Journal of Industrial and Engineering Chemistry 19 (2013) 932–937

Remediation of contaminated marine sediment using electrokinetic–Fentontechnology

M. Pazos, O. Iglesias, J. Gomez, E. Rosales, M.A. Sanroman *

Department of Chemical Engineering, University of Vigo, Isaac Newton Building, Campus As Lagoas, Marcosende 36310, Vigo, Spain

A R T I C L E I N F O

Article history:

Received 29 July 2012

Accepted 12 November 2012

Available online 21 November 2012

Keywords:

Dredged marine sediment

Electrokinetic

Electrokinetic–Fenton treatment

Metals

TPH

A B S T R A C T

In this work dredge marine sediments contaminated by petroleum hydrocarbon (TPH) and metals, such

as Zn, Pb, Cu and Hg, were treated by electrokinetic treatment. EDTA and Tween 80 were used as

processing fluid to enhance the solubility of metals and TPH, respectively. On the other hand, a

combination of a Fenton’s reagent and EDTA was evaluated to promote the in situ degradation of TPH and

to solubilize the metals. After 30 days of treatment, the best results were obtained by EK–Fenton–EDTA

process with a removal of about 90% for TPH, 57.3% of Zn, 59.8% of Pb, 59.4% of Cu and 54.5% of Hg.

� 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights

reserved.

Contents lists available at SciVerse ScienceDirect

Journal of Industrial and Engineering Chemistry

jou r n al h o mep ag e: w ww .e lsev ier . co m / loc ate / j iec

1. Introduction

Dredging activities are necessary for maintenance of existingnavigation channels, and construction of new port and harborfacilities. This continued necessity for dredging produces largevolumes of material each year, resulting in hundreds of millions oftons per year of dredged sediments all around the world [1].Dredged marine sediments often contain hazardous compoundssince they receive discharges of numerous liquid and solid wastes,thus these sediments become a toxic product not suitable forother use. Therefore, the development of new technologies forthe treatment of these residues is increasing the attention of thescientific community [2]. However, the characteristics of thesesediments: low permeability, high salt, organic and watercontents as well as the presence of organic and inorganiccontaminants, hinder their remediation using conventionalremediation technologies.

Electrokinetic remediation deserves particular attention to soiland sediment treatment due to its peculiar advantages, includingthe capability of treating fine and low-permeability materials, aswell as achieving consolidation, dewatering and removal of saltsand inorganic contaminants in a single stage [3]. A substantial list

* Corresponding author. Tel.: +34 986 812383; fax: +34 986 812380.

E-mail addresses: mcurras@uvigo.es (M. Pazos), olaiaic@uvigo.es (O. Iglesias),

josegomez@uvigo.es (J. Gomez), emiliorv@uvigo.es (E. Rosales),

sanroman@uvigo.es (M.A. Sanroman).

1226-086X/$ – see front matter � 2012 The Korean Society of Industrial and Engineer

http://dx.doi.org/10.1016/j.jiec.2012.11.010

of applications of electroremediation for the elimination of metalsand some undesirable inorganic anions such as fluoride exists inthe bibliography [3–7]. Also, in recent years several researchgroups have begun to analyze the application of this technology tosoils contaminated by organic compounds, such as polycyclicaromatic hydrocarbons (PAHs) and benzene, toluene, ethylben-zene, and xylenes (BTEX) [8–14], phenol [15], organochlorates[16], trichloroethelene and tetrachloroethane [17] and dyes [18].

Recently, the application of electrokinetic technology tomarine sediments is attracting interest from the scientificcommunity. De Gioannis et al. [19] carried the electrokinetictreatment of marine sediment however, negligible removal ofcationic contaminants due to precipitation phenomena as a resultof the high pH developed during the treatment. This concern hasbeen detected in other researches [20–22], who determined thatto improve the metal removal enhancement methods, such asdifferent conditioning solutions (HCl, HNO3, EDTA) or the use ofmembranes are necessary to improve the overall performance ofthe process. Thus, the use of these improvements sets free themetals from solid matrix favoring their removal. Neverthelesswhen organic pollutant, as PAHs, is present in the sediment poorremoval capacity was found even when a surfactant was used topromote the contaminant mobilization [23]. Thus, furtherinvestigations on organics removal from this type of solid matrixthrough electrokinetic technology are required.

