UV-LEDs/chlorine 공정에서의 iopromide 분해 메커니즘 연구

학위논문(석사) -- 서울대학교대학원 : 보건대학원 환경보건학과, 2022.2. 조경덕.Iopromide (IPM) is a representative iodinated contrast media compound for diagnostic medicine, and is widely detected in hospital wastewater due to its high consumption and biochemical stability. In this study, three different UV-LED wavelengths (265, 310, 365 nm) were used in the UV-LED/chlorine reaction to investigate the degradation mechanism of IPM. Although fluence-based rate constant (kIPM) was decreased with increasing wavelengths (6.55 10-2 cm2 mJ-1 at 265 nm to 1.0010-5 cm2 mJ-1 at 365 nm), the synergistic effect of UV-LED and chlorine was greater at a higher wavelength (kobs increased 99 times at 365 nm). At 265 nm, the degradation rate of IPM increased from pH 6 to 8. However, at 310 nm and 365 nm, the degradation rate of IPM was decreased as pH increased. Radical scavenging experiment showed that the contribution of OH• increased as wavelength increased (2.4% at 265 nm to 16.4% at 365 nm). On the other hand, the contribution of RCS decreased as wavelength increased (93.2% at 265 nm to 82.5% at 365 nm). The largest portion of RCS was found to be ClO• (70~80% among RCS). Among nine transformation products (TPs) during the UV-LED/chlorine reaction of IPM, TP-699, TP-667, and TP-607 were newly identified in this study, and TP-699, a chlorinated transformation product of IPM, was only detected with higher levels at lower wavelength. As a result of the Microtox inhibition test using V. fischeri, no increase in toxicity was observed in all three wavelengths. This study can provide information for selecting an appropriate wavelength when applying UV-LED to WWTPs through a radical contribution experiment.요오드계 조영제의 일종인 iopromide(IPM)는 환경부 지정 1 순위 난분해성 물질로 폐수처리장에서 높은 농도로 검출되는 실정이다. IPM 은 염소에 전혀 반응하지 않고 OH 래디컬과도 상대적으로 반응성이 적기 때문에 다량의 활성염소종을 발생시키는 UV-LED/chlorine 공정을 적용하는 것이 효율적일 수 있다. 본 연구에서는 세 파장(265 nm, 310 nm, 365 nm)을 사용하여 UV-LED/chlorine 실험을 진행하여 효율성 및 제거 메커니즘을 정량적으로 비교, 평가하였다. Fluence-based rate constant (kIPM¢)는 조사 파장이 증가함에 따라 감소하였지만, UV-LED와 염소의 시너지 효과는 365 nm에서 가장 컸다. 265 nm 을 사용한 경우는 pH 8 > pH 7> pH 6 > pH 9 순으로 kIPM¢가 컸고 310 nm 과 365 nm 는 모두 pH 가 증가할수록 kIPM¢가 일정하게 감소하였다. 활성염소종과 OH 래디컬의 기여도를 확인하기 위해 nitrobenzene, benzoic acid, 1,4-dimethoxybenzene 을 프로브 물질로 사용하였다. 활성염소종은 파장이 증가함에 따라 기여도가 감소하였고 OH 래디컬은 증가하였다. 또한 이번 실험 결과로 활성염소종 중 가장 많은 기여율을 차지하는 종은 ClO 래디컬인 것으로 밝혀졌다. LC-qToF/MS 를 이용하여 UV-LED/chlorine 공정 중 발생하는 소독부산물 9 개를 특정하였고, 이 중 염소화 부산물인 TP-699 가 짧은 파장에서 더 많이 생성되는 것 확인하였다. 이들 소독부산물의 mixture effect 를 확인하기 위해 Vibrio fischeri 발광 저해도 실험을 진행하였고 초기 독성 대비 최종 처리수의 독성 증가율은 모두 10%이내였다.Contents ３ List of Table ４ Abstract 7 Chapter 1. Introduction 9 1.1. Study Background 9 1.2. Purpose of Research 12 Chapter 2. Materials and methods 13 2.1. Materials 13 2.2. UV-LED reactor 13 2.3. Experimental procedure 15 2.4. Analytical methods 15 2.5. Toxicity assessment 16 Chapter 3. Results and discussion 17 3.1. IPM Degradation kinetics 17 3.2. Effect of chlorine 23 3.3. Radical contribution 26 3.4. Energy efficiency evaluation dependent on irradiation wavelengths 32 3.5. Identified transformation products 35 3.6. Acute toxicity evaluation 40 Chapter 4. Conclusions 45 Bibliography 46 국문초록 51 Supplementary Information 52석

Disinfection effects of chlorine, chlorine dioxide and ozone treatment on the polluted algae in the drinking water supply system

