• Journal of Korean Society of Water and Wastewater
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• v.20 no.1
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• pp.156-163
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• 2006

While sludge is settling in batch column, sludge concentration becomes high. Because the characteristic of sludge settling changes in function of time due to the sludge concentration change, the sludge settling velocity changes too. Also, because the sludge settling characteristic is influenced by a physical characteristic of sludge and a column height etc, it is difficult to exactly measure the sludge settling characteristic. Although the sludge volume indexes, SVI, SSVI and $SSVI_{3.5}$, are used to predict sludge settling characteristic, these indexes are not reliable values. Because the previously established models for sludge settling velocity predict the sludge settling velocity only, it is difficult to predict sluge-water interface height by using those models. The purpose of this experiment is to establish the empirical model which predicts the sludge interface height change with respect to the sludge physical characteristic and the settling condition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.233-236
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• 2002

다양한 산업활동에 의하여 발생하는 6가 크롬 (Cr(Ⅵ))은 대표적인 토양 및 지하수 오염물질이다. Cr(Ⅵ)은 3가크롬(Cr(III))로의 환원에 의한 침전반응으로 이동성이 저하된다고 알려져 있다. 본 연구에서는 기존의 고형화/안정화 공정에 환원.분해 반응을 추가한 2가철 기반 분해성 고형화/안정화(Degradative Solidification/Stabilization)공정에 의한 Cr(Ⅵ) 처리 특성을 고찰하였다. 회분식 실험결과 cemen/Fe(II) system내에 Cr(Ⅵ)은 환원반응 뿐만 아니라 cement에 의한 침전에 의해서도 제거됨이 밝혀졌다. Cr(Ⅵ)의 제거속도는 Fe(II)의 반응당량에 비례하는 것으로 보여진 반면, cement/solution ratio에 따른 Cr(Ⅵ) 제거동역학의 차이는 그다지 크지 않았다

• Korean Journal of Crystallography
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• v.14 no.1
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• pp.35-38
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• 2003

A simple multistep-concentration setting in capillaries was used to control the water-evaporation rate in vapor-diffusion protein crystallization. In the method used, a variety of evaporation rate curves were obtained by using the secondary precipitant solution referred to as “regulatory solution”, which is not directly exposed to the protein solution. The curves were applied to the crystallization of lysozyme as a model protein. The results clearly showed that crystal growth is dependent on the evaporation rate. Especially, the decoupling curves in which precipitant concentration in protein solutions increases to a certain point and then decreases to the equilibrium concentration gave the best crystals.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.798-807
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• 2008

Due to economic impairment derived from metal corrosion of pumping station installed around coastal area, it was needed for related cause-effect to be investigated for understanding practical corrosion behavior and providing proper control. This research was thus carried out to determine whether the microbe can influence on metal corrosion along with its control in the laboratory. For this study, groundwater was sampled from the underground pump station(i.e. I Gas Station) where corrosion was observed. Microbial diversity on the samples were then obtained by 16S rDNA methods. From this, microbial populations showing corrosion behaviors against metals were reported as Leptothrix sp.(Iron oxidizing) and Desulfovibrio sp.(Sulfur reducing) Iron oxidizing bacteria were dominantly participating in the corrosion of iron, while sulfate reducing bacteria were more preferably producing precipitate of iron. In case of galvanized steel and stainless steel, iron oxidizing bacteria not only enhanced the corrosion, but also generated its scale of precipitate. Sulfate reducing bacteria had zinc steel corroded greater extent than that of iron oxidizing bacteria. In the inactivation test, chlorine or UV exposure could efficiently control bacterial growth. However as the inactivation intensity being increased beyond a threshold level, corrosion rate was unlikely escalated due to augmented chemical effect. It is decided that microbial corrosion could be differently taken place depending upon type of microbes or materials, although they were highly correlated. It could be efficiently retarded by given disinfection practices.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.1
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• pp.147-155
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• 2006

For the further study of the solids flux theory, several researchers have proposed models to predict sludge settling velocity for each different concentration by using sludge indexes, SVI, SSVI and $SSVI_{3.5}$. It is difficult to apply the above models to predict sludge-water interface height in a batch column because sludge settling velocity changes while sludge settle down. While sludge settle down in a batch column, sludge concentration becomes high. The sludge concentration change is one of the most critical causes of the change of sludge settling velocity. Also, sludge concentration change causes of sludge index to change. SVI is more sensitive than SSVI or $SSVI_{3.5}$ to the change of sludge concentration. Each sludge has physical characteristics of its own which makes the settling velocity for each sludge different. The purpose of this study is to establish the correction factors that are able to compensate the errors derived from each different sludge settling characteristic by using sludge indexes, therefore the correction factors are applicable to the model for the change of sludge-water interface height.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.126-130
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• 1998

