• Economic and Environmental Geology
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• v.46 no.6
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• pp.509-520
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• 2013

In this study, heavy metals are removed by soil washing from soils contaminated with Cu, Zn, and Pb, whose maximum concentrations are up to 3350, 1220, and 2240 mg/kg, respectively. Through various soil washing experiments, the optimum conditions, including type and concentration of washing reagent, washing time, mixing ratio of soil and washing reagent, and stirring speed, are derived for effective removal of the heavy metals. It is found that the most effective washing reagent and its concentration are hydrochloric acid and 50 mM, respectively. The most suitable washing time is 30 minutes and the optimal mixing ratio of soil and washing reagent is 1:30 (g/mL). The removal efficiency, on the other hand, is not affected by stirring speed. The removal efficiencies of the heavy metals decrease when washing reagent is reused. Furthermore, the heavy metals are readsorbed onto soil in case of consecutive reuse of washing reagent.

• Korean Journal of Environmental Agriculture
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• v.35 no.1
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• pp.79-86
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• 2016

BACKGROUND: This study was initiated to quantitatively evaluate the effects of five heavy metals on the growth and P removal efficiencies of Alcaligenes sp., known as the Phosphorus Accumulating Organisms (PAOs). It was cultivated in the batch system with five heavy metals, such as Cd, Cu, Zn, Pb and Ni, added in single and binary mixtures, respectively.METHODS AND RESULTS: IC₅₀ (half of inhibition concentration of bacterial growth) and EC₅₀ (half of effective concentration of phosphorus removal Efficiencies) were used to quantitatively evaluate the effects of heavy metals on the growth and phosphorus removal Efficiencies of Alcaligenes sp. In addition, Additive Index Value (A.I.V.) method was used to evaluate the interactive effects between Alcaligenes sp. and heavy metals. As a result, as the five heavy metals were singly added to Alcaligenes sp., the greatest inhibitory effects on the growth and P removal efficiencies of each bacteria was observed in the cadmium (Cd). In the binary mixture treatments of heavy metals, the treatments of lowest IC₅₀ and EC₅₀ were the Cd + Cu treatment. Based on the IC₅₀ and EC₅₀ of the binary mixtures of heavy metals treatments, most interactive effects between the heavy metals were found to be antagonistic.CONCLUSION: Based on the results obtained from this study, it appears that they could provide the basic information about the toxic effects of the respective treatments of single and binary mixtures of heavy metals on the growth and P removal efficiencies of Alcaligenes sp. through further study about the characterization of functional proteins involved in toxic effects of heavy metals.

• Environmental Engineering Research
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• v.12 no.1
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• pp.1-7
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• 2007

Most of the herb residue producing from oriental medical clinics(OMC) and hospitals(OMH) is wasted in Korea. To develop of adsorbent for removing heavy metal from wastewater, the various pre-treatment methods of the herb residue were evaluated by potentiometric titration, Freundlich isotherm adsorption test and the kinetic adsorption test. The herb residue was pre-treated for increasing the adsorption capacity by cleaning with distilled water, 0.1 N HCl and 0.1 N NaOH and by heating at $370^{\circ}C$ for 30 min. It showed a typical weak acid-weak base titration curve and a short pH break like commercial activated carbon during photentiometric titration of pre-treated herb residue. The log-log plots in the Freundlich isotherm test were linear on the herb residue pre-treated with NaOH or HCl like commercial activated carbon. The adsorption capacity(qe) in the Freundlich isotherm test for $Cr^{6+}$ was 1.5 times higher in the pre-treated herb residue with HCl than in activated carbon. On the other hand the herb residue pre-treated with NaOH showed the good adsorption capacities for $Pb^{2+}$, $Cu^{2+}$ and $Cd^{2+}$ even though those adsorption capacities were lower than that of activated carbon. In kinetic test, most of heavy metals removed within the first 10 min of contact and then approached to equilibrium with increasing contact time. The removal rate of heavy metals increased with an increase of the amount of adsorbent. Likewise, the removal rates of heavy metals were higher in the herb residue pre-treated with NaOH than in that pre-treated with HCl. The adsorption preference of herb residues pre-treated with NaOH or HCl was $Pb^{2+}>Cu^{2+}$ or $Cd^{2+}>Cr^{6+}$ in the order. Conclusively, the herb residue can be used as an alternative adsorbent for the removal of heavy metals depending on pr-treatment methods.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.25-34
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• 2014

