Surface Catalyzed Fenton Treatment of bis(2-chloroethyl) ether (BCEE), bis(2-chloroethoxy)

methane (BCEM) and 1,2-dichloroethane (1,2-DCA)

Maria Divina M. Mutuc

Thesis submitted to the faculty of the Virginia Polytechnic

Institute and State University in partial fulfillment of the requirements for the degree

of

Masters of Science

In Environmental Engineering

Peter J. Vikesland, Chair Nancy G. Love John T. Novak

June 8, 2005 Blacksburg, VA

Keywords: bis(2-chloroethyl) ether, bis(2-chloroethoxy) methane, dichloroethane, BCEE, BCEM, 1,2-DCA, surface

catalyzed, Fenton, hydroxyl radicals, hydrogen peroxide

Surface Catalyzed Fenton Treatment of bis(2-chloroethyl) ether (BCEE), bis(2-chloroethoxy)

methane (BCEM) and 1,2-dichloroethane (1,2-DCA)

Maria Divina M. Mutuc

(ABSTRACT)

This study determined the potential feasibility of surface catalyzed Fenton treatment to remediate soil and groundwater contaminated with bis(2-chloroethyl ether (BCEE), bis(2-chloroethoxy) methane (BCEM), and 1,2-dichloroethane (1,2-DCA) among other contaminants. Parameters that affect the contaminant loss rate such as pH, hydrogen peroxide concentration and solid/water ratio were systematically evaluated. Batch reactors were set-up utilizing either contaminated or uncontaminated soil that was mixed with synthetic groundwater containing the contaminants of interest. The results show an increase in contaminant reduction with a decrease in pH, an increase in hydrogen peroxide concentration, or an increase in the solid/water ratio. For the same set of conditions, contaminant reduction was greater for systems utilizing contaminated soil as compared to the systems containing uncontaminated soil. In addition, specific oxygen uptake rates were measured for an activated sludge exposed to different dilutions of untreated and surface catalyzed Fenton treated water to evaluate whether the residual BCEE, BCEM, and 1,2 DCA as well as their oxidation by products were potentially inhibitory or can potentially serve as a substrate for the activated sludge. The measured specific oxygen uptake rates show that the surface catalyzed Fenton treatment enhanced the biodegradability of the contaminated groundwater and served as a substrate for the activated sludge.

iii

Acknowledgments My deepest gratitude to Dr. Peter J. Vikesland for his guidance, patience and support. I would also like to thank Dr. Nancy G. Love, Dr. John T. Novak and Dr. John C. Little for serving on my committee. Many thanks to Jody Smiley and Julie Petruska for their assistance and patience. To my family and friends, most especially my husband Bob, who have always stood by me, I believe this would be a good opportunity to thank you all for everything. And lastly, I�d like to offer this to God who has continuously showered me with all His blessings.

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Table of Contents List of Tables......................................................................................................... v List of Figures ....................................................................................................... v Introduction ...........................................................................................................1 Materials and Methods..........................................................................................5

Soil Characterization .........................................................................................6 Preparation of Experimental Batch Reactors ....................................................8 BCEE and BCEM Analyses...............................................................................9 1,2-DCA Analysis ..............................................................................................9 H2O2 Analysis..................................................................................................10 DOC Analysis..................................................................................................11 Inhibition Test..................................................................................................11

Results and Discussion.......................................................................................12 BCEE and BCEM ............................................................................................12

Uncontaminated Soil Experiments...............................................................13 Sorption Test............................................................................................13 Effect of pH ..............................................................................................13 Effect of Solid to Water Ratio ...................................................................14 Effect of Hydrogen Peroxide Concentration .............................................15 Mineralization of BCEE and BCEM ..........................................................16

Contaminated Soil Experiments...................................................................17 General Contaminant Behavior ................................................................18 Experimental Control................................................................................19 Effect of Fe2+ Addition ..............................................................................20 Sequential Spike Experiments .................................................................21

Mineralization of BCEE and BCEM..............................................................22 1,2-DCA ..........................................................................................................22

1,2-DCA with Uncontaminated and Contaminated Soils..............................22 1,2-DCA Analysis for Chauny Groundwater with Uncontaminated Soil .......23 1,2-DCA Analysis with Chauny Groundwater and Contaminated Soil .........24

INHIBITION TEST..........................................................................................24 Conclusions ........................................................................................................27 References .........................................................................................................50 Vita......................................................................................................................52

v

List of Tables Table 1. Proposed Mechanism for the Fenton Process ........................................4 Table 2. Groundwater concentrations of the different contaminants in monitoring

wells: MW-05, MW-36 and MW-86 at an industrial site at Moss Point, Mississippi Samples were taken in May 2003................................................7

Table 3. Groundwater concentrations of different contaminants in monitoring well DW07 at an industrial site in Chauny, France. Samples were taken in October 2004.................................................................................................8

Table 4. Average oxygen consumption rates in mg/L and specific oxygen uptake rates for the controls and the different samples. ..........................................26

Table 5. Average oxygen consumption rate, specific oxygen uptake rate and dissolved organic carbon for different dilutions of untreated and Fenton treated water................................................................................................26

List of Figures Figure 1. Chemical structures and formula of A) BCEE and B) BCEM. ................1 Figure 2. Proposed reaction mechanism for BCEE degradation via ●OH radical

attack (modified from Li et al, 1995)...............................................................3 Figure 3. Sorption test performed by spiking 10 mg/L each of BCEE and BCEM

to uncontaminated soil / synthetic groundwater mixture. [BCEE]0 = 10 mg/L; [BCEM]0 = 10 mg/L; solid/water = 2 g/mL; pH = 4.0. Error bars represent 95% confidence intervals.............................................................................28

Figure 4. A) [BCEE]/[BCEE]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different pH values for initially uncontaminated soil. [BCEE]0 = 1.0 mg/L; [H2O2]0 = 5.0 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals. .................................29

Figure 5. A) [BCEE]/[BCEE]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different pH values for initially uncontaminated soil. [BCEE]0 = 1.0 mg/L; [H2O2]0 = 10.4 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals. ..............................30

Figure 6. A) [BCEM]/[[BCEM]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different initial pH values for initially uncontaminated soil. [BCEM]0 = 1.0 mg/L; [H2O2]0 = 5.0 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals. .........31

Figure 7. A) [BCEM]/[BCEM]0 and B) [H2O2]/[H2O2]0 as a function of time at different pH values for initially uncontaminated soil. [BCEM]0 = 1.0 mg/L; [H2O2]0 = 10.4 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals. ..............................32

Figure 8. A) [BCEM]/[BCEM]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different solids/water ratio for initially uncontaminated soil. [BCEM]0 = 1 mg/L; [H2O2]0 = 5.0 g/L; pH = 4.0. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.....................................................33

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Figure 9. A) [BCEE]/[BCEE]0 B) [H2O2]0 = 132 ± 21.98 mg/L C) [H2O2]0 = 1143 ± 10.45 mg/L D) [H2O2]0 = 11538 ± 501.39 mg/L as a function of time for initially uncontaminated soil. [BCEE]0 = 1.0 mg/L; solid/water ratio = 1 g/mL; pH = 4.0. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals. ....................................................................................34

Figure 10. DOC concentration reduction over a period of 40 hours for uncontaminated soil spiked with A) 1 mg/L of BCEE or BCEM or 1,2-DCA and B) 10 mg/L of BCEE or BCEM or 1,2-DCA at pH = 4.0; solid/water ratio = 1 g/mL. [H2O2]0 = 10 g/L. Error bars represent 95% confidence intervals.35

Figure 11. A) [BCEE]/[BCEE]0, B) [BCEM]/[BCEM]0, and C) [H2O2]0 loss as a function of time in contaminated soil. [H2O2]0 = 10 g/L; solid/water ratio = 2 g/mL; pH = 4.0. [BCEE]0=1.68 ± 0.04 mg/L. [BCEM]0= 201.52 ± 10.17 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.............................................................36

Figure 12. A) [BCEE]/[BCEE]0, B) [BCEM]/[BCEM]0, and C) [H2O2]/ [H2O2]0 as a function of time in contaminated soil. [H2O2]0 = 20 g/L; solid/water ratio = 3 g/mL; pH = 4.0. [BCEE]0= 0.83 ± 0.05 mg/L. [BCEM]0= 156.07 ± 19.06 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals. ...........................................37

Figure 13. Inhibition study using TBA. A) [BCEE]/[[BCEE]0, B) [BCEM]/[BCEM]0, and C) [H2O2]/[H2O2]0 loss as a function of time in contaminated soil. [H2O2]0 = 10 g/L; solid/water ratio = 2 g/mL; pH = 4.0; [TBA] = 5.5 M. [BCEE]0 = 1.59 ± 0.26 mg/L. [BCEM]0 = 259.22 ± 20.60 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals. ......................................................................................................38

Figure 14. Inhibition study using TBA. [H2O2]/ [H2O2]0 as a function of time in contaminated soil. [H2O2]0 = 10 g/L; solid/water ratio = 2 g/mL; pH = 4.0; [TBA] = 5.5 M. Error bars represent 95% confidence intervals. ...................39

Figure 15. A) [BCEE]/[BCEE]0 B) [BCEM]/[BCEM]0 C) [H2O2]/[H2O2]0 as a function of time for contaminated soil. An initial hydrogen peroxide dose of 5 g/L was added at t = 0. [BCEE]0= 1.78 ± 0.06 mg/L. [BCEM]0= 353.74 ± 25.01 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. The solid/water ratio for the reactors was at 2 g/mL and the pH = 4.0. The Fe2+ dose of 400 mg/L was added to the second set of reactors at the start of the equilibration period (t < 0). Error bars represent 95% confidence intervals.....................................................40

Figure 16. A) BCEE B) BCEM C) H2O2 loss as a function of time for contaminated soil. An initial hydrogen peroxide dose of 10 g/L was added at time 0. An additional hydrogen peroxide dose of 10 g/L was added at time = 31 hrs to the third set of reactors. The solid/water ratio for the reactors was at 2 g/mL and the pH = 4.0. Error bars represent 95% confidence intervals......................................................................................................................41

vii

Figure 17. DOC concentration reduction over a period of 40 hours for contaminated soil. [H2O2]0 = 10 g/L; pH = 4.0; solid/water ratio = 2 g/mL. [H2O2]0 = 10 g/L. Error bars represent 95% confidence intervals.................42

