Pilot and Field Scale ISCO with Activated Persulfate of Chlorinated Benzenes
Ian T. Osgerby, U.S. Army Corps of Engineers, New England, Concord, MA

Adaptive Remediation: Using a Membrane Interface Probe to Define Permanganate Distribution and CVOC Concentrations during a Pressure Pulse In-Situ Chemical Oxidation Application to Enhance Remedial Results

Michael R. Ravella, ERM, 399 Boylston St., 6^th Floor, Boston, MA 02116, Tel: 617-646-7808, Fax: 617-267-6447, Email: mike.ravella@erm.com
Louis J. Burkhardt, Raytheon, 528 Boston Post Road, MS 1880, Sudbury, MA 01776; Tel:978-440-1855, Fax: 978-440-1800, Email: louis_j_burkhardt@raytheon.com
Joseph Fiacco, ERM, 399 Boylston St., 6^th Floor, Boston, MA 02116, Tel: 617-646-7840, Fax: 617-267-6447, Email: Joe.Fiacco@erm.com
Timothy Pac, ERM, 399 Boylston St., 6th Floor, Boston, MA 02116, Tel: 617-646-7875, Fax: 617-267-6447, Email: tim.pac@erm.com
Rick Lewis, ERM, 399 Boylston St., 6th Floor, Boston, MA 02116, Tel: 617-646-7815, Fax: 617-267-6447, Email: rick.lewis@erm.com

In an effort to enhance the efficacy of oxidant contact in an in-situ chemical oxidation (ISCO) application in a chlorinated volatile organic compound (CVOC) source area (primarily Trichloroethene (TCE)) in a heterogeneous overburden deposit, a membrane interface probe (MIP) was used to determine the vertical and horizontal distribution of permanganate in relationship to CVOC concentrations.  Traditional dual screened and single screened pressure pulse wells were installed in the CVOC source area based on historical data collected in the area using traditional investigation techniques.  An initial application of sodium permanganate was injected into the traditional pressure pulse wells using pressure pulse down-hole technology.  Following an initial source zone injection of sodium permanganate, MIP borings were advanced in the area surrounding each pressure pulse injection well.  The electrical conductivity (EC) dipole array on the MIP was used to determine the presence or absence of unreacted sodium permanganate in the subsurface in real time.  The MIP was also used in conjunction with a photo ionized detector (PID) electron capture detector (ECD) and a field gas chromatograph (GC) to determine the distribution, relative concentrations and speciation of CVOCs in the subsurface.  The real time data provided by the MIP during the mid permanganate injection characterization stage, was used to pin point remaining high concentration CVOC zones in the subsurface that were not in contact with permanganate.  A direct push pressure pulse tool was used to apply sodium permanganate or potassium permanganate in the remaining high concentration zones that were not in contact with the initial sodium permanganate injection.  The real time data provided by the MIP allowed the second permanganate applications to be conducted without site breakdown or remobilization.

The Effects of In-Situ Oxidation of Organic Contaminants on Metals Mobility in Sediments

Deborah L. Cussen, Frontier Geosciences, 414 Pontius Ave N, Seattle, WA, 98109, Tel: 206-622-6960, Fax: 206-622-6870, Email: DebC@FrontierGeosciences.com
Carl E. Hensman, PhD, Frontier Geosciences, 414 Pontius Ave N, Seattle, WA, 98109, Tel: 206-622-6960, Fax: 206-622-6870, Email: CarlH@FrontierGeosciences.com
Trevor Baker, Frontier Geosciences, 414 Pontius Ave N, Seattle, WA, 98109, Tel: 206-622-6960, Fax: 206-622-6870, Email: TrevorB@FrontierGeosciences.com
Diane Saber, Gas Technology Institute, 1700 S Mount Prospect Rd, Des Plaines, IL 60018, Tel: 847-768-0538, Fax: 847-768-0546, Email: Diane.Saber@GasTechnology.org
Michael Samuel, Gas Technology Institute, 1700 S Mount Prospect Rd, Des Plaines, IL 60018, Tel: 847-768-0901, Fax: 847-768-0546, Email: Michael.Samuel@GasTechnology.org

