• Journal of Korean Society of Water and Wastewater
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• v.34 no.5
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• pp.373-383
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• 2020

The purpose of this study was to evaluate the corrosion damage of large diameter metallic pipes buried in reclaimed land due to the corrosion effect by soil, and to propose a method of installing metal pipes in the reclaimed land. The results are as follow. First, the soil of the reclaimed land was gray clay, the soil specific resistance indicating soil corrosiveness was at least 120 Ω-cm, the pH was weakly acidic(5.04 to 5.60), the redox potential was at least 62 mV, the moisture content was at most 48.8%, and chlorine ions and sulfate ions were up to 4,706.1 mg/kg and 420 mg/kg. Therefore, the overall soil corrosivity score was up to 19, and the external corrosion effect seems to be very large. Second, the condition of straight part of pipes was in good condition, but most of KP joints were affected by corrosion at a severe level. The reason for this seems to be that KP joints accelerated corrosion due to stress and crevice corrosion in addition to galvanic corrosion in the same environment. Third, as a result of evaluating correlations of each item that affects the corrosion on the external part, the lower the soil resistivity and redox potential, the greater the effect on the KP joints corrosion, and the moisture content, chloride ion, and sulfate ion, the higher the value, the greater the effect on the corrosion of KP joints. In addition, among soil corrosion items, the coefficient of determination of soil resistivity with corrosion of KP joints was the highest with 0.6439~0.7672. Fourth, when installing metal pipes or other accessories because the soil of the reclaimed land is highly corrosive, it is necessary to apply a corrosion preventive method to extend the life of pipes and prevent leakage accidents caused by corrosion damage to the joint.

• Resources Recycling
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• v.13 no.4
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• pp.23-31
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• 2004

Basic studies have been conducted regarding the attempt of the utilization of waste Undaria pinnatifida as an adsorbent for the adsorption treatment of lead-containing wastewater. Undaria pinnatifida was found to be chiefly composed of hyo-carbonaceous compounds and have a fairly high specific surface area, which suggesting the possibility of its application as a Potential adsorbent. The electrokinetic Potential of Undaria pinnatifida particles was observed to be negatively highest at around pH 8 and the fact that its electrokinetic potentials are negative at the whole pH range supported it might be an efficient adsorbent especially for cationic adsorbates. Under the experimental conditions, $Pb^{2+}$ was found to mostly adsorb onto Undaria pinnatifida within a few minutes and reach the equilibrium in adsorption within ca. 30 minutes. The adsorption of $Pb^{2+}$ was exothermic and explained well by e Freundlich model. Acidic pretreatment of Undaria pinnatifida enhanced its adsorption capacity for $Pb^{2+}$ , however, the reverse was observed for alkaline pretreatment. The formation of organometallic complex between $Pb^{2+}$ and some functional groups on the surface of Undaria pinnatifida was considered to be one of the main drives for adsorption. Finally the adsorbability of$ Pb^{2+}$ was examined to be rather affected by several solution features such as the coexistence of other adsorbate, the variation of ionic strength, and the concentration of complexing agent.

• Journal of Soil and Groundwater Environment
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• v.13 no.3
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• pp.52-58
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• 2008

Mn-impregnated activated carbon (Mn-AC) prepared at different conditions was applied in the treatment of synthetic wastewater containing both organic and inorganic contaminants. Phenol and As(III) was used as the representative organic and inorganic contaminants, respectively. After evaluation of the physicochemical characteristic and stability of Mn-AC, oxidation of As(III) as well as adsorption of phenol by activated carbon(AC) and Mn-AC were investigated in a batch reactor. To investigate the stability of Mn-AC, dissolution of Mn from each Mn-AC was measured pH ranging from 2 to 4. Although Mn-AC was unstable at a strong acidic condition, the dissoluted Mn was below 3 ppm at pH 4. XRD analysis of Mn-AC indicated that the mineral type of the impregnated manganese was $Mn_2O_3$. From the simultaneous treatment of As(III) and phenol by AC and Mn-AC, As(III) oxidation by Mn-AC was greater than that by AC at lower pH, while the reverse order was observed at higher pH. After impregnation of Mn onto AC, 13% decrease of the surface area was observed, causing 8% reduction of phenol removal. Considering removal properties of As(III) and phenol, Mn-AC could be applied in the simultaneous treatment of wastewater contaminated with multi-contaminants.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.560-568
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• 2007