Figure 18. A) 1,2-DCA B) H2O2 loss as a function of time for uncontaminated soil spiked with 10 mg/L 1,2-DCA with an initial hydrogen peroxide dose of 10 g/L. Hydrogen peroxide was added at t = 0. Solid/water ratio = 2 g/mL and pH = 4.0. Error bars represent 95% confidence intervals. ...........................43

Figure 19. A) [1,2-DCA]/[1.2-DCA]0 B) [H2O2]/[H2O2]0 as a function of time for contaminated soil spiked with 10 mg/L 1,2-DCA with an initial hydrogen peroxide dose of 10 g/L. The initial Fe2+ dose of 400 mg/L was added to a set of reactors at the start of the equilibration period (t = -48 hrs). Hydrogen peroxide was added at t = 0. solid/water ratio = 2 g/mL and pH = 4.0. Error bars represent 95% confidence intervals.....................................................44

Figure 20. A) [1,2-DCA]/[1,2-DCA]0 B) [H2O2]/[H2O2]0 as a function of time for the Chauny groundwater mixed with uncontaminated soil. [H2O2]0 = 10 g/L. Soil/water ratio = 2 g/mL and the pH = 4.0. Addition of H2O2 occurred at t = 0. Error bars represent 95% confidence intervals. .......................................45

Figure 21. Percent Loss of 1,2-DCA as a function of H2O2 concentration for Chauny groundwater mixed with contaminated soil. Solid/water ratio = 2 g/mL, pH = 4.0. Error bars represent 95% confidence intervals. .................46

Figure 22. Dissolved oxygen uptake of activated sludge as a function of time for exogenous and endogenous control and for different dilutions of untreated and Fenton treated water.............................................................................47

Figure 23. Specific oxygen uptake rates of activated sludge as as a function of time for exogenous and endogenous control and for different dilutions of untreated and Fenton treated water.............................................................48

Figure 24. Specific oxygen uptake rates of the different dilutions of the untreated and Fenton treated water as a function of dissolved organic carbon ...........49

1

Introduction The clean-up of sites contaminated by bis(2-chloroethyl ether (BCEE) and

bis(2-chloroethoxy) methane (BCEM) has received scant attention in the

contaminant remediation literature and thus little is known about the fate of these

compounds in subsurface environments. Although a limited number of treatability

studies have examined the abiotic and biotic degradation of BCEE (Li et al, 1995;

Rodriguez, 2003), nothing appears (or at least has been documented in readily

available literature) about BCEM degradation.

BCEE is a synthetic colorless, nonflammable liquid with a strong

unpleasant odor. Its primary industrial use is as a chemical intermediate in

pesticide manufacturing, with additional uses as a solvent, cleaner, rust inhibitor,

or as a chemical intermediate in the production of other chemicals (Agency for

Toxic Substances and Disease Registry, 1999). BCEM is a synthetic organic

compound primarily used in the production of polysulfide polymers (National

Toxicology Program, Department of Health and Human Services). BCEE and

BCEM are readily dissolved in water with reported solubilities of 17,200 mg/L and

7,800 mg/L (SRC PhysProp database). Furthermore, because of their high

solubilities and low log Kow values of 1.29 and 1.3 (SRC Physprop database),

both compounds are considered to be highly mobile. Furthermore, the extremely

low Henry�s constants for both compounds suggest that volatilization is not an

important fate process. Because of these characteristics, both BCEE and BCEM

have proven to be highly recalcitrant.

A) B)

C4H8Cl2O (BCEE) C5H10Cl2O2 (BCEM)

Figure 1. Chemical structures and formula of A) BCEE and B) BCEM.

A number of treatment options for BCEE have been explored including

thermal treatment (Battin-Leclerc et al, 1999) and air stripping which was found

2

to be unfeasible as a result of the extremely low Henry�s constant for BCEE.

Previous studies suggest that the required air flow rates for BCEE stripping are at

least eight times greater than those for 1,2-DCA (Huang et al., 1999).

Among the limited treatability studies reported in the literature, the

treatment option that appears to be most promising for BCEE remediation is the

use of Advanced Oxidation Processes (AOPs) wherein highly reactive hydroxyl

radicals (●OH) attack the alpha-carbons adjacent to the ether linkage via

hydrogen abstraction (Acero et al, 2001). Li et al (1995) proposed a mechanism

for BCEE destruction by hydroxyl radicals produced via photodegradation of

H2O2 (Figure 2). The identified major intermediate products produced by these

reactions were 2-chloroethyl acetate, 2-chloroethanol, acetaldehyde, ethylene

oxide, and cholorethane. In a similar study, Mabijish and O�Shea (1996)

determined that chloroacetaldehyde can also form, but it is readily oxidized to

chloroacetic acid and ultimately to carbon dioxide. In general, it was found that

the oxidation rate of BCEE by H2O2 photolysis is not affected by the temperature,

the alkalinity and the salinity of the solution (Li et al, 1995; Huang et al., 1999).

The results show that when an initial ratio of 1:10 (BCEE: H2O2) was used, the

intermediates could be reduced to undetectable levels within 30 minutes of

irradiation. Nevertheless, the potential formation of vinyl chloride by these

reactions is of concern since this species is known to be a carcinogen that is

recalcitrant under many circumstances (He et al, 2003).

In a similar study, Watts et al (1994) employed hydroxyl radicals

generated by the photolysis of titanium dioxide (TiO2) to oxidize BCEE. They

noted that BCEE oxidation was pH dependent and was most rapid at pH 4 and

that the overall oxidation rates were inversely proportional to the soluble

chemical oxygen demand (COD). It was concluded that ●OH mediated treatment

is possible for systems of low chemical oxygen demand where the concentration

of radical scavengers is not substantially high.

3

Figure 2. Proposed reaction mechanism for BCEE degradation via ●OH radical attack (modified from Li et al, 1995).

Another method to produce reactive hydroxyl radicals is to use Fenton�s

reagent. Fenton treatment involves the use of a transition metal such as iron

(Fe2+) to catalyze the decomposition of hydrogen peroxide to reactive hydroxyl

radicals (Neyens et al., 2003) Although, the use of Fenton treatment in

remediating BCEE or BCEM has not been thoroughly explored, this treatment

has been used in the remediation of a variety of organic pollutants in variable

systems such as wastewater and groundwater contamination. The proposed

reaction mechanism for the Fenton process was developed through several

studies (Haber and Weiss, 1934; Barb et al, 1951; Symons and Gutteridge,

1998) and includes the following:

4

Table 1. Proposed Mechanism for the Fenton Process

Reactions Rate Constants Reaction Number

Fe2+ + H2O2 → •OH + OH- + Fe3+ k1 = 76 M-1 s-1 (1) •OH + H2O2 → H2O + HO2

• k2 = (1.2 - 4.5) x 107 M-1 s-1 (2) •OH + Fe2+ → Fe3+ + OH-− k3 = 4.3 x 108 M-1 s-1 (3)

HO2• ↔ O2

-• + H+ pKa= 4.8 (4)

Fe2+ + O2-• → Fe3+ + O2 k5 = 1 x107 M-1 s-1 (5)

Fe3+ + O2-•→ Fe2+ + O2 k6 = 1.5 x 108 M-1 s-1 (6)

Fe3+ + H2O2 → Fe2+ + HO2• + H+ k7 = 0.01 - 0.02 M-1 s-1 (7)

2•OH → H2O2 k8 = 5.3 x 109 M-1 s-1 (8)

2HO2• → H2O2 + O2 k9 = 8.5 x 105 M-1 s-1 (9)

RH + •OH → H2O + R• k10 (10)

R• + •OH → ROH k11 (11)

R• + H2O2 → ROH + •OH k12 (12)

R• + Fe2+ → Fe3+ + products k13 (13)

R• + Fe3+ → Fe2+ + products k14 (14)

R• + O2 → products k15 (15)

2R• → products k16 (16)

R• + R1• → products k17 (17)

The generation of •OH primarily occurs via reaction (1). Reactions (2) to

(17) occur in parallel after •OH radical generation. Reaction (3) shows the

reaction of Fe2+ with the hydroxyl radical to produce Fe3+ and OH-. Reaction (2)

represents the reaction of hydrogen peroxide with the •OH radical to produce

hydroperoxyl radicals (HO2•). The hydroperoxyl radicals are in equilibrium with

superoxide radical (O2-•) via reaction (4). Both the hydroperoxyl radicals and the

superoxide radical can cause H2O2 regeneration (reactions 8 and 9). The

superoxide radical can react with iron to either oxidize or reduce it as seen in

reaction (5) and (6).

Modified Fenton treatment processes, such as catalysis by iron chelates

(Sun et al, 1995) and by iron oxides in soils, also referred to as surface catalyzed

Fenton process (Watts et al, 1993), have also been developed and have proven

to be effective in remediating various contaminants.

5

Surface catalyzed Fenton treatment combined with aerobic biostimulation

is a combined biological/chemical technique that has led to the successful

remediation of the recalcitrant ether, methyl tert-butyl ether (MTBE; Yeh and

Novak, 1995) as well as the pesticides pendimethalin and atrazine (Miller and

Valentine, 1995; Miller et al, 1996) in soil microcosms. In this process, hydrogen

peroxide is injected into the soil as an oxygen source for aerobic

microorganisms. The added hydrogen peroxide also undergoes surface

catalyzed decomposition to produce ●OH and O2- radicals that can oxidize

recalcitrant contaminants, producing daughter products that may be further

oxidized chemically or biologically. The ●OH and O2- decomposition reactions

occur most readily in aquifer sediments that contain iron and manganese oxides,

but also occur under conditions where these oxides are absent.

Fenton treatment should also be able to remediate 1,2 DCA as outlined in

the innovative technology summary report of the US Department of Energy in

1999. H2O2/Ozone advanced oxidation process, have also shown to be effective

in the remediation of 1,2-DCA. (www.epa.gov).