The objective of this study was to investigate the removal characteristics and the elimination mechanism of heavy metals in Acid Mine Drainage (AMD) using spherical-type porous Zeolite-StarFish ceramics (porous ZSF ceramics) packed in a continuous column reactor system. The average removal efficiencies of heavy metals in AMD were Al 98.7, As 98.7, Cd 96.0, Cu 89.1, Fe 99.5, Mn 94.4, Pb 96.3 and Zn 80.8 % during 110 days of operation time. The average removal capacity of porous ZSF ceramics for heavy metals were measured to be Al 21.76, As 1.52, Cd 1.27, Cu 3.41, Fe 44.83, Mn 3.48, Pb 2.36 and Zn $3.76mg/kg{\cdot}day$. The analysis results of mechanism using SEM, EDS and XRD exhibited that the porous ZSF ceramics could act as a multi-functional ceramics for the removal of heavy metals in AMD through the reactions of precipitation, adsorption and ion-exchange. The experimental results of column reactor system displayed that the porous ZSF ceramics would be a consistently efficient agent for the removal of heavy metals in AMD for a long term.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.97-101
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• 2021

Adsorption properties of heavy metals and organics in the mixed packed column of scoria and activated carbon, as well as physicochemical properties and functional groups of scoria were investigated. As the mixing ratio of scoria increased, the average removal ratios of cadmium, nickel, chromium, and lead ions increased, but that of benzene and toluene decreased. The mixed packed column of scoria and activated carbon could be effectively used for the simultaneous removal of heavy metals and organics. Scoria has Si-H and Si-O functional groups, and it was confirmed that Si-O functional groups greatly contributed to the adsorption of heavy metals.

• Membrane and Water Treatment
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• v.10 no.3
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• pp.239-244
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• 2019

Plating wastewater containing various heavy metals can be produced by several industries. Specifically, we focused on the removal of copper (Cu2+) and nickel (Ni+) ions from the plating wastewater because all these ions are strictly regulated when discharged into watershed in Korea. The application of both nanofiltration (NF) and reverse osmosis (RO) technologies for the treatment of wastewater containing copper and nickel ions to reduce fresh water consumption and environmental degradation was investigated. In this work, the removal of copper (Cu2+) and nickel (Ni+) ions from synthetic water was studied on pilot scale remove by before using two commercial nanofiltration (NF) and reverse osmosis(RO) spiral-wound membrane modules (NE2521-90 and RE2521-FEN by Toray Chemical). The influence of main operating parameters such as feed concentration on the heavy metals rejection and permeate flux of both membranes, was investigated. Synthetic plating wastewater samples containing copper ($Cu^{2+}$) and nickel ($Ni^{2+}$) ions at various concentrations(1, 20, 100, 400 mg/L) were prepared and subjected to treatment by NF and RO in the pilot plant. The results showed that NF, RO process, with 98% and 99% removal for copper and nickel, respectively, could achieve high removal efficiency of the heavy metals.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.740-744
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• 1994