The objectives of this study were to analyze ecological effects on effluents from the Sagok Stream (Chonnam province) as an abandoned mine drainage through necropsy-based health assessments and fish exposure tests, and to conduct In situ field pilot tests for restoration of stream water. Also, we analyzed water quality including general parameters and heavy metals. The tests were performed three times on April 2005, April 2006, and April 2007. Also, we constructed a reactor facility in the outflowing point of the abandoned mine for the remediation of AMD wastewater. In lab test, death rates in all three treatments were ${\geq}50%$ in the experiments. Necropsybased fish tissue assessments using the Health Assessment Index (HAI), indicated that the most frequently damaged tissue was liver (average: 20.8). Values of Health Assessment Index were lower in the control than any other treatments of T1, T2, and T3 and three treatments showed a distinct toxicity impacts by the AMD. In situ lethal test, concentration of Fe, Al and Zn decreased particularly by 85%, 99% and 94%, respectively through the disposal facility. Values of pH, ranged from 3.1 to 7.0, increased by 2.3 fold (mean=5.1) along with the reduction of metal contents. All fishes in P1 cage died 100% on 3 days later after the experimental setting, while all fishes in the P6 died 100% on 9 days later. Overall, these results evidently provide a key methodology for pilot test using the disposal facility and also clarify the toxicity of AMD once again, so this approach used in the pilot facilities here may reduce the acidic and toxic effects in the abandoned mining drainage.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.166-172
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• 2013

The purpose of this study is to evaluate the treatment ability of refractory organics in hot rolling precess waste water by redox(reduction and oxidation) reaction. Metal is oxidized in an aqueous solution to generate electron which can reduce water to generate hydroxy radical. These hydroxy radical is very effective to conduct hydrogen abstraction reaction and addition reaction to the carbon - carbon unsaturated link. The surface area of metal alloy reaction material is more than enough to get equilibrium at a single treatment. The efficiency of COD treatment by redox reaction showed maximum at mild pH of pH 7 and pH 6. But it was not effective in acidic atmosphere of pH 3, 4, 5 and basic atmosphere of pH 8 or over. Redox reaction system in much more helpful in a commercial coagulation sedimentation treatment than exclusive system.

• Journal of environmental and Sanitary engineering
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• v.10 no.2
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• pp.1-12
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• 1995

Under accelerated industrial developments environment pollution comes out to be very stirious. Especially the ions of heavy metal from wastewater, even if they are minimal, accumulated in ecology circle and do finally injury to human health. The general process for removal of heavy metals include coagulation and following sedimentation, ion -exchange and active carbon adsorption and sedimentation that applicate in popular, needs the expense of coagulant the additional treatment of sludge on the general process of coagulation and sedimentation. It is also a serious problem that the second pollution caused by coagulant. However chelating adsorption that uses natural chelating high- molecular compound has not pollution problem Among chelating high- molecules, the diminishing chitin that contained in crustaceans as crawfish and crab in our country with affluent water resources are easy to get. So it is advantageous to use this ubiquitous material for removing heavy metals because we could reuse natural resource. In this research, the author tested the effectiveness of the adsorption and removal of heavy metal ions by chitin and its derivatives. Chitin and cellulose became beads and used as flocculant, in this test. The results are as follows . First, bead showed higher removal ratio than powder in the comparative test on adsorbents such as chitin, chitosan and cellulose. Secondly, in the variety test by the kinds of adsorbent and time. chitosan bead and cellulose bead that showed the highest removal ratio. One hour need to remove the ions of heavy metal. Thirdly, the results of the adsorption degree test by pH revealed high removal ratio adsorption of chitin, cellulose and chitosan bead in alkalin condition but chitosan bead in acidic condition.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.180-186
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• 2005

This paper discusses the development of mixtures for silica fume as a stabilization/solidification agent and a binder for industrial wastewater residue containing organic and heavy metal contaminants. The UCS (unconfined compressive strength) gradually increased to 66.7% as the silica fume content increased to 15%. The leaching of TOC (total organic carbon) and chromium decreased as more OPC (Ordinary Portland Cement) was substituted with the silica fume. When a mixture had 5% silica fume, it retained about 85% TOC, and chromium leached out 0.76 mg-Cr/g-Cr in acidic solution. Also, microstructural studies of the solidified analysis showed that the silica fume caused an inhibition to the ettringite formation which did not contrilbute to setting but coated the cement particles and retarded the setting reactions. The results indicated that the incorporation of silica fume into the cement matrix minimized the detrimental effects of organic materials on the cement hydration reaction and the contaminant leachability.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.733-742
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• 2000