This study evaluated the suitability of a surface catalyzed Fenton

treatment to remediate soil and groundwater containing BCEE, BCEM and 1,2-

DCA. As part of this study, the effects of various parameters such as pH, H2O2

concentration and soil/water ratio on the treatment process were evaluated.

Materials and Methods Preparation of Stock Solutions

The reagent grade water used in these experiments was purified by

deionization and distillation. All glassware employed was cleaned by sequentially

soaking it in a nitric acid bath and then in a concentrated chlorine bath followed

by rinsing with deionized water. BCEE, BCEM and 1,2-DCA (each > 99% purity)

were obtained from Sigma Aldrich, MP Biomedicals and Ultra Scientific,

respectively, and were used without further purification. Individual stocks of

6

BCEE, BCEM, and 1,2-DCA were prepared by adding 8 µL of pure compound to

100 mL of 50% methanol/50% water. In some experiments, baseline synthetic

groundwater (BSGW) solution was used to simulate groundwater. This solution

consisted of 5 mM sodium bicarbonate, 3 mM sodium sulfate, 2 mM calcium

chloride, and 1 mM sodium chloride in reagent grade water (Miller and Valentine,

1999). The hydrogen peroxide solution was obtained from Fisher Scientific (30%)

and FMC Corporation (50% standard bulk).

Soil Characterization

Both uncontaminated and contaminated soils from an industrial site in

Moss Point, Mississippi were used in these experiments. The industrial site

contains two former wastewater retention ponds and a solid waste landfill that

have been identified as the source area for the subsurface contamination. The

soil samples utilized in the experiments were taken from the Alluvial layer

because this layer was identified to be more highly contaminated than the Upper

and Lower Citronelle layers. Soil from this layer was found to be an oxidized low

organic carbon alluvium. Soil obtained from the Alluvial aquifer near the vicinity of

monitoring well MW-05 was classified as uncontaminated soil since the

groundwater samples taken from MW-05 show that the concentrations of BCEE

and BCEM were each less than 5 µg/L and less than 1 µg/L for 1,2-DCA. The

concentrations of other co-contaminants as well as dissolved metals were found

to be minimal (Table 2). On the other hand, the contaminated soil utilized in the

experiments was obtained from near the vicinity of two monitoring wells: MW-36

and MW-86. Analytical results show that the groundwater concentration of BCEE

is 11 µg/L for MW-36 and 1,700 µg/L for MW-86. For BCEM, it was found to be

1,400 µg/L for MW-36 and 2,300 mg/L for MW-86. The 1,2-DCA concentrations

were found to be less than 1 µg/L for MW-36 and 21,000 µg/L for MW-86. The

groundwater concentrations of the co-contaminants at MW-36 and MW-86 can

be found in Table 2.

In some of the experiments, the contaminated groundwater employed was

obtained from an industrial site in Chauny, France. The main contamination

7

source in the subsurface is located in the center of the industrial facility, within a

heavily constructed area having numerous underground and aboveground

utilities. Several wells were screened in three different aquifer layers. The

groundwater utilized in the experiment was taken from a monitoring well in the

semi-permeable layer (DW-07). The semi-permeable layer was identified to be

highly mineralized with iron, manganese and other heavy metals and low oxygen

content with very low redox potential and relatively low pH. The groundwater

analysis for this well shows that the 1,2-DCA concentration is 146,000 µg/L. The

concentrations of the co-contaminants in the groundwater are summarized in

Table 3.

Table 2. Groundwater concentrations of the different contaminants in monitoring wells: MW-05, MW-36 and MW-86 at an industrial site at Moss Point, Mississippi Samples were taken in May 2003.

Chemical Name MW-05 MW-36 MW-86 Contaminants of Concern (µg/L) (µg/L) (µg/L) bis(2-chloroethyl) ether <5 11 1,700 bis(2-chloroethoxy) methane <5 1,400 2,300,000 1,2-dichloroethane <1 <1 21,000 Co-contaminants (µg/L) (µg/L) (µg/L) Vinyl chloride <2 <2 <200 Chloroethane <2 <1 <100 1,1-dichloroethane <2 <1 <100 1,1-dichloroethene <2 <1 <100 Toluene <2 <1 <100 1,1,1-trichloroethane <1 <1 <100 1,1,2-trichloroethane <1 <1 <100 Carbon disulfide <1 <1 <100 Metals (mg/L) (mg/L) (mg/L) Beryllium <0.004 <0.004 0.0046 Cadmium <0.005 <0.005 0.062 Lead <0.005 <0.005 0.018 Tin <0.01 <0.01 0.032

8

Table 3. Groundwater concentrations of different contaminants in monitoring well DW07 at an industrial site in Chauny, France. Samples were taken in October 2004.

Chemical Name DW07 Contaminant of Concern (µg/L) 1,2-Dichloroethane 146,000 Co-contaminants (µg/L) 1,1-Dichloroethene 27.3 Dichloromethane 79,800 trans-1,2-Dichloroethene 5.8 1,1-Dichloroethane 15.5 cis-1,2-Dichloroethene 14.4 Trichloroethene 31.0 1,2-Dichloropropane 37.9 Toluene 210 Tetrachloroethene 2.5 Ethylbenzene 28.9 m- + p-Xylene 0.9 Vinyl Chloride 476

Preparation of Experimental Batch Reactors

Surface catalyzed Fenton experiments were performed in triplicate.

Typically, serum bottles with a nominal volume of 100 mL were used as batch

reactors. The bottles were filled with a known mass of soil and a known volume

of BSGW. Subsequently, the solution pH was adjusted using 1 N sulfuric acid to

a pH value dependent on the required experimental condition. The range of initial

pH values tested was from 4 to 7. Known concentrations of BCEE, BCEM, and/or

1,2-DCA were added to the reactors and they were sealed using an aluminum

cap and Teflon lined rubber septa and covered with aluminum foil to eliminate

any potential photochemical reactions. Prepared reactors were placed on a bottle

roller (Wheaton sample roller purchased from Fisher Scientific) and allowed to

equilibrate for a period of ≈ 24-48 hours. The surface catalyzed Fenton reaction

was initiated by adding hydrogen peroxide to the reactors at a specified

concentration. Periodic samples were then taken for BCEE, BCEM, 1,2-DCA and

H2O2.

9

BCEE and BCEM Analyses

Samples for the quantification of BCEE and BCEM were extracted in

methylene chloride. In a 4 mL amber vial, 1 mL of aqueous sample was added to

1 mL of methylene chloride. The vials were then capped and placed on the bottle

roller for 24 hours to facilitate extraction. Following this period, the methylene

chloride phase was removed and transferred to a 2 mL autosampler vial

containing a microvolume insert and the sample vial was sealed. Immediately

prior to GC/MS analysis, 10 µL of internal standard (10 mg/L dibromopropane)

was injected into each of the vials.

GC-MS analysis of BCEE and BCEM was performed on an Agilent

6890/5973 system that contained a DB-5ms GC-column (Agilent Technologies,

30 m × 0.25 mm ID, film thickness = 0.30 µm). Helium was used as the carrier

gas with a column flow rate of 1.3 mL/min with a pressure of 99.2 kPa and an

average velocity of 30 cm/sec. Initial temperature was set at 50 ºC and this

temperature was held for 4.0 minutes. The temperature was then ramped to 100

ºC at 10 ºC/min and held for another 4.0 minutes. The first ramp was followed by

a second ramp at 10 ºC/min to 150 ºC and held for 1 minute. A 1 µL injection

volume was used. Samples were run in full scan mode. BCEE was identified

based on its elution time of 9.2 minutes and monitored with ions at m/z 93 and

63. BCEM was identified based on its elution time of 13.0 minutes and monitored

with ions at m/z 123, 93, and 63. BCEE and BCEM were quantified using

analytical standards purchased from Sigma Aldrich and MP Biomedicals,

respectively.

. 1,2-DCA Analysis

Samples for quantification of 1,2-DCA were analyzed using a Tekmar

2016 purge and trap autosampler attached to a Tekmar (Cincinnati, OH) 3000

purge and trap concentrator. From a given reactor, a 1 mL sample was taken and

transferred to a 2 mL autosampler vial for 1,2-DCA analysis. Tert-butyl alcohol at

a concentration of 0.1 M was subsequently added to the vial to quench the

hydrogen peroxide at a volume of 100 µL per 1 mL of sample. The vial was then

10

crimp sealed. For this analysis, the sample was diluted to a 1,2 DCA

concentration range of 60 � 600 ppb for better peak integration by injecting a

known volume of sample into a gas tight syringe containing a known volume of

reagent grade water to make up a total of 5 mL solution. Prior to injection of this

solution into the autosampler port, 10 µL of 10 mg/L 1,2-dibromopropane was

added to serve as the internal standard for the analysis. The purge and trap

concentrator was equipped with a Supelco (Bellefonte, PA) VOCARB 300 Purge

Trap K. A Tremetrics (Austin, TX) 9001 gas chromatograph with a Tracer (Austin,

TX) 1000 Hall detector and a Restek RTX-Volatiles column (30 m × 0.55 mm

internal diameter, film thickness = 2.0 µm) was used for compound separation.

Nitrogen was used as the carrier gas. Samples were purged for 7 minutes and

then baked from the trap at 250 ºC for 10 minutes. The initial temperature for the

GC temperature program was 35 ºC and was held for 5 minutes. The GC

temperature was then ramped to 95 ºC at 6 ºC/min followed by a second ramp to

225 ºC at 25 ºC/min. A Hewlett Packard Series II Integrator was used to integrate

the peak areas of the sample results. 1,2-DCA was quantified based on its

elution time of 5.28 minutes determined from analytical standards purchased

from Ultra Scientific

H2O2 Analysis

Hydrogen peroxide was measured using the modified N.N-diethyl-p-

phenylenediamine (DPD) method (Voelker and Sulzberger, 1996). This method

was designed to measure hydrogen peroxide concentrations within a range of

170 - 1700 µg/L. Because the H2O2 concentrations in our reactors were above

this range, it was often necessary to dilute the samples. A 10 mL aliquot of

diluted sample was then transferred to a reaction vial containing 2 mL of

phosphate buffer (pH = 6.0) and 0.10 mL EDTA (10-2 M Na2EDTA) solution. The

reaction vial was shaken and 2 mL of solution was transferred to a 1 cm

pathlength cuvette. An aliquot of 50 µL of DPD reagent (3.8 x 10-2 M in 0.1 M

H2SO4) was added directly to the cuvette followed by 25 µL (100 units/mL) of

horseradish peroxidase. The cell was manually shaken for a minute for color

11

development. Absorbance readings were taken at 551 nm using a Milton Roy

Spectronic 1200 UV-VIS spectrophotometer.

