• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.505-510
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• 2000

In this study the effects of pre-chlorination on the coagulation of water which contain Microcystis aeruginosa. were investigated on the laboratory scale. We prepared the sample of $10^5cell/mL$ Microcystis aeruginosa and then applied 0.2, 1.0, 10 mg-Cl/L chlorine on the sample After reaction period(1 minute and 1 hour), each sample was coagulated. As a result, after 0.4 mg-Al/L coagulant dose, turbidities of all samples were below 2 mg-Kaolin/L. Turbidity was not affected by chlorine dose. As the dose of chlorine was increased, the residual aluminum was decreased, but result of $UV_{254}$ was adverse.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.445-448
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• 2008

The application of the membrane filtration process has been increased for the drinking water treatment system because of excellent quality of treated water compared with the sand filtration process. The selection of suitable pre-treatment processes and optimum flux according to the characteristics of raw water are important factors for the design of membrane processes. In this study, the most efficient pre-treatment processes for drinking water was selected by investigating the effects of pre-treatment processes on the operational stability of the membrane filtration process. Both lab-scale and pilot-scale experiments were conducted. In the lab-scale test, the effect of pre-treatment processes on the stability of the membrane filtration process was investigated indirectly by comparing the performance of membrane flux for raw water, pre-treated water, and membrane permeated water. In the pilot-scale test, the usefulness of prefiltration processes was assessed by comparing the performance of single membrane process and hybrid coagulation-membrane process. The results indicated that the coagulation process contributed to the stabilization of trans-membrane pressure (TMP) by removing contaminants on membranes, though the pre-filtration process had little effect on the TMP.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.39-50
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• 2017

In the coagulation/sedimentation (C/S) process of the water treatment process, the inflow of massive algal bloom causes many problems including fouling of filter media. This study was conducted to find out the way to remove the algae's harmful effects by addition of pre-treatment prior to C/S process. Many Jar-tests were conducted such as (1) ACF (Algae Coagulation Flotation) process using natural algae coagulant (Water $Health^{(R)}$), (2) ACF + C/S process and (3) C/S process with a variety of conditions using cultured algae. The average values of turbidity were (1) 0.42 NTU for ACF process, (2) 0.13 NTU for ACF + C/S process and (3) 0.25 NTU for C/S process. It was shown that the treatment efficiency of ACF process could get low turbidity results, and ACF + C/S process could achieve more efficient results than those of C/S process. Any negative effects of ACF process to the efficiency of C/S process were not observed in ACF + C/S process. In order to reduce the unfavorable effects of algae, it was found out that the introduction of ACF process in the forms of (1) ACF or (2) ACF + C/S could be one of the effective and alternative solutions.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.13 no.1
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• pp.23-29
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• 2010

Purpose: The aim of this study was to assess the benefits of routine pre-endoscopy coagulation screening tests and platelet counts in Korean children. Methods: Between March 2004 and December 2009, children who underwent gastrointestinal endoscopy for the evaluation of various gastrointestinal symptoms were included. All of the subjects included in the study also underwent routine coagulation screening and platelet count determinations prior to endoscopy and biopsy. The clinical records and laboratory tests were retrospectively reviewed in all patients. Results: One hundred sixty-two of 1,476 (11%) patients who underwent endoscopy had abnormal results on pre-screening coagulation tests. Fourteen patients underwent coagulation factor assays due to abnormal clotting results in consecutive tests or due to clinical evidence of a bleeding tendency. Seven patients were diagnosed with factor XII deficiency, one patient was diagnosed with von Willebrand disease, one patient had von Willebrand disease and factor XII deficiency, and one patient was presumed to have mild hemophilia. The remaining 4 patients had normal results with the factor assays. The results of platelet counts were normal with the exception of 1 patient. No patient had significant bleeding during the endoscopic procedures, despite abnormal pre-endoscopic coagulation tests. Conclusion: Routine coagulation screening tests and platelet counts revealed abnormal results in some patients. Most of the patients with abnormal clotting were shown to have a factor XII deficiency, which had no significant associated bleeding tendencies; the other patients were diagnosed with hemophilia or von Willebrand disease. Therefore, although abnormal pre-endoscopic coagulation is not always related to significant bleeding complications, pre-endoscopic coagulation screening may be useful in some children in predicting the risk of bleeding tendency during endoscopic procedures.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.522-528
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• 2004

Microfiltration with in-line rapid coagulation for drinking water production was examined. The in-line rapid coagulation was conducted using newly developed mixing device instantaneous flash mixer. The flux decline during membrane filtration was monitored with coagulant dosage varied. Flux decline was minimized at 1.1mg/L of coagulant dosage, where streaming potential of coagulated water was near zero. The optimum dosage for the process control was explained by dimensionless distance (${\kappa}{\times}a$) of particle pairs, obtained from electrophoresis parameter describing electrostatic repulsion relative to Van der Waals energy between particle pairs in the pre-coagulated water.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.2059-2065
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• 2000