To obtain high efficiency in the treatment of soil contaminatedwith organic compounds several techniques have been coupled toelectrokinetic remediation. Electrokinetic technology combined

ing Chemistry. Published by Elsevier B.V. All rights reserved.

Table 1Chemical characterization of collected sediment samples in terms of their heavy

metal and TPH content.

Parameters Sediment CEDEXa Limit AL1

Total organic carbon 1.70%

Moisture 46.59%

Electrical conductivity 12.40 mS/cm

pH 7.8

Carbonate <0.1 mg/kg

TPH 11,680 mg/kg

Fe 20,880 mg/kg

Zn 680.6 mg/kg 500 mg/kg

Cd <1 mg/kg 1.0 mg/kg

Pb 133.0 mg/kg 120 mg/kg

Cu 263.1 mg/kg 100 mg/kg

Ni 22.3 mg/kg 100 mg/kg

Cr 42.3 mg/kg 200 mg/kg

As 25.1 mg/kg 80 mg/kg

Hg 1.17 mg/kg 0.6 mg/kg

AL1: Action Level 1.a [31,32].

Table 2Particle size distribution of the dredge marine sediment.

Material Particle size (mm) Distribution (%)

Clay 0–0.062 47.24

Silt 0.062–0.5 42.44

Sand 0.5–2 3.17

Gravel >2 7.15

M. Pazos et al. / Journal of Industrial and Engineering Chemistry 19 (2013) 932–937 933

with ultrasound was suggested by Chung and Kamon [24]. Theyfound that the phenanthrene removal rate was increased in 5% forelectrokinetic coupling with ultrasound. Pham et al. [25] deter-mined that ultrasonic enhancement can increase from 2 to 9% thepollutant removal rate of a mixture of hexachlorobenzene,phenanthrene and fluoranthene.

Other alternative is the electrokinetic–Fenton (EK–Fenton). Theconjunction of electrokinetic treatment with Fenton’s reagentcould be an environmentally friendly option to degrade in situ

organic compounds [26]. In the Fenton’s reaction (1) the H2O2 isdecomposed by the catalytic action of Fe2+ in acid mediumgenerating hydroxyl radicals who are powerful oxidizing agentsand attack organic compounds.

Feþ2þ H2O2 ! Feþ3þ OH� þ OH� (1)

Under this hybrid technology, the electric field is used tomobilize the Fenton’s reagent through the soil and provides anappropriate environment for in situ degradation of organicpollutant [27]. In Fenton reactions inside the soil, organiccompound oxidation takes place by hydrogen peroxide and it iscatalyzed by iron minerals [28]. The hydroxyl radicals generated inthe Fenton reaction are strong and relatively unspecific oxidantsthat react with most organic contaminants by abstractinghydrogen atoms or by adding to double bonds [29]. Pazos et al.[30] studied the removal of diesel fuel from contaminated soilusing 10% H2O2 as processing fluid. Approximately 87% dieselremoval was achieved after 30 days of treatment. The authorsindicated that the homogeneous distribution of reagents, which isthe main drawback of the Fenton treatment, can be easily achievedwith electric field action.

It is known that the Fenton oxidation efficiency in aqueousphase increases in acidic pH. However, the pH of many soils can beoften near neutral or slightly alkaline and under this condition theFe2+ is easily oxidized to Fe3+. In the literature to distinguishbetween the Fe2+ and Fe3+ combinations, the term Fenton-likereagent is used for the Fe3+/H2O2 mixture while Fenton’s reagent isrestricted to denote the Fe2+/H2O2 mixture. Moreover, due to thesoil or sediment pH, it is noticed that the Fe2+ quickly precipitatesdisappearing from the aqueous phase. Therefore, chelating agents(such as EDTA) have been used to maintain soluble iron, employingFe3+ as catalytic specie in a Fenton-like process.

