KR20140122332A - Method for stabilizing heavy metals contained in marine contaminated sediment - Google Patents

Abstract

The present invention relates to a method for stabilizing heavy metals in contaminated marine sediment. The method according to the present invention can be applied usefully in stabilizing contaminated marine sediment as oxides and heavy metals in the shape of organic matters, which account for a large portion of the contaminated marine sediment, is converted into a state of low solubility and mobility by a stabilizing agent such as red mud, oyster shells and mixture thereof and the amount of eluted heavy metals can be reduced greatly.

Description

[0001] METHOD FOR STABILIZING HEAVY METALS CONTAINED IN MARINE CONTAMINATED SEDIMENT [0002]

The present invention relates to a method for stabilizing heavy metals in marine polluted sediments, and more particularly to a method for stabilizing heavy metals in marine polluted sediments using red mud, oyster shells or mixtures thereof.

Heavy metal pollution in marine sediments has become a global problem, and the accumulation of heavy metals in marine sediments has adversely affected marine products, sediment quality and benthic ecology (Gray, CW et al , Environmental Pollution , 142 , pp 530-539 (2006)). For this reason, the development of purification technology for sediments contaminated with heavy metals is considered to be very important, but Korea currently lacks appropriate management and disposal methods for marine polluted sediments.

The monitoring techniques for marine sediment purification are Monitored Natural Recovery, In-Situ Capping and Dredging (Ministry of Land, Transport, and Maritime Affairs, 2010) ). Natural purification technology is an environmentally friendly purification technology, but it has limitations applied to long-term treatment periods and relatively low concentrations of heavy metal pollution areas. Dredging technology is a technology based on dredging, transportation and landfill of polluted sediments. On the other hand it is costly. On the other hand, in-situ stabilization in the field coating method is a technique for reducing the diffusion of heavy metals from contaminated sites by changing the heavy metals to a state of low solubility and mobility, and research has been conducted by many researchers Conner, JR, et al. , Van Nostrand Reinhold, New York, 1990, and Keun-Young Lee, Korean Society of Environmental Engineering, 33 , pp71-76 (2011)). The field stabilization method has high field application and economic efficiency compared with other purification treatment methods and it is also possible to treat relatively heavy metal contaminated sediments in a relatively short time. In the field stabilization method, development of stabilized materials is important as well as importance of coating technology. Therefore, researches are still being carried out, but development of stabilized materials having economic feasibility is insufficient.

On the other hand, the recent increase in waste and by-products emitted by various industrial activities causes various problems in socio-environment, and purification technologies for removing heavy metals using such wastes and by-products have been reported (Ahmaruzzaman, M., et al . , Advances in Colloid and Interface Science , 166 , pp36-59 (2011)). In particular, the red mud from the bauxite mineral refining process for aluminum production and the oyster shell from oyster farms and related industries are under investigation as adsorbents for the removal of heavy metals from industrial wastewater and contaminated soils, They show high adsorption properties (Liu, Y., et al ., Geoderma , 163 , pp1-12 (2011); And Kim Eunho, Korea Institute of Geoscience and Mineral Resources, 34 , pp414-419 (1997)). In the previous studies, the adsorption characteristics of red mud and oyster shells in single heavy metals were studied for the removal of selective heavy metals such as industrial wastewater and mine drainage. However, in the case of marine contaminated sediments with high possibility of contamination by various heavy metals, And studies on the change of the presence of heavy metals in contaminated sediments by addition of stabilizers have not yet been conducted.

Accordingly, the present inventors have completed the present invention by discovering a method for stabilizing heavy metals in marine polluted sediments using red mud, oyster shells, or mixtures thereof, against marine contaminated sediments contaminated with heavy metals.