DOC Analysis

The dissolved organic concentration (DOC) of the samples was measured

using a Dohrmann TOC Analyzer. The Dohrmann TOC analyzer uses the UV-

persulfate oxidation technique to convert organic carbon compounds to CO2. The

CO2 is then measured via an infrared detector to determine the total organic

concentration of the sample. By the interaction of the UV light and persulfate and

the carrier gas at an elevated temperature, the organic carbon compounds are

oxidized to CO2. The gas stream containing CO2 then passes through gas/liquid

separation devices prior to entering a non-dispersive infrared device that

measures CO2 and reflects it as TOC in mg/L. Prior to DOC measurements,

samples were filtered using a 0.45 µM filter membrane and oxygen was bubbled

through the samples for 5 minutes. This purging step was done to remove

inorganic carbon that otherwise would have interfered with DOC quantification.

Initial DOC was measured from reactors containing

uncontaminated/contaminated soil, BSGW and a known amount of BCEE, BCEM

and 1,2-DCA at a specified pH and solid/water ratio. Final DOC was measured

for the same reactors 40 hours after hydrogen peroxide addition.

Inhibition Test Specific oxygen uptake rate (SOUR) tests were done using a dissolved

oxygen (DO) probe (Orion 97-08-99, Beverly, MA) connected to a meter

(Accument Research AR25 Dual Channel ph/Ion Meter, Fisher Scientific,

Pittsburgh, PA) and computerized data acquisition system (LabView version 6.0,

National Instruments, Austin, TX) that records the dissolved oxygen

concentration of the system at specified time intervals. The data acquisition was

set to record data at intervals of 0.10 minutes over a period of 15 minutes.

Duplicate specific oxygen uptake rate (SOUR) measurements were done for

12

activated sludge exposed to undiluted, 50% diluted, and 90% diluted Fenton

treated and untreated water. Prior to mixing with activated sludge, the pH for the

Fenton treated and untreated water was adjusted to 7.0 using 0.1 N NaOH. For

the undiluted reactor, 100 mL of activated sludge obtained form Blacksburg-VPI

Sanitation Authority was mixed with 20 mL of Fenton treated or untreated liquid

and 180 mL of reagent grade water in a 300 mL BOD bottle. For the 50%

diluted, 100 mL of activated sludge was mixed with 10 mL of Fenton treated or

untreated liquid and 190 mL of deionized, distilled water in a 300 mL BOD bottle.

For the 90% diluted, 100 mL of activated sludge were mixed with 1.8 mL of

Fenton treated or untreated water and 198.2 mL of deionized, distilled water in a

300 mL BOD bottle. Both endogenous and exogenous controls were employed.

The endogenous control consisted of 100 mL of activated sludge mixed with 200

mL deionized, distilled water. The exogenous control consisted of 100 mL

activated sludge mixed with 6 mL of nutrient solution (0.94 g proteins as COD/L,

0.51 g sugars as COD/L, 1.31 g organic acids as COD/L) and 194 mL of

deionized, distilled water. Each of the BOD bottles containing the different

solutions were then placed on magnetic stirring plates to allow for adequate

mixing. DO probes were immediately inserted to the bottles, ensuring that the

solution was tightly sealed from the atmosphere and that no headspace

remained. SOUR measurements were recorded over a period of 15 minutes.

Results and Discussion BCEE and BCEM

The surface catalyzed Fenton reaction is affected by a variety of

parameters such as pH, solid/water ratio, hydrogen peroxide concentration, and

contaminant concentration. To evaluate whether BCEE and BCEM are amenable

to surface catalyzed Fenton treatment and to characterize the effects of these

different parameters on the loss of BCEE and BCEM, experiments utilizing

uncontaminated soil spiked with either compound were performed. After the

13

conditions for effective surface catalyzed Fenton treatment were established,

contaminated soil containing BCEE, BCEM and other contaminants was

subjected to these conditions to evaluate the degree of contaminant reduction

under simulated field conditions.

Uncontaminated Soil Experiments

Sorption Test

To assess the potential for BCEE or BCEM to sorb to the soil or to the

reaction vessel, a simple sorption test was performed by spiking 10 mg/L of

either compound to a reactor containing 2 g/mL uncontaminated soil and

baseline synthetic groundwater at pH 4. Results of the sorption test show that

after 96 hours, the aqueous phase BCEE concentration had decreased by 8.6 ±

0.8% while BCEM had decreased by 5.3 ± 1.5% (Figure 3). These minor losses

indicate that there is little sorption of either BCEE or BCEM to the

uncontaminated Moss Point soil or the reaction apparatus. These control

experiments demonstrate that any BCEE or BCEM loss greater than ~ 9% in the

Fenton treated reactors is a result of added H2O2 and not sorption.

Effect of pH

Numerous prior studies have shown that the Fenton reaction is enhanced

at acidic pH and is optimized at pH ≈ 4.0 (Tang, 1996; Casero et al, 1997; Kwon,

et al, 1999). A study to examine the effect of pH on the rate of BCEE and BCEM

loss was conducted. Batch reactors containing uncontaminated soil mixed with

baseline synthetic groundwater at a soil/water ratio of 0.1 g/mL were utilized.

Experiments for BCEE and BCEM were conducted independently and the initial

contaminant concentration was set to 1.0 mg/L. Two sets of experiments were

carried out for each chlorinated ether. The first set utilized a 5.0 g/L initial dose of

hydrogen peroxide at pH = 4.0, 5.5, 7.0 and the second set was run over the

same pH range but at a hydrogen peroxide concentration of 10 g/L. The results

14

of the experiments for BCEE (Figures 4 & 5) show that contaminant reduction

was greatest at pH = 4.0. For BCEM (Figures 6 & 7), on the other hand, there

was very little variation in the contaminant reduction rates between pH = 4.0 and

pH = 5.5. Experiments with both BCEE and BCEM consistently showed that

contaminant reduction is slowest at pH = 7.0 and faster at lower pH values.

These results agree with previous studies (Sedlak and Andren, 1991; Dong,

1993).

It is known that the oxidation potential of the �OH radical decreases with

increasing pH (Eisenhauer, 1994). The �OH radical is a strong oxidant with an

oxidation potential of 2.65 - 2.80 V at pH = 3.0. However, this value drops to 1.90

V at pH = 7.0. (Buxton et al, 1988) Thus, the observed decrease in contaminant

loss rates at neutral pH can be attributed to the reduced oxidation capacity of �OH radical at pH = 7.

Effect of Solid to Water Ratio

For surface catalyzed Fenton treatment processes, the solid/water ratio

plays a significant role in the rate of contaminant loss because the iron and other

metals that can react with hydrogen peroxide to generate hydroxyl radicals are

sourced solely from the soil (Miller and Valentine, 1996). A study to characterize

the effect of the solid/water ratio on the rate of BCEM loss was conducted using

batch reactors containing uncontaminated soil mixed with baseline synthetic

groundwater at pH 4.0 and three different solid/water ratios (0.1 g/mL, 1 g/mL, 2

g/mL). The results show that the rate of BCEM loss increased as the solid/water

ratio increased (Figure 8), and thus it is possible to conclude that the rate and

extent of contaminant destruction is dependent on the solid/water ratio.

In addition to the iron content of the soil, a study by Miller and Valentine in

1998 showed that other transition metals such as manganese significantly

influence the rate of hydrogen peroxide decay. The amount of available transition

metals in the soil that can catalyze the production of hydroxyl radical is a key

parameter for formation of hydroxyl radicals using the surface catalyzed Fenton

15

process and thus the higher the soil/water ratio of the reactor, the faster the rate

at which the contaminant will degrade. The soil is the sole source of iron and

other reduced metals in the surface catalyzed Fenton treatment. Assuming a

homogenous soil, the amount of reduced metal in a given reactor is proportional

to the amount of soil. Increasing the rate of production of hydroxyl radicals that

can react with BCEM increases the rate of BCEM loss. The hydrogen peroxide

decay profile (Figure 8) for this experiment supports this conclusion. For a

solid/water ratio of 0.1 g/mL, the hydrogen peroxide decay was considerably

slower as compared to the higher soil/water ratio of 1.0 g/mL and 2.0 g/mL. This

finding suggests that the hydrogen peroxide decay was limited by the amount of

reduced metals present.

Effect of Hydrogen Peroxide Concentration

The previous results examining the effect of pH on contaminant oxidation

rates (Figures 2, 3, 4, 5) can be analyzed to determine the effect of the initial

hydrogen peroxide concentration on BCEE and BCEM loss. After 15 hours at pH

= 4.0 for the reactor with an initial [H2O2] = 5.0 g/L (Figure 4) there was a 35%

BCEE reduction compared to a 50% reduction after the same period of time for

an initial [H2O2] = 10.4 g/L (Figure 5). Similar trends in BCEE destruction were

observed at pH 5.5 and 7.

For BCEM, on the other hand, increasing the initial H2O2 concentration

had little or no effect on its destruction. After 30 hrs at pH = 4.0, the BCEM

reduction for an initial [H2O2] = 5.0 g/L (Figure 6) and for an initial [H2O2] = 10 g/L

(Figure 7) was around 40%. The reason for the differential behavior of BCEE and

BCEM toward changes in the hydrogen peroxide concentration may reflect the

more recalcitrant nature of BCEM to oxidation via Fenton based treatment. We

note that BCEM loss after 30 hrs is just 40% as compared to as much as 50%

loss for BCEE at pH = 4.0.