The aim of this work is to apply electrokinetic remediationtechnology to marine sediment contaminated by hydrocarbonsand metals taken from sampling campaigns in the North-west ofSpain. These sediments are characterized by a high content ofhydrocarbons (TPH) and metals such as Zn, Pb, Cu and Hg, withconcentration higher than the recommendation of CEDEX[31,32]. Furthermore, due to the existing industrial activitynear the ports, the Fe content in sediments is also high so thatthey are suitable samples for the Fenton’s treatment. Twodifferent approaches were used to improve the pollutantremoval. On the one hand, EDTA and Tween 80 were used asprocessing fluid to enhance the solubility of metals and TPH,respectively. On the other hand, a combination of a Fenton’sreagent and EDTA was used as processing fluid to promote the in

situ degradation of TPH and to solubilize the metals, at the sametime.

2. Materials and methods

2.1. Sediments

Sediment samples were collected from the North-west of Spain.The samples were sieved and the fraction containing particles ofsizes lower than 2 mm was selected. Sediment properties aredescribed in Table 1 and Table 2.

2.2. Electrokinetic cell

Electroremediation process behavior will be studied at labora-tory scale in electrokinetic cells developed for this purpose by ourresearch group (Fig. 1) [33]. The central tube was 100 mm in lengthand had a 32 mm internal diameter. Two electrode chambers, witha working volume of 0.3 L, were placed at each end of the samplecompartment and isolated from the solid sample by means of filterpaper and porous stones. Electrode chambers were filled with theprocessing fluid (Table 3), and a pump was connected to eachelectrode chamber to achieve a homogeneous mixing degree insidethe electrode chamber. The sediment sample was placed betweentwo electrodes, anode and cathode, through which an electric fieldwas applied. Auxiliary electrodes allowed measurement of theelectric field distribution along the sample at three different points.

A constant potential difference (3 V/cm) was applied by twographite electrodes with a power supply (HP model 6030A). For theacquisition of electrical parameters and electrodes pH over time,we had developed automatic data acquisition software called EK-Data (Fig. 1).

2.3. Analytical methods

At the beginning and at the end of each experiment, sampleswere taken from the cathode and anode solutions as well as fromthe solid matrix for chemical analysis. After the experiment, thesediment sample was divided in five sections (S1-S5, namely fromanode to cathode) and each one was analyzed for moisturecontent, pH and pollutant concentrations. All analytical determi-nations were done in duplicated and the showed results are themean values.

2.3.1. Total petroleum hydrocarbon (TPH) concentration

Total petroleum hydrocarbon (TPH) was determined followingthe EPA 9074 method. TPH was extracted with methanol from solidsample. The resulting mixture was allowed to settle and the freeliquid was decanted into the barrel of a filter-syringe assembly.

Fig. 1. Schematic of electrokinetic cell and EK-data acquisition system.

M. Pazos et al. / Journal of Industrial and Engineering Chemistry 19 (2013) 932–937934

This liquid was filtered through a 0.2-mm filter into a cuvettecontaining water. The filtered sample was allowed to develop for10 min. During the development, any hydrocarbons presentprecipitate out and become suspended in solution. The developedsample was measured spectrophotometrically (Unicam Helios b,Thermo Electron Corp.) based on the constructed calibrationcurves at absorption wavelength of 585 nm. The concentration oftotal recoverable petroleum hydrocarbons present was calculatedrelative to the standard curve realized with commercial diesel fuel.Duplicate measures were carried out with an experimental errorlower than 3%.

2.3.2. Heavy metal concentration

The protocols used for the chemical extraction and analysis ofmetals were performed in accordance with EPA Methods 3010 and3050. Inductively Coupled Plasma Optical Emission Spectrometry(ICP-OES) was used to analyze metals. Duplicate measures werecarried out with an experimental error lower than 3%.

2.3.3. Sediment pH, electrical conductivity, moisture content, TOC and

carbonate content

pH was determined adding 1 M KCl solution to dry sediment ina ratio 2.5 mL/g. After 1 h contact time, pH was reading using a pHmeter (Sentron model 1001).

The sediment electrical conductivity was measured addingdistilled water in ratio 2.5 mL/g dry sediment and the suspen-sion agitated for 30 min. After 20 min of repose period (20 min),conductivity was measured using a conductivimeter (CrisonBasic 30).