In-situ oxidation is increasingly being used as a treatment mechanism for organically polluted soils. However, the oxidation reagents and their byproducts will impact the surrounding sediment and groundwater chemistry.  A change in the oxidative/reductive environment of the system could possibly increase metals mobility and also impact the toxicity of those metals by changing their oxidative state (e.g. Cr(III) to Cr(VI)).  It is also possible that the end products of oxidation can reduce the mobility of metals in a treated system.  For example, in-situ oxidation using a permanganate solution yields MnO₂, which has been found to bind and precipitate metals.  It is possible that this binding and stabilization could counter-act the increase in mobility caused by the change in the oxidative/reductive environment.

The effects on metals mobility of in-situ oxidation of organically-impacted soils and sediments are tested by comparing the total metals concentrations, speciation, and extraction profiles both before and after chemical oxidation for a suite of metals including As, Ba, Pb, Mn, Cr, Se, and Hg.  Two extraction methods are tested: the US EPA 1312 Synthetic Precipitation Leaching Procedure (SPLP), and a selective sequential extraction (SSE).  Each fraction of the SSE uses a sequentially stronger extractant, and represents a range of metals mobility.  In addition, natural organic fractions (humic and fulvic acids and humin) will be interrogated for associated metals to understand the fate of metals from an ion exchange standpoint. The results of these experiments will be discussed, along with conclusions regarding the fate of metal mobility and toxicity after in-situ oxidation of organic pollutants.

Successful Application of Activated Persulfate Chemical Oxidation Followed by Bioremediation in a Tight Soil Matrix

Richard Cartwright P.E., CHMM, MECX, 8096 Clarherst Drive, East Amherst, NY 14051, Tel: 713-412-9697, Fax: 713-585-7049, Email: richard.cartwright@mecx.net
Larry Rader, P.G., MECX, P.O. Box 155, 1766 North 46^th Road, Leland, IL 60531, Tel: 815-495-9683, Fax: 815-495-9683, Email: larry.rader@mecx.net

An innovative sequential three step remediation approach has been developed to successfully treat contaminants in a tight soil matrix. The first step is to pre-condition low permeability soils using both chemical and mechanical means. During the pre-conditioning step, “unactivated” sodium persulfate and other conditioning agents are chemically injected and/or mechanically applied into the formation. The second step is to “activate” the sodium persulfate thus enabling a chemical oxidation process to desorb the contaminant mass from the tight soil matrix and reduce the biotoxicity in the source area. Field experience has demonstrated that persulfate can successfully be “activated” using a combination of hydrogen peroxide, transition metal catalysts, temperature, and pH adjustment. After the second step (chemical oxidation process) is completed, a third step (bioremediation polishing) is applied to treat the remaining contaminant mass. 

Bench scale studies have indicated that use of high temperature (greater than 180^oF) chemical oxidant applications in the saturated zone negatively impacts the subsequent bioremediation polishing step (third remediation stage). Use of low temperature (less than 100^oF) chemical oxidant applications in the saturated zone have resulted in significant dissolved phase rebound problems. When the saturated zone temperature is optimally maintained consistently between 140^oF and 170^oF, contaminants are still effectively desorbed from the tight soil matrix through a mass transfer partitioning process without overly stressing the indigenous biological species needed for subsequent bioremediation while avoiding subsequent dissolved phase rebound problems.

The second chemical-oxidation/desorption-extraction step facilitates the third treatment step used to reduce total contaminant mass transferred from the soil matrix into the dissolved phase within the saturated zone. The final treatment step is an aerobic and/or anaerobic biostimulation process, which cost-effectively completes the innovative sequence of complementary treatment technologies needed to optimize the reduction of total contaminant mass in a tight soil matrix.

