• Proceedings of the Korean Environmental Sciences Society Conference
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• 1997.10a
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• pp.67-67
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• 1997

정수공정은 "원수 -1 침사지 1 전염소 -1 전오존 -1 침전지 1 여과지 1 후오존 1 GAC 4 후염소 1 가정수"로 이루어져 있으며 전처리 공정으로 염 소와 오존을 주입하게 되는데, 여기서 전염소 처리 공정으로 인해 잔류 유리염 소가 수중의 유기물질과 반웅하여 유해성 유기염소 화합물 (i.e.. Trihalomethane, Haloacetonitriles, Chlorophenol 등)을 생성하는 것으로 알려져 있다. 이러한 이유로 고도 정수처리 공정에서는 강한 산화력을 지닌 대체 산화 제로서 오존을 이용하고 있다. 전오존 처리공정은 OOC와 탁도 제거에 있어 응 집제 주입량을 감소시키는 것과 더불어 전오존 효과 (산화, 생분해 증대, 살균 등)를 얻을 수 있는 것으로 알려져 왔다. 그러나 낙동강과 같이 유기물이 많은 원수에 과다한 오존이 주입되면 수중 의 유기물이 저분자화 또는 응집이 어려운 오존 산화물로 변화하여 응집제의 소비가 많아지게 된다. 실제, 오존을 응집 효과에 대해서 pilot plant로 운전한 결과 전오존에 의해 입자성 물질의 제거 효율은 향상된 반면에 유기물 제거는 뚜렷한 효과를 볼 수 없었다고 보고되었다 (류, 1997). 본 연구에서는 물금 지역의 원수와 응집-침전 공정까지 거치는 각각의 처 리수에 대해서 전처리가 응집에 미치는 영향을 천연유기물질 (NOM)의 조성 변화로 파악하였다. 그 방법으로 천연유기물질 (NOM)을 XAD-1, -4 수지를 이 용하여 소수성 물질 (hydrophobic components)과 친수성 물질 (hydrophilic components)로 분리 및 농축하여 용존 유기물이 처리 과정에서 어떻게 변화하 는지를 조사하여 개선된 상수 처리 시스템을 설계하는데 기초 자료를 제공하고 수질 관리 분야에서도 적용하고자 하였다. 상수원수인 물금 지역의 소수성 물질(hydrophobic components)은 75~80%, 친수성 물질(hydrophilic components)은 30~33%정도의 분포를 보였고, 전염소 및 전오존 공정을 거친 처리수에서는 각각 62.2-62.8%, 43.9~49.0% 및 50~ 55%, 40~57% 정도의 분포를 보였다. 그리고 웅집-침전을 거친 처리수에서는 그 분포가 77~82%, 24-48%였다. 전주리 공정을 통하여 소수성 물질(byoghobic components)의 분포가 감 소하는 것을 볼 때 전염소 및 전오존 처리가 용존유기물의 응집에는 오히려 역 효과를 나타내는 것으로 판단된다. 것으로 판단된다.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.749-754
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• 2010

In this study, rubber vulcanization property, change in physical property, morphology and chemical characteristics of blended rubber depending on various IR/CR ratio were investigated for the purpose of the improvement of material property and durability. The effect of surface treatment by chlorine on the friction coefficient was also studied with various conditions of surface treatment. In terms of vulcanization property, as the amount of CR content increased, the speed of cure was decreased, while the density of crosslinking stayed constant. It means hardness and modulus were increased as the CR content increased. It is related to change in cure property and mechanical strength was improved by the effect of crystallization reaction. In the aging property, as the CR content increases, the changed amount of basic properties were decreased, which acts as a reducing factor in change of aged property by complementing weak point in mechanical property. It was found that the degree of property change for surface treated samples were reduced. According to the microscopic result, the degree of surface dispersion on rubber blends was increased by increasing CR content. Rubber surface showed uniform direction in pattern with increased smoothness and luster by treatment with chlorine. The degree of rubber reforming was measured by the remaining amount of chlorine and the friction coefficient was dependent on the amount of chlorine combined with rubber. In the initial stage of surface treatment, from 10 to 40 phr, the friction coefficient of specimen was rapidly reduced. However, as the concentration of chlorine solution increased, the change in friction coefficient was decreased.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.223-229
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• 2022

