Comparison of mineral-based amendments for ex-situ stabilization of trace elements (As, Cd, Cu, Mo, Ni, Zn) in marine dredged sediments: A pilot-scale experiment

Journal of Hazardous Materials 252–253 (2013) 213–219

Contents lists available at SciVerse ScienceDirect

Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat

Comparison of mineral-based amendments for ex-situ stabilization of trace elements (As, Cd, Cu, Mo, Ni, Zn) in marine dredged sediments: A pilot-scale experiment Yannick Mamindy-Pajany a,∗ , Charlotte Hurel a , Florence Geret b , Michèle Roméo a , Nicolas Marmier a a b

University of Nice Sophia Antipolis, ECOMERS, Nice, France University Center Jean-Franc¸ois Champollion, GEODE, Albi, France

h i g h l i g h t s

g r a p h i c a l

a b s t r a c t

• A pilot experiment was conducted to • • • •

study metal stabilization in marine sediments. Hematite, zero-valent iron and zeolite were used as mineral amendments. Hematite and zero-valent iron allowed reducing the leaching of metals by 50%. Zeolite as powder or millimetric particles was unsuitable to stabilize metals. Hematite and zero-valent iron decreased the toxicity of polluted marine sediments.

a r t i c l e

i n f o

Article history: Received 8 December 2012 Received in revised form 26 February 2013 Accepted 1 March 2013 Available online 14 March 2013 Keywords: Chemical stabilization Trace elements Marine sediment Mineral-based amendments Pilot-scale experiment

a b s t r a c t Trace element pollution of marine dredged sediments is an emerging problem all over the world. Comparing to other wastes, trace elements stabilization is more difficult both due to the wide range of contaminants present in the marine sediments and their inherent physicochemical properties. In this study, a pilot-scale experiment was performed to stabilize As, Cd, Cu, Mo, Ni, and Zn in a multi-contaminated sediment sample using hematite, zero-valent iron and zeolite. Results showed that iron-based amendments were able to reduce the leaching and the bioavailability of trace elements in the sediment sample, while zeolite was unsuitable. Chemical stabilization through iron-based amendments seems to be a promising approach as a low-cost alternative to traditional stabilization methods involving chemical reagents. © 2013 Elsevier B.V. All rights reserved.

1. Introduction

∗ Corresponding author at: University of Nice Sophia Antipolis, ECOMERS, Faculty of Sciences, Parc Valrose, 06108 Nice Cedex 02, France. Tel.: +33 0 4 92 07 63 70; fax: +33 0 4 92 07 63 64. E-mail address: [email protected] (Y. Mamindy-Pajany). 0304-3894/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jhazmat.2013.03.001

Large volumes of sediments are dredged worldwide to prevent excessive marine pollution and maintain the depth of navigation waterways, harbours and estuaries. In France, 50 million m3 of sediments are dredged each year from the major maritime ports. The management of these dredged sediments is a priority issue

214

Y. Mamindy-Pajany et al. / Journal of Hazardous Materials 252–253 (2013) 213–219

in the Mediterranean Sea where sediments are contaminated by trace elements such as As, Cd, Cu, Ni and Zn [1,2]. Marine sediment quality in France is defined by the national decree of 14th of June 2000 which proposed guideline values for each trace element (sediment quality guidelines, also called N1 and N2 levels in France) [3]. According to this decree, if the contamination level is below N1 threshold, the sediment is considered as uncontaminated. If the contaminant concentrations are between N1 and N2 thresholds, the sediment is classified as contaminated and its associated ecological impacts must be assessed. If at least one contaminant is higher than N2 threshold, the sediment is considered as highly contaminated with potential ecological impacts on the aquatic environment. Ifremer and the Geode inter-ministerial group have developed the Geodrisk software that facilitates the assessment of ecological risks of dredged sediments, on the basis of chemical analysis results recommended by the national decree above mentioned. This software tool enables to differentiate dredged sediments according to their contamination level and their potential and measured toxicity, thus providing a decision support tool to managers [3]. Uncontaminated sediments are usually dumped back to sea whereas the polluted sediments (contamination level between N1 and N2 threshold) are usually managed in shore; hence the issue of the management of polluted sediments on land. The Var Department (French Public Administration) has conducted the “SEDIMARD” project to evaluate the different possible issues for the management of contaminated dredged sediments [4]. In this project, several pre-treatments and treatments methods were tested at a pilot site located near Toulon (France) using approximately 2000 m3 of dredged sediments. Two main stabilization methods were tested: i) the Novosol process (Solvay) using phosphoric acid, and ii) the lime treatment applying CaO. The pilot project demonstrated that both techniques were able to stabilize most of the cationic pollutants i.e. Cd, Cu, Ni, and Zn while promoting the mobility of anionic species such as As, Mo and Cr(VI). In addition, since marine sediments physicochemical properties (such as high carbonate content, basic pH, salinity, etc.) difficult trace element stabilization processes compared to most other wastes, it is urgent to develop economically feasible remediation methods which enable contaminated sediments stabilization for in land safe storage. Chemical stabilization through mineral-based amendments has been reported as an insitu treatment for contaminated soils [5–9] and, more recently, for polluted sediments [10–14]. Among the various tested amendments, iron-bearing materials (e.g. zero-valent-iron, goethite, hematite, and ferrihydrite) have shown satisfactory performances to reduce trace elements mobility in multiple element contaminated soils [11,15–17]. Other adsorbents such as alumino-silicates (clays, zeolites) were also efficient to stabilize metals in polluted soils and sediments [15,17,18]. The present work aimed at evaluating the application of mineral amendments to stabilize trace elements in marine dredged sediments as a way to solve problems associated with traditional ex-situ stabilization technologies. This technique involves the introduction of mineral adsorbents in order to increase trace element binding, and reduce metal mobility in the environment. It was previously demonstrated that addition of hematite, zero-valent iron and zeolite to marine composted sediments reduced the availability of pollutants and sediment toxicity towards several living organisms [19,20]. To upscale the technique from the laboratory to field application, a pilot experiment was designed, based on previous laboratory experiments [19–22], to assess the effect of hematite, zero-valent iron and zeolite on trace elements (As, Cd, Cu, Mo, Ni, and Zn) mobility in a marine sediment sample subjected to humidification cycles (draining and mixing as in large-scale) [3].