This study was undertaken to prove the suppressing effect of green tea on the intestinal absorption of heavy metals using in vitro membrane filtration system. From drinking water contaminated with 10 and 100 times level of water quality standard for heavy metals, the removal ratio of lead (Pb) was $50{\sim}70%$ by green and black teas, and $30{\sim}40%$ by roasted barley tea. The removal ratio of cadmium (Cd) was $30{\sim}40%$ by green tea and black teas, and $10{\sim}20%$ by roasted barley tea. The removal effect from drinking water contaminated with both lead and cadmium was lower than that from water contaminated singly with lead or cadmium. It appears that tea components and filter membrane compete toward the adsorption of two heavy metals. Among the extraction conditions of raw tea materials at $70^{\circ}C$, 2 minutes and $95^{\circ}C$ , 10 minutes, the removal ratios of heavy metals were similar.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.979-983
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• 2009

The mean pH of wastewater discharged from the plating process is 2, so a less amount of alkali is required to raise pH 2 to 5. In addition, if sodium sulfite is used to raise pH 5 to 9 in the secondary treatment, caustic soda or slaked lime is not necessary or only a small amount is necessary because sodium sulfite is alkali. Thus, it is considered desirable to use only $FeSO_4{\cdot}7H_2O$ in the primary treatment. At that time, the free cyanide removal rate was highest as around 99.3%, and among heavy metals, Ni showed the highest removal rate as around 92%, but zinc and chrome showed a low removal rate. In addition, the optimal amount of $FeSO_4{\cdot}7H_2O$ was 0.3g/L, at which the cyanide removal rate was highest. Besides, the free cyanide removal rate was highest when pH value was 5. Of cyanide removed in the primary treatment, the largest part was removed through the precipitation of ferric ferrocyanide: $[Fe_4(Fe(CN)_6]_3$, and the rest was precipitated and removed through the production of $Cu_2[Fe(CN)_6]$, $Ni_2[Fe(CN)_6]$, CuCN, etc. Furthermore, it appeared more effective in removing residual cyanide in wastewater to mix $Na_2SO_3$ and $Na_2S_2O_5$ at an optimal ratio and put the mixture than to put them separately, and the optimal weight ratio of $Na_2SO_3$ to $Na_2S_2O_5$ was 1:2, at which the oxidative decomposition of residual cyanide was the most active. However, further research is required on the simultaneous removal of heavy metals such as chrome and zinc.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.2
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• pp.44-49
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• 2014

In order to remove the heavy metals from synthetic wastewater containing Pb, Cr, and Cd, the experiment was conducted with a variety of concentration and pH by using the washed and dried coffee grounds as adsorbent. Almost of the heavy metals were removed in thirty minutes and the removal efficiency was maximized to the 80 percents following the different pH conditions. Furthermore, in the case of Cr, the removal efficiency was declined with the increasing of pH. As a result of this study, coffee grounds is proved to be a very good adsorbent to remove the heavy metals.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.143-146
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• 2004

Natural zeolites have exhibited high sorption capacity for inorganic cations including heavy metals and ammonium. Moreover, they were proven to be effective for environmental applications such as permeable barriers for controlling the spread of cation-contaminated groundwater. However zeolites have little or no affinity for anionic species like chromium, as they possess a net negative structural charge. To achieve the simultaneous sorption for anionic contaminants, surfactant-modified zeolite (SMZ) has been employed as the possible sorbents. Current study focuses on simultaneous removal of heavy metals having different ionic form in aqueous solution, cadmium (C $d^{2+}$) and chromium (Cr $O_{4}$$^{2-}$), using newly developed materials, ZanF. ZanF, a potential alternative to SMZ, was derived from zeolite modified by Fe(II) chloride followed by reduction with sodium borohydride. Batch experiments were performed to estimate the removal efficiency of ZanF at different conditions. Under different pH ranging from 2 to 6, removal efficiency was investigated. And C $d^{2+}$ removal efficiency was estimated by varying background concentration of Cr $O_{4}$$^{2-}$, and vice versa. With the test results, ZanF was expected to be a possible reactive materials alternative to SMZ in permeable reactive barriers (PRBs) for treating the contaminated groundwater with cationic and anionic heavy metals.als.