• 대한환경공학회지
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• 제27권6호
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• pp.663-669
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• 2005

본 연구에서는 정수처리 공정에서 오존을 보다 효율적으로 적용하기 위하여 수중의 오존소비특성을 파악하고자 하였다. 오존의 소비특성을 측정하기 위하여 흐름주입분석법(FIA: Flow injection analysis)의 원리를 이용하여 오존분해속도 측정 자동화장치를 제작하였다. 수중의 오존농도를 연속적으로 측정함으로써 오존의 소비 경향은 순간적으로 오존이 소모되는 구간(I.D: instantaneous ozone demand)과 의사 1차 반응($k_c$: pseudo first-order rate constant)으로 소모되는 두 구간으로 나누어지며, 각 구간에서 오존 주입량에 의하여 영향을 받는 것으로 나타났다. 또한 I.D와 $k_c$값을 이용하여 구한 모델식으로부터 시간에 따른 오존 잔류농도를 예측할 수 있었으며, 예측된 모델간은 실험값과 비교하였을 때 거의 일치하는 것을 알 수 있었다. OH 라디칼의 농도 및 $R_{ct}$는 OH 라디칼 probe compound를 이용하여 간접적으로 계산하였다. I.D와 $k_c$ 구간에서 OH 라디칼 생성 경향을 파악할 수 있었으며, OH 라디칼 생성 또한 오존 주입량에 의하여 영향을 받는다는 것을 확인하였다. 마지막으로 정수처리 공정 및 계절에 따른 수질 차이에 의해서 오존소비인자가 변화하는 것을 확인하였으며, 이에 따라 오존공정의 적절한 도입위치 및 주입량을 효과적으로 결정해야 할 것으로 판단되었다.

• 한국입자에어로졸학회지
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• 제14권4호
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• pp.171-180
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• 2018

To optimize the shape of the electrostatic precipitator for the removal of particulate matter in subway environments, the wind-tunnel experiments were carried out to characterize collection efficiency and ozone emission rate. As a standardized parameter, power consumption divided by the square of flow velocity, was increased, the $PM_{10}$ collection efficiency increased. If the standardized parameter is higher than 1.0 due to high power consumption or low flow velocity, increase in thickness of electrodes from 1 to 2 mm, or increase in distance of collection plates from 5 to 10 cm did not change the $PM_{10}$ collection efficiency much. Increase in thickness of high-voltage electrodes, however, can cause decrease in $PM_{10}$ collection efficiency by 28% for low power consumption and high flow velocity. The ozone emission rate decreased as distance of collection plates became wider, because the ozone emission rate per unit channel was constant, and the number of collection channels decreased as the distance of collection plates increased. When the distance of collection plates was narrow, the ozone emission rate increased with the increase of the thickness of electrodes, but the difference was negligible when the distance of collection plates was wide. It was found that the electrostatic precipitator having a thin high-voltage electrodes and a narrow distance of collection plates is advantageous. However, to increase the thickness of high-voltage electrodes, or to increase the distance of collection plates is needed, it is necessary to increase the applied voltage or reduce the flow rate to compensate reduction of the collection efficiency.

• 상하수도학회지
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• 제25권6호
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• pp.815-824
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• 2011

In this study, a non-thermal plasma system was employed to simultaneously remove odorous compounds and organic sludge. The system consisted of two reactors; the first one was the non-thermal plasma reactor where ozone was produced by the plasma reaction and the ozone oxidized hydrogen sulfide, the model odorous compound, and then the ozone-laden gas stream was introduced to the second reactor where wasted sludge was disintegrated and solubilized by ozone oxidation. In this study, the gas retention time (GRT) and the hydraulic retention time (HRT) were changed in the two-reactor system, and the effects of GRT and HRT on reduction efficiencies of odor and sludge were determined. As the GRT increased, the ozone concentration increased resulting in an increasing efficiency of hydrogen sulfide removal. However, the overall ozone loading rate to the second sludge reactor was the same at any GRT, which resulted in an insignificant change in sludge reduction rate. When HRTs in the sludge reactor were 1, 2, 4 hours, the sludge reduction rates were approximately 30% during the four-hour operation, while the rate increased to 70% at the HRT of 6 hours. Nevertheless, at HRTs greater than 4 hours, the solubilization efficiency was not proportionally increased with increasing specific input energy, indicating that an appropriate sludge retention time needs to be applied to achieve effective solubilization efficiencies at a minimal power consumption for the non-thermal plasma reaction.

