• 한국수산과학회지
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• 제55권6호
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• pp.910-916
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• 2022

The purpose of this study is to evaluate the effect of underwater non-thermal dielectric barrier discharge plasma (DBD plasma) on the sterilization of three types of pathogenic bacteria that cause diseases in freshwater fish and the reduction of a tetracycline antibiotics. This experiment was conducted in the DBD plasma generator, and the voltages used to generate plasma were 11.6 kV and 23.1 kV. The measurement intervals were 0, 1, 5, 10 and 15 min. As a result of DBD plasma treatment, Aeromonas hydrophila, Edwardsiella tarda and Pseudomonas fluorescens were removed 93-99% after 5 min at 23.1 kV, and the tetracycline antibiotics were reduced 70-95% after 15 min at 23.1 kV. In this study, as a result of treating the effluent with DBD plasma at a fish farm where the medicinal bath was conducted with oxytetracycline-HCl (OTC-HCl) products, OTC-HCl decreased by 62% after 10 min at 23.1 kV.

• 한국표면공학회지
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• 제50권2호
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• pp.108-113
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• 2017

We investigated the effect of graphite electrode geometry and combination on nanocarbon material synthesis using underwater discharge plasma(UDP). The UDP system consists of two graphite electrodes and beaker filled with de-ionized water. A high voltage of 15 kV with a frequency of 25 kHz is applied to produce UDP using an alternating-current power source. The UDP system with conical electrodes produced the largest amount of products due to the concentration of electrical fields between electrodes. In addition, hollow-shaped stationary electrode and conical-shaped moving electrode stores discharge-induced bubbles and maintains longer reaction time. We found from Raman spectroscopy and electron microscopy that high quality carbon nanomaterials including carbon nanotubes are synthesized by the UDP system.

• 환경생물
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• 제40권4호
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• pp.641-650
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• 2022

본 연구의 목적은 양식장 배출수 내에 포함된 5종의 항생제(tetracycline, doxycycline, oxytetracycline, clindamycin 및 erythromycin)를 제거하기 위해 사용한 수중 비열 유전체장벽 방전 플라즈마(Dielectric Barrier Discharge plasma, DBD plasma) 장치 안으로 공기와 산소를 각각 주입했을 때 항생제의 제거효율을 비교하는 것이다. DBD plasma를 발생시키기 위해서 주어진 전압은 27.8 kV이었고, 처리간격은 0, 0.5, 1, 2, 4, 8, 16 및 32분이었다. 3종의 tetracycline계 항생제는 공기를 주입했을 때는 4분만에 유의하게 감소하였고, 산소를 주입했을 때는 30초만에 유의성을 나타내었다. 32분째 공기와 산소를 각각 주입한 결과, tetracycline은 78.1%와 95.8%, doxycycline은 77.1%와 96.3% 그리고 oxytetracycline은 77.1%와 95.5% 감소하였다. Clindamycin은 공기를 주입했을 때 59.6%가 감소되었고, 산소는 83.0% 감소되었다. 또한, erythromycin은 공기주입 시 53.3%가 감소되었고 산소 주입 시 74.3%가 감소하여 두 항생제 모두 tetracycline계 항생제보다 낮은 제거 효율을 보였다. 결론적으로 수중 DBD plasma는 양식장 배출수 내에 포함된 5종의 항생제를 감소시킬 수 있고, 제거 효율은 공기보다 산소를 주입하는 것이 더 효과적이다.

• 상하수도학회지
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• 제30권2호
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• pp.167-177
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• 2016

This work investigated the decomposition of aqueous anatoxin-a originated from cyanobacteria using an underwater dielectric barrier discharge plasma system based on a porous ceramic tube and an alternating current (AC) high voltage. Plasmatic gas generated inside the porous ceramic tube was uniformly dispersed in the form of numerous bubbles into the aqueous solution through the micro-pores of the ceramic tube, which allowed an effective contact between the plasmatic gas and the aqueous anatoxin-a solution. Effect of applied voltage, treatment time and the coexistence of nutrients such as $NO_3{^-}$, $H_2PO_4{^-}$ and glucose on the decomposition of anatoxin-a was examined. Chemical analyses of the plasma-treated anatoxin-a solution using liquid chromatography-mass spectrometry (LC-MS) and ion chromatography (IC) were performed to elucidate the mineralization mechanisms. Increasing the voltage improved the anatoxin-a decomposition efficiency due to the increased discharge power, but the energy required to remove a given amount of anatoxin-a was similar, regardless of the voltage. At an applied voltage of 17.2 kV (oxygen flow rate: $1.0L\;min^{-1}$), anatoxin-a at an initial concentration of $1mg\;L^{-1}$ (volume: 0.5 L) was successfully treated within 3 min. The chemical analyses using LC-MS and IC suggested that the intermediates with molecular weights of 123~161 produced by the attack of plasma-induced reactive species on anatoxin-a molecule were further oxidized to stable compounds such as acetic acid, formic acid and oxalic acid.