Persulfate Decomposition Kinetics in Presence of Aquifer Materials

Student Presenter

Kanwartej S. Sra, Department of Civil Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1, Tel: +1 519 888 4567 (x 3828), Fax: 519-888-4349, Email: ksra@uwaterloo.ca
Jessica J. Whitney, Department of Civil Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1, Tel: +1 519 888 4567 (x 3847), Fax: 519-888-4349, Email: jjwhitne@uwaterloo.ca
Neil R. Thomson, Department of Civil Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1, Tel: +1 519 888 4567 (x 2111), Fax: 519-888-6197, Email: nthomson@uwaterloo.ca
Jim F. Barker, Department of Earth Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1, Tel: +1 519 888 4567 (x 2103 ), Fax: 519-746-7484 , Email: jfbarker@uwaterloo.ca

Persulfate is an emerging oxidant for in situ chemical oxidation (ISCO) applications with a high oxidation potential on activation (E^o = 2.6 V).  The design of an oxidant remedial system involves a comprehensive understanding of a number of underlying physical and chemical processes.  One of these processes, which impacts oxidant efficiency, involves the stability of the oxidant in the presence of natural aquifer materials.  To improve our understanding and develop predictive relationships a series of batch and column experiments were designed to quantify the interaction between persulfate and aquifer materials.  Well-characterized aquifer materials collected from seven sites across North America were used in this investigation.  The batch experiments, run in triplicates for each aquifer material, were conducted to primarily observe and derive decomposition kinetic parameters for an experimental system comprising of 100 g of solids, and 100 mL of solution with an initial persulfate concentration of 1000 mg/L.  The column experiments, which were more representative of in situ conditions, consisted of 40 cm long columns packed with aquifer material and flushed with a 1000 mg/L persulfate solution.  The decomposition of persulfate followed a first-order mass action law in the presence of all aquifer materials used in this study although the reaction rate coefficient varied by an order of magnitude (10^-4 to 10^-3 hr^-1).  As expected the column experiments yielded a higher reaction rate coefficient relative to the corresponding batch test data, suggesting that persulfate decomposition is a function of the persulfate to solid mass ratio. In general, the observed reaction rate coefficients were small indicating that persulfate will have a high stability in these aquifer systems.  Dissolved organic carbon, iron, and manganese concentrations decreased relative to background conditions; however, no correlation with the reaction rate coefficients was determined.

Cyclodextrin Enhanced Iron Activated Persulfate Oxidation of TCE

Chenju Liang, D.Eng., Dept. of Environmental Engineering, National Chung Hsing University , 250 Kuo-Kuang Rd., Taichung, Taiwan, Tel: 886-4-22856610, Fax: 886-4-22862587, Email: Cliang@dragon.nchu.edu.tw
Chiu-Fen Huang, Dept. of Environmental Engineering, National Chung Hsing University , 250 Kuo-Kuang Rd., Taichung, Taiwan, Tel: 886-4-22856610, Fax: 886-4-22862587, Email: prinssin@gmail.com
Nihar Mohanty, Massachusetts Dept. of Environmental Protection, Bureau of Resource Protection, 205B Lowell St., Wilmington, MA 01887, Tel: 978-694 3237, Fax: 978-694 3498, Email: Nihar.Mohanty@state.ma.us
Clifford J. Bruell, Dept. of Civil & Environmental Engineering, University of Massachusetts Lowell, One University Ave., Lowell, MA 01854, Tel: 978-934-2284, Fax: 978-934-3052, Email: Clifford_Bruell@uml.edu