To further investigate the effects of changes in [H2O2] on contaminant

degradation, another set of experiments was conducted using BCEE and H2O2

16

doses of 100 � 10,000 mg/L at pH 4 (Figure 9). Again, BCEE degradation

occurred more rapidly with higher H2O2 doses thus corroborating the previous

result. Interestingly, however, even at the highest H2O2 level utilized, BCEE

degradation after 40 hours was incomplete. This observation suggests that

reactive surface sites, which are responsible for the formation of the reactive

hydroxyl radicals, may be limiting at the low solid/water ratio (0.1 g/mL) employed

in these experiments. As discussed previously, greater contaminant removal was

observed at higher solid/water ratios.

A possible explanation for the effect of the initial hydrogen peroxide

concentration can be found by looking at Table 1. Reactions (6), (7) and (13)

show that Fe3+ is reduced by O2, H2O2 and R• to Fe2+ which creates a cycle

where additional OH• is generated via Reaction (1). In this case, the greater the

amount of initial hydrogen peroxide present, the more hydrogen peroxide is

available for hydroxyl radical generation through Reaction (1) as well as for the

reduction of Fe3+ to Fe2+ via Reaction (7) which subsequently adds to OH•

production.

Both BCEE and BCEM reduction should increase with increasing initial

hydrogen peroxide dose. With a higher initial hydrogen peroxide dose, after the

reaction of the hydrogen peroxide with Fe2+ to produce hydroxyl radicals and

after all the Fe2+ is oxidized to Fe3+, the remaining hydrogen peroxide can reduce

Fe3+ to Fe2+ which can again react with the remaining hydrogen peroxide to

produce additional hydroxyl radicals.

Mineralization of BCEE and BCEM

To evaluate whether contaminant loss results in mineralization of BCEE

and BCEM, the change in DOC following Fenton treatment of uncontaminated

soil spiked individually with BCEE and BCEM was measured in selected

experiments. The results (Figure 10) indicate there was a 50% reduction in DOC

for the BCEE and BCEM reactors following H2O2 addition, thus suggesting that a

17

significant portion of the initial DOC was oxidized to CO2 or volatile organic

compounds.

A significant fraction of the initial DOC concentration measured in the

uncontaminated soil experiments can be attributed to the methanol used to

prepare the BCEE or BCEM stock solutions (which were prepared with 50%

methanol). For the reactors that were spiked with 1 mg/L of contaminant,

methanol accounts for 0.5% of the total solution which can be calculated to

contribute 1481.3 mg C/L. For the reactors spiked with 10 mg/L, methanol was

calculated to be 5% of the total solution which was calculated to contribute

14,813 mg C/L. Given that the measured DOC values in the non-Fenton treated

reactors were considerably higher than these calculated levels, it is apparent that

DOC present in the soil also contributed by a significant portion of the DOC

measured in each sample. Unfortunately due to the potential for methanol

volatilization during oxygen purging of the samples prior to DOC analysis, it is

impossible to accurately determine the contribution of methanol to the initial and

final DOC levels. Although the final BCEE and BCEM concentrations were not

determined for these reactors, prior results from the experiment done with BCEE

under the same experimental conditions shows an 85% reduction in BCEE for a

reactor spiked with an initial BCEE concentration of 1 mg/L (Figure 9). The

measured loss of DOC and contaminant support the general conclusion that a

significant fraction of the contaminants are oxidized to CO2 or other volatile

compounds. Although, no daughter products were detected via GC-MS analysis,

a study to identify the formation of specific daughter products should be done to

further support these findings.

Contaminated Soil Experiments

The previously described experiments done to evaluate the behavior of

BCEE and BCEM were carried out using uncontaminated Moss Point soil.

However, at the actual site these contaminants are found in the presence of

other organic substances that may also exert an oxidant demand and thus the

18

ability of a Fenton Process to remove BCEE and BCEM from solution under

these conditions needs to be examined.

General Contaminant Behavior

The conditions used for the contaminated soil experiments were selected

based on the conclusions drawn from the experiments with the uncontaminated

soil. All experiments were conducted at pH = 4.0, with the following experimental

conditions: 1) solids/water ratio = 2 g/mL, with and without initial [H2O2] = 10 g/L

(Figure 11); 2) solids/water ratio = 3 g/mL, with and without initial [H2O2] = 20 g/L

(Figure 12).

Prior to addition of H2O2, the contaminated soil was allowed to equilibrate

with the BSGW for at least 24 hours. The contaminant concentrations were

monitored during this equilibration period to quantify the rate of contaminant

desorption into clean BSGW. Following BSGW addition, equilibration with the soil

phase was immediate and there were no significant additional changes in the

contaminant concentrations during this 24 hour period. This result indicates that

the contaminants that were sorbed to the soil or present within residual pore

water rapidly equilibrated with the BSGW. Following equilibration, no significant

loss of BCEE or BCEM was observed in the control experiments (no H2O2

addition) over several days of sampling, indicating that any measured decrease

in the experiments with added H2O2 was the result of H2O2 addition.

In the system with a solids/water ratio of 2 g/mL and an initial hydrogen

peroxide dose of 10 g/L, removal efficiencies for BCEE were 71% and 86% after

21 and 58 hours, respectively (Figure11A). Removal efficiencies for BCEM over

the same time periods were 66% and 96% (Figure 11B). Removal of BCEE in the

experiments with a higher solids/water ratio of 3 g/mL and higher initial hydrogen

peroxide dose of 20 g/L improved to 88% after 21.5 hours (Figure 12A). For

BCEM, removal after 21.5 hours also improved to 88% (Figure 12B).

The limited improvement in destruction efficiency with the higher H2O2

dose may be explained by the higher solids/water ratio of the second set of

19

experiments, which increased the potential for competing reactions involving the

hydroxyl radicals with other constituents in the matrix. In other words, if only the

initial H2O2 concentration had been increased (and the soil to water ratio kept the

same), it is expected that a greater improvement in BCEE and BCEM removal

efficiency (as demonstrated by the work with uncontaminated sediment) would

have been observed.

The first two sets of experiments using contaminated soil demonstrated a

sharp reduction of BCEE and BCEM concentration within the first 21 hours, and

minimal reduction after this period (Figures 11 and 12). For the control condition

from the TBA experiments (no TBA addition, soil to water ratio of 2 g/mL, initial

H2O2 = 10 g/L) the H2O2 destroyed 87% of the BCEE and 94% of the BCEM

within a period of 6 hours (Figure 13). This indicates that the majority of the

contaminant destruction likely occurred within the first 6 hours of addition of H2O2

in the experiments depicted in Figures 11 and 12.

Experimental Control

An inhibition experiment using tert-butyl alcohol was performed to verify

that measured contaminant loss was the result of the reaction of hydroxyl

radicals with the contaminants. Tert-butyl alcohol (TBA) is a good scavenger of

hydroxyl radicals (Miller and Valentine, 1999) and when added to a system it

efficiently reacts with any hydroxyl radicals that form, thus inhibiting the reactions

of hydroxyl radicals with H2O2 or other compounds (including BCEE and BCEM).

The results of these experiments demonstrate that the presence of TBA

prevented BCEE and BCEM destruction after addition of H2O2, while significant

reduction of BCEE and BCEM was observed in the experiments where TBA was

absent (Figure 13). These results indicate that the destruction of BCEE and

BCEM can be attributed to the reaction of these contaminants with the hydroxyl

radicals formed through the reaction of the surface sites with hydrogen peroxide.

20

Interestingly, the results shown in Figure 13C suggest that TBA hinders

H2O2 loss, a result that seems counter-intuitive given that TBA scavenges �OH

radicals. An additional experiment looking only at hydrogen peroxide loss over

time with and without the presence of TBA was done to better characterize this

effect. The results show that the rate of H2O2 loss in the system with TBA is

slightly slower than the rate of loss in the system without TBA (Figure 14). To

understand this system more fully, the reactions with respect to hydrogen

peroxide and hydroxyl radical formation that are taking place in the system

should be examined (Table 1). Based on these equations it is inferred that the

slower rate of H2O2 residual depletion in the system with TBA is the result of the

consumption of the hydroxyl radicals by the TBA which prevents the hydroxyl

radicals from reacting with additional hydrogen peroxide. In other words, the TBA

inhibits one of the primary hydrogen peroxide degradation pathways in the

solution phase (reaction 2 in Table 1).

Effect of Fe2+ Addition

The effect of Fe2+ addition on the contaminant loss rate was investigated

to determine whether the addition of Fe2+ could help decrease the initial

hydrogen peroxide dose required to achieve a desired level of contaminant loss.

The initial hydrogen peroxide dose for this experiment was 5 g/L, or half of the

initial hydrogen peroxide dose (10 g/L) employed for the previous experiments

involving contaminated soil (Figure 11). For this experiment, three sets of

reactors were set-up containing contaminated soil and baseline synthetic

groundwater at pH = 4.0 and at a solid/water ratio of 2 g/mL. The first set of

reactors served as the control and hence neither Fe2+ nor hydrogen peroxide

was added to it throughout the experiment. In the second set of reactors, Fe2+

was initially added at a concentration of 400 mg/L. At t = 0, 5 g/L of hydrogen

peroxide was added to the second and third sets of reactors. The results show

that the rate of contaminant loss in the second set of reactors, where Fe2+ was

added, was faster than that for the third set of reactors, where Fe2+ was not

21

present (Figure 15). The rate of contaminant loss is comparable to that of the

previous results with contaminated soil involving the same conditions but

employing a higher initial dose of 10 g/L hydrogen peroxide (Figure 11). The

overall contaminant loss after 38 hours, however, did not significantly change for

the two sets of reactors. This result suggests that the H2O2 concentrations may

have been limiting under these conditions. The addition of Fe2+ increases the

total Fe2+ in the system available to react with the hydrogen peroxide to produce

hydroxyl radicals, thus increasing the efficiency of hydroxyl radical production.