• Advances in environmental research
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• 제4권3호
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• pp.155-172
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• 2015

In this study, a complete set of recirculating cooling water system and the required instruments were built in a semi-industrial-scale and a 50 g/h ozone generation plant and a chlorine system were designed for cooling water treatment. Both chlorination and ozonation treatment methods were studied and the results were analyzed during two 45-days periods. The concentrations of ozone and chlorine in recirculating water were constant at 0.1 mg/lit and 0.6 mg/lit, respectively. In ozone treatment, by increasing the concentration cycle to 33%, the total water consumption decreased by 26% while 11.5% higher energy efficiency achieved thanks to a better elimination of bio-films. In case of Carbon Steel, the corrosion rate reached to 0.012 mm/yr and 0.025 mm/yr for the ozonation and chlorination processes, respectively. Furthermore, consumptions of the anti-corrosion and anti-sedimentation materials in the ozone cooling water treatment were reduced about 60% without using any oxidant and non-oxidant biocides. No significant changes in sediment load were seen in ozonation compared to chlorination. The Chemical Oxygen Demand of the blow-down in ozonation method decreased to one-sixth of that in the chlorination method. Moreover, the soluble iron and water turbidity in the ozonation method were reduced by 97.5% and 70%, respectively. Although no anaerobic bacteria were seen in the cooling water at the proper concentration range of ozone and chlorine, the aerobic bacteria in chlorine and ozone treatment methods were 900 and 200 CFU/ml, respectively. The results showed that the payback time for the ozone treatment is about 2.6 years.

• 대한환경공학회지
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• 제30권7호
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• pp.743-750
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• 2008

본 연구에서는 용존오존부상법(Dissolved Ozone Flotation; DOF)을 이용한 정수처리 효과를 파악하기 위하여 적정 오존 주입 농도와 오존 주입 농도별 처리 특성에 대해서 연구하였으며, 또한 용존공기부상법(Dissolved Air Flotation; DAF) 및 중력식 침전법(Conventional Gravity Sedimentation; CGS)과 DOF의 처리 성능을 비교하였다. 최적 오존 주입 농도를 산정하기 위한 실험에서 최적 오존 주입농도는 2.7 mg/L로 나타났으며, 오존 주입 농도가 증가할수록 탁도 및 KMnO$_4$ 소모량, UV$_{254}$ 흡수도, TOC 등과 같은 제거효율이 낮아지는 것으로 나타났다. DOF와 DAF, CGS의 처리성능을 비교한 결과 오존 주입 농도 2.7 mg/L로 운전한 DOF시스템의 탁도 제거효율은 88.9%, 유기물질 항목의 경우 KMnO$_4$ 소모량은 62.9%, TOC 47%, 그리고 UV$_{254}$ 흡수도 77.3% 그리고 THMFP 제거율의 경우 51.6%로 다른 두 공정보다 높거나 비슷하게 나타났다. 따라서 응집 부상 공정과 오존 산화 공정이 하나의 반응기에서 일어나는 DOF 시스템은 정수처리시설의 소유부지 감소와 기존 CGS 시스템에서 처리가 어려운 조류 및 용존성 유기물질의 제거를 통해 소독부산물의 생성을 감소시킴으로 향후 고도정수처리시스템으로 적용 가능성이 충분한 것으로 판단된다.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권3호
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• pp.77-80
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• 2003

An innovative ozonizer has been developed using a high frequency, surface discharge and a high purity Ti-Si-AI ceramic catalyst as a dielectric component. Using a type of thin film, a thin cylindrical compound ceramic catalyst layer was adhered to the outside surface of its inner electrode. An alternating current (AC) exciting voltage with frequencies from 0.6 KHz to 1.0 KHz and peak-to-peak voltages of 4-6 ㎸ was applied between the electrodes to produce a stable high-frequency silent discharge. A substantial reduction of the exciting voltage was also enabled by means of a thin Ti-Si-Al ceramic catalyst tube. As a result, the ozonizer can effortlessly obtain the required ozone concentration (50-60 g/$m^2$ for oxygen) and high ozone efficiency consumption power (180 g/kWh for oxygen) with-out the assistance of any particular methods. For purposes of this experiment, oxygen gas temperature was set at 2$0^{\circ}C$, with an inner reactor pressure of 1.6 atm at 600 Hz and a flow rate of 2 l/min.

• 한국안전학회지
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• 제15권3호
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• pp.66-70
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• 2000

In order to cope with environmental problems caused by harmful gases emitted from various industrial sources, a new technology which employs discharge plasma formed in ordinary atmospheric pressure has been intensively investigated in many industrialized nations. Although a plenty of useful outcomes and suggestions have been made public by scientists in this field, few commercial products which effectively decompose pollutant gases have appeared as yet. This is partly because that the energy efficiency of a most effective plasma reactor has not reached a satisfactory level in comparison with those of devices using conventional technologies. In an attempt to solve the problem mentioned above, we noticed to combine heterogeneous electrical discharges. This concepts is based on that each plasma reactor has its specific spatial region in which chemical reaction are active and by electrically affected with another reactor of different type, the activated region would increase - which may lead to cutting down the energy consumption. To prove this concept experimentally, two different discharge equipments, a plane ceramic-based surface discharge electrode and a corona electrode with tungsten needle may, are selected and combined to fabricate a hybrid plasma reactor. The results are summarized as follows; (1) Ozone concentration generated in the plasma region drastically increases when the positive corona discharge is added to the surface discharge. The rate of increase of ozone depends on the frequency of the surface discharge. The negative corona, however, does not contribute to the improvement of the ozone generation. (2) NO(nitrogen monoxide) decomposition rate also improves by simultaneously applying the surface and the positive corona discharges. The effect of the corona superposition is more evident when the level of the surface discharge is moderate. (3) By adjusting the corona level, the net energy efficiency during NO decomposition improves in comparison with the simple surface discharge reactor.