2. Materials and methods 2.1. Sediment and mineral-based amendments properties The dredged sediment sample was provided by the French public administration from the Var in the framework of the SEDIMARD project [4]. It was dredged in a French navy harbour (Toulon, SouthEast of France) using a Shipek grab and stored on land for one month (from 05/10/2008 to 06/11/2008) prior to pilot experiment. The main properties of the sediment sample are shown in Table 1. The water content (%) was determined after gravimetric assessment by drying the sediment samples in replicates of three at 105 ◦ C for 24 h. The sediment texture was determined by measuring particle size distribution using a Mastersizer laser granulometer (Malvern Instruments). Sediment characteristics were determined at the “Laboratoire de l’Environnement de Nice” (Nice, France) using analytical methods defined by the International Organization for Standardization (ISO): sediment pH was measured in water at 1:5 solid: liquid ratio using a KCl combined electrode and total organic carbon was measured with a total carbon analyser (Shimadzu TOC 5000A). The acid digestion of the sediment was carried out, on sieved and homogenized samples, in Teflon reactors prior to determination of inorganic pollutant concentrations. In order to evaluate method accuracy it was performed the digestion of a Certified Reference Material (CRM) (marine sediment IAEA-433 from International Atomic Energy Agency) using an analogous protocol as described below. Before digestion, all vessels were previously washed with nitric acid (HNO3 , 10%) solution and rinsed with 18 M UPW. Firstly, 100 mg of sediment was oxidized by 1 mL H2 O2 (30%) at room temperature in order to remove particulate organic matter. Then, the sediment samples were digested in 0.3 mL of HNO3 (65%) and heated to 100 ◦ C in a heating bath. Before complete dryness, 0.5 mL HNO3 was added with 0.5 mL of hydrofluoric acid (HF, 40%). The last digestion step was performed mixing 0.5 mL of HNO3 with 0.5 mL of HF until the mixture evaporated to dryness. The resulting residue was leached with 0.25 mL of HNO3 and diluted to 50 mL with ultrapure water (MilliQ, Millipore). All reagents used in the digestion procedure were of ultrapure grade. The mineralogical analyses were run on a Philips PW 1710 Xray diffractometer. Clay mineralogy was determined on previously acidified (0.2N HCl) samples, then repeatedly washed (with water) and centrifuged to remove acid excess. Lastly the clay-size fraction (< 2 ␮m) was isolated through settling and oriented on glass slides [23]. Three X-ray diffraction (XRD) determinations were performed on: (a) untreated sample; (b) glycolated sample (after saturation for 12 hours in ethylene glycol); (c) sample heated at 490 ◦ C for 2 h. Each clay mineral was characterized by its layer plus interlayer interval. Hematite, zero-valent iron, and zeolite (as powder and millimetric particles) were used as amendments and their physicochemical properties are reported in Table 2. Table 1 Main physicochemical properties of sediment sample. Sediment characteristics Initial pH–H2 O (1:5 solid:liquid) Initial water content (%) Organic matter (g/kg dry matter) Particle size fraction <2 ␮m(%) 2–63 ␮m(%) >63–2000 ␮m (%) Mineralogical major phases (XRD) Quartz (Si Quartz (SiO2 ), Calcite (CaCO3 ), Feldspar, Illite, Kaolinite, Smectite (in fraction < 2 ␮m)

8.7 ± 0.2 57.3 ± 0.4 103 ± 4 2.03 36.27 61.70

Y. Mamindy-Pajany et al. / Journal of Hazardous Materials 252–253 (2013) 213–219

215

Table 2 Physicochemical characteristics of mineral-based amendments. Amendments

Manufacturer

Material density (g/cm3 )

Particle size (␮m)

Specific surface area (m2 /g)

Composition

Hematite (H) Zero-valent iron (ZVI) Coarse zeolite (CZ) Fine zeolite (FZ)

Alfa Aesar Sigma Aldrich Zeochem (France) Zeochem (France)

