• Journal of Soil and Groundwater Environment
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• v.24 no.1
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• pp.10-16
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• 2019

Alkalinity is an essential parameter for understanding geochemical processes and calculating partial pressure of $CO_2$, dissolved inorganic carbon, and mineral saturation indices. The Gran Titration Method (GTM) is one of the most accurate methods for measuring the alkalinity in water samples. However, this method has not been widely employed in measuring groundwater alkalinity in Korea, probably due to inadequate and insufficient understanding of the method. In this regard, this article was prepared to introduce GTM and related know-hows learned from the authors' experiences in measuring alkalinity. This paper also introduces a MS Excel-based alkalinity calculator as a handy tool for GTM.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.8
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• pp.583-590
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• 2011

The effect of the physical parameters in the reactor (aeration depth, bubble size, and surface area) and the alkalinity of the solution on the ammonia stripping by bubbling were evaluated. When an airflow of 30 L/min was bubbled below the solution surface in the range 6-53 cm, the ammonia removal rate were observed to be the same regardless of the bubbling depths. At pH 10.0 and a temperature of $30^{\circ}C$, the average rate constant and the standard deviation were $0.178h^{-1}$ and 0.004. No appreciable changes in the ammonia removal rate were also observed with varying the bubble size and the air-contacting surface area. Alkalinity of the solution was found to affect the ammonia removal rate indirectly. This is expected because the pH of the solution would vary with dissolution of gaseous $CO_2$ by air bubbling. The real wastewaters from landfill site and domestic wastewater treatment plant were tested. In the case of domestic wastewater (pH = 7.1, alkalinity = 75 mg/L), the ammonia removal rate was poor even with the control of pH to 9.3. The raw landfill leachate (pH = 8.0, alkalinity = 6,525 mg/L), however, showed the appreciable removal rate with increasing pH during aeration. When the initial pH of the leachate was adjusted 9.4, the removal rate was significantly increased without changing the pH during aeration.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.81-82
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• 2009

IEC 60456 declared the cocoa soiled cloth to be one of the standard soiled test cloths for measuring the performance of the clothes washing machines. Researchers for textile washing have known that cocoa soiled cloth has shown unpredictable washing performance. The color of cocoa mainly comes from flavonoids, and flavonoids reversibly change color with alkalinity from pH 1 to pH 7 as food colorants. The color change of flavonoids under various washing conditions, in the alkali solution, has not yet been confirmed. In this study, we have investigated the color change and the soil removal of the cocoa soiled cloth which were washed with alkaline washing liquids of various hardnesses. The cocoa soiled cloth which was washed in the water which was 60ppm or higher became darker than the soiled cloth. When the cloth was washed in the detergent solution, the cloth was slightly darker only when the washing condition was $20^{\circ}$ and 250ppm. As the water hardness increased, the soil removal decreased and the higher washing temperature was more effective.

• Journal of Environmental Impact Assessment
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• v.22 no.5
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• pp.427-437
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• 2013

Generation rate of construction wastes in Korea has occupied preponderantly in recent years. To understand chemical properties of recycled concrete aggregate (RCA), RCA samples were tested for their leaching characteristics. Leaching tests were conducted according to Korean Standard Leaching Test (KLT) and Toxicity Characteristics Leaching Procedure (TCLP) respectively. The RCA samples were characterized using X-ray fluorescence (XRF). Alkalinity of the leachate was determined using a pH meter titration method. The XRF analysis result shows that the calcium oxide (CaO) content in the RCA sample is 25.3~50.4 %. When the RCA sample was mixed with water in a batch reactor, pH in the solution was rapidly increased, and 70% of the total pH change was found in 1 hour. The TCLP showed slightly higher efficiency for leaching heavy metals than the KLT. The leaching efficiency was also higher as the particle size of RCA sample was smaller. The leaching test results suggest that RCA can be generally classified as nonhazardous waste.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.727-736
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• 2022

Ice wedges are subsurface ice mass structures that formed mainly by freezing precipitation with airborne dust and surrounding soil particles flowed through the active layer into the cracks growing by repeating thermal contractions in the deeper permafrost layer over time. These ice masses characteristically contain high concentrations of solutes and solids. Because of their unique properties and distribution, the possibility of harnessing ice wedges as an alternative archive for reconstructing paleoclimate and paleoenvironment has been recently suggested despite limited studies. It is imperative to preserve the physicochemical properties of the ice wedge (e.g., solute concentration, mineral particles) without any potential alteration to use it as a proxy for reconstructing the paleo-information. Thawing the ice wedge samples is prerequisite for the assessment of their physicochemical properties, during which the paleo-information could be unintentionally altered by any methodological artifact. This study examined the effect of thawing conditions and procedures on the physicochemical properties of solutes and solid particles in ice wedge samples collected from Cyuie, East Siberia. Four different thawing conditions with varying temperatures (4 and 23℃) and oxygen exposures (oxic and anoxic) for the ice wedge sample treatment were examined. Ice wedge samples thawed at 4℃ under anoxic conditions, wherein biological activity and oxidation were kept to a minimum, were set as the standard thawing conditions to which the effects of temperature and oxygen were compared. The results indicate that temperature and oxygen exposure have negligible effects on the physicochemical characteristics of the solid particles. However, the chemical features of the solution (e.g., pH, electric conductivity, alkalinity, and concentration of major cations and trace elements) at 4℃ under oxic conditions were considerably altered, compared to those measured under the standard thawing conditions. This study shows that the thawing condition of ice wedge samples can affect their chemical features and thereby the geochemical information therein for the reconstruction of the paleoclimate and/or paleoenvironment.