환경관리학과/석사[한글] 현재 상수처리시 소독제로 사용하고 있는 염소는 상수에 오염되어 정수처리효과를 저하시키며 물의 맛과 냄새의 원인인 조류에 대하여는 완전한 사멸효과를 기대할 수가 없다. 조류의 과다성장은 정수처리시 여과지에 조류막을 형성하여 여과지 및 배관을 막아 상수처리기능을 저하시킨다. 염소처리시 생성되는 수중의 잔류염소는 유기물질과 반응하여 발암성물질인 THM(trihalomethane)등의 인체에 유해한 화합물질을 생성하는 커다란 단점이 있다. 이에 염소이외에 대체소독제로 이용되고 있는 이산화염소, 오존을 적용하여 각 소독제의 조류멸살효과와 각종 소독제들의 농도변화, 접촉시간 경과 및 복합투입에 따른 조 류멸살효과를 비교 측정하여 보았다. 실험방법은 상수원 및 수도수에서 분류한 조류를 접종한 후 염소, 이산화염소, 오존을 각각 0.2㎎/ℓ, 0.5㎎/ℓ, 0.5㎎/ℓ, 1.0㎎/ℓ, 10.0㎎/ℓ의 농도로 투입한 후 10㎎/ℓ씩을 취하여 조류배양액에 접종하고 조도 400O±400lux, 온도20±1℃를 유지하면서 6일간 배양하였다. 매일 1∼2 ㎖의 배양액을 취하여 spectrophotometer의 700nm에서 흡광도의 변화를 측정하여 증식율을 구하였다. 본 실험에서 얻어진 결과는 다음과 같다. 1. 상수원수(정수장 유입수)의 현존 상수처리과정 중 적용되고 있는 염소주입처리에 의해서는 조류의 완전한 제거가 이루어지지 않고 있었으며 수도수에서는 Anabena sp., Fragilaria sp.등이 출현되었다. 2. 염소 단독투입의 경우 10.O㎎/ℓ의 농도로 1시간, 2시간, 5시간, 24시간 접촉 후 6일 배양에 따른 조류증식율은 대조군이 146.0%인 반면 74.0%, 68.0%, 48.0%, 36.0%로 각각 증식이 억제되었다.. 3. 이산화염소의 경우 10.0㎎/ℓ의 농도로 1시간, 2시간, 5시간, 24시간 접촉후 6일배양에 따른 조류증식율은 대조군이 146.0%인 반면 64.0%, 56.0%, 52.0%, 35.1%로 각각 중식이 억제되었다. 또한 염소단독투입군 보다는 양호한 증식억제를 보여주었다. 4. 오존외 경우 10.O㎎/ℓ의 농도로 1시간, 2시간, 5시간, 24시간 접촉후 6일 배양에 따른 조류증식율은 대조군이 146.0%인 반면 15.6%, 11.3%, 7.6%, 5.0%로 각각 증식이 억제되었다. 또한 오존 단독투입군은 염소 및 이산화염소 단독투입군보다 양호한 증식억제 를 보여 주었다. 5 .복합투입의 경우 농도변화(0.2, 0.5, 1.O㎎/ℓ)와 동시에 순차투입하였을때 동일농도(1.0㎎/ℓ)에서의 증식율을 비교하여 보면 대조군의 증식율이 146.0%인데 비하여 염소투입 후 이산화염소투입의 6일후 조류 증식율은 36.0%였다. 또한 염소투입후 오존투입, 이산화염소투입후 오존투입, 오존투입 후 이산화염소투입에 따른 조류증식율은 각각 36.7%, 31.6%, 22.8%로 대조군에 비하여 뚜렷한 성장의 감소를 볼 수 있었다. 6. 단독 및 복합투입의 경우 농도의 증가와 접촉시간 증가에 따라 조류의 증식율은 억제됨을 알 수 있었다. 이상의 결과로 보아 단독투입의 경우 상수 소독제의 조류멸살효과는 오존>이산화염소>염소의 순이었으며 앞으로 복합투여를 실시할 경우 경제성 및 실제 적용가능성을 고려한 소독방법의 경우는, 염소투입후, 이산화염소처리나, 염소투입후 오존의 복합투입이 효과적이라고 생각된다. [영문] While the chlorine has been used as one of the major disinfectants of the drinking water supply system, it is not effective to distroy the polluted algae with the practical concentration in drinking water treatment. Overgrow of algae forms membraneous block in the filter bed whereby closing the filteration plants and pipeline. This results in weakening the efficiency of drinking water supply system. In chlorine treatment, the residual chlorine in drinking water reacts with organic materials(humic substances), and produce THMs(trihalomethanes) which is known as carcinogenic substance. Recently, chlorine dioxide and ozone have been used for disinfection of microorganisms as an alternative to chlorine disinfactant. In the experiment, sample of drinking water was mixed with algae, and then the chlorine, chlorine dioxide and ozone were added to the testing vessels at the concentration of 0.2㎎/1, o.5㎎/1, 1.O㎎/1, 10.O㎎/1. From this mixed materials in the vessel, a sample of 10㎖ was again extracted to fed into the algae cultured media and incubated for six days with luminous density at 4000±400 lux and temperature at 20±1℃. To estimate the growth rate of algae, changes in optical density were measured at the 700nm in a spectrophotometer using 1-2㎖ of cultured solution from the sample. The results were summarized as follows: 1. The existing treatment of water supply, with chlorine treatment was not effective to the removal of algae. Species of Anabena and Fragilaria were detected in the drinking tap water. 2. When chlorine treatment was used only, It was contacted in 1hr, 2hrs, 5hrs, 24hrs with concentrations of 10.O㎎/1 and cultured in incubator for 6 days, the control algal growth rate was 146.0%, whereas chlorine contacted algal growth rates were limited to 78%, 68%, 48% and 36%. 3. When chlorine dioxide treatment was used only, contacted in 1hr, 2hrs, 5hrs, 24hrs with concentration of 10.0㎎/1 and then cultured in incubator for 6 days the control algal growth rate were limited to 64%, 56%, 52%, 35.1%. 4. When ozone treatment was used only, it was contacted in 1hr, 2hrs, 5hrs, 24hrs with concentrations of 10.0㎎/l and then cultured in incubator for 6 days, the control algal growth rate were grown about 146.0%, in contrast to ozone contacted algal growth rate were limited to 15.6%, 11.3%, 7.6%, 5.0%. 5. In the cases of combined treatments of disinfectants, the control algal growth rate were demonstrated about 146.0%, and then in the order of injection with the chlorine and chlorine dioxide contacted algal growth rates were demonstrated as about 36.0%. Each algal growth rates of the treatment of sample, the chlorine dioxide contact sample, were limited to 36.7%, 31.6%, 22.8%. 6. In the case of single or combined treatments, the algal growth rates were inhibited by increases of concentration and prolongation of contact time. From these results, disinfection effects of single treatment were in the order of Ozone, Chroline dioxide and chlorine. However, the combined treatments tested In this study were found to be more effective then the above single treatments.restrictio