5.1 7.3 1.2 0.8

0.2–4 2–120 200–500 0.2–45

8.4 0.2 4 23

99.5% Fe2 O3 99.9% Fe 84% clinoptilolite 8% cristobalite 4% feldspar, 4% illite

The particle size of mineral-based amendments was measured using a laser granulometer (Mastersizer 2000, Malvern Instruments). The specific surface area of the mineral amendments was measured by N2 adsorption onto minerals using BET method with a Coulter SA 3100 apparatus. After degassing under vacuum at 60 ◦ C, the amount of adsorbed N2 was determined at constant temperature (77 K). The density of mineral particles and their chemical composition were provided by the manufacturer (Table 2). 2.2. Pilot experiment The pilot experiment was conducted in Nice, on the French Riviera (Mediterranean climate) on summer during three months (from June to August). The pilot experiment consisted of six vats (40x40x20 cm), each containing 6 kg of sediment (d.w. equivalent), and arranged as shown in Fig. 1. A square plastic mesh was placed at the bottom to allow leachates collection under each box. The inner surfaces of the vats were covered with geotextile to limit the loss of fine particles. Six treatments were prepared: 1) untreated sediment, 2) Sediment + 5% hematite, 3) Sediment + 15% hematite, 4) Sediment + 5% fine zeolite, 5) Sediment + 5% coarse zeolite, and 6) Sediment + 5% zero-valent-iron. Amendment concentrations were selected based on preliminary laboratory experiments [20,21]. All sediment samples were then subjected to humidification cycles (draining and mixing as in large-scale) during 3 months to monitor trace elements leaching. The successive sediments leaching with water is a pre-treatment widely used to manage dredged sediments since it promotes salts leaching and organic pollutants degradation. In addition, the field study on the same marine sediment demonstrated that this pre-treatment method resulted in a

positive change of the redox potential (Eh) due to sulphide oxidation reactions [24]. The pre-treatment method (the liquid to solid ratio and its duration) was optimized in a field study prior to this pilot experiment [4]. Two litres of water were needed to pre-treat a mass of 6 kg of dry sediment and its duration period was fixed at 3 months. This water amount was added to sediment samples as follows: 1) 1 L of tap water was sprayed homogeneously, 2) sediment samples were manually aerated using a garden shovel, and 3) 1 L of water was added on sediment samples. Then, leachates were allowed to drain through the sediment samples during 1 h and then collected in plastic containers placed under each box. This draining and mixing procedure was weekly repeated during 3 months. Leachates were filtrated through a 0.45 ␮m cellulose acetate membrane and acidified at 2% (v/v) with HNO3 (65%) before chemical analysis. Several physicochemical parameters were monitored in sediment leachates such as pH, conductivity, and dissolved trace element concentrations (As, Cd, Cu, Mo, Ni, and Zn). 2.3. Physicochemical analyses Electric conductivity of the leachates was measured using a CRISON CM35 conductimeter previously calibrated with a NIST standard solution at 12 mS/cm. The pH of leachates was monitored by a WTW pH metre, with a combined pH electrode, calibrated using buffer solutions at pH 7.01 and 4.00 at room temperature. As, Cd, Cu, Mo, Ni, and Zn concentrations were measured in leachates and digested sediment using ICP-MS (inductively coupled plasma mass spectrometer) (ELAN DRC II Perkin Elmer). The limits of detection were 0.01 ␮g/L for As and Cd; 0.31 ␮g/L for Cu, Mo and Ni; and 1.08 ␮g/L for Zn. Calibration solutions were prepared by the dilution of a certified multi-elemental solution (10,000 ␮g/L). 2.4. Microtox solid phase test

Fig. 1. The experimental design consisted of six vats, each containing 6 kg of sediment (d.w. equivalent). Box 1: control sediment (without amendment), boxes 2 and 3: sediment samples mixed with hematite at 5 and 15%, box 4: sediment mixed with zero-valent iron and boxes 5 and 6: sediment mixed with 5% of fine and coarse zeolite.

The microtox solid phase test (MSPT) was performed on all sediment samples after the pilot experiment. The MSPT is an acute toxicity test applied to solid matrices based on the natural bioluminescence inhibition of marine bacteria, Vibrio fischeri. The test was performed using the Azur Environmental standard protocol [20]. A quantity of dried sediment (10.0 g) was re-suspended in 100 ml of diluent solution (2% NaCl) by magnetic stirring at 1000 rpm for 10 min. Sub-samples were serially diluted (1.5 mL, three replicates) and equilibrated for 10 min in a thermostatic bath at 15 ◦ C, then all samples were added with 20 ␮L of reconstituted bacteria, gently mixed with a pipet and left in the thermostatic bath to incubate at the same temperature for 20 min. The bacteria were then separated by filtration and a 500 ␮L subsample of the liquid phase was transferred into the glass cuvettes in the Microtox analyzer and allowed to equilibrate for 15 min before bioluminescence acquisition and data record using Microtox Omni software Version 1.18. Effective concentration required to induce toxic effect on 50% of the population (EC50 ) was determined for each sediment samples. Moreover, toxicity data was ranked using a French classification based on the EC50 values (expressed in g/L) [3]. Following the quality of sediments, four toxicity scores (0–3) are established:

216

Y. Mamindy-Pajany et al. / Journal of Hazardous Materials 252–253 (2013) 213–219

Table 3 Trace element concentrations measured in the sediment and certified marine sediment (IAEA-433). French sediment quality guidelines also called N1 and N2 levels are reported for As, Cd, Cu, Ni and Zn.