This study was conducted to investigate the effect of packaging methods and sterilization treatment on storability and microbial control in paprika fruits. When treated with chlorine dioxide gas for 3, 6, and 12 hours and cold plasma gas for 1, 3, and 6 hours, and then packed in a carton box and stored in a 8 ± 1℃ chamber for 7 days, chlorine dioxide treated 12 hours and plasma treated 6 hours was prevented the development of E·coli and YM(yeast and mold). Accordingly, the control was treated with chlorine dioxide for 12 hours and plasma for 6 hours, packed using a carton box and 40,000 cc·m^-2·day^-1·atm^-1 OTR film (MAP), and stored in a 8 ± 1℃ chamber for 20 days. Fresh weight loss rate during storage was less than 1% in the MAP treatments, and the visual quality of the MAP treatments was above the marketability limit until the end of storage. There was no difference in the contents of oxygen, carbon dioxide, and ethylene in the film. In the case of firmness, the chlorine dioxide treatments was low, and the Hunter a^* value, which showed chromaticity, was highest in the Plasma 6h MAP treatment. Off-odor was investigated in the MAP treatments, but it was very low. The rate of mold growth on the fruit stalk of paprika was the fastest and highest in the chlorine dioxide treated box packaging treatments, and the lowest in the chlorine dioxide treated MAP treatments at the end of storage. The aerobic count in the pulp on the storage end date was the lowest in the plasma treated box packaging treatments, the lowest number of E·coli in the chlorine dioxide treated MAP treatments, and the lowest yeast & mold in the chlorine dioxide treated box packaging treatments. As a result, for the inhibition of microorganisms during paprika storage, it is considered appropriate to treat plasma for 6 hours before storage regardless of the packaging method.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.377-384
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• 2005

Algae causes not only the eutrophication of lake, but also the deterioration of drinking water process. Especially, algogenic organic matters(AOM) are assumed as disinfection by-products(DBPs) precursors like humic and fulvic acids. In this study, it was investigated the characteristics changes of algogenic organic matter(AOM) by prechlorination and coagulation treatment. Evaluation of enhanced coagulation and applicability of UV oxidation process were also evaluated as the drinking water treatment system for the eutrophicated water source. prechlorination was effective process for algae removal but caused releasing of dissolved organic matter(DOC) into water due to the destruction of algae's cell. In coagulation treatment with Fe(III) coagulant, reaction pH is an important factor for the removal of AOM and triholomathanes(THMs). At pH 5, removal efficiency of DOC and THMs were dramatically improved by 50% and 28%, respectively, in comparison with the conventional coagulation treatment at about pH 7. Photo-Fenton($UV/H_2O_2/Fe^{3+}$) process among the UV oxidations is the most effective system to remove AOM, but its removal efficiency was lower than that of enhanced coagulation treatment at pH 5.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.197-203
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• 2019

This study was carried out to investigate the effect of chlorine water and plasma gas treatment on the quality and microbial control of Latuca indica L. baby Leaf during storage. Latuca indica L. baby leaves were harvested from a plant height of 10cm. They were sterilized with $100{\mu}L{\cdot}L^{-1}$ chlorine water and plasma-gas (1, 3, and 6hours), and packaged with $1,300cc{\cdot}m^{-2}{\cdot}day^{-1}{\cdot}atm^{-1}$ films and then stored at $8{\pm}1^{\circ}C$ and RH $85{\pm}5%$ for 25days. During storage, the fresh weight loss of all treatments were less than 1.0%, and the carbon dioxide and oxygen concentrations in packages were 6-8% and 16-17%, respectively for all treatments in the final storage day. The concentration of ethylene in the packages fluctuated between $1-3{\mu}L{\cdot}L^{-1}$ during the storage and the highest concentration of ethylene was observed at 6 hours plasma treatment in the final storage day. The off-odor of all treatments were almost odorless, the treatments of chlorine water and 1 hour plasma maintained the marketable visual quality until the end of storage. Chlorophyll content and Hue angle value measured at the final storage day were similar to those measured before storage in chlorine water and 1 hour of plasma treatments. E. coli was not detected immediately after sterilization in all sterilization treatments. After 6 hours of plasma treatment, the total bacteria fungus counts were lower than the domestic microbial standard for agricultural product in all sterilization treatments. The total aerobic counts in the end storage day increased compared to before storage, whereas E. coli was not detected in all sterilization treatments. The sterilization effect against bacteria and fungi was the best in chlorine water treatment. Plasma treatment showed sterilization effects, but within a prolonged period of time. In addition, the sterilization effect decreased gradually. These results suggest that chlorine water and plasma treatment were effective in maintaining Latuca indica L. baby Leaf commerciality and controlling microorganisms during postharvest storage.

• Journal of Animal Environmental Science
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• v.18 no.sup
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• pp.1-6
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• 2012

This study was conducted to verify the effect of chlorine dioxide ($ClO_2$) on odor reduction at a commercial swine facility consisting of a compost ficility. Compost facility in $NH_3$ concentration was around 550 ppm and less than 78 ppm before and after the $ClO_2$ spraying, respectively, which was over 86% reduction. There was no H2S detection. $NH_3$ concentration was around 420 ppm and less than 35 ppm before and after the $ClO_2$ spraying, respectively, which was over 83% reduction. $H_2S$ concentration was around 210 ppb and less than 32 ppb before and after the $ClO_2$ spraying, respectively, which was over 85% reduction. Hence, $ClO_2$ spraying at windowless barns was compost facility decreased malodor such as $NH_3$.