The moisture content of the sediment was calculated with theloss of weight of the sample after heating at 105 8C during 24 h.

Total organic carbon (TOC) was determine using dichromatemethod following Schumacher [34].

Carbonate content was determined by volumetric methodfollowing UNE 103200:1993 [35].

Table 3Experimental design and working conditions.

Exp. Time (d) Voltage

(V/cm)

Processing fluid in the

electrode chamber

1 15 3 Tween 80 3%

2 30 3 Tween 80 3%

3 15 3 10% H2O2 M EDTA

4 30 3 10% H2O2 M EDTA

2.3.4. Sediment acid buffering capacity

Buffering capacity is defined as the ability of solid matrix toresist changes in pH. The assays were performed based on theprocedure described by Reddy et al. [36]. Acid buffering capacity ofthe sludge was assayed by titration. A suspension of sludge samplein water (6.7%, w/v) was stirred for 30 min and the pH wasanalyzed. Successive 1 mL additions of HCl 1 M were made every30 min and pH was measured thereafter. This procedure wasrepeated until the pH value was constant. The obtained resultswere plotted as pH versus HCl added (mL). The results wereelucidated in qualitative form, comparing the profiles correspond-ing to sludge sample with those of kaolin, which is commonlyknown to have low acid buffering capacity.

3. Results and discussion

3.1. Sediment characterization

Initially, the chemical characterization of collected sedimentsamples, in terms of their heavy metal and TPH content wasrealized (Table 1). It is noticeable the high concentration of Fe, Zn,Pb, Cu and Hg. High concentration of these metals, may have apotential risk and, hence, remediation technique must beconsidered in order to use these dredged sediments to otherapplication. Furthermore, some of these metals are over the limitconcentration determined by the CEDEX [32] where the recom-mended metal concentration by the Spanish related agencies ondredged material management appears. On the other hand, the Fecontent (higher than 20,000 mg/kg) makes this sediment appro-priate to the Fenton’s reactions take place.

The acid buffering capacity of kaolin versus sediment sample isrepresented in Fig. 2. Opposite to the kaolin behavior, a slight pHchange in the suspension was detected in the sediment. The acidbuffering capacity of this sediment kept practically constant afterthe addition of 9 mL of HCl. Thus, it was demonstrated the high

pH Control (A: anode C: cathode)

A: Tris-Acetate–EDTA 0.1 M pH 8.5 C: Tris-Acetate–EDTA 0.1 M pH 8.5

A: Tris-Acetate–EDTA 0.1 M pH 8.5 C: Tris-Acetate–EDTA 0.1 M pH 8.5

A: 0.5 M NaOH pH 5 C: 0.5 M HNO3 pH 5

A: 0.5 M NaOH pH 5 C: 0.5 M HNO3 pH 5

Fig. 2. Comparing buffering capacity of the profiles corresponding to sediment (&)

with those of kaolin (*).

M. Pazos et al. / Journal of Industrial and Engineering Chemistry 19 (2013) 932–937 935

acid buffering capacity of this sediment, this fact can be attributedto the sediment chemical composition. This parameter has a greatinfluence on the remediation process, given desorption of metalpollutants from the sediment is favored at low pH. For this reasonin this sediment with high acid buffering capacity, the addition ofenhancing agents such as complexing agents, such as EDTA, isnecessary to improve the metal remediation, thus an electrokineticprocess can be developed in a basic environment.

In addition, the electrical conductivity value can be used toextract information on the behavior of the sediment under theelectric field action. In this study, the sediment has highconductivity (Table 1); therefore, it is expected a low electricalresistance which will favors the electrokinetic treatment.