[Non-Patent Document 1] Gray, CW meat al ., Environmental Pollution , 142, pp 530-539 (2006)

[Non-Patent Document 2] Ministry of Land, Transport and Maritime Affairs, Working Guide for Promoting Cleanup and Restoration of Marine Contaminated Sediments (2010)

[Non-Patent Document 3] Conner, JR et al ., Van Nostrand Reinhold, New York, 1990

[Non-Patent Document 4] Lee, Keun-Young et al., Korean Society of Environmental Engineering, 33, pp71-76 (2011)

[Non-Patent Document 5] Ahmaruzzaman, M. et al. , ≪ / RTI > Advances in Colloid and Interface Science , 166, pp36-59 (2011)

[Non-Patent Document 6] Liu, Y. et al ., < / RTI & gt ; Geoderma , 163, pp1-12 (2011)

[Non-Patent Document 7] Kim, Eunho et al., Journal of Korean Society of Materials Science and Technology, 34, pp414-419 (1997)

It is therefore an object of the present invention to provide a method for stabilizing heavy metals in marine polluted sediments using red mud, oyster shells or mixtures thereof.

In order to achieve the above object, the present invention provides a method for treating marine polluted sediments containing heavy metals such as lead (Pb), zinc (Zn), copper (Cu) The method comprising the steps of:

According to the method of the present invention, the heavy metals in the form of oxides and organic substances, which occupy a large proportion in marine polluted sediments, are converted into low solubility and low mobility by stabilizers such as red mud, oyster shell or mixture thereof, It can be usefully used for stabilization treatment of marine polluted sediments.

Fig. 1 shows the pH measurement results of the experimental group stabilized with the control group and red mud and oyster shells (contents 5%, 10% and 15%).
Figure 2 shows the distribution of lead (Pb) content in the continuous fractionation step of the experimental group stabilized with control and red mud and oyster shells (contents 5%, 10% and 15%).
Figure 3 shows the distribution of zinc (Zn) content in the continuous fractionation step of the experimental group stabilized with control and red mud and oyster shells (contents 5%, 10% and 15%).
Figure 4 shows the distribution of copper (Cu) content in the continuous fractionation step of the experimental group stabilized with control and red mud and oyster shells (contents 5%, 10% and 15%).

Hereinafter, the present invention will be described in detail.

The present invention provides a method for stabilizing heavy metals in marine fouling sediments by treating oyster shells, oyster shells or mixtures thereof, with marine fouling sediments containing heavy metals such as lead (Pb), zinc (Zn), copper .

In the present invention, marine polluted sediments means polluted sediments in which heavy metals are accumulated in marine polluted sediments due to continuous inflow of waste and by-products discharged from various industrial activities, and municipal sewage and industrial wastewater.

The heavy metals contained in these marine polluted sediments are present in the form of oxides or organic substances, and are highly likely to elute heavy metals due to changes in the physical environment and serve as sedimentation sources due to substances such as sulfides.

Studies have been reported to apply red mud or oyster shells as adsorbents for the removal of heavy metals in industrial wastewater or contaminated soils. However, when red mud or oyster shells are used for the removal of heavy metals in general industrial wastewater or contaminated soil, pretreatment is indispensable in order to prevent the pH rise (Brunori, C., et al., Journal of hazardous materials , 117 , pp55-63 (2005)). The present inventors tried to stabilize heavy metals in marine polluted sediments by applying red mud, oyster shell or mixture thereof to marine polluted sediments contaminated with various heavy metals rather than general industrial wastewater and contaminated soil. In order to stabilize heavy metals in marine polluted sediments, Or a mixture thereof, it is confirmed that the buffering effect of the oceanic and seawater is small and the effect of the pH is small, so that the red mud or oyster shell can be effectively used without pretreatment.

Specifically, the method according to the present invention is a method of stabilizing heavy metals in marine contaminated sediments including heavy metals such as lead (Pb), zinc (Zn) and copper (Cu) , And such red mud or oyster shells can be used in the form of powder, particulate or granular particles.

The red mud, oyster shell or mixture thereof may be treated in an amount of 1 to 15 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of marine polluted sediments.