As Cd Cu Mo Ni Zn

IAEA-433

Sediment sample

Regulatory levels

Certified values (mg/kg)

Mean Concentration (mg/kg)

Coefficient of variation (%)

Mean Concentration (mg/kg)

Coefficient of variation (%)

N1 (mg/kg)

N2 (mg/kg)

18.9 ± 0.15 ± 30.8 ± – 39.4 ± 101 ±

16.9 ± 0.18 ± 30.8 ± – 38.6 ± 94 ±

4.7 2.9 7.1 – 6.8 5.3

128 ± 3 1.64 ± 0.07 1582 ± 69 13.20 ± 0.09 34.75 ± 0.33 1723 ± 48

2.1 4.2 4.4 0.7 1.0 2.8

25 1.2 45 – 37 276

50 2.4 90 – 74 552

1.8 0.03 2.6 3.1 8

0.8 0.01 2.2 2.7 5

insignificant (EC50 > 10, score 0), low (0.5 < EC50 < 10, score 1), moderate (0.2 < EC50 < 0.5, score 2) and high (EC50 < 0.2, score 3). One way ANOVA was used in the analysis of toxicity data to assess statistical differences in toxicity level among the sediments. When ANOVA was significant, post-hoc comparisons between samples were made using the Fisher’s test to determine which values significantly differed. 3. Results and discussion 3.1. Chemical analyses of fresh dredged sediment Total As, Cd, Cu, Mo, Ni and Zn concentrations in sediment and the reference material were reported in Table 3. Trace element concentrations in the certified material were in agreement with the reference values since the values of variation coefficient ranged from 3 to 7%. As, Cu, and Zn concentrations in the whole sediment were 2.5, 18 and 1200 times greater than the N2 levels, respectively. The concentration of Cd was below its specific N2 level and Ni concentration was inferior to its N1 level. No reference level was defined for Mo (Table 3). Chemical analysis showed that the sediment sample was mainly contaminated by As and other trace elements, due to its location in a ship chandler zone [25]. The Geodrisk software analysis indicated a risk score higher than 2, and according to the current French legislation it could not be dumped back into the sea and needed in shore remediation [3]. 3.2. Trace elements stabilization The pH values decreased from 7.8 to 7 during the three first weeks; then it stabilized at a value of 7.6 until the end of the experiment for all the leachates (Fig. 2). The initial decrease of the pH value was possibly due to oxidation during the first leaching events, as observed in previous works on dredged sediments [26,27]. Subsequent rise of pH values were likely due to the inherent sediment buffering capacity, related to their high carbonate content, as previously reported [21].

The conductivity value was equivalent to the one measured in seawater i.e. 56 mS/cm during the first weeks of treatment and then it stabilized at 5 mS/cm after 8 weeks in all the leachates. Therefore, repeated leaching allowed a rapid decrease of the conductivity until an acceptable value for a land management (Fig. 2). The presence of mineral-based amendments in sediment samples did not seem to affect the pH and conductivity values, suggesting that sediment properties (pH and salinity) play an important role on the binding capacities of mineral amendments towards trace elements. The cumulative amounts of trace element released per kg of sediment as a function of time are shown in Fig. 3. The trace element leaching was higher in the first three weeks for all treated samples indicating that the ecological risk mainly occurred at short term after the sediment deposit. A similar trend was also observed in a field study on terrestrial deposit of fluvial dredged sediment submitted to atmospheric conditions [28]. Trace element leaching rates (calculated over total concentrations) in the control sample during the first 3 months was: Mo (5.3%), Cd (1.5%), Ni (0.3%), Zn (0.08%), As (0.07%), Cu (0.03%). Leaching rates were not in agreement with the sediment contamination since the higher leaching percentages were observed for the less concentrated pollutants (Mo and Cd). Possibly, the high chloride content of marine sediments could promote chloride complex formation and decreased the adsorption of cadmium on sediment, thereby increasing cadmium mobility [29]. In a study of Mo-contaminated sediment wetlands it was reported that Mo was transformed into water soluble forms after air-drying [30]. This phenomenon may be important for sediment pre-treatment since this technique could lead to potentially large amounts of Mo in leaching waters from land disposed dredged sediment. Mineral amendments altered trace element mobility in all treatments (Fig. 3). Coarse zeolite (CZ) treatment reduced the cumulative amount of trace elements in leachates as compared to control sediment (Fig. 3), with the following rates: Cd (20%), Cu (19%), Zn (7%), Ni (5%). Differently, the fine zeolite (FZ) treatment enhanced the release of trace elements in leachates (Fig. 3). The fine zeolite (FZ) was not efficient to stabilize trace elements in marine sediments at the following rates: Cu (4%), Zn (16%), As (21%), Mo (26%), Ni (50%), Cd (54%). Reactivity of CZ could be attributed to

Electrical Conductivity mS cm -1

80

8 Control 5% hematite 15% hematite zero valent iron fine zeolite coarse zeolite

60 40 20 0

pH

Pollutants

7

6

0

2

4

6

8

10 12 14 16

Weeks

0

2

4

6

8

10 12 14 16

Weeks

Fig. 2. Electrical conductivity and pH values in leachates from control sample and stabilized sediments as a function of time.