• Membrane Journal
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• v.24 no.2
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• pp.88-99
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• 2014

Demand for water is increasing due to rapid population growth and increased industrial activities. Membrane technologies have attracted most attention as a promising advanced technology for the supply of sustainable water resources. Chemical and structural properties of polyamide membranes, one of the most widely used membranes in water treatment plant, has been reported to be affected by residual chlorine dissolved in water after chlorine disinfection. This paper focuses on the chlorine speciation at various solution pHs and change of surface properties/performance of polyamide membranes due to the chlorine exposure.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.105-111
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• 2017

This study was conducted to evaluate the effects of pH control and ozonation, coagulation on trihalomethanes (THMs) formation during prechlorination of the Nakdong river water. The results showed that lower pH was reduced THMs formation during prechlorination. THMs formation of water lowered pH 9.5 to 9.0, was reduced 18.3% and lowered pH 9.0 to 8.0 was reduced 14%, lowered pH 8.0 to 7.0 was reduced 7%, lowered pH 9.5 to 8.0 was reduced 29%. A low ozone dose ($0.11{\sim}0.48mg{\cdot}O_3/DOC$) before chlorination reduced the yields of THMs (reduced 6~24% in chlorination) compared with no preozonation. Thus the low ozone dose pretreatment is relatively effective plan to reduce THMs formation during chlorination. When ozone 1.0 mg/L, Alum 40 mg/L and sulfuric acid 6 mg/L dosed, The yields of THMs formation was reduced 42% compared with only chlorination. Input of chlorine after preozonation (followed coagulation, pH control) is more effective than only decline pH at a intake station to control THMs formation in a water treatment process. When chlorine 2.5 mg/L was added before coagulation (alum 40 mg/L), THMs formation was reduced 19% by lower pH and decreased 18% by a natural organic matter (NOM) removal compared with only chlorine 2.5 mg/L addition. Because coagulation could induce simultaneously lower pH and NOM removal, THM formation concentration is more effectively lowed than decreasing pH in the Nakdong river water.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.721-728
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• 2008

DBPs(Disinfection By-Products) are most formed through the reactions between chlorine and NOM(Natural Organic Matter) in water treatment. In this study, occurrence of DBPs including THMs(Trihalomethanes) is evaluated. Also, influencing factors by the seasons and raw water quality were investigated for correlation among them and the characteristics of THMs formation by prechlorination process. This study investigated the operation condition for THMs removal depending on raw water quality. Water treatment plant from intake station to gauging well flows for about 10 hours in Y Water Supply Office. It is limited to control of THMs formation because of excessive reaction time between chlorine and THMs precursors in the intake station. Therefore, as multi-points prechlorination from intake station to gauging well, THMs formation was decreased in the water treatment, and it was willing to prevent overdosage of chlorine. The concentration of THMs was 0.021 mg/L in the summer, 0.015 mg/L in the winter, respectively. Also, THMs formation showed that 0.013 mg/L in the water of gauging well after prechlorination, 0.014 mg/L in the flocculation/sedimentation/filtration, 0.016 mg/L in the water after postchlorination, respectively. THMFP(Trihalomethane Formation Potential) removed 42.7% and 50% through the flocculation/sedimentation and filtration, respectively, and it is similar TOC removal efficiency. In this study, multi-points prechlorination from intake station to gauging well decreases in contact time and concencrations of NOM and chlorine. Also, it decreases in THMs and amount of chlorine uesd. In the result of multi-points prechlorination in the summer, the concentration of THMs was 0.013mg/L in the treated water. In view of these facts, THMs formation can be decreased approximately 50%.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.1-6
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• 2012

Down Stream K River has high COD (4-10 mg/L) and high $NH_3$-N concentration (3.5 mg/L during winter period). Although $NH_3$-N itself is not reported harmful at this level, it must be removed to meet drinking water standard (0.5 mg/L). We constructed a pilot plant modifying the processes of conventional drinking water facilities. Prechlorination and powdered activated carbon (PAC) dechlorination was adopted prior to a flocculation tank to remove ammonia and prevent disinfection byproducts (DBPs) formation. Also, GAC processes was included after sand filter to remove residual DOC. This pilot having a capacity of 36 ton/day was operated for one year. The GAC processes were successful to remove ammonia and many organic pollutants (DOC, MBAS, UV-254 nm absorbance, etc). Influent DOC concentrations were very high as 3~6 mg/L throughout the plant operation. It was impossible to achieve 1.0 mg/L effluent DOC, indicating that bed depth (2 m) should be increased to achieve more strict DOC quality standards. When $Cl_2$ dose was well controlled ($Cl_2/NH_3$-N ratio 10~11 on a weight basis), $NH_3$-N removal was 98% and THMs was very low possibly due to low free residual chlorine and PAC dechlorination.