• 한국물환경학회지
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• 제28권3호
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• pp.367-374
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• 2012

A flotation process has a shorter processing time and needs less space than a sedimentation process. Dissolved air flotation process (DAF) is an efficient flotation method and used in a conventional wastewater treatment process. However, DAF requires the circulation of water containing compressed air and requires expensive installation and operation cost. Plasma Air Flotation (PAF) process is able to float flocs by micro bubbles generated from underwater plasma without the circulation of bubbly water and additional saturators. Therefore, PAF can be an alternative solution overcoming economic barriers. In this study, Humic acid removal efficiency by PAF process was compared with that of sedimentation process. 44.67% and 87.3% reduction rate based on UV 254 absorbance has been measured in sedimentation and PAF respectively. In particular, PAF in the flocculation zone can dramatically remove humic acid from water. In flocculation zone, PAF can separate organic matters but sedimentation cannot.

• 상하수도학회지
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• 제33권4호
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• pp.243-250
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• 2019

This objective of this study was to investigate the degradation characteristics of phenol, a refractory substance, by using a submerged dielectric barrier discharge (DBD) plasma reactor. To indirectly determine the concentration of active species produced in the DBD plasma, the dissolved ozone was measured. To investigate the phenol degradation characteristics, the phenol and chemical oxygen demand (COD) concentrations were evaluated based on pH and the discharge power. The dissolved ozone was measured based on the air flow rate and power discharged. The highest dissolved ozone concentration was recorded when the injected air flow rate was 5 L/min. At a discharge power of 40W as compared to 70W, the dissolved ozone was approximately 2.7 - 6.5 times higher. In regards to phenol degradation, the final degradation rate was highest at about 74.06%, when the initial pH was 10. At a discharged power of 40W, the rate of phenol decomposition was observed to be approximately 1.25 times higher compared to when the discharged power was 70W. It was established that the phenol degradation reaction was a primary reaction, and when the discharge power was 40W as opposed to 70W, the reaction rate constant(k) was approximately 1.72 times higher.

• 공업화학
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• 제24권5호
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• pp.544-550
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• 2013

본 연구에서는 소수성 다공질 세라믹관이 결합된 수중 유전체장벽방전 플라즈마 반응기를 이용하여 모사 염색폐수의 색도저감을 조사하였다. 플라즈마에 의해 생성되는 활성성분들은 수명이 매우 짧으므로 생성되는 즉시 물과 접촉시켜야 효과적인 폐수처리가 가능하며, 또한 반응속도를 증가시키기 위해서는 기/액 접촉면적이 커야 하는데, 본 연구의 반응기는 두 가지 목적을 동시에 이룰 수 있다. 아조 염료로는 amaranth, 그리고 플라즈마 생성을 위한 기체로는 공기가 사용되었으며, 방전전력, 기체 유량, 용존 음이온, 염료 초기농도 등 색도 제거에 미치는 다양한 변수의 영향이 평가되었다. 기체유량이 $1.5Lmin^{-1}$일 때, 플라즈마 기체가 염색폐수와 가장 효과적으로 접촉하였으며, 색도 제거가 가장 빠르게 일어났다. 염료 초기농도 $40.2{\mu}molL^{-1}$ (폐수부피 : 0.8 L), 방전전력 3.37 W의 조건에서 색도를 99% 이상 제거하는데 약 25 min이 소요되었다. 그밖에 염료의 초기농도가 낮을수록, 방전전력이 높을수록 색도 제거 속도가 증가하는 것으로 나타났다. 염소이온이 존재할 경우 색도 제거 속도가 빨라졌으나, 질산이온은 색도 제거 속도에 영향을 주지 않았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.47-47
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• 2010

Discharge under the water is very hard and demand considerable high voltage. But specially improved electrode can generate plasma discharge to salty water with relatively low voltage. A round shape ceramic electrode having many pinholes combined with metallic one can generate plasma. 400 volt, 10 kHz and 3 micro second pulse width were applied to repeatedly running synthetic seawater with 10 L/m velocity, containing cultivated E. coli and Bacillus. As a result, 18, 94, 99.97, 100, 100 % disinfection rates to E. coli and 17.1, 17.1, 82.9, 99.4, 99.9 % disinfection rates to Bacillus subtilis were achieved to 1, 2, 3, 4, 5 times repetitive treatment respectively. In the plasma condition, the ions and electrons are separated and new kinds of components are re-synthesized by the intensive movement of the components. Especially chlorine ions are separated and recombined to residual free chlorine like HOCl, $OCl^-$. The residual free chlorine concentrations of discharged water were 0.25, 0.88, 1.39, 1.59, 1.66 mg $Cl_2$/L after 5 times treatment respectively. Another unconfirmed radical and oxidants for example, OH, $H_2O_2$, and $O_3$ can have an effect on microorganism of course.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.336-336
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• 2004

EDTA contained in decontamination wastes can cause complexation of radioactive captions resulting from its various treatment process such as chemical precipitation, and ion exchange etc. It might also import for elevated teachability and higher mobility of cationic contaminants from conditioned wastes such as waste immobilized in cement or other matrices. Therefore, various cheated or unchlelated EDTAS must be treated to environmentally safe materials.(omitted)