• Clean Technology
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• v.29 no.1
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• pp.31-38
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• 2023

Due to water shortages caused by water pollution and climate change, total organic carbon (TOC) standards have been implemented for wastewater discharged from public sewage treatment facilities. Furthermore, there is a growing interest and body of research pertaining to the reuse of sewage treatment water as a secure alternative water resource. The membrane bio-reactor (MBR) method is commonly used for advanced wastewater treatment because it can remove organic and inorganic ions and it does not require or emit any chemicals. However, the MBR process uses a separation membrane (MF), which requires frequent film cleaning due to fouling caused by a high concentration of mixed liquor suspended solid (MLSS). In this study, process improvement and microbubble cleaning efficiency were evaluated to improve the differential pressure, water flow, and MF fouling, which are the biggest disadvantages of operating the MF. The existing MBR method was improved by installing a precipitation tank between the air tank and the MBR tank in which raw water was introduced. Microbubbles were injected into a separation membrane tank into which the supernatant water from the precipitation tank was introduced. The microbubble generator was operated with a 15 day on, 15 day off cycle for 5 months to collect discharged water samples (4L) and measure TOC. As the supernatant water from the precipitation tank flowed into the separation membrane tank, about 95% of the supernatant water MLSS was removed so the MF fouling from biological contamination was prevented. Due to the application of microbubbles to supernatant water from the precipitation tank, the differential pressure of the separation membrane tank decreased by 1.6 to 2.3 times and the water flow increased by 1.4 times. Applying microbubbles increased the TOC removal rate by more than 58%. This study showed that separately operating the air tank and the separation membrane tank can reduce fouling, and suggested that applying additional microbubbles could improve the differential pressure, water flow, and fouling to provide a more efficient advanced treatment method.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.4
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• pp.325-332
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• 2010

This study was conducted with the experiment of solubilisation of excess sludge by microbubble ozone process. To improve ozone contact efficiency, microbubble ozones which its diameter were the avearge 30 ${\mu}m$, microbubble size less than 40 ${\mu}m$ occupied about over 90% of all. In treating sludge using microbubble ozones, in case microbubble ozones are injected at microbubble ozone dosage of 0.34 g $O_3/g$ SS or less regardless of sludge concentration, microbubble ozone consumption rate was found to be 100% with no emission of waste ozones. In treating sludges by each concentration, in case the initial SS concentration of sludge is set to 6,447 mg/L, 5,557 mg/L, 3,180 mg/L, 1,092 mg/L and 515 mg/L, the amount of removed SS tended to increase with increase in initial SS concentration for the same microbubble ozone dosage, and treatment of sludge with high initial SS concentration was effective in raising the oxidation efficiency of microbubble ozones. On the other hand, as a result of reviewing acid, alkali and microbubble ozone treatment as composite treatment of sludge, use of acid treatment for the pre-treatment of microbubble ozone was more effective than alkali treatment, and in case of treatment at microbubble ozone dosage 0.05g $O_3/g$ SS with the concentration of sulfuric acid infused in the sludge, the amount of removed SS, 153.9 g, was 1.9 times more than 81.2 g the amount of single treatment of microbubble ozone.

• 어항어장
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• s.103
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• pp.37-42
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• 2013

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.651-657
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• 2016

The purpose of this research was to examine the possibility on the recycling of foodwaste leachate as external carbon sources using microbubble. The following operating conditions were selected: pressurizing tank 3 bar, circulation flow rate 3.65 LPM, and air flow rate 0.3 LPM with batch type. Microbubble contact time of 18 hours is optimal time to satisfy the recycling of foodwaste leachate as external carbon sources with batch type. HRT 18 hours came up to standard for external carbon sources, except for T-P concentration with continuous type. Coagulants need to be used for removal of dissolved phosphorus concentration by more than 88.5% of the total phosphorus concentration. The VFA was influenced by the organic decomposition rate and the concentration in the aerobic condition. It was considered that the VFA was needed for selection the optimal HRT or the addition of acid fermentation process in order to meet recycling standard of foodwaste leachate.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.286-291
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• 2016

This study was carried out to evaluate the feasibility of air-stripping by DIWS(Dip Injection Wet Scrubber) system on high concentration of ammonia wastewater more than 10,000 mg/L. In the case of changing temperature from $30^{\circ}C$ to $70^{\circ}C$ maintaining pH 12.5 within the 72 hours, the removal efficiency of T-N by the present treatment plant was increased to 90.5% which was initially kept 70.3%. Although the high concentration of T-N with 9,120~12,955 mg/L was treated by micro-bubble through DIWS system maintaining the temperature of $30^{\circ}C$ within the 20 hours, the removal efficiency of T-N reached 91.9%, which indicated the possibility of air-stripping.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2011.10a
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• pp.353-354
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.169-170
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• 2010

• 한국도로학회:학술대회논문집
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• 2004.02a
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• pp.25-28
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• 2004

• Journal of Wetlands Research
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• v.17 no.2
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• pp.118-123
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• 2015

This work has performed to examine the operation status of regeneration and scrubber system of cold rolling mill plant and established the DIWS(Dip Injection Wet Scrubber) system for the removal of hydrochloric acid with micro bubble. When the initial 22.3 ppm of HCl gas was injected into the system, the average exhaust HCl gas was 0.59 ppm with the removal efficiency of 97.3%. Hydrochloric acid was effectively removed by DIWS system. In the long term monitoring for 10 hours by 5 minutes through TMS(Tele Monitoring System), the average exhaust HCl gas was stably kept 0.69 ppm, which was also verified by manual measurement.

• Composites Research
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• v.28 no.2
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• pp.70-74
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• 2015

In this paper, carbon nanotubes (CNTs) and micro glass bubbles (GBs) have been incorporated into a polyamide6 (PA6) matrix to impart thermoelectric properties. The spaces created in the matrix by GBs allows the formation of "segregated" CNT network. The tightly bound CNT network, if controlled properly, can serve as a conductive path for electron transport, while prohibiting phonon transport, which would provide an ideal configuration for thermoelectric applications. The CNTs and GBs were dispersed in a nylon-formic acid solution using horn sonication followed by coagulation in deionized water, and nanocomposite panels were fabricated using a hot press. The performance of nanocomposite panels was evaluated from thermal and electrical conductivities and Seebeck coefficient, and a thermoelectric figure of merit as high as 0.016 was achieved.