Aluminum sulfate, $AI_{2}(SO_4)_3\cdot18H_2O$ was prepared by adding of kaolin-dissolved sulphuric acid into ethanol and its thermal decomposition behavior was discussed. As-synthesized high purity precipitate particles were platelike shapes of $2\mu\textrm{m}$ size. With increasing drop rate of leach liquor into ethanol, the crystallite sizes of the precipitate decreased. The apparent activation energies for dehydration and sulfate decomposition of the precipitate were $11.9Kcal mol^{-1}$ and $48.2kcal mol^{-1}$ respectively.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.295-302
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• 2006

Over the past decades, a flocculation and/or sedimentation process have been adopted to remove pollutants from CSOs. It has been learned that major factors affecting settlement of pollutants are the particle size distribution, their settling velocities and their specific gravity. It is, therefore, a good idea to analyze the particle size distribution and settleability of CSOs pollutants in order to develop details in designing a process. Discussed in this study are pollutant characteristics of CSOs such as particle size distribution and settleability of pollutants. The power law function is applied and is found to be an effective and reliable index for expressing the particle size distribution of pollutants in CSOs. Based on the regression analysis it is observed that the derived constants of curves representing settling velocity profile are proportional to the initial concentration of particles and to the ${\beta}$-values of power law distributions.

• Clean Technology
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• v.7 no.1
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• pp.35-42
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• 2001

This study was performed to evaluate the effect of zeolite addition on biofloc in aictvated sludge process. Two units were compared each other, in which one was operated as control unit (CU) and the other was managed by adding zeolite into aeration basin to sustain 4,000 mg/l (ZU). It was observed that flocs of both units were enduringly increased in medium size by extending SRT (Solid Retention Time), although their effect size of ZU was smaller than theirs of CU. Zeolite application excessively improved sludge settling property and ZU presented sludge settling velocity of 3.4 to 11 m/h regardless of SRT variation. The sludge volume index (SVI) was in the range of 50 and 108 ml/g. Conversely, the sludge settling velocity of CU seriously depended on SRT increase, and sludge sedimentation was not achieved at a 40 days of SRT due to Sphaerotilus appeared predominantly in reactor.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.629-635
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• 2012

This study was conducted to evaluate the removal behaviors of DOM(dissolved organic matter) and phosphorus in eutrophic lake water by coagulation process with PAC(powdered activated carbon). It was observed that the removal characteristic of soluble matter was different from that of dissolved one, and the removal of DOM was effected by both pH and coagulant dosage. It was founded that PAC could increase the removal efficiency by an adsorption of DOM in coagulation process. A formation of soluble and colloidal matters resulted in the degradation of phosphorus removal efficiency in a chemical precipitation process. The phosphorus removal efficiency could be enhanced by an absorption of colloidal matter and dissolved complex with PAC addition. In addition, the PAC addition caused the increase of floc density in coagulation process, that led to the rise of sedimentation rate, and resulted in a significant improvement of solid-liquid separation efficiency.

• The Korean Journal of Food And Nutrition
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• v.19 no.3
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• pp.288-295
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• 2006

This study was conducted to examine the possibility of improvement effect in suppression of precipitation and nasty smell creation in Takju mash. First of all, gum shown to be lowest precipitation velocity was selected and this was applied to the fermentation of Takju mash for comparing with the control in terms of fermentation aspects and various qualities of Takju mash. Precipitation amount and precipitation velocity of suspension in Takju mash added with carrageenan was shown to be the lowest than that of others. Compared with the control, alcohol was highly generated in Takju mash added with carrageenan, especially between two and four days. Total acidity was shown to be highly increased until 2 days in Takju mash and thereafter to be slightly increased. Takju mash added with carrageenan was shown to be lower on the second stage than the control. Fusel oil produced from mash added with carrageenan was 0.046${\sim}$0.113${\mu}$l/ml and mash added with carrageenan generated less fusel oil than the control by 1.6${\sim}$3.2 fold. Yeast growth on the mash added with carrageenan was revealed to be helpful during fermentation periods. In general, sensory characteristics of Takju mash were shown to be more superior in mash added with carrageenan than in other samples. While nasty smell produced from a sample without gums was perceived after 2 days of Takju mash storage, nasty smell of Takju mash added with carrageenan was recognized after 6 days during storage. In conclusion, precipitation of suspension and nasty smell production in Takju mash were found to be suppressed by addition of carrageenan during Takju fermentation.