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Impacts of Highly Turbid Water on Microfiltration with Coagulation Pretreatment
최양훈,권지향 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.3
The high turbidity of the raw water impedes the application of membrane filtration. Elevated concentration of particles has been occurred in intake water for a drinking water in Korea, especially during a rainy season. Effects of the high turbidity waters on microfiltration were investigated. Due to the fluctuated inflow of particles as well as organic matter in the intake water, conventional water treatment processes including coagulation, sedimentation, and filtration have been applied in the drinking water plant. Coagulation was applied as a pretreatment for the microfiltration with an immersed type of module. In addition to particles from the raw water, great amounts of flocs produced from the coagulation pretreatment process could aggravate the immersed membrane system. The turbid matter in the river water was concentrated and spiked to produce the desired concentrations (i.e., up to approximately 39 NTU and 220 NTU). Kaolin particles were also used with similar concentrations. Membrane flux decline behaviors of samples and the cake resistances on membrane surfaces were investigated. It has shown that adding kaolin particles to the raw water was beneficial to flux. The results from experiments with the increased turbidity by natural particles showed the relatively great flux decline, probably due to organic matters adsorbed to the particles. Coagulation pretreatment showed improvement in water production, regardless of applying a settling process, compared to the raw water. However, the flux decline of pretreated water was greater when settling was not applied. Therefore, we could conclude that coagulated flocs from a high turbidity water could decrease water production of microfiltration, especially when NOM concentration is significant.
자성체 이온교환 수지와 PACl 응집에 의한 국내 주요 수계 내 자연유기물 제거 특성 및 막오염 저감 효과
최양훈,정영미,김영삼,이승렬,권지향,권순범 대한상하수도학회 2008 상하수도학회지 Vol.22 No.1
The application of magnetic ion exchange resin(MIEXⓇ) is effective for natural organic matter(NOM) removal and for control of the formation of disinfection byproducts(DBPs). NOM removal is also enhanced by adding MIEXⓇ with coagulant such as polyaluminium chloride(PACl) in conventional drinking water treatment systems. In the application of MIEXⓇ, it is important to understand changes of NOM characteristics such as hydrophobicity and molecular weight distributions with MIEXⓇ or MIEXⓇ+coagulant treatment. To observe characteristics of NOM by treatment with MIEXⓇ or MIEXⓇ+coagulant, four major drinking water sources were employed. Results showed that the addition of MIEXⓇ to coagulation significantly reduced the amount of coagulant required for the optimum removal of dissolved organic matter(DOC) and turbidity in the all four waters. The DOC removal was also increased approximately 20%, compared to coagulant treatment alone. The process with MIEXⓇ and coagulant showed that complementary removal of hydrophobic and hydrophilic fraction of DOC. The combined processes preferentially removed the fractions of intermediate (3,000-10,000 Da) and low (< 500 Da) molecular weight. The microfiltration test showed that membrane cake resistance was decreased for waters with flocs from MIEXⓇ+coagulant. A porous layer was formed to MIEXⓇ on the membrane surface and the layer consequently inhibited settling of coagulant flocs, which could act on a foulant. The application of magnetic ion exchange resin(MIEXⓇ) is effective for natural organic matter(NOM) removal and for control of the formation of disinfection byproducts(DBPs). NOM removal is also enhanced by adding MIEXⓇ with coagulant such as polyaluminium chloride(PACl) in conventional drinking water treatment systems. In the application of MIEXⓇ, it is important to understand changes of NOM characteristics such as hydrophobicity and molecular weight distributions with MIEXⓇ or MIEXⓇ+coagulant treatment. To observe characteristics of NOM by treatment with MIEXⓇ or MIEXⓇ+coagulant, four major drinking water sources were employed. Results showed that the addition of MIEXⓇ to coagulation significantly reduced the amount of coagulant required for the optimum removal of dissolved organic matter(DOC) and turbidity in the all four waters. The DOC removal was also increased approximately 20%, compared to coagulant treatment alone. The process with MIEXⓇ and coagulant showed that complementary removal of hydrophobic and hydrophilic fraction of DOC. The combined processes preferentially removed the fractions of intermediate (3,000-10,000 Da) and low (< 500 Da) molecular weight. The microfiltration test showed that membrane cake resistance was decreased for waters with flocs from MIEXⓇ+coagulant. A porous layer was formed to MIEXⓇ on the membrane surface and the layer consequently inhibited settling of coagulant flocs, which could act on a foulant.
알루미늄 수화물 나노여과 막오염에 대한 공존염의 영향에 관한 연구
최양훈,권지향 대한상하수도학회 2011 상하수도학회지 Vol.25 No.4
Nanofiltration was performed with polyaluminium chloride solutions at different pH conditions to understand effects of inorganic compounds on aluminum hydrolysis products, i.e., three distinctive groups of aluminum species: polymeric Al at low pH; Al(OH)_3 at neutral pH; and Al(OH)_4^ˉ at high pH. The PACl solution was prepared to be approximately 4.0 mM and adjusted to the designated pH. The influence of inorganic compounds on Al species fouling was investigated with 4.9 mM CaCl_2 and 3.5mM MgSO_4 because Ca^(2+), Mg^(2+), Cl-, SO_4^(2-) are the most common inorganics in the drinking water. NF membrane fouling was measured by flux decline rate. The impact of CaCl_2 was not significant on the individual Al hydrolysis products fouling. However, the flux decline rate was drastically changed in the presence of MgSO4. The concentration of particulate matters was considerably increased possibly due to interaction between Al species and SO_4^(2-) where MgSO_4 was introduced. The particulates were accumulated on the membrane and enhanced the hydraulic resistance of the cake layer. In addition, conductivity removal of the membrane was decreased when Al-hydroxide was dominant due to reduction of membrane surface charge. The rejection of Ca^(2+)and Mg^(2+) were considerably different, which implys that composition of inorganics paly a role on conductivity removal.
호소수 처리를 위한 침지식 한외여과 공정의 pilot 연구
최양훈,윤태광,김종표 한국막학회 2018 한국막학회 총회 및 학술발표회 Vol.2018 No.11
호소수에 대한 막여과 공정 설계 및 운영인자를 도출하기 위하여 부산시 소재 회동 수원지의 물을 원수로 하는 200 m3/일 용량의 정수처리 침지식 막여과 pilot을 운영하였다 (운영기간 : 2018년 1월 ~ 9월). 막여과 공정 운영 관점에서 주요한 원수 수질변화로는 1월 ~ 2월 사이 수온이 5 ℃ 이하를 유지하였고, 6~7월의 평균 탁도는 24±40 NTU 이었으며, 7월 중 태풍 발생으로 인하여 약 229 NTU의 고탁도가 유입되었다. 막여과 pilot 운영결과를 바탕으로 막여과 공정의 주요 설계값인 막여과 유속, 막여과 차압, 약품 세척 주기 및 단위공정의 운전순서를 결정하였다. 운영결과 중에서 특별히 괄목할 만한 관찰점은 막여과 배출수 탁도의 중력침전 제거율이 평균 94±4%로 분석된 것이다.