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멤브레인 막오염 최소화전략을 위한 나노 및 마이크로 콜로이드 입자의 입자크기 및 확산계수 분석
조재원(Jae Weon Cho) 대한환경공학회 2004 대한환경공학회 학술발표논문집 Vol.2004 No.12
Membrane filtration for sustainable wastewater reuse has been encountering particle deposition (i.e., particle cake fouling) with mostly micron-sized particles including bacteria, and nano-sized colloids/particles as well. Particle size may influence membrane fouling and flux decline through cake formation as particles with different sizes exhibit different back diffusivity and packing density of the cake. A theoretical diffusivity equation was proposed by Einstein (1906) (Einstein, 1956); thermodynamic and drag (i.e., resistance or mobility relation) forces were compared in a equilibrium. The diffusivity relationship, ratio of thermodynamic and drag forces, was combined with steady-state convection and diffusion equation and finally came up with a relationship between retention times from flow field-flow-fractionation (fl-FFF) and diffusivity of a particle. A asymmetric fl-FFF system (Postnova, Germany) equipped with a regenerated cellulose membrane with molecular weight cutoff of 1,000 molecular mass and a micro-channel employing both laminar channel and cross flows, was used to obtain chromatography using an UV detector. A wide range of colloids and particles were used; both traceable polymer and latex microsphere colloids/particles with nominal diameters of 0.09 (i.e., 90nm), 0.152, 0.2, 0.5, 0.701, 0.82, 0.993, 1.0μm (Duke Scientific, US), and micro silica particles with nominal diameters of 3.0, 6.0, 10.0μm (Nanotech, Korea). Each colloid or particle was characterized in terms of either its size or diffusivity with analyses of chromatography obtained from fl-FFF. It was found in this work that ca. 0.5μm is a critical size below and above which diffusivity of a particle increases (i.e., particle of 0.5 μm has a minimum diffusivity). An empirical equation for the shear-induced diffusivity will be suggested in the presentation based on the results obtained from the fl-FFF. There may be many important implications on this observation; for example, bacteria with a 0.5μm size may provide significant cake deposition and subsequently flux decline and possibly bio-fouling. These nano-/micro-size and diffusivity information is being investigated in conjunction with membrane filtration with the corresponding particles and various membranes.
조재원 ( Jae Weon Cho ) 한국하천호수학회 2012 생태와 환경 Vol.45 No.1
This study investigated the characteristics of natural organic matter (NOM) with general water characteristics (pH, DO, electrical conductivity, BOD, COD, TN, TP, Chl-a, DOC, UV254, SUVA) and the 3D fluorescence excitation-emission matrix (FEEM) in the Yeongsan River basin. FEEM was used to classify protein-like and fulvic & humiclike substances with fluorescence intensity in the matrix of excitation and emission wavelength. The concentration of BOD, COD, TN, electrical conductivity and DOC in the region of Gwangju city (Gwangju sewage treatment plant: GJS, Gwangjucheon: GJC, Gwangju 2: GJ2) was relatively higher than the upper reaches and lower reaches of the Yeongsan River basin. SUVA in most sites was lower than 3 L mg--1 m--1 as the hydrophilic substances, except Damyang (DY) in the upper reaches of Yeongsan river was higher than 3 L mg--1 m--1 as the hydrophobic substances during winter and autumn. In the FEEM investigation the fulvic and humic substances were found in most sites, and in sites regarding Gwangju city (GJS, GJC, GJ2) during winter and GJC in summer, protein-like substances were found. The trend of fluorescence intensities from the upper reaches to the lower reaches in most sites corresponded to that regarding the concentration of water characteristics (BOD, COD, TN, DOC). That is why the region of Gwangju city (GJS, GJC, GJ2) was relatively higher. This results were an equivalent trend to those of fluorescence index (FI) in most sites, and the higher FIs in the sites of Gwangju city indicate more microbial-derived substances due to enormous effluent organic matters (EfOM) from huge Gwangju sewage treatment plants.