계획사격 상황하에서의 표적할당 및 사격순서 결정에 관한 연구

학위논문(박사) - 한국과학기술원 : 산업및시스템공학과, 2009. 8., [ viii, 114 p. ]This dissertation focuses on scheduling problems arising in the military. In planned artillery attack operations, a large number of threatening enemy targets should be destroyed effectively to minimize fatal loss to the friendly forces. We consider a situation in which the number of available weapons is smaller than the number of targets and the available weapons are not identical. Therefore, it is required to develop new scheduling methodologies that coordinate heterogeneous weapon types to achieve specific objectives such as minimizing the latest completion time of firing operations (makespan) and minimizing total threat of the targets after engagement is finished. In this dissertation, we develop scheduling algorithms for the fire scheduling problem (FSP) with given assignment results, and then, we develop a methodology combining both assignment and scheduling decision for the entire planned artillery attack operation. First, we address the minimization of the makespan criterion for the FSP, in which the sequence of targets to be fired at is determined. In this environment, we assume that there are m available weapons to fire at n targets (>m) and the weapons are already allocated to targets. One target can be fired by not only a weapon but also multiple weapons, and these fire operations should start simultaneously regardless of the weapons while the finish time of them may be different. We develop several dominance properties and a lower bound for the problem, and suggest a branch and bound algorithm exploiting them. Also, we introduce several local search methods and compare the solutions with the optimal solutions obtained from the branch and bound algorithm. Secondly, we consider the situation in which targets may move and hence the probability that a target is destroyed by a firing attack decreases as time passes. We present a branch and bound algorithm for the FSP with the objective of minimizing total threat of the targets, which is expressed as a ...한국과학기술원 : 산업및시스템공학과

Water bottom seismic refraction survey for engineering applications

Accurate mapping of the basement is one of the most crucial factors to the construction of harbour facilities and bridges in the coastal areas. In shallow waters, the seismic reflection method employing acoustic profiling technology often fails to image the basement geometry beneath the sediment cover in many cases. We present the result of a shallow marine seismic refraction survey using two ships, 12-channel hydrophone arrays deployed on the bottom and a borehole sparker or percussion powder as sources. Velocity structure was computed by tomography since data from more than 6 different source points had been collected for one spread. A comparison of the results of the refraction survey with drilling logs demonstrates remarkable consistency in basement ge-ometry. It thus appears that the refraction method in this study is an efficient and cost-effective way to investigate the basement structure in coastal area, river, and lake.1

Seismic reflection survey for the investigation of basement in tidal flat zone

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