3.2. Electrokinetic remediation

As well as the phenomena of transport electromigration,electro-osmosis and electrophoresis [37], reactions on the surfaceof the electrodes will take place. Among them, the most importantis the electrolysis of the water, which will give rise to the

Table 4Zn, Pb, Cu and Hg metal fraction distribution in the original sediment and that remedi

Metal Sampling location Initial concentration

(mg/kg)

Ex

(m

Zn S1 680.64 47

S2 680.64 53

S3 680.64 48

S4 680.64 45

S5 680.64 40

Pb S1 133.02 10

S2 133.02 10

S3 133.02 9

S4 133.02 8

S5 133.02 8

Cu S1 263.11 18

S2 263.11 21

S3 263.11 19

S4 263.11 16

S5 263.11 15

Hg S1 1.17

S2 1.17

S3 1.17

S4 1.17

S5 1.17

generation of H+ ions in the anode and OH� ions in the cathode. Inthis way, the sediment will become more acidic near the anode andmore basic near the cathode. In the case of metals, the increase ofpH can originate the precipitation of the metallic ions avoiding thecorrect functioning of the system. To solve this problem, we can actby means of electrode solutions, so-called processing fluid.Through these, it is possible to introduce in the sediment (bythe aforementioned mechanisms of transport) diverse chemicalreagents. Thus, a control of the pH in the chambers of theelectrodes and the addition of specific reagents (tensioactive,solvents, chelating agents, etc.) allow to generate within thesediment adequate conditions for the extraction or desorption ofthe pollutants so that they are transferred to the fluid phase andcan be transported by electro-osmosis or electromigration moreeffectively and maintaining the sediment in the desired pH value.

Several studies reported the need to have a basic medium insidethe soil to enhance the removal of pollutants by electro-osmoticflow when surfactants or cyclodextrin are used [30,38]. Therefore,in the present work pHs in the chambers were maintained to 8.5with the addition of Tris-acetate buffer solution (Table 3) and thedeveloped of the acid front was avoided.

In Table 4, the concentration distribution of polluting metalsobtained by electrokinetic treatment, using solubilizing agents,after 15 and 30 days are showed. It is known that a complexingagent such as EDTA increases the solubility of metal species,forming soluble complexes in a wide range of pHs [3]. As it isshown in Table 4 (Exp. 1 and 2), metals concentrations werereduced in all soil sections for both experiments and as it wasexpected the 30-day experiment achieved the highest metalremovals. The reached concentrations of metals were notuniform in the soil sections and according to Pazos et al. [3]the significant reduction of metal concentrations detected in thesections close to the cathode chamber were due to the metalsmigration to the anode chamber because under the operationalconditions, metals seem to form a negative complex with EDTA.This fact was verified during the treatment as the apparition ofdifferent colors in the anode chamber, which is typical ofcomplex formation [3] and after the experiment by measuringthe metal content in the anode chamber. Furthermore, thesediment pH was measured and it was determined basicconditions which favoring metal complexation. The total metals

ated by the different EK–Fenton experiments developed.

p. 1 15 d

g/kg)

Exp. 2 30 d

(mg/kg)

Exp. 3 15 d

(mg/kg)

Exp. 4 30 d

(mg/kg)

1.01 469.43 432.90 381.78

8.27 485.06 433.63 405.54

8.00 345.66 359.04 300.21

5.82 306.64 263.39 216.87

2.30 293.57 246.60 146.62

7.18 99.69 86.73 67.89

9.47 105.98 107.28 76.24

5.95 66.94 87.05 55.15

9.60 56.38 52.96 33.09

0.86 54.08 47.20 35.04

6.59 190.28 120.86 128.44

8.30 207.45 176.32 133.42

1.73 138.09 162.05 123.18

4.00 128.85 107.00 100.71

4.40 127.72 89.36 47.96

0.78 0.64 0.58 0.58

0.82 0.72 0.66 0.57

0.80 0.60 0.63 0.53

0.78 0.60 0.60 0.51

0.73 0.59 0.62 0.48

Fig. 3. Normalized concentration of polluting metals and TPH obtained by EK

treatment after 15 and 30 days.Fig. 4. Normalized concentration of polluting metals and TPH obtained by EK–

Fenton–EDTA treatment after 15 and 30 days.

M. Pazos et al. / Journal of Industrial and Engineering Chemistry 19 (2013) 932–937936

reduction, determined by differences between the total initialand final metals present in the sediment sample, was 28 and 42%after 15 and 30 days, respectively. As illustrated in Table 4, themetals Zn, Pb, Cu and Hg, which are over the limit concentrationdetermined by the CEDEX [32], migrated into the sediment tothe anode chamber. Considering the average concentration fromthe five sections removal efficiencies after 15 and 30 days were30.7% and 44.1% of Zn, 27.3% and 42.9% of Pb, 30.4% and 39.7% ofCu, 33.7% and 46.1% of Hg, respectively.

