Fouling and cleaning of seawater reverse osmosis membranes in Kalpakkam nuclear desalination plant
01 Jan 2006-International Journal of Nuclear Desalination (Inderscience Publishers)-Vol. 2, Iss: 2, pp 172-178
TL;DR: In this paper, a seawater reverse osmosis plant of 1800 m³/day capacity is part of the 6300 ³ /day capacity nuclear desalination demonstration project at Kalpakkam.
Abstract: A seawater reverse osmosis plant of 1800 m³/day capacity is part of the 6300 ³/day capacity nuclear desalination demonstration project at Kalpakkam. The plant was commissioned in October 2002 and is in continuous operation. This paper deals with types of foulants, membrane cleaning procedures and the improvement in the reverse osmosis system after cleaning. This paper also describes the analysis of foulants, which may consist of adsorbed organic compounds, particulate matter, micro-organisms and metallic oxides, and describes the chemical cleaning procedure to be adopted, which is specific the seawater used because the membrane foulants are very specific with respect to the seawater constituents. The cleaning of the membranes in the Kalpakkam nuclear desalination plant was taken up because the quality of the permeate had deteriorated and the differential pressure across the membrane had gone up. This paper essentially deals with the selection of cleaning chemicals, the experience gained with the cleaning procedure adopted and the effects of cleaning on the membrane system.
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TL;DR: In this article, a review of membrane technology is classified into different processes and, for each process, progress made since the onset of this millennium in the radioactive decontamination of water is shown.
Abstract: The recent accident at the Fukushima Daiichi Nuclear Power Plant caused by the Great East Japan Earthquake of March 11, 2012 reminded us vividly of the serious hazards of radioactive substances spread over a wide range of the affected region. Currently, there is a great concern over the effect of contaminated soil and water on the health and safety of the inhabitants of the region. Hence, the advancement in the technologies of nuclear waste treatment is of vital importance if we decide to live with nuclear power to maintain our modern civilization. Among various separation technologies used, membrane technologies have been chosen in this article since they are considered as one of the emerging technologies with many advantages over the conventional processes. In this review the membrane technology is classified into different processes and, for each process, progress made since the onset of this millennium in the radioactive decontamination of water is shown