The purpose of this study is to improve coagulation efficiency by pre-treatment of high pH water using sulfuric acid. The common reason of pH increasing at down stream of Nakdong river is water blooming. The pH go above 9.0 during water blooming periods. The higher pH water demands more coagulant and pre-chlorine dosage than lower pH water for better coagulation condition. The DOC, THMFP, UV-254 after coagulation with the same coagulant dosage by pre-treatment from pH 9.2 down to 8.1 with sulfuric acid are 1.84mg/L, $51{\mu}g/L$ and $0.032cm^{-1}$, by pretreatment of chlorine are 2.09mg/L, $78{\mu}g/L$ and $0.030cm^{-1}$, by pre-treatment of sulfuric acid and chlorine are 2.14mg/L, $72{\mu}g/L$ and $0.031cm^{-1}$ respectively. Pretreatment with sulfuric acid can improve water quality and reduce coagulant demand.

• Membrane and Water Treatment
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• v.14 no.2
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• pp.77-83
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• 2023

As a result of algal bloom, algal organic matters (AOMs) are rapidly increased in surface water. AOMs can act as precursors for the formation of harmful disinfection by-products (DBPs), which are serious problems in water treatment and human health. The main aim of this study is to characterize the formation of DBPs from AOMs produced by three different algae such as Oscillatoria sp., Anabaena sp., and Microcystis aeruginosa under different algal growth phases. In an effort to examine formation of DBPs during chlorination, chloroform (TCM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were determined under various CT (product of disinfectant concentration and contact time, mg·min/L) values. Generally, the amounts of DBPs tended to increase with increasing CT values at the most growth phases. However, there was a significant difference between the amounts of DBPs produced by the three algal species at different growth phases. This result is likely due to the chemical composition variability of AOM from different algae at different growth phases. In addition, the effect of pre-ozonation on coagulation for the removal of AOMs from three algal species was investigated. The pre-ozonation had a positive effect on the coagulation/flocculation of AOMs.

• YAKHAK HOEJI
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• v.56 no.6
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• pp.382-389
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• 2012

Effects of citrate-capped silver nanoparticles (AgNPs) on the blood coagulation and platelet aggregation were investigated using whole blood, platelet rich plasma (PRP) and washed platelet obtained from SD male rats. To confirm the stability of AgNPs in the test, size distribution of the nanoparticles was measured in the vehicles including distilled water, serum, and platelet buffers. The average size of AgNPs was 20 nm in the vehicles, which means that the stability was maintained during the whole experimental period. When blood coagulation was monitored by using whole blood impedance aggregometer, coagulation was not observed at the concentration of 1, 10 and 50 ppm. Platelets in plasma or in buffer were not aggregated by AgNPs at the concentration of 1, 2 and 4 ppm, respectively. The test concentration of AgNPs could not be increased because the dark color of the nanoparticles impeded the transmission of light, which is an indicator of aggregation. Although the blood or platelets were pre-activated by collagen, thrombin, or ADP with sub-threshold level, aggregation was not observed at the test concentration. Microscopic observation also supported the result obtained by the aggregometer.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1139-1145
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• 2008

The objectives of this research are to investigate the mechanism of coagulation affecting UF and find out the optimum conditions of the combined of coagulation with UF membrane filtration for NOM removal. During the mixing period, substantial changes in particle size distribution occurred under rapid and slow mixing condition due to the simultaneous formation of microflocs and NOM precipitates. Therefore, combined pretreatment using coagulation (both rapid mixing and slow mixing) improved dissolved removal efficiency. Also, for combined coagulation to membrane process, flux reduction rate showed lower than only UF process. The rate of flux decline for the hydrophobic membrane was considerably greater than for the hydrophilic membrane. Applying coagulation process before membrane filtration showed not only reducing membrane fouling, but also improving the removal of dissolved organic materials that might otherwise not be removed by the membrane.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.479-485
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• 2018

Large amounts of oily wastewater discharged from various industrial operations (petroleum refining, machinery industries and chemical industries) cause serious pollution in the aquatic environment. Although dissolved air flotation (DAF) separating oil pollutants using microbubbles represents current practice, bubble size cannot be selectively controlled, and lots of power is required to generate microbubbles. Therefore, to investigate performance of the DAF process, this study examined the distribution of different sizes of microbubbles resulting from changes in physical shear force via modifying shapes of a slit-nozzle without an additional power supply. Three types of slit-nozzles (different angle, shape and length of the slit-nozzle) were used to analyze the distribution of bubble size. At a slit angle of $60^{\circ}$, shear force was 4.29 times higher than a conventional slit, and particle size distribution (PSD) in the range between 2 and $20{\mu}m$ more than doubled. Treatment efficiency of synthetic oily wastewater through the coagulation-DAF process achieved 90% removal of COD by injecting $FeCl_3$ and PACl of 250 mg/L and 100 mg/L, respectively, and the same performance resulted using $FeCl_3$ of 200 mg/L and PACl of 80 mg/L employing a slit-nozzle angle of $60^{\circ}$. This study shows that a coagulation-DAF process using a modified slit-nozzle can improve the pre-treatment of oily wastewater.