In Fig. 3, the normalized concentrations of TPH obtained byelectrokinetic treatment, using solubilizing agents, after 15 and 30days are showed. The presence of Tween 80 in the processing fluidsolubilized the TPH, and they were mobilized by electro-osmoticflow (around 5 mL/d) and collected in cathode chamber. Amaximum TPH remediation (31%) was obtained after 30 days.

Our results are in accordance with those reported in theliterature. Kim et al. [39] found that during the electrokinetictechnique removal efficiencies of metals were significantlydependent on their speciation in the sludge matrices. In additionColaccio et al. [23] found the main drawback using solubilizingagents for sediment polluted with metals and organic compoundsis the poor removal capacity of organic compound even when asurfactant Tween 80 was used.

3.3. EK–Fenton–EDTA remediation

This study was an attempt to develop a technology todecontaminate organics and inorganics in dredged sedimentsusing electrokinetic remediation coupled with Fenton’s reactionand solubilizing agents. It is evident that the presence of specificcompounds and the solid matrix have a great influence in theremoval efficiency during the EK–Fenton process. For this reason,in some cases, several compounds can be added to the EK–Fentonprocess to enhance the Fenton’s reaction. Kim et al. [40] utilized7% H2O2 and 0.01 N H2SO4 in the anode chamber in the EK–Fenton treatment of kaolin polluted with phenanthrene. On theother hand, the effectiveness of the EK–Fenton technique to treatsoils contaminated with PAHs has been proved by Alcantara et al.[12]. They found that when anode and cathode chambers werefilled with H2O2 (10%) the overall removal and a destructionefficiency of phenanthrene of 99% were obtained in 14 days.Reddy and Karri [41] performed experiments to determine theinfluence of the oxidant dosage in the EK–Fenton treatment ofkaolin spiked with nickel and phenanthrene. The results obtainedin these studies emphasize that the optimization of H2O2/Feconcentration and voltage gradient as well as the control of soilpH are required to increase the removal of heavy metal and theoxidation of organic compounds.

In accordance with these previous papers, in this study the EK–Fenton was employed to remediate the TPH present in thesediment and EDTA was added as solubilizing agent to improve theheavy metal removal. In this sediment the high iron concentrationshown in Table 1, permits to develop the Fenton’s process byaddition from anode and cathode chambers of H2O2. Valentine andWang [42] determined that the Fenton’s reaction is only effectiveat low pH values. For this reason, pH control at 5 on the electrodeschambers was proposed as necessary in order to achieve effectiveremoval (Table 3).

In Fig. 4, the normalized concentrations of TPH obtained byelectrokinetic treatments, using EDTA and H2O2 as processingfluid, are presented. Around 90% of TPH removal was achieved after15 days of treatment. Similar profile of TPH removal was detectedfor 30 days treatment; meaning that the main TPH removal wasobtained in the first days. The electric field expended to removeTPH was 0.45 kWh/gTPH, however must be to take into accountthat part of this electricity was used to remove metals too.

Control pH had an insignificant influence in soil pH and afterexperiments the pH in the soil was kept in basic values, between 8and 10. This fact confirms the high acid buffering capacity detectedin the sample characterization. Although the pH profile in thesediment was higher to the optimum determined to Fenton’sreagent it is hypothesized that the presence of EDTA favored theiron solubilization. This fact is in accordance to that reported byVicente et al. [43] who determined that the presence of chelatingagents, as EDTA, improves the Fenton’s treatment because theseagents stabilize the hydrogen peroxide, enhance desorption of theentrapped pollutant and solubilize part of the iron from the soil.Hence, it can be stated that TPH removal was associated with thepollutant in situ degradation during the action of Fenton’s reagentformed inside the sediment.