The marine contaminated sediment may have a particle size of 10 to 1000 μm, preferably 10 to 300 μm, and may be composed of sand, silt, clay, and the like. In addition, marine polluted sediments in the mud area often have a moisture content (water content) of more than 50% (Koster, M., et al., Aquatic Microbial Ecology , 39 , pp69-83 (2005)), marine fouling sediments applicable in the process of the present invention may have similar water contents, for example, a water content of 40 to 60%.

The marine polluted sediments are selected from the group consisting of nickel (Ni), cadmium (Cd), arsenic (As), chromium (Cr) and combinations thereof in addition to lead (Pb), zinc (Zn) It may include, but is not limited to, various types of heavy metals.

The stabilized marine fouling sediment according to the method of the present invention preferably has a pH of 8 to 9.5.

According to one embodiment of the present invention, when the red mud, the oyster shell, or a mixture thereof is treated to 5 to 15 parts by weight with respect to 100 parts by weight of the marine polluted sediment sample, the marine polluted sediment sample having the red mud or oyster content of 5 parts by weight, (pH 8.04). The samples of marine polluted sediments with red mud or oyster shell contents of 10 parts by weight and 15 parts by weight showed pH of 8.90 and pH of 9.36, respectively, in red mud , And oyster shell pH 8.17 and pH 8.31, respectively (Fig. 1).

According to one embodiment of the present invention, the content of Cu contained in the stabilized marine polluted sediment according to the method of the present invention is 0.8 to 1.3 mg / L, which is about the maximum (about 27.1 mg / L) (3.1 mg / L), and the content of Zn was 12.3 to 24.9 mg / L, which was about 11 times lower than that of the control (140.6 mg / L). The content of Pb was 1.4 to 2.3 mg / Which is about twice the maximum.

According to the method of the present invention, it is possible to prevent the heavy metals from diffusing from spreading by changing and stabilizing the heavy metals contained in marine polluted sediments to low solubility and low mobility. In the analysis of the chemical form of heavy metals in marine contaminated sediments, general marine pollution sediments have a high possibility of leaching of heavy metals due to the change of physical environment due to many oxide forms in the case of Pb and Zn, and Cu has many organic matters, And thus precipitation of sulfides. However, by treating the red mud, oyster shell, or mixtures thereof in accordance with the method of the present invention, the oxide form of Pb and Zn is reduced and the residue form is increased to convert into insoluble material and remain in the specific surface area and stabilizer of the stabilizer The heavy metal can be effectively immobilized by the action of an organic component or the like (see Example 5).

Thus, the use of red mud, oyster shells or mixtures thereof in marine polluted sediments containing large amounts of heavy metal species that are easily exposed to external environmental changes (eg tidal tides, typhoons and floods) can stabilize the release of heavy metals It shows the effect.

[Example]

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example 1: Stabilization of marine polluted sediments using red mud or oyster shell

1-1. Preparation of marine contaminated sediments and stabilizers

Sediments from marine contaminated sediments were collected from the coastal pier (37˚29'N, 126˚37'E) located in Incheon, and sediments about 10-30 cm deep were taken from the surface and transported to the laboratory as a closed vessel. Only sediments with debris removed by air (<1mm) at room temperature were used for the experiment.

The red mite used as a stabilizer was supplied by Jeonnam Youngam KC Co., Ltd. (formerly Korea Chemical Industry Co., Ltd.), and the oyster shell was discarded in Anmyeondo, Chungnam Province. Red mud (<63 μm) was used as a powder after natural drying, and oyster shell (1-2 mm) was washed and dried at 105 ° C. for 24 hours.

1-2. Stabilization treatment

In the stabilization treatment experiment, the marine sediment and the stabilizer (red mud or oyster shell) were mixed and agitated, and then water was added to perform an airtight reaction.

Specifically, 5 g, 10 g and 15 g of red mud or oyster shell were added to 100 g of marine polluted sediments, respectively, and mixed. The mixture was stirred sufficiently to make it homogeneous.