Y. Mamindy-Pajany et al. / Journal of Hazardous Materials 252–253 (2013) 213–219

control 15 % hematite fine zeolite

5 % hematite zero valent iron coarse zeolite 50 40

90

Cd µg kg-1

As µg kg-1

120

60 30

30 20 10

0

0

0

2

4

6

8

10

12

14

16

0

2

4

6

Wee ks

8

10

12

14

16

10

12

14

16

10

12

14

16

Wee ks

500

1000

400

800

Mo µg kg-1

Cu µg kg-1

217

300 200

600 400 200

100 0

0 0

2

4

6

8

10

12

14

16

0

2

4

6

Wee ks

8

Wee ks

200 1600

Zn µg kg-1

Ni µg kg-1

160 120 80

1200 800 400

40

0

0 0

2

4

6

8

10

12

14

16

Wee ks

0

2

4

6

8

Wee ks

Fig. 3. Amounts of metals released in leachates from control sample and stabilized sediments as a function of time.

its specific surface area (4 m2 /g) whereas the increase of trace element in leachates after FZ treatment could be explained by their transport in solid phase associated to the fine zeolite particles (< 0.45 ␮m) during successive leaching events, due to their density (0.8 g/cm3 ) lower than water density [31,32]. Hematite at 5% amendment rate stabilized the trace elements at the following rates over total concentrations: Zn (35%), As (37%), Cu (41%), Ni (50%), Cd (56%), Mo (72%). Hematite at 15% amendment rate stabilized the trace elements at the following rates over total concentrations: Ni (12%), As (15%), Cd (24%), Cu (32%), Zn (48%), Mo (82%). If we compare the stabilization in sediment samples treated with 5% of hematite and 15% of hematite, it appeared that the stabilization rate was lower when the sample was treated with 15% of hematite, except for the most mobile elements i.e. Mo and Zn. The stabilization of trace element in sediments treated with hematite is due to complexation reactions onto hematite surface sites [33]. Because of its physicochemical properties (point of zero charge, surface charge density, high specific surface area) [34–37], hematite is able to trap anionic and cationic contaminants in circum-neutral pH range [38]. The zero-valent iron (ZVI) treatment stabilized the trace elements at the following rates over total concentrations: Mo (62%), Cd (59%), Zn (44%), Cu (30%), Ni (22%), As (19%) (Fig. 3). Results demonstrated that ZVI could be used to stabilize cationic and anionic trace elements in the marine sediment to different extents, due to their

specific surface area (0.2 m2 /g) and likely decreased both the reaction rate and the fraction of Fe available for the reaction within the sediment particles. The reactivity of ZVI was mainly explained by the reactivity of iron corrosion products. When ZVI was added to the soil, it could be oxidized to form amorphous/poorly crystalline Fe oxides according to the following equations: Fe0 + 2H2 O + O2 → Fe2+ + 4OH− Fe2+ + 2H2 O + O2 → Fe3+ + 4OH− Fe3+ + 2H2 O → FeOOH + 3H+ The use of ZVI has proved to be a potentially effective treatment to decrease the mobility of various trace elements in contaminated soils [6]. Taking into account the solubility products of the main Fe (III) oxides, reaching 10-39 for ferrihydrite, 10-41 for goethite and 10-43 for hematite, these mineral phases tend to be very stable at circum-neutral pH values, typical of marine sediments [16]. The total amount of pollutants released from the control sediment and the stabilized sediment samples, after 3 months was reported in Fig. 4. Results showed that ZVI and hematite were the most efficient amendments to reduce the leaching of trace elements from marine dredged sediments, with stabilization rates ranging from 45 to 51%. Zeolite particles were not efficient for trace element

218

Y. Mamindy-Pajany et al. / Journal of Hazardous Materials 252–253 (2013) 213–219

sediment. This finding suggested that iron-based amendments could be suitable to stabilize trace elements in dredged sediments prior to their reuse as backfill materials or disposal. 3.3. Toxicity of sediment samples

Fig. 4. Total amounts of pollutants released after three months from control sample and stabilized sediments (H: hematite, FZ: fine zeolite, CZ: coarse zeolite).

stabilization since CZ decreased only by 12% the leaching of pollutants and FZ mobilized pollutants by 18% compared to the control sediment. Contrary to waste storage units, the technical and regulatory requirements applicable to dredged materials from ports are still rather imprecise. One of the main techniques consists in depositing the dredged material directly on the ground. The former is kept in place by a dike composed of permeable material to allow the water from the dredged material to drain and filter through [39]. In this context, the disposal of polluted sediments must satisfy the environmental criteria for waste disposal [40]. Thus, regulatory levels are available for the leaching of trace elements from non-hazardous wastes for a liquid to solid ratio (L/S) equal to 2. This ratio represents the cumulative amount of water after 6 weeks of successive leaching events in the pilot experiment. In Table 5, the regulatory levels were compared to the trace element concentrations measured in the leachates of each sediment samples for L/S = 2. In the control sediment, all pollutants concentrations were below regulatory levels except Mo that was higher by 166% (Table 5). The Mo concentration decreased in the sediment samples treated with iron-based amendments in the following order: ZVI (decrease by 41% compared with control sediment) < 5% hematite (73%) < 15% hematite (83%). Iron-based amendments tend to also decrease the leaching of other trace elements from stabilized sediment samples compared to the control