• Environmental Engineering Research
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• 제16권4호
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• pp.237-242
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• 2011

In this study, three pilot-scale plants with the capacity 30 $m^3$/day were designed and set up to treat reservoir water for the production of drinking water. Three treatment processes were compared in the pilot testing: process 1 (coagulation- flocculation- sedimentationsand filtration- ozone- BAC); process 2 (coagulation- flocculation- sedimentation- microfiltration-ozone- BAC); and process 3 (coagulation- flocculation- sedimentation- sand filtration- GAC). The quality of water has been evaluated on the basis of selected parameters such as turbidity, color, consumption of $KMnO_4$, dissolved organic carbon (DOC), trihalomethane formation potential (THMFP), geosmin and 2-MIB. A detailed assessment of performance was carried out during a five months operation. Process 2 was found to have better removal efficiency of DOC, THMFP, geosmin and 2-MIB than process 1 and process 3 under identical conditions, although the removal rate of color was found to be the same in the three cases.

• 대한환경공학회지
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• 제22권10호
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• pp.1825-1832
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• 2000

유류화합물(디젤)로 오염된 불포화층 토양에 대한 현장오존복원공정의 기초연구로, 토양조건에 따른 오존의 이동과 분해, 디젤과의 반응경향을 조사하였다. 건조상태에서 유기물을 제거한 모래와 glass beads 충진컬럼에서 기상 오존의 분해를 조사한 결과 일차반응으로 가정시 반응 속도상수값(k)이 각각 $9.9{\times}10^{-3}s{^{-1}}$와 $4.3{\times}10^{-4}s{^{-1}}$로 나타나 모래의 경우 철 (Fe), 망간(Mn) 성분 등의 촉매작용으로 25배 가량 반감기가 짧은 것을 확인할 수 있었다. 디젤로 오염시킨 현장 토양과 모래를 컬럼에 충진하여 동일조건하에서 오존주입시 토양입자의 크기와 유 무기물의 함량 차에 의한 오존이동상에 지체효과 및 소모량의 차이를 관찰하였고, 50mL/min의 유속에서 공기만을 주입시 DRO(diesel range organic) 기준 초기 디젤총량($800{\pm}50mg/kg$)의 30%가 제거된데 비해 오존을 6mg/min으로 16시간 주입한 결과 각각 80% 이상이 제거되었다. 오존주입시간에 따라 컬럼의 유출 입부에 잔류하는 TPH(total petroleum hydrocarbon)와 DRO 중 aliphatic계열 8개 물질들의 농도를 비교/분석한 결과, 낮은 탄소수 물질들로의 전환과정을 거쳐 유체의 흐름에 따라 컬럼 밖으로 이동됨을 확인하였고, 토양내 수분함량은 오염 토양복원에 오존을 적용시 중요한 인자임을 확인하였다.

• 대한환경공학회지
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• 제32권4호
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• pp.325-332
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• 2010

본 연구에서는 오존을 이용한 잉여슬러지의 가용화 실험을 실시하였다. 오존의 접촉효율을 높이기 위해 마이크로버블화된 오존(이하 마이크로버블 오존이라 함)을 이용하였으며, 생성된 마이크로버블 오존의 사이즈는 평균 직경 30 ${\mu}m$ 정도였고, 40 ${\mu}m$ 이하가 전체의 약 90% 정도를 나타내었다. 마이크로버블 오존을 이용한 슬러지 처리에 있어서는 슬러지 농도에 상관없이 오존주입율을 0.34 g $O_3/g$ SS 이하로 주입할 경우, 폐오존의 발생 없이 오존소모율이 100%인 것으로 조사되었다. 각 농도별 슬러지 처리에 있어서 슬러지의 초기 SS 농도를 6,447 mg/L, 5,557 mg/L, 3,180 mg/L, 1,092 mg/L 및 515mg/L로 하였을 경우, 동일한 오존주입율에 있어서 초기 SS의 농도가 증가할수록 제거되는 SS량이 증가하는 경향을 나타내어, 오존의 산화효율을 높이기 위해서는 초기 SS의 농도가 높은 슬러지를 처리하는 것이 효과적이었다. 한편, 슬러지의 복합 처리로서 산과 알칼리 그리고 오존처리를 검토한 결과, 오존의 전처리로서 산처리를 이용하는 것이 알칼리처리에 비해 효과적이었으며, 슬러지에 주입하는 황산의 농도를 0.01 N로 하고, 오존주입율 0.05 g $O_3/g$ SS로 처리한 경우, 제거된 SS의 양은 153.9 g으로 오존단독처리시 81.2 g에 비해 1.9배의 많은 양이 제거되었다.