Sequential Spike Experiments

Prior results have shown that once the hydrogen peroxide added to a soil

sample is depleted that the contaminant concentration starts to plateau (Figures

12, 13 and 15). One of the factors considered to explain this behavior is that

hydrogen peroxide, the source of hydroxyl radicals, is the limiting factor for

continued contaminant loss. To test this hypothesis, a set of reactors was re-

spiked with hydrogen peroxide once the initial dose of hydrogen peroxide was

consumed. Three sets of reactors were set up and consisted of contaminated soil

and baseline synthetic groundwater at pH = 4.0 at a solid/water ratio of 2 g/mL.

The first set of reactors was the control for the experiment and hence no

hydrogen peroxide was added to it. An initial hydrogen peroxide dose of 10 g/L

was added to both the second and third set of reactors at t = 0. At t = 31 hrs, the

third set of reactors was re-spiked with 10 g/L hydrogen peroxide. BCEE and

BCEM loss were monitored for all sets of reactors for comparison. The results of

the experiment are shown in Figure 16. Comparing contaminant loss for the

second and third sets of reactors from t = 31 hrs (e.g., the time third set of

reactors were re-spiked) until t = 43 hrs, we see that the BCEE level was reduced

from 0.56 mg/L to 0.25 mg/L and the BCEM concentration was reduced from

88.8 mg/L to 41.7 mg/L in the re-spiked reactor. These values account for 55%

and 53% declines in these concentrations. Over the same time period, the BCEE

level decreased from 0.36 mg/L to 0.21 mg/L (42% reduction) and the BCEM

level decreased from 52.5 mg/L to 22.8 mg/L (52.5% reduction) for the reactors

22

not re-spiked with hydrogen peroxide. There was a significant difference in

overall BCEE reduction between the two sets of reactors, while there was no

significant difference in BCEM loss. The results from the BCEE experiment

suggest that hydrogen peroxide is a limiting factor in BCEE removal. For BCEM

on the other hand, the results suggest that hydrogen peroxide does not limit

BCEM reduction.

Mineralization of BCEE and BCEM

DOC analysis was performed for selected contaminated soil experiments

before and after H2O2 addition. Similar to the uncontaminated soil experiments,

an 80% reduction in DOC was observed after the H2O2 reaction period (Figure

17). This suggests that the surface catalyzed Fenton treatment converts a

significant fraction of organic material in the soil (including the contaminants) to

CO2 or other volatile organic compounds. The identity of these products requires

further work.

1,2-DCA 1,2-DCA with Uncontaminated and Contaminated Soils

No significant loss of 1,2-DCA was observed when uncontaminated soil

spiked with 10 mg/L 1,2-DCA was reacted with 10 g/L of hydrogen peroxide

(Figure 18). Similar results were observed for contaminated soil spiked with 10

mg/L of 1,2-DCA. Although 1,2-DCA was detected at the Moss Point site, it was

necessary to spike the contaminated soil with 1,2-DCA because any 1,2-DCA

present in the soil when it was extracted from the ground had volatilized during

storage.

Based on the observation that there is no 1,2-DCA loss seen both in the

reactors containing uncontaminated soil spiked with 1,2-DCA and reacted with

hydrogen peroxide (Figure 18), and the reactors containing contaminated soil

spiked with 1,2-DCA and reacted with hydrogen peroxide (Figure 19), we can say

that 1,2-DCA is not as readily amenable to Fenton treatment as compared to

23

BCEE and BCEM since we observed BCEE and BCEM reduction when

subjected to the same experimental conditions.

A set of reactors was set up containing contaminated soil spiked with 10

mg/L 1,2-DCA and 400 mg/L of Fe2+ and then reacted with 10 g/L of hydrogen

peroxide to investigate whether Fe2+ addition would aid in 1,2-DCA reduction. For

the reactors where Fe2+ was added, 1,2-DCA loss was observed (Figure 19). The

addition of Fe2+ catalyzes the production of hydroxyl radicals from hydrogen

peroxide. If Fe2+ is present in a system with hydrogen peroxide, this might

translate to more efficient production of hydroxyl radicals relative to the other

hydrogen peroxide breakdown products. Thus, if there are more hydroxyl radicals

present in the system, there is a greater possibility of reaction with 1,2-DCA. In

addition, the hydroxyl radicals might have a lower preference for 1,2-DCA as

compared to the other contaminants from the contaminated soil (i.e., BCEE or

BCEM) present in the system. In this case, for 1,2-DCA loss to occur, there must

be an abundance of hydroxyl radicals to ensure that there are hydroxyl radicals

left to react with 1,2-DCA after the other hydroxyl radicals have reacted with the

other contaminants; or there must be an abundance of 1,2-DCA so that it is

preferred by the hydroxyl radicals over the other contaminants which might be of

less concentration.

1,2-DCA Analysis for Chauny Groundwater with Uncontaminated Soil

The groundwater from Chauny, France was analyzed at the site to contain

1,2-DCA at a concentration of 146,000 µg/L. For this experiment, the average

initial concentration of 1,2-DCA was found to be at around 186,000 µg/L.

Chauny groundwater was added to uncontaminated soil at a solid/water ratio of 2

g/mL. The initial hydrogen peroxide dose used was 10 g/L. The results show a

significant loss of 1,2-DCA shortly after the addition of hydrogen peroxide (Figure

20). This is an interesting result given the previous experiment that was

conducted using uncontaminated soil spiked with 1,2-DCA and reacted with

hydrogen peroxide did not show any 1,2-DCA loss over the course of the

24

experiment. As previously mentioned, one reason for the observed contaminant

loss might be the high concentration of 1,2-DCA in the system. Even if there is a

limited amount of hydroxyl radical present in the system, the abundance of 1,2-

DCA increases the possibility of reacting with the hydroxyl radicals. In addition,

the Chauny groundwater might contain some amount of Fe2+ or other dissolved

metals which could serve as a catalyst for hydroxyl radical production.

1,2-DCA Analysis with Chauny Groundwater and Contaminated Soil An additional experiment was done using Chauny groundwater mixed with

contaminated soil at a solid/water ratio of 2 g/mL with varying initial doses of

hydrogen peroxide from 10 g/L to 30 g/L. This experiment was done to assess

whether 1,2 DCA loss will increase with increasing initial hydrogen peroxide

dose. The results show that when the initial hydrogen peroxide dose was

increased from 10 g/L to 30 g/L, there was an increase of 1,2 DCA loss from 26%

to 71% (Figure 21). However, the 26% loss of 1,2 DCA for the system containing

Chauny groundwater mixed with contaminated soil where the initial hydrogen

peroxide dose was 10 g/L was lower than the 50% loss seen in the system

containing Chauny groundwater mixed with uncontaminated soil (Figure 20).

This decrease can be attributed to the increase concentration of co-

contaminants, thereby increasing the potential for competing hydroxyl radical

reactions, in the system where contaminated soil was used.

INHIBITION TEST

An inhibition test was performed to evaluate whether the by-products

produced via surface catalyzed Fenton treatment would potentially inhibit the

activity of a given microbial community or possibly serve as a substrate for

microbial growth. To evaluate this possibility, the specific oxygen uptake rate

(SOUR) of untreated and surface catalyzed Fenton treated waters was

evaluated.

For this experiment, four separate solutions were tested: 1) Endogenous

control � This control was used to measure the endogenous respiration rate (i.e.,

25

oxygen consumption rate) of activated sludge at its resting state. 2) Exogenous

control � This control was run to measure the oxygen consumption of activated

sludge when a readily degradable substrate is present. 3) Untreated BSGW

Equilibrated with Moss Point Soil � This solution was tested to determine the

SOUR of the untreated water. 4) Fenton treated BSGW Equilibrated with Moss

Point Soil � This solution was tested to determine the SOUR of water that had

undergone Fenton treatment. For solutions 3 and 4, three different dilutions were

employed (undiluted, 50% diluted, 90% diluted). These dilutions were done to

ensure that the oxygen demand of at least one of the reactors would be

quantifiable. Oxygen uptake rates were determined from the slopes of linear

regressions of the dissolved oxygen profiles taken over a period of 15 minutes

(Figure 22; Table 4). These rates were then converted to specific oxygen uptake

rates by dividing the average oxygen uptake rates by the total suspended solids

concentration (Figure 23, Table 4).

The results show that there was an increase in the specific oxygen uptake

rate of the activated sludge when it was exposed to undiluted untreated water,

undiluted Fenton treated water, and 50% diluted Fenton treated water compared

to the oxygen uptake rates for the endogenous and exogenous controls (Figure

23 and Table 4). For the 50% diluted untreated water and the 90% diluted Fenton

treated and 90% diluted untreated water, the specific oxygen uptake rate was

greater than that of the endogenous control, but was a little less than the specific

oxygen uptake rate for the exogenous control (Figure 23 and Table 4). This

result is not believed to be indicative of inhibition, but is associated with the

decreased substrate concentration that occurs with increased dilution.

The associated dissolved organic carbon concentrations for the dilutions

of untreated and Fenton treated water is shown in Table 5 and Figure 24.

Interestingly, the specific oxygen uptake rates for the activated sludge exposed

to the different dilutions of the Fenton treated water were always larger than the

specific oxygen uptake rates of the activated sludge for the corresponding

dilution of the untreated water. This observation indicates that the Fenton treated

water contains more readily biodegradable substrates than the untreated water.

26

Thus, it can be concluded that Fenton surface catalyzed treatment enhances the

biodegradability of the contaminated groundwater. This finding is consistent with

the study done by Rodriguez, 2003 on the biodegradability enhancement of

Fenton based oxidation in wastewater.

Table 4. Average oxygen consumption rates in mg/L and specific oxygen uptake rates for the controls and the different samples.

Sample Average Oxygen

Consumption Rate (mg O2/min/L)

Specific Oxygen Uptake Rate

(SOUR) (mg O2/hr/g solids)

Endogenous Control 0.04 ± 0.00 1.98 ± 0.38 Exogenous Control 0.21 ± 0.00 9.59 ± 0.02 Undiluted Fenton Treated Water 0.35 ± 0.04 16.1 ± 1.61 Undiluted Untreated Water 0.26 ± 0.00 11.8 ± 0.18 50% Diluted Fenton Treated Water 0.24 ± 0.04 11.0 ± 1.72 50% Diluted Untreated Water 0.20 ± 0.01 9.07 ± 0.36 90% Diluted Fenton Treated Water 0.20 ± 0.01 9.23 ± 0.59 90% Diluted Untreated Water 0.18 ± 0.02 8.42 ± 0.67

Table 5. Average oxygen consumption rate, specific oxygen uptake rate and dissolved organic carbon for different dilutions of untreated and Fenton treated water.