Toxicity results, expressed as EC50 (effective sediment concentration causing 50% bioluminescence inhibition of V. fischeri) are reported in Table 4. Based on EC50 values, the toxicity level decreased in the following order: Control sediment > 5% hematite ∼ 5% ZVI > 5% CZ > 5% FZ > 15% hematite. Results demonstrated that stabilized sediment samples were less toxic than the control sediment. According to the toxicity scores, it emerged that hematite, zero-valent iron and zeolite could reduce significantly the toxicity level in sediment samples (Table 4). This result was in agreement with previous laboratory experiments demonstrating that hematite, ZVI and zeolite were able to decrease toxicity of marine composted sediments towards oyster larvae and bacteria [19,20]. Zero-valent iron have been proved to reduce the trace element mobility in polluted soils, with no symptoms of residual toxicity for plants and microorganisms even on a relatively long timescale [41–43]. Other works have also shown that soils stabilized with iron oxides and zeolite decreased significantly metal transfer in plant and phytotoxicity effects [44–46]. 3.4. Environmental implications The results of this pilot-scale experiment showed that Fecontaining minerals at 5% amendment rate were sufficient to efficiently stabilize several trace elements in the dredged marine sediments. Toxicity study indicates that application of hematite and zero-valent iron can be an effective ex-situ stabilization method to reduce trace element availability in leachates of polluted sediments. Further work is required to study (i) the geochemical/mineralogical transformations of the iron-based amendments within the marine sediments and (ii) in-situ trace element speciation onto the stabilized sediments, in order to assess the long-term efficiency of the stabilization process. Each polluted sediment sample will require specific consideration to find an appropriate amendment and application rate. The cost of amendment application will depends on several factors including the needs for mixing the mineral with the dredged sediment, and whether the application and mixtures can be

Table 4 Microtox solid phase test (n = 3): Results are presented as effective sediment concentration producing 50% (EC50 ) inhibition of bioluminescence of Vibrio fischeri after 15 min. Means (±1 SD) with different letters differed significantly (Fisher’s test) after significant global ANOVA at p < 0.0001. Samples

EC50 (g/L) a

Control sediment Sediment + 5% hematite Sediment + 15% hematite Sediment + 5% zero-valent iron Sediment + 5% coarse zeolite Sediment + 5% fine zeolite

0.37 0.53b 1.25c 0.55b 0.78d 0.94e

± ± ± ± ± ±

0.01 0.02 0.05 0.01 0.02 0.04

Toxicity score

Toxicity level

2 1 1 1 1 1

Moderate Low Low Low Low Low

Table 5 Comparison of metal concentrations (As, Cd, Cu, Mo, Ni and Zn) measured in leachates from sediment samples (after 6 weeks) with regulatory levels defined for inert wastes for the liquid to solid ratio of 2 L/kg [40]. Regulatory level ␮g/kg As Cd Cu Mo Ni Zn

100 30 900 300 200 2000

Control sediment ␮g/kg

5% Hematite ␮g/kg

15% Hematite ␮g/kg

5% Zero-valent iron ␮g/kg

5% Fine Zeolite ␮g/kg

5% Coarse Zeolite ␮g/kg

70 22 304 500 94 949

36 9 146 82 41 551

54 16 177 50 72 446

48 8 174 116 45 550

80 34 293 583 132 1116

47 17 204 361 54 971

Y. Mamindy-Pajany et al. / Journal of Hazardous Materials 252–253 (2013) 213–219

accomplished on the wet dredged sediment or need to be performed after dewatering or others pre-treatments. The high efficiency of the Fe-based amendments and the competitive price of this technique (in comparison with others available disposal and remediation technologies) make the proposed technology a sustainable solution for in shore management of contaminated dredged sediments. A large-scale study will provide valuable information to address concerns about the full cost of amendment application and long-term effectiveness of iron-based amendments.

[21]

[22]

[23]

[24]

Acknowledgements This work has been financed by the SEDIMARD project (French national project) and the “Agence de l’eau PACA”. The authors gratefully acknowledge anonymous reviewers for their time and effort to improve this manuscript, as well as Dr. Maria Gonzalez-Rey (University of Algarve, Portugal) for her help with the editing of our manuscript.

[25]

[26]

[27]

[28]