In the present invention, distilled water is added to the sample at a weight ratio of 1: 1 to adjust the water content to 49.5%. Since the moisture content of the marine sediment in the Pearl area is often more than 50% Lt; / RTI &gt; After 15 days of reaction time, the obtained samples were separately collected and air-dried, and then used for analysis.

Example 2: Characterization of marine contaminated sediments and stabilizers

2-1. Characterization of marine polluted sediments

The pH value was measured by using a pH meter to measure 10.0 g of marine polluted sediments by air drying, and then 50 ml of distilled water was added to the sample. The pH was measured 1 hour after the sample was intermittently agitated (Pak Gil Ok et al., 41 pp166-173 )). Particle size analysis was performed using a particle size analyzer (Bluewave, Microtrac, USA). Organic carbon and total nitrogen were analyzed by elemental analyzer (EA-1110, Instruments, Italy). The results are shown in Table 1 below.

Sediment indicator Measures pH 8.04 Sand (%) 15.0 Silt (%) 77.5 Clay (%) 7.5 C (%) 1.54 N (%) 0.17

As shown in Table 1, the pH of marine polluted sediments was 8.04, the particle size of all sediments was less than 300 ㎛, and silt (4 ㎛ <f <63 ㎛) was the most abundant at 77.5%. Organic carbon and total nitrogen were 1.54% and 0.17%, respectively.

2-2. Characterization of Stabilizers

The results of analysis using an X-ray fluorescence spectrometer (X-ray fluorescence, XRF-1700, Shimadzu, Japan) are shown in Table 2 below to confirm the constituents of red mud and oyster shells used as stabilizers in the present invention .

unit(%) SiO ₂ Al ₂ O ₃ TiO ₂ Fe ₂ O ₃ MgO CaO Na ₂ O Cl K ₂ O P ₂ O ₅ SO ₃ Redness 20.1 28.4 6.6 27.6 ND 3.3 13.0 ND 0.04 0.2 0.4 Oyster shell 1.8 0.6 ND 0.3 1.2 90.9 2.2 1.6 0.2 0.3 0.8 ND: Not measured

As shown in Table 2, in the case of red mud, oxide forms Fe ₂ O ₃ , Al ₂ O ₃ , SiO ₂ And TiO ₂ were 82.7% or more, whereas the content of CaO in the oyster shell was 90.9%. X-ray fluorescence analysis showed that red oysters and oyster shell stabilizers contained different chemical components, which was similar to the previously reported results (Liu, Y., Naidu, R. and Ming , H., Geoderma , 163 , 1-12 (2011)).

2-3. Characteristics of stabilized sample

The pH change of the stabilized samples obtained in Example 1-2 was measured according to the content of red mud or oyster shell, and the results are shown in FIG.

As shown in FIG. 1, when the content of red mud or oyster shell was 5%, the pH was similar to that of the control, but the pH was also increased as the content was increased to 10% and 15%. Especially, pH (8.90 and 9.36) in red mats was higher than pH (8.17 and 8.31) in oyster shell. It is considered that the pH of the red mud is increased due to the presence of OH ^{-, which} is a strong base in the red mud, due to precipitation in the NaOH aqueous solution during the aluminum hydroxide production process. On the other hand, oyster shell contains CO ₃ ^{2 -} component, which is weak base, and pH was increased but it was relatively lower than olivine.

Example 3: Analysis of heavy metals by continuous extraction method

In order to compare chemical differences in the presence of Pb, Zn and Cu present in marine polluted sediments, the control (stabilized untreated marine polluted sediments) and the stabilized samples obtained in Example 1-2 were subjected to continuous extraction (Tessier, A., et al., Analytical Chemistry , 51 , pp. 844-851 (1979)).