As it was determined in the previous experiments EDTAfavored the metals removal and their movement towards theanode chamber (Table 4). The reduction of concentration in theExp. 3 and 4 were slightly higher than previous experiments inwhich only solubilizing agents were used. Considering theconcentration of the metals showed in Table 4, the removalefficiencies after 15 and 30 days were 48.9% and 57.3% of Zn, 42.6%and 59.8% of Pb, 50.1% and 59.4% of Cu, 47.24% and 54.5% of Hg,respectively. Although not all sections of soil reached aconcentration below CEDEX legislation, for all metals a significantmetal reduction was obtained in all sections. After Exp. 4 themaximum global metal removal of 59% was obtained.

Therefore, these results showed that EK–Fenton–EDTA reme-diation is an adequate technology to treat sediments polluted byheavy metal and TPH, although treatment time higher than onemonth is necessary.

M. Pazos et al. / Journal of Industrial and Engineering Chemistry 19 (2013) 932–937 937

4. Conclusions

The showed results point out the relevance as well as thenovelty of the technology used. Between the two proposedalternatives for dredged sediments, EK with solubilizing agentsand EK–Fenton–EDTA, this last one obtained the highest removalfor metals and TPH. The performance of EK–Fenton–EDTAremediation is described by:

- EDTA increases the solubility of metal species, forming solublecomplexes in a wide range of pHs.

- The presence of iron and EDTA in sediments and the addition ofH2O2 permits that the Fenton’s reactions take place and TPH aredegraded in situ.

- The reduction of TPH in sediment favors the mobilization ofmetallic species.

The results obtained in this study, indicate the suitability of EK–Fenton–EDTA remediation in sediments with high content in ironand contaminated by petroleum hydrocarbon (TPH) and metals.

Acknowledgements

This work was supported by Spanish Ministry of Science andInnovation (National R&D&I Plan) and European FEDER by ProjectIPT-310000-2010-17 and Project CTM2011-26423. The authors aregrateful to Spanish Ministry of Science and Innovation for financialsupport of Marta Pazos under the Ramon y Cajal programme.

References

[1] R. Boutin, Amelioration des connaissances sur le comportement des rejets en merdes produits de dragage type vase: phenomenes court terme champ proche(improvement of knowledge about the outputs of dredging products as mud insea: phenomena short term–close field), Lyon, France, 1999.

[2] V. Dubois, N.E. Abriak, R. Zentar, G. Ballivy, Waste Management 29 (2009) 774–782.[3] M. Pazos, M.T. Alcantara, C. Cameselle, M.A. Sanroman, Separation Science and

Technology 44 (2009) 2304–2321.[4] S. Pamukcu, Electronic Journal of Geotechnical Engineering (Online) 2 (1997)

Available from Web Wide Web: http://www.ejge.com/1997/Ppr9704/Abs9704.htm.

[5] T. Vengris, R. Binkien, A. Sveikauskait, Journal of Chemical Technology andBiotechnology 76 (2001) 1165–1170.

[6] A.Z. Al-Hamdan, K.R. Reddy, Chemosphere 71 (2008) 860–871.[7] D. Kim, B. Ryu, S. Park, C. Seo, K. Baek, Journal of Hazardous Materials 165 (2009)

501–505.[8] R.E. Saichek, K.R. Reddy, Environmental Technology 24 (2003) 503–515.[9] R.E. Saichek, K.R. Reddy, Chemosphere 51 (2003) 273–287.

[10] K. Maturi, K.R. Reddy, Chemosphere 63 (2006) 1022–1031.[11] T. Alcantara, M. Pazos, C. Cameselle, M.A. Sanroman, Environmental Geochemis-

try and Health 30 (2008) 89–94.

[12] T. Alcantara, M. Pazos, S. Gouveia, C. Cameselle, M.A. Sanroman, Journal ofEnvironmental Science and Health, Part A. Toxic/Hazardous Substances andEnvironmental Engineering 43 (2008) 901–906.

[13] J. Gomez, M.T. Alcantara, M. Pazos, M.A. Sanroman, Chemosphere 74 (2009)1516–1521.

[14] M. Pazos, E. Rosales, T. Alcantara, J. Gomez, M.A. Sanroman, Journal of HazardousMaterials 177 (2010) 1–11.