Fundamental materialistic characterization and adsorption/neutralization behavior of waste egg shell for heavy metal ion have been studied for its application to wastewater treatment. To investigate the structural change and thermal decomposition characteristics of egg shell. X-ray diffraction and FT-IR analysis were conducted for egg shell treated at $105^{\circ}C$ and $700^{\circ}C$, respectively. For the result of FT-IR analysis, the sample treated at $700^{\circ}C$ showed a reduced C-O absorption band compared with that of egg shell treated at $105^{\circ}C$, which may be due to the $CO_2$ release. Unlike to the result of FT-IR analysis, the XRD patterns of egg shell were almost similar for the cases of $105^{\circ}C$ and $700^{\circ}C$ treatment. however, characteristic diffraction pattern of CaO was observed for $850^{\circ}C$ treatment, at which $CaCO_3$ is known to be completely converted to CaO. TGA/DTA analysis showed a slow decline in weight loss up to $600^{\circ}C$ and, for $600{\sim}800^{\circ}C$ range, the weight loss became drastic by reason of $CO_2$ discharge, which was accompanied by an appearance of major endothermic peak. The ratio of practical breakthrough time to ideal one, total transfer unit, and mass transfer coefficient were observed to be increased as the adsorption was progressed in a multiple-column fixed-bed reactor using egg shell as an adsorbent, which signified the distribution effect of mass transfer for continuous adsorption reaction. The neutralization effect of egg shell for several types of acidic wastewater made of different mineral acids was not much different from each other except for the case of $H_2SO_4$, for which the neutralization reaction was thought to be retarded by the formation of gypsum.

• Clean Technology
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• v.26 no.3
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• pp.177-185
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• 2020

All coal ash, generated from coal-fired power plants, is entirely dumped onto a landfill site. As coal ash contains 80% fly ash, a clean floating process was developed in this study to recover useful components from coal ash and to use them as high value-added industrial materials. When the unburned carbon (UC) was recovered from the fly ash, soybean oil, an eco-friendly vegetable oil, was used as collector instead of a non-ionic kerosene collector to prevent the occurrence of odor from the kerosene. After the UC was separated by flotation, particulate ceramic microsphere (CM) was recovered, without generating acidic wastewater, through hydro-cyclone instead of sulfuric acid solution in order to separate ceramic microsphere (CM) and cleaned ash (CA) from the residue. By utilizing soybean oil as a collector, the recovery rate of UC turned high at 85.8% due to the increased adsorption of UC, the high viscosity of soybean oil, and the increase in floating properties caused by the linoleic acid contained in soybean oil. All of the combustible components contained in the recovered UC were carbon components, with the carbon content registering high when soybean oil was used. The recovered UC had many pores with a rough surface; thus, it could be easily ground and then used as an industrial material for its fine particles. The CM and CA recovered by the clean separation process using hydro-cyclone had a spherical shape, and the particles were clearly separated without clumping together. The average diameter (D₅₀) of the particles was 5 ㎛, so it was possible to realize the atomization of CM through a process change.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.2
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• pp.136-143
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• 2013

In the sewage structures and wastewater facilities, concrete is exposed to hydrogen sulfide ($H_2S$) which acts as an acid material in a solution, and a strongly acidic sulfate ion ($SO{_4}^{-2}$) is generated by a sulfuric bacteria. Hence, a degradation of concrete with biochemical corrosion would be accelerated. Finally, durability of concrete and concrete structures may be greatly reduced. In this study, in order to remove the hydrogen sulfide which is used by the sulfuric bacteria organic-biologically, the antibiotic metal and metallic salt powders were mixed to concrete, and a suppressing performance of the sulfate ion was assessed. For the sulfuric acid bacteria, a comparative evaluation of antimicrobial performance on neutralized concrete specimens were carried out, also by a rapid chloride penetration test, chloride penetration depths and diffusion coefficients were measured for antibiotic concrete in accordance with the amount of metal and metallic salt-based antibacterial agents. Eventually, by an observation of the biochemical state of the surface of concrete specimens exposed outdoors, the performance and applicability of antibiotic concrete were confirmed.