In situ chemical oxidation (ISCO) is an innovative remediation technology that shows promise as a method for destroying dense nonaqueous phase liquids (DNAPLs) such as trichloroethylene (TCE) in soil and groundwater.  Sodium persulfate is often used as an oxidant for ISCO because the persulfate anion (S₂O₈^2-) can be activated with ferrous ions (Fe²⁺) to generate a strong oxidant known as the sulfate free radical (SO₄^-·) (E^o = 2.4 V).  ISCO methods are usually most successful for the remediation of dissolved contaminants.   Therefore, if DNAPLs are present, the effectiveness of the oxidation process is highly dependent upon mass transfer from non-aqueous (i.e., DNAPL) to aqueous phases (i.e., dissolved phase).  Moreover, an increased concentration of an oxidant results in accelerated oxidation of a contaminant in the aqueous phase, which in turn could lead to an increase in the concentration gradient driving the mass transfer (i.e., dissolution) of DNAPL into the aqueous phase.  The use of cyclodextrins such as hydroxypropyl-β-cyclodextrin (HP-β-CD) in conjunction with iron activated persulfate offers several advantages.  For example, HP-β-CD is able to complex metal ions such as Fe²⁺ for persulfate activation while simultaneously complexing an organic molecule such as TCE.   

Laboratory experiments revealed that increases in HP-β-CD concentrations resulted in increased solubilization of TCE.  This increase was linear and indicated formation of a 1:1 binding complex.  Moreover, the presence of Fe²⁺ did not affect the solubilization of the contaminant by HP-β-CD.  Comparison of the use of ferrous ion activated persulfate with and without HP-β-CD demonstrated that HP-β-CD can regulate the availability of Fe²⁺ and this resulted in a gradual controlled decomposition of persulfate.  In the presence of HP-β-CD and ferrous ions, TCE solubility can be increased above its normal aqueous solubility (i.e., 1,100 mg/L) and its degradation by persulfate can be accelerated.

Case Study: Bench, Pilot and Field Scale ISCO with Activated Persulfate of Chlorinated Benzenes

Ian T. Osgerby, Ph.D, P.E, and Scott Acone, U.S. Army Corps of Engineers, New England, 696 Virginia Road, Concord, MA 01742
Brant Smith, Ph.D, P.E., Scott C. Crawford and Ken Sperry, Xpert Design and Diagnostics, LLC, 22 Marin Way, Unit 3, Stratham, NH 03885
Andrew J. Boeckeler and Stefanie A. Getchell, P.G., Nobis Engineering, Inc., 18 Chenell Drive, Concord, NH  03301
Ed Hathaway, EPA New England, 11 Technology Drive, Chelmsford, MA 01863

A field scale insitu Chemical Oxidation (ISCO) project was performed with activated persulfate in July through August 2005 at the Eastland Woolen Mills Superfund site (site) in Corinna, Maine.  The ISCO application was designed to treat chlorinated benzene compounds present as residual DNAPL contamination.  The site is managed by the U.S. Army Corps of Engineers for the U.S. EPA with Nobis Engineering (Concord, NH) as the primary contractor and Xpert Design and Diagnostics, LLC (XDD, Stratham, NH) as the ISCO specialist.

Preliminary work included bench tests designed to compare Modified Fenton’s and activated persulfate and pilot scale tests.  The results of bench tests indicated the Modified Fenton’s system would be superior but persulfate was a close enough second that both systems were retained for the full scale field program.

For the pilot tests, Modified Fenton’s reagent and activated persulfate were applied in two separate test areas (each area consisting of two injection wells at approximately 20 foot on center spacing).  A comparison of baseline and 60-day post-treatment sample results indicated that the application of hydrogen peroxide had minimal effectiveness or was effective for a limited radius of influence (ROI).  Conversely, the concentration of chlorinated benzenes in soil and groundwater was observed to significantly decrease in the persulfate area.  The post-treatment soil data indicated approximately 50 percent to 80 percent of chlorinated benzenes were degraded with a ratio of 8 lbs of persulfate per lb of contaminant degraded.  Carbonates are suspected to have been the deciding factor in influencing reactant system effectiveness.  The results of these pilot tests underscore the importance of site specific characteristics when applying ISCO technologies.

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