[15] S. Kim, S. Moon, K. Kim, Environmental Technology 21 (2000) 417–426.[16] D. Rahner, G. Ludwig, J. Rohrs, Electrochimica Acta 47 (2002) 1395–1403.[17] G.C.C. Yang, C. Liu, Journal of Hazardous Materials 85 (2001) 317–331.[18] M. Pazos, C. Cameselle, M.A. Sanroman, Environmental Engineering Science 25

(2008) 419–428.[19] G. De Gioannis, A. Muntoni, A. Polettini, R. Pomi, Journal of Environmental Science

and Health, Part A. Toxic/Hazardous Substances and Environmental Engineering43 (2008) 852–865.

[20] G.M. Nystrøm, L.M. Ottosen, A. Villumsen, Engineering Geology 77 (2005) 349–357.

[21] G.M. Kirkelund, L.M. Ottosen, A. Villumsen, Chemosphere 79 (2010) 997–1002.[22] K. Kim, D. Kim, J. Yoo, K. Baek, Separation and Purification Technology 79 (2011)

164–169.[23] A. Colacicco, G. De Gioannis, A. Muntoni, E. Pettinao, A. Polettini, R. Pomi,

Chemosphere 81 (2010) 46–56.[24] H.I. Chung, M. Kamon, Proceedings of the International Offshore and Polar

Engineering Conference 2005 (2005) 652–657.[25] T.D. Pham, R.A. Shrestha, J. Virkutyte, M. Sillanpaa, Electrochimica Acta 54 (2009)

1403–1407.[26] G.C.C. Yang, Y. Long, Journal of Hazardous Materials 69 (1999) 259–271.[27] P. Isosaari, R. Piskonen, P. Ojala, S. Voipio, K. Eilola, E. Lehmus, M. Itavaara, Journal

of Hazardous Materials 144 (2007) 538–548.[28] A. Romero, A. Santos, F. Vicente, Journal of Hazardous Materials 162 (2009) 785–

790.[29] J.J. Pignatello, E. Oliveros, A. MacKay, Critical Reviews in Environmental Science

and Technology 36 (2006) 1–84.[30] M. Pazos, M.T. Alcantara, E. Rosales, M.A. Sanroman, Chemical Engineering and

Technology 34 (2011) 2077–2082.[31] M.C. Casado-Martınez, J.L. Buceta, M.J. Belzunce, T.A. DelValls, Environment

International 32 (2006) 388–396.[32] Centro de Estudios y Experimentacion de Obras Publicas CEDEX (Ed.), Recomen-

daciones para la gestion del material de dragado en los puertos Espanoles, Puertosdel Estado, Spain, 1994.

[33] M.G. Nogueira, M. Pazos, M.A. Sanroman, C. Cameselle, Electrochimica Acta 52(2007) 3349–3354.

[34] B.A. Schumacher (Ed.), Methods for the Determination of Total Organic Carbon(TOC) in Soils and Sediments NCEA-C-1282, Ecological Risk Assessment SupportCenter, Office of Research and Development. US Environmental Protection Agen-cy, 2002.

[35] AEN/CTN 103: 98, UNE 103200:1993 (1993).[36] K.R. Reddy, M. Donahue, R.E. Saichek, R. Sasaoka, Journal of the Air and Waste

Management Association 49 (1999) 823–830.[37] Y.B. Acar, A.N. Alshawabkeh, Environmental Science and Technology 27 (1993)

2638–2647.[38] T. Li, S. Yuan, J. Wan, L. Lin, H. Long, X. Wu, X. Lu, Chemosphere 76 (2009) 1226–

1232.[39] S. Kim, S. Moon, K. Kim, S. Yun, Water Research 36 (2002) 4765–4774.[40] S. Kim, J. Kim, S. Han, Journal of Hazardous Materials 118 (2005) 121–131.[41] K.R. Reddy, M.R. Karri, Journal of Environmental Science and Health, Part A. Toxic/

Hazardous Substances and Environmental Engineering 43 (2008) 881–893.[42] R.L. Valentine, H.C. Ann Wang, Journal of Environment Engineering 124 (1998)

31–38.[43] F. Vicente, J.M. Rosas, A. Santos, A. Romero, Chemical Engineering Journal 172

(2011) 689–697.