• 한국산학기술학회논문지
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• 제15권5호
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• pp.3336-3344
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• 2014

본 연구의 목적은 소규모 응집침전모듈의 개발 및 lab-scale 테스트를 통한 실증이다. 최근 하수처리율이 높아짐에 따라 비점오염원 관리에 대한 관심이 높아지고 있어 소규모 처리장치 개발의 필요성이 증대되고 있다. 본 연구의 응집침전모듈은 응집공정 이후 외부 영역에서 선회류를 통한 플럭(floc)의 추가 성장 및 미세 플럭 수의 감소, 내부 침전 영역에서 수직 수평류 복합침전방식을 통한 침전효율 증대로 효과적인 고액분리가 가능토록 하였다. 응집침전모듈은 수직 수평류 복합침전 방식을 통해 재래식침전조에 비해 같은 체적에서 침전면적 및 표면부하율을 4.4배 증가시킬 수 있었다. 본 연구에서 외부 및 내부 침전 영역에서의 선회류 형성 유지와 내부 침전영역에서의 균등한 유량분배를 본 공정의 중요한 설계인자로 선정하였고, 이의 도출을 위해 유체유동해석 모델인 FLUENT를 이용하였다. 선회류 유동경향 모사를 통해 유입속도, 외부조의 규격, 하부콘호퍼 깊이 등을 결정하였고 속도분포 및 유량분배 해석을 통해 유출공 직경과 개수, 유출홀 직경 등 내부 침전영역의 세부 규격을 도출하였다. $60{\ell}/hr$규모의 파일럿 테스트 결과 20분의 체류시간 동안(표면부하율은 $37.3m^3/m^2$일)탁도 300~800 NTU의 폐수를 고분자응집제 주입 없이 10 NTU 이하로 처리할 수 있었으며, 유체유동해석 모델을 활용한 설계인자 도출의 가능성을 확인하였다.

• 상하수도학회지
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• 제19권4호
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• pp.429-436
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• 2005

A coagulation/ultrafiltration membrane hybrid system was operated to treat river water with capacity of $0.06m^3/d$. The impact on membrane fouling by flux and linear velocity was investigated. It is known that pressure increase is proportional to flux increase. However, pressure increase was much faster than theoretical value in the pilot plant test. So it was suggested that flux was on important factor in ultrafiltration of continuous operation. Membrane fouling was decreased when linear velocity was increased. This phenomenon was found more obviously without coagulation. With the combination of coagulation and sedimentation, membrane fouling was not reduced conspicuously. Big particles formed during coagulation and sedimentation were destroyed by feed and circulation pumping, which resulted in little effect on membrane fouling reduction. The degree of destruction was similar at various linear velocities. In this study, the hollow fiber membrane was used and the system was operated in pressure type module. In case of the system used in this study, membrane fouling has been affected lightly by linear velocity variation when coagulation pretreatment was applied.

• 상하수도학회지
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• 제18권5호
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• pp.598-607
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• 2004

In this study, the effects of two pre-treatment processes were observed prior to membrane filtration: pre-coagulation and pre-ozonation. To compare the effect of two above-mentioned pre-treatments, we adopted the four schemes: first one is direct membrane filtration of river surface water, second one is membrane filtration after pre-coagulation, third one is membrane filtration after pre-ozonation and fourth one is membrane filtration after pre-coagulation and pre-ozonation. There are two exceptional characteristics in applied processes. One is the usage of the MF membrane which has high ozone resisting characteristic. Therefore, ozone resides in membrane module during filtration. The other is adoption of Jet Mixed Separator (JMS) as coagulation-sedimentation process. The change in transmembrane pressure and permeate water quality were also examined. As a result, considering the filtration performance efficiency and permeate water quality, the process composed of filtration with combination of both pre-coagulation and pre-ozonation was proved most effective. The improved efficiency was due to the reduction of loading rate of fouling inducing materials to membrane module by coagulation process as well as variable reactions, such as degradation, particle destabilization and coagulation, occurred by residual ozone in membrane module. The additional effect of pre-coagulation before pre-ozonation is suppression of AOC, one of the by-products induced by ozonation. Therefore, combination of pre-coagulation and pre-ozonation is the effective process to overcome the major de-merit of ozonation i.e. by-products formation.

• 상하수도학회지
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• 제18권5호
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• pp.588-597
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• 2004

In this research, we investigated the variation of transmembrane pressure and permeate water quality with pre coagulation and sedimentation with iron based coagulant and chlorination of feed water for PVDF (polyvinylidene fluoride) based MF membrane filtration. NaCIO was fed to the membrane module with dosage of 0.5mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were applied. In case of river surface water, the transmembrane pressure increased drastically in 500 hours of operation. On the contrary, no significant increase in transmembrane pressure was observed for 1,200 hours of operation for coagulated water and coagulated-settled waters. The turbidity of permeate was lower than a detection limit of equipment for all raw waters. The removal efficiency of humic substances of coagulated water and coagulated-settled water was approximate ten times of that of surface river water. And, the removal efficiency of TOC and DOC was approximate two times of that of surface river water. From the results of plant operation, stable operation was maintained at $0.9m^3/m^2{\cdot}day$ filtration flux through the combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when pre-coagulation-sedimentation process was combined with pre-chlorination.