The extraction method according to the continuous extraction method is characterized in that the step I is an exchangeable form, the step II is a carbonate form, the step III is an oxide form of iron and manganese, the step IV is an organic form, The V stage is divided into the residual form, and the total amount of heavy metal is calculated as the total heavy metal amount from I step to V step. Table 3 shows the extraction conditions at each step.

step Extraction conditions (per g of marine contaminated sediment) I 8 ml 1 M MgCl ₂ (pH 7), 1 hour, room temperature, constant stirring II 8 ml 1 M NaOAc (pH 5), 5 hours, room temperature, constant stirring III 20 ml 0.04 M NH ₂ OH · HCl in 25% HOAc, 5 hours, 96 ° C, slightly stirred IV 3 ml 0.02 M HNO ₃ and 2 ml 30% H ₂ O ₂ (pH 2), 2 hours, 85 ° C, slight stirring;
Additionally 3 ml 30% H ₂ O ₂ , 3 h, 85 ° C, slight stirring; And
5 ml of 3.2 M NH ₄ OAc in 20% HNO ₃ , 0.5 h, room temperature, constant stirring V 0.5 ml conc. HNO _3, 5 ml HF and 2 ml HCl, 2 sigan, 140 ℃,
Decomposition in Teflon bomb, dissolution in 15% HCl Total heavy metal amount Sum of heavy metals generated in I + II + III + IV + V

The extracted solution was analyzed by ICP-MS (Agilent 7500 Series, USA), which was filtered with 0.45 ㎛ filter paper (PTFE syringe filter, Whatman) .

Example 4: TCLP elution assay analysis

Toxicity Characteristic Leaching Procedure (TCLP) was performed according to USEPA Method 1311 on the control and the stabilized samples obtained in Example 1-2. At this time, only the amount (1 g) of the sample and the extraction solvent (20 ml) were used while maintaining the same liquid ratio (1:20).

Meanwhile, the pH of the marine contaminated sediment control was 8.04. The pH was adjusted to 2.88 ± 0.05 as an extraction solvent (acetic acid was adjusted to 2.88 ± 0.05) and the shaking was maintained for 18 hours at a constant temperature (23 ± 2 ° C) . After elution, the supernatant was filtered with a 0.45 μm filter paper (PTFE syringe filter, Whatman), and the filtrate was adjusted to pH 2 or less using 1N HNO ₃ . The concentration was analyzed using ICP-MS (Agilent 7500 Series, USA).

Example 5: Evaluation of the presence form and mobility of heavy metals

5-1. Concentrations and ratios of heavy metals in the control group

The contents and ratios of Pb, Zn, and Cu present in the control group as measured in Example 3 are shown in Table 4 below.

Fraction (unit: mg / kg- ¹ ) I II III IV V Total Pb 0.3 4.2 22.9 8.1 14.9 50.4 Zn 1.5 6.6 97.8 18.6 25.3 149.8 Cu 0.8 0.7 4.5 60.7 18.6 85.3

As shown in Table 4, in the case of Pb, the content ratio was in the form of oxide (22.9 mg / kg- ¹ , 45.5%), the residual form (14.9 mg / kg- ¹ , 29.5%), the organic form (8.1 mg / kg ^-1 , 16.1%), the carbonate form (4.2 mg kg ^-1 , (97.8 mg / kg- ¹ , 65.3%) and the residual form (25.3 mg / kg ^{- 1} , 0.6% ^1, with 16.8%), the organic form ^{(18.6 mg / kg -1, 12.4} %), carbonate form ^{(6.6 mg / kg -1, 4.4} %) and ion-exchanged form ^{(1.5 mg / kg -1, 1.0} %) pure appear. On the other hand, in the case of Cu organic form ^{(60.7 mg / kg -1, 71.2} %), the residue form ^{(18.6 mg / kg -1, 21.8} %), an oxide form ^{(4.5 mg / kg -1, 5.3} %), ion-exchange (0.8 mg / kg ^-1 , 1.0%) and the carbonate form (0.7 mg / kg ^-1 , 0.8%) in that order.

In other words, the marine contaminated sediments showed higher content of oxides and organic bonds than ion exchange type and carbonate type, followed by a higher residual ratio. The type of heavy metals in contaminated sediments can vary depending on the source and deposition conditions. In addition, heavy metals (Pb, Zn and Cu) in marine contaminated sediments are easily destroyed by pH change and oxidation, and if the environment changes, these heavy metals are likely to be eluted into the water layer.