References [1] B. Andral, J.Y. Stanisiere, D. Sauzade, E. Damier, H. Thebault, F. Galgani, P. Boissery, Monitoring chemical contamination levels in the Mediterranean based on the use of mussel caging, Mar. Pollut. Bull. 49 (2004) 704–712. [2] G. Damiens, C. Mouneyrac, F. Quiniou, E. His, M. Gnassia-Barelli, M. Roméo, Metal bioaccumulation and metallothionein concentrations in larvae of Crassostrea gigas, Environ. Pollut. 140 (2006) 492–499. [3] C. Alzieu, F. Quiniou, Geodrisk, in: CD-ROM Geodrisk “Software to Assess Risks Related to Dumping of Dredged Sediments from Maritime Harbours”, 2001. [4] D. Grosdemange, F. Leveque, D. Drousie, J.L. Aqua, J. Mehu, C. Bazin, The SEDIMARD project: presentation and results, in: International Symposium on Sediment Management –I2SM, Lille, France, 2008. [5] W. Hartley, R. Edwards, N.W. Lepp, Arsenic and heavy metal mobility in iron oxide amended contaminated soils as evaluated by short- and long-term leaching tests, Environ. Pollut. 131 (2004) 495–504. [6] J. Kumpiene, S. Ore, G. Renella, M. Mench, A. Lagerkvist, C. Maurice, Assessment of zerovalent iron for stabilization of chromium, copper, and arsenic in soil, Environ. Pollut. 144 (2006) 62–69. [7] J. Kumpiene, D. Ragnvaldsson, L. Lövgren, S. Tesfalidet, B. Gustavsson, A. Lättström, P. Leffler, C. Maurice, Impact of water saturation level on arsenic and metal mobility in the Fe amended soil, Chemosphere 74 (2009) 206– 215. [8] C. Maurice, S. Lidelöw, B. Gustavsson, A. Lättström, D. Ragnvaldsson, P. Leffler, L. Lövgren, S. Tesfalidet, J. Kumpiene, Techniques for the stabilisation and assessment of treated CCA-contaminated soil, Ambio 36 (2007) 430–436. [9] A. Xenidis, C. Stouraiti, N. Papassiopi, Stabilization of Pb and As in soils by applying combined treatment with phosphates and ferrous iron, J. Hazard. Mater. 177 (2010) 929–937. [10] G. Qian, W. Chen, T.T. Lim, P. Chui, In-situ stabilization of Pb, Zn, Cu, Cd and Ni in the multi-contaminated sediments with ferrihydrite and apatite composite additives, J. Hazard. Mater. 170 (2009) 1093–1100. [11] J. Peng, Y. Song, P. Yuan, X. Cui, G. Qiu, The remediation of heavy metals contaminated sediment, J. Hazard. Mater. 161 (2009) 633–640. [12] Z. Zhang, M. Li, W. Chen, S. Zhu, N. Liu, L. Zhu, Immobilization of lead and cadmium from aqueous solution and contaminated sediment using nanohydroxyapatite, Environ. Pollut. 158 (2010) 514–519. [13] Y.W. Chiang, R.M. Santos, K. Ghyselbrecht, V. Cappuyns, J.A. Martens, R. Swennen, T. Van Gerven, B. Meesschaert, Strategic selection of an optimal sorbent mixture for in-situ remediation of heavy metal contaminated sediments: framework and case study, J. Environ. Manage. 105 (2012) 1–11. [14] S. Lee, J. An, Y.J. Kim, K. Nam, Binding strength-associated toxicity reduction by birnessite and hydroxyapatite in Pb and Cd contaminated sediments, J. Hazard. Mater. 186 (2011) 2117–2122. [15] J. Kumpiene, A. Lagerkvist, C. Maurice, Stabilization of As, Cr, Cu, Pb and Zn in soil using amendments – A review, Waste Manage. 28 (2008) 215–225. [16] M. Komarek, A. Vanek, V. Ettler, Chemical stabilization of metals and arsenic in contaminated soils using oxides – a review, Environ. Pollut. 172 (2013) 9–22. [17] P.A. O’Day, D. Vlassopoulos, Mineral-based amendments for remediation, Elements 6 (2010) 375–381. [18] A.A. Mahabadi, M.A. Hajabbasi, H. Khademi, H. Kazemian, Soil cadmium stabilization using an Iranian natural zeolite, Geoderma 137 (2007) 388–393. [19] Y. Mamindy-Pajany, F. Galgani, M. Roméo, C. Hurel, N. Marmier, Minerals as additives for decreasing the toxicity of Mediterranean contaminated dredged sediments, Ecotoxicol. Environ. Saf. 73 (2010) 1748–1754. [20] Y. Mamindy-Pajany, F. Geret, M. Roméo, C. Hurel, N. Marmier, Ex situ remediation of contaminated sediments using mineral additives: Assessment of

[29]

[30] [31] [32]

[33] [34] [35]

[36]

[37]

[38] [39]

[40]

[41]

[42]

[43]

[44]

[45] [46]