Sample Average Oxygen

Consumption Rate (mg O2/min/L)

Specific Oxygen Uptake Rate

(SOUR) (mg O2/hr/g solids)

Dissolved Organic Carbon (mg C/L)

Undiluted Untreated Water 0.26 11.84 157.8 50% Diluted Untreated Water 0.2 9.07 78.9 90% Diluted Untreated Water 0.18 8.42 15.8 Undiluted Fenton Treated Water 0.35 16.12 31.1 50% Diluted Fenton Treated Water 0.24 10.99 15.5 90% Diluted Fenton Treated Water 0.2 9.23 3.1

27

Conclusions

Bis(2-chloroethyl) ether, bis(2-chloroethoxy) methane and 1,2

dichloroethane have been shown to be amenable to surface catalyzed Fenton

treatment. The inhibition study using t-butanol proves that the contaminant loss is

due to the reaction of the hydroxyl radical (generated by H2O2 interaction with

native minerals in the soil) with the contaminants. BCEE destruction via Fenton�s

reactions with the uncontaminated Moss Point soil was faster at pH = 4.0

compared to higher values. On the other hand, BCEM destruction for the

uncontaminated soil did not appear to significantly improve below pH 5.5.

Increasing H2O2 concentration increased the destruction of BCEE but not

necessarily BCEM. Given the same experimental conditions, the rate of BCEE

destruction is faster than BCEM. The solid / water ratio of the system was seen

to be very important because it translates to the amount of Fe2+ and other

transition metals that are available to react with H2O2 to produce hydroxyl

radicals. BCEE and BCEM destruction were both found to increase with

increasing solids/water ratio. 1,2-DCA was not as readily amenable to surface

catalyzed treatment was compared to BCEE and BCEM. The rate of contaminant

loss and the degree of contaminant reduction was greater with systems involving

contaminated soil as compared to systems with uncontaminated soil for BCEE

and BCEM. On the other hand, 1,2-DCA reduction was greater for systems

involving Chauny groundwater mixed with uncontaminated soil as compared to

the system with Chauny groundwater mixed with contaminated soil. The by-

products and residuals of the surface catalyzed Fenton treatment is not inhibitory

to activated sludge but can serve as a readily degradable substrate and

enhances the biodegradability of the contaminated water.

28

Time (hrs)

0 20 40 60 80 100 120

Con

tam

inan

t Con

cent

ratio

n (m

g/L)

0

2

4

6

8

10

12

BCEMBCEM

Figure 3. Sorption test performed by spiking 10 mg/L each of BCEE and BCEM to uncontaminated soil / synthetic groundwater mixture. [BCEE]0 = 10 mg/L; [BCEM]0 = 10 mg/L; solid/water = 2 g/mL; pH = 4.0. Error bars represent 95% confidence intervals.

29

Time (hrs)

0 5 10 15 20 25

[BC

EE]/[

BC

EE] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

pH = 4.0 pH = 5.5pH = 7.0

Time (hrs)

0 5 10 15 20 25

[H2O

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

pH = 4.0 pH = 5.5pH = 7.0

A

B

Figure 4. A) [BCEE]/[BCEE]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different pH values for initially uncontaminated soil. [BCEE]0 = 1.0 mg/L; [H2O2]0 = 5.0 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

30

Time (hrs)

0 2 4 6 8 10 12 14 16

[BC

EE]

/[BC

EE] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

pH = 4.0 pH = 5.5pH = 7.0

Time (hrs)

0 2 4 6 8 10 12 14 16

[H2O

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

pH = 4.0 pH = 5.5pH = 7.0

A

B

Figure 5. A) [BCEE]/[BCEE]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different pH values for initially uncontaminated soil. [BCEE]0 = 1.0 mg/L; [H2O2]0 = 10.4 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

31

Time (hrs)

0 10 20 30 40 50

[BC

EM

]/[B

CEM

] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

pH = 4.0 pH = 5.5pH = 7.0

Time (hrs)

0 10 20 30 40 50

[H2O

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

pH = 4.0 pH = 5.5pH = 7.0

A

B

Figure 6. A) [BCEM]/[[BCEM]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different initial pH values for initially uncontaminated soil. [BCEM]0 = 1.0 mg/L; [H2O2]0 = 5.0 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

32

Time (hrs)

0 10 20 30 40 50

[BC

EM

]/[B

CE

M] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

pH = 4.0 pH = 5.5pH = 7.0

Time (hrs)

0 10 20 30 40 50

[H20

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

pH = 4.0 pH = 5.5pH = 7.0

A

B

Figure 7. A) [BCEM]/[BCEM]0 and B) [H2O2]/[H2O2]0 as a function of time at different pH values for initially uncontaminated soil. [BCEM]0 = 1.0 mg/L; [H2O2]0 = 10.4 g/L; solids/water ratio = 0.1 g/mL. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

33

Time (hrs)

0 10 20 30 40 50

[BC

EM

]/[B

CE

M] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2 solid/water = 0.1 g/mLsolid/water = 1.0 g/mLsolid/water = 2.0 g/mL

Time (hrs)

0 10 20 30 40 50

[H2O

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2solid/water = 0.1 g/mLsolid/water = 1.0 g/mLsolid/water = 2.0 g/mL

A

B

Figure 8. A) [BCEM]/[BCEM]0 and B) [H2O2]/[H2O2]0 loss as a function of time at different solids/water ratio for initially uncontaminated soil. [BCEM]0 = 1 mg/L; [H2O2]0 = 5.0 g/L; pH = 4.0. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

34

Time (hrs)

0 10 20 30 40 50

[BC

EE

]/[B

CE

E]0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

H2O2 = 132 ± 21.98 mg/LH2O2 = 1143 ± 10.45 mg/LH2O2 = 11538 ± 501.39 mg/ L

Time (hrs)

0 10 20 30 40 50

H2O

2 Con

c'n

(mg/

L)

020406080

100120140160180

H2O2 = 132 ± 21.98 mg/L

Time (hrs)

0 10 20 30 40 50

H2O

2 Con

c'n

(mg/

L)

0200400600800

100012001400

H2O2 = 1143 ± 10.45 mg/L

Time (hrs)

0 10 20 30 40 50

H2O

2 Con

c'n

(mg/

L)

02000400060008000

100001200014000

H2O2 = 11538 ± 501.39 mg/ L

A

B

C

D

Figure 9. A) [BCEE]/[BCEE]0 B) [H2O2]0 = 132 ± 21.98 mg/L C) [H2O2]0 = 1143 ± 10.45 mg/L D) [H2O2]0 = 11538 ± 501.39 mg/L as a function of time for initially uncontaminated soil. [BCEE]0 = 1.0 mg/L; solid/water ratio = 1 g/mL; pH = 4.0. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

35

Figure 10. DOC concentration reduction over a period of 40 hours for uncontaminated soil spiked with A) 1 mg/L of BCEE or BCEM or 1,2-DCA and B) 10 mg/L of BCEE or BCEM or 1,2-DCA at pH = 4.0; solid/water ratio = 1 g/mL. [H2O2]0 = 10 g/L. Error bars represent 95% confidence intervals.

A

BCEE BCEM 1,2-DCA

DO

C (m

g C

/L)

0

1000

2000

3000

4000

5000

6000Initial DOCFinal DOC

B

BCEE BCEM 1,2-DCA

DO

C (m

g C

/L)

0

5000

10000

15000

20000

25000

30000 Initial DOCFinal DOC

36

Time (hrs)

0 10 20 30 40 50 60 70

[BC

EE]/[

BCE

E] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

contaminated soil + BSGW + H2O2

contaminated soil + BSGW (control)

Time (hrs)

0 10 20 30 40 50 60 70

[BC

EM

]/{BC

EM

] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

contaminated soil + BSGW + H2O2 contaminated soil + BSGW

Time (hrs)

0 10 20 30 40 50 60 70

[H2O

2]/[H

2O2] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

contaminated soil + BSGW + H2O2

A

B

C

Figure 11. A) [BCEE]/[BCEE]0, B) [BCEM]/[BCEM]0, and C) [H2O2]0 loss as a function of time in contaminated soil. [H2O2]0 = 10 g/L; solid/water ratio = 2 g/mL; pH = 4.0. [BCEE]0=1.68 ± 0.04 mg/L. [BCEM]0= 201.52 ± 10.17 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

37

Time (hrs)

0 20 40 60 80 100

[BC

EE]/[

BCEE

] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

contaminated soil + BSGW + H2O2

contaminated soil + BSGW (control)

Time (hrs)

0 20 40 60 80 100

[BC

EM]/[

BCEM

] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

contaminated soil + BSGW + H2O2

contaminated soil + BSGW (control)

Time (hrs)

0 20 40 60 80 100

[H2O

2]/[H

2O2] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

contaminated soil + BSGW + H2O2

A

B

C

Figure 12. A) [BCEE]/[BCEE]0, B) [BCEM]/[BCEM]0, and C) [H2O2]/ [H2O2]0 as a function of time in contaminated soil. [H2O2]0 = 20 g/L; solid/water ratio = 3 g/mL; pH = 4.0. [BCEE]0= 0.83 ± 0.05 mg/L. [BCEM]0= 156.07 ± 19.06 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

38

Time (hrs)

0 10 20 30 40 50 60

[BC

EE]/[

BC

EE] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4 contaminated soil + BSGW + H2O2 + TBAcontaminated soil + BSGW + H2O2

Time (hrs)

0 10 20 30 40 50 60

[BC

EM

]/[B

CEM

] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4contaminated soil + BSGW + H2O2 + TBAcontaminated soil + BSGW + H2O2

Time (hrs)

0 10 20 30 40 50 60

[H2O

2]/[H

2O2] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2contaminated soil + BSGW + H2O2 + TBAcontaminated soil +BSGW + H2O2

BSGW + H2O2

A

B

C

Figure 13. Inhibition study using TBA. A) [BCEE]/[[BCEE]0, B) [BCEM]/[BCEM]0, and C) [H2O2]/[H2O2]0 loss as a function of time in contaminated soil. [H2O2]0 = 10 g/L; solid/water ratio = 2 g/mL; pH = 4.0; [TBA] = 5.5 M. [BCEE]0 = 1.59 ± 0.26 mg/L. [BCEM]0 = 259.22 ± 20.60 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. H2O2 addition occurred at t = 0 hrs. Error bars represent 95% confidence intervals.