5-2. Stabilizer  Concentrations and ratios of heavy metals contained in the treated samples

The results of confirming the contents and ratios of Pb, Zn and Cu in the chemical form of the stabilized samples measured in Example 3 are shown in Figs. 2 to 4 in comparison with untreated contaminated sediments.

(1) Pb

As shown in FIG. 2, the content of Pb in the presence of ion exchange form and carbonate form did not show a significant difference according to the content of red mud and oyster shells, and showed a low content ratio. Oxide type showed the highest content ratio in the control group and showed a tendency to decrease as the content of red oyster and oyster shell increased. Compared with the other forms, the stable residue form showed a tendency to increase (except for oyster shell 10%) compared to the control group.

Stabilization of Pb in soil causes the surface of metal oxide to have a negative electric charge once the pH is changed to basic (pH> 7), along with reduction of heavy metal activity and induction of formation of precipitate due to pH increase When negative charge is generated on the surface, it is stabilized by the principle that the heavy metal ions in the ion state are adsorbed on the surface (Kim, MJ et al., Journal of Korean Society of Environmental Engineering, 33, pp93-102 (2011) and Moon Duk Hyun et al., Korean Journal of Environmental Engineering, 32 , pp185-192 2010). When Pb is adsorbed at high pH, adsorption is facilitated by the formation of PbOH ⁺ ions, and a decrease in the concentration of H ⁺ in the competitive ion exchange of metal ions and H ⁺ ions can lead to an increase in adsorption (Singer , A et al., Environmental Science and Technology , 29, pp 1748-1753 (1995)).

Since the pH of the stabilized sediment in the present invention is maintained between 8 and 9.5, it is considered that this precipitation phenomenon is closely correlated with the substances bonded with Al, Si and O, and that the effective immobilization takes place . In addition, in the existing heavy metal stabilization studies, it has been reported that Pb is converted into an insoluble material and reacted with a lime-based stabilizer, resulting in immobilization. However, in the present invention, it is considered that the complex function such as the specific surface area of the stabilizer and the immobilization of heavy metal by the organic component remaining in the stabilizer contributes to the stabilization of Pb.

(2) Zn

As shown in FIG. 3, the content ratio of Zn in the presence of Zn was the lowest in ion exchanged form and carbonate form in the control group, and the type of oxide that could be eluted likewise Pb was the highest in the untreated sample. These results suggest that Zn is present in a reducing form, mainly Fe / Mn oxide, even in acidic soils (Levy, DB, Journal of Environmental Quality , 21 , pp. 185-195 (1992)). Also, as in the case of Pb, the oxide form gradually decreased with increasing the content of red oyster shell, and the residual form tended to increase with increasing content of red oysters and oyster shells.

Stabilization and immobilization of Zn in marine contaminated sediments are affected by pH increase (over 8) similar to Pb. In particular, in the solution state, the activity of Zn ²⁺ at pH 5 is about 10 ^-4 M at pH 5, while it decreases to about 10 ^-10 M at pH 8 (Alloway, BJ, Heavy metals in soils, Chapman and Hall, 1995). In addition, precipitation by ZnCO ₃ and Zn (OH) ₂ formation is expected to occur (Benefield, LD et al., Water Quality and Treatment, Pontius, FW (Ed.). McGraw-Hill Inc., New York , pp 641-708 (1990)).

(3) Cu

As shown in FIG. 4, the content of Cu in the form of ion was lower in the control group than in the ion exchange and carbonate form, and decreased with the content of the red oyster shell stabilizer (except oyster shell 15%). The oxide form tended to decrease with the addition of the stabilizer.