219

pollutant bioavailability with the Microtox solid phase test, Chemosphere 86 (2012) 1112–1116. Y. Mamindy Pajany, C. Hurel, N. Marmier, M. Roméo, Leaching tests and arsenic immobilization in contaminated harbour sediment, Eur. J. Environ. Civil Eng. 14 (2010) 233–251. Y. Mamindy-Pajany, C. Hurel, N. Marmier, M. Roméo, Arsenic (V) adsorption from aqueous solution onto goethite, hematite, magnetite and zero-valent iron: Effects of pH, concentration and reversibility, Desalination 281 (2011) 93–99. C. Viscosi-Shirley, K. Mammone, N. Pisias, J. Dymond, Clay mineralogy and multi-element chemistry of surface sediments on the Siberian-Arctic shelf: implications for sediment provenance and grain size sorting, Cont. Shelf Res. 23 (2003) 1175–1200. F. Séby, C. Benoit-Bonnemason, E. Tessier, C. Alzieu, J.L. Aqua, L. Sannier, O.F.X. Donard, Evolution of metals and their chemical forms in land-disposed dredged marine sediments, Paralia 2 (2009) 1–12. R. Cassi, I. Tolosa, S. Mora, A survey of antifoulants in sediments from Ports and Marinas along the French Mediterranean coast, Mar. Pollut. Bull. 56 (2008) 1943–1948. F.M. Tack, O.W.J.J. Callewaert, M.G. Verloo, Metal solubility as a function of pH in a contaminated, dredged sediment affected by oxidation, Environ, Pollut. 91 (1996) 199–208. M. Caetano, M.J. Madureira, C. Vale, Metal remobilisation during resuspension of anoxic contaminated sediment: short-term laboratory study, Water Air Soil Pollut. 143 (2003) 23–40. M.P. Isaure, A. Laboudigue, A. Manceau, G. Sarret, C. Tiffreau, P. Trocellier, G. Lamble, J.L. Hazemann, D. Chateigner, Quantitative Zn speciation in a contaminated dredged sediment by ␮PIXE, ␮SXRF, EXAFS spectroscopy and principal component analysis, Geochim. Cosmochim. Acta 66 (2002) 1549–1567. L.J.A. Gerringa, Aerobic degradation of organic matter and the mobility of Cu, Cd, Ni, Pb, Zn, Fe and Mn in marine sediment slurries, Mar. Chem. 29 (1990) 355–374. P.M. Fox, H.E. Doner, Trace element retention and release on minerals and soil in a constructed wetland, J. Environ. Qual. 31 (2002) 331–338. R. Kretzschmar, H. Sticher, Colloid transport in natural porous media: influence of surface chemistry and flow velocity, Phys. Chem. Earth 23 (1998) 133–139. M. Rousseau, Preferential transport of particles in an unsaturated soil: column lysimeter experiment to develop a physically-based model, Ph.D. Thesis, INPG, Paris, 2003, p. 242. W. Stumm, Chemistry of the Solid-Water Interface, Wiley, 1992. Y. Mamindy-Pajany, C. Hurel, N. Marmier, M. Roméo, Arsenic adsorption onto hematite and goethite, C. R. Chim. 12 (2009) 876–881. N. Marmier, J. Dumonceau, J. Chupeau, F. Fromage, Experimental study and surface complexation modeling of trivalent lanthanide ion sorption on hematite, C. R. Acad. Sci. Paris 317 (1993) 1561–1567. M. Duc, G. Lefevre, M. Fedoroff, J. Jeanjean, J.C. Rouchaud, F. Monteil-Rivera, J. Dumonceau, S. Milonjic, Sorption of selenium anionic species on apatites and iron oxides from aqueous solutions, J. Environ. Radioactiv. 70 (2003) 61–72. B.H. Jeon, B.A. Dempsey, W.D. Burgos, R.A. Royer, Sorption kinetics of Fe(II), Zn(II), Co(II), Ni(II), Cd(II), and Fe(II)/Me(II) onto hematite, Water Res. 37 (2003) 4135–4142. R.M. Cornell, U. Schwertmann, The Iron Oxides (Structure, Properties, Occurrences and Uses), Wiley-VCH Verlag GmbH & Co, KGaA, 2003. Y. Perrodin, M. Babut, J.-P. Bedell, M. Bray, B. Clement, C. Delolme, A. Devaux, C. Durrieu, J. Garric, B. Montuelle, Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil, Environ. Int. 32 (2006) 804–814. European Council, Council decision of 19 December 2002 establishing criteria and procedures for the acceptance of waste at landfills pursuant to Article 16 of Annex II to Directive 1999/31/EC(2003/33/EC), Official Journal of European Communities L11/27 [16.1.2003], 2002. J. Ascher, M.T. Ceccherini, L. Landi, M. Mench, G. Pietramellara, P. Nannipieri, G. Renella, Composition, biomass and activity of microflora, and leaf yields and foliar elemental concentrations of lettuce, after in situ stabilization of an arsenic-contaminated soil, Appl. Soil Ecol. 41 (2009) 351–359. G. Renella, L. Landi, J. Ascher, M.T. Ceccherini, G. Pietramellara, M. Mench, P. Nannipieri, Long-term effects of aided phytostabilisation of trace elements on microbial biomass and activity, enzyme activities, and composition of microbial community in the Jales contaminated mine spoils, Environ. Pollut. 152 (2008) 702–712. J. Kumpiene, G. Guerri, L. Landi, G. Pietramellara, P. Nannipieri, G. Renella, Microbial biomass, respiration and enzyme activities after in situ aided phytostabilization of a Pb- and Cu-contaminated soil, Ecotoxicol. Environ. Saf. 72 (2009) 115–119. S.H. Lee, J.S. Lee, Y. Jeong Choi, J.G. Kim, In situ stabilization of cadmium, lead, and zinc-contaminated soil using various amendments, Chemosphere 77 (2009) 1069–1075. H. Li, W. Shi, H. Shao, M. Shao, The remediation of the lead-polluted garden soil by natural zeolite, J. Hazard. Mater. 169 (2009) 1106–1111. E. Lombi, F.J. Zhao, G. Zhang, B. Sun, W. Fitz, H. Zhang, S.P. McGrath, In situ fixation of metals in soils using bauxite residue: chemical assessment, Environ. Pollut. 118 (2002) 435–443.