39

Time (mins)

0 20 40 60 80 100 120 140 160 180 200

[H2O

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

contaminated soil + BSGW + H2O2 + TBAcontaminated soil + BSGW + H2O2

Figure 14. Inhibition study using TBA. [H2O2]/ [H2O2]0 as a function of time in contaminated soil. [H2O2]0 = 10 g/L; solid/water ratio = 2 g/mL; pH = 4.0; [TBA] = 5.5 M. Error bars represent 95% confidence intervals.

40

Time (hrs)

0 10 20 30 40

[BC

EE

]/[B

CE

E] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4contaminated soil + BSGW + H2O2

contaminated soil + BSGW + H2O2 + Fe2+

contaminated soil + BSGW (control)

Time (hrs)

0 10 20 30 40

[BC

EM

}/[B

CE

M] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

contaminated soil + BSGW + H2O2

contaminated soil + BSGW + H2O2 + Fe2+

contaminated soil + BSGW

Time (hrs)

0 10 20 30 40

[H2O

2]/[H

2O2] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

contaminated soil + BSGW + H2O2

contaminated soil + BSGW + H2O2 + Fe2+

A

B

C

Figure 15. A) [BCEE]/[BCEE]0 B) [BCEM]/[BCEM]0 C) [H2O2]/[H2O2]0 as a function of time for contaminated soil. An initial hydrogen peroxide dose of 5 g/L was added at t = 0. [BCEE]0= 1.78 ± 0.06 mg/L. [BCEM]0= 353.74 ± 25.01 mg/L. [BCEE]0 and [BCEM]0 concentrations were levels in water after equilibration with contaminated soil. The solid/water ratio for the reactors was at 2 g/mL and the pH = 4.0. The Fe2+ dose of 400 mg/L was added to the second set of reactors at the start of the equilibration period (t < 0). Error bars represent 95% confidence intervals.

41

Time (hrs)

0 10 20 30 40 50

BC

EE

Con

cent

ratio

n (m

g/L)

0.00.20.40.60.81.01.21.41.61.8

contaminated soil + H2O2

contaminated soil + H2O2 (respiked with10 g/L H2O2 at t = 31 hrs)

Time (hrs)

0 10 20 30 40 50

BCEM

Con

cent

ratio

n (m

g/L)

0

20

40

60

80

100

120

contaminated soil + H2O2

contaminated soil + H2O2 (respiked with10 g/L H2O2 at t = 31 hrs)

Time (hrs)

0 10 20 30 40 50

H2O

2 Con

cent

ratio

n (m

g/L)

02000400060008000

1000012000140001600018000

contaminated soil + H2O2

contaminated soil + H2O2 (respiked with10 g/L H2O2 at t = 31 hrs)

B

C

re-spike with 10 g/L H2O2

re-spike with 10 g/L H2O2

re-spike with 10 g/L H2O2

Figure 16. A) BCEE B) BCEM C) H2O2 loss as a function of time for contaminated soil. An initial hydrogen peroxide dose of 10 g/L was added at time 0. An additional hydrogen peroxide dose of 10 g/L was added at time = 31 hrs to the third set of reactors. The solid/water ratio for the reactors was at 2 g/mL and the pH = 4.0. Error bars represent 95% confidence intervals.

42

contaminated soil

DO

C C

once

ntra

tion

(mg

C/L

)

0

500

1000

1500

2000

2500

3000

3500 Initial ConcentrationFinal Concentration

Figure 17. DOC concentration reduction over a period of 40 hours for contaminated soil. [H2O2]0 = 10 g/L; pH = 4.0; solid/water ratio = 2 g/mL. [H2O2]0 = 10 g/L. Error bars represent 95% confidence intervals.

43

Time (hrs)

0 5 10 15 20 25

1,2-

DC

A C

once

ntra

tion

(mg/

L)

0

2

4

6

8

10

uncontaminated soil + BSGW + 1,2-DCAuncontaminated soil + BSGW + 1,2-DCA + H2O2

Time (hrs)

0 5 10 15 20 25

H2O

2 C

once

ntra

tion

(mg/

L)

0

2000

4000

6000

8000

10000

12000uncontaminated soil + BSGW + 1,2-DCA + H2O2

A

B

Figure 18. A) 1,2-DCA B) H2O2 loss as a function of time for uncontaminated soil spiked with 10 mg/L 1,2-DCA with an initial hydrogen peroxide dose of 10 g/L. Hydrogen peroxide was added at t = 0. Solid/water ratio = 2 g/mL and pH = 4.0. Error bars represent 95% confidence intervals.

44

Time (hrs)

0 5 10 15 20 25 30

[1,2

-DC

A]/[

1,2-

DC

A] 0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

contaminated soil + BSGW + 1,2-DCA + H2O2contaminated soil + BSGW + 1,2-DCA + H2O2 + Fe2+

contaminated soil + BSGW + 1,2-DCA

Time (hrs)

0 5 10 15 20 25 30

[H2O

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2contaminated soil + BSGW + 1,2-DCA + H2O2contaminated soil + BSGW + 1,2-DCA + H2O2 + Fe2+

A

B

Figure 19. A) [1,2-DCA]/[1.2-DCA]0 B) [H2O2]/[H2O2]0 as a function of time for contaminated soil spiked with 10 mg/L 1,2-DCA with an initial hydrogen peroxide dose of 10 g/L. The initial Fe2+ dose of 400 mg/L was added to a set of reactors at the start of the equilibration period (t = -48 hrs). Hydrogen peroxide was added at t = 0. solid/water ratio = 2 g/mL and pH = 4.0. Error bars represent 95% confidence intervals.

45

Time (hrs)

0 5 10 15 20 25 30

[1,2

DC

A]/[1

,2 D

CA]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

uncontaminated soil + Chauny GW + H2O2uncontaminated soil + Chauny GW

Time (hrs)

0 5 10 15 20 25 30

[H2O

2]/[H

2O2]

0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

uncontaminated soil + Chauny GW + H2O2

A

B

Figure 20. A) [1,2-DCA]/[1,2-DCA]0 B) [H2O2]/[H2O2]0 as a function of time for the Chauny groundwater mixed with uncontaminated soil. [H2O2]0 = 10 g/L. Soil/water ratio = 2 g/mL and the pH = 4.0. Addition of H2O2 occurred at t = 0. Error bars represent 95% confidence intervals.

46

H2O2 Concentration (g/L)

0 10 20 30 40

% L

oss

of 1

,2-D

CA

0

20

40

60

80

100% Loss of 1-2 DCA

Figure 21. Percent Loss of 1,2-DCA as a function of H2O2 concentration for Chauny groundwater mixed with contaminated soil. Solid/water ratio = 2 g/mL, pH = 4.0. Error bars represent 95% confidence intervals.

47

Figure 22. Dissolved oxygen uptake of activated sludge as a function of time for exogenous and endogenous control and for different dilutions of untreated and Fenton treated water.

Time (min)

0 5 10 15 20

Dis

solv

ed O

xyge

n (m

g/L)

0

2

4

6

8

10Endogenous ControlExogenous ControlUndiluted Fenton Treated WaterUndiluted Untreated Water50% Diluted Fenton Treated Water50% Diluted Untreated Water90% Diluted Fenton Treated Water90% Diluted Untreated Water

48

Endo Cont Exo Cont Undil 50% Dil 90% Dil

Spec

ific

Oxy

gen

Upt

ake

Rat

e (m

g O

2/hr/g

tota

l sol

ids)

0

2

4

6

8

10

12

14

16

18

20 Endogenous ControlExogenous ControlFenton Treated WaterUntreated Water

Figure 23. Specific oxygen uptake rates of activated sludge as a function of time for exogenous and endogenous control and for different dilutions of untreated and Fenton treated water.

49

Figure 24. Specific oxygen uptake rates of the different dilutions of the untreated and Fenton treated water as a function of dissolved organic carbon

Dissolved Organic Carbon (mg C/L)

0 20 40 60 80 100 120 140 160 180

Spec

ific

Oxy

gen

Upt

ake

Rat

e(m

g O

2/hr

/g to

tal s

olid

s)

0

2

4

6

8

10

12

14

16

18

Untreated WaterFenton Treated Water

50

References

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2. Rodriguez, M. (2003). �Fenton and UV-vis based advanced oxidation processes in wastewater treatment: Degradation, mineralization and biodegradability enhancement�. PhD Dissertation. University of Barcelona.

3. Agency for Toxic substances and Disease Registry, 1999 4. National Toxicology Program, Department of Health and Human Services. 5. SRC Physprop database. 6. Acero, J.L., S.B. Haderlein, T.C. Schmidt, M.J.F. Suter and U. von Gunten

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8. Huang, F.Y.C., K.Y. Li and C.C. Liu (1999). �Treatability Studies of Groundwater Contaminated with Bis(2-chloroethyl) Ether�. Environmental Progress 18(1): 55-59.

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Vita Maria Divina Mutuc was born in Manila, Philippines to Julio and Erlinda Mutuc on April 22, 1976. She earned her B.S. in Chemical Engineering from the University of the Philippines, Diliman on May 1999. She earned her Philippine license as a professional chemical engineer on November 2000. Afterwhich she worked as a Project Evaluation and Monitoring Officer for the Department of Environment and Natural Resources for 2 years and then worked in an environmental consulting firm for six months prior to beginning her M.S. in Environmental Engineering at Virginia Polytechnic Institute and State University in August 2003.