In the control group, Cu showed the highest proportion of organisms that could migrate to the water layer when anaerobically under anaerobic condition, and increased tendency due to the content of stabilizer (except 15% oyster shell) in contrast to Pb and Zn appear. This is due to the fact that the mobility of Cu in the basic environment of pH 8 or higher during the stabilization treatment of the soil contaminated with the heavy metals is rather poor and the stabilization efficiency is not good. This is because, in the environment of high organic matter content, DOC) compounds can be formed. The content of residues in the crystals of minerals showed a tendency to decrease with increasing stabilizer content.

5.3 Evaluation of stabilization efficiency by stabilizer treatment

Heavy metals (Pb, Zn and Cu) in marine contaminated sediments contain ion exchange, carbonate and oxide forms, which are easily transportable to the water layer in response to physico-chemical environmental changes, in the following proportions:

Pb was 54.4% in the control group and 36.5%, 37.1% and 37% in the redness content 5%, 10% and 15% respectively and 48.4%, 41.4% and 49.3% in the oyster shell content, respectively.

Zn contents were 67.7%, 62.3%, and 62.4% in the control, and 65.7%, 61.3%, and 57% in the oyster shell contents, respectively, from 5%, 10% and 15%

The content of Cu was 7.1% in control and 5.9%, 2.8% and 3.3% in red, 5%, 10% and 15%, respectively. The content of oyster shell was 3.0%, 1.9% and 3.6%, respectively.

Marine polluted sediments are easily destroyed by pH change and oxidation, and heavy metals of this type (ie ion exchange, carbonate and oxide form) are formed in the water layer according to environmental changes (tidal tide, typhoon, The possibility of elution is high. However, the release of heavy metals can be stabilized by external environmental changes by using red oysters and oysters as stabilizers. This tendency can be confirmed by the TCLP dissolution test result.

Specifically, after completion of the TCLP elution experiment according to Example 4, the pH and the content of Cu, Zn and Pb in the control group and the stabilized sample group were measured, and the results are shown in Table 5.

Unit (mg / L) pH Cu Zn Pb Control group 3.3 27.1 140.6 3.1 Redness

5% 4.5 1.1 13.2 1.8 10% 4.9 0.9 18.4 2.1 15% 5.5 1.1 15.8 1.4 Oyster shell

5% 4.3 0.8 24.9 2.1 10% 4.5 0.9 12.3 1.9 15% 4.8 1.3 13.4 2.3

As shown in Table 5, the pH of the control group was relatively strong at 3.3, while the stabilized samples showed a neutral to neutral range (pH 4.3-5.5) due to the neutralization of the stabilizer, And showed a tendency to stabilize. These results are generally due to the fact that the leaching amount of heavy metals is not much in neutral or weakly acidic environment than strong acidic environment.

Considering the characteristics of leaching of heavy metals from sediments according to pH, it is known that the maximum elution occurs from neutral to basic, from basic to small amount and acidity. It is concluded that stabilizers such as red mud or oyster shells are effective in the stabilization of marine polluted sediments in the contaminated sediments with heavy metal form that can easily dissolve in the external environmental changes.

In addition, according to Qian et al., Since the stabilization efficiency is higher when the ferrihydrite and apatite are mixed with each other than when they are used respectively, the red and oyster shells used in this experiment are also used respectively (Qian, G., et al ., Journal of Hazardous Materials , 170, pp1093-1100).

Claims (5)

A method for treating a marine contaminated sediment containing heavy metals such as lead (Pb), zinc (Zn) and copper (Cu) by treating red mud, oyster shell or a mixture thereof to stabilize heavy metals in the marine polluted sediments How to do it. The method according to claim 1,
Characterized in that the pH of the marine fouling sediment after treating the red mud, oyster shell or mixture thereof is between 8 and 9.5. The method according to claim 1,
Characterized in that the red mud, oyster shell or mixtures thereof are treated in an amount of 1 to 15 parts by weight based on 100 parts by weight of marine contaminated sediments. The method according to claim 1,
Characterized in that the particle size of the marine contaminated sediment is between 10 and 1,000 microns. The method according to claim 1,
Characterized in that the marine contaminated sediment has a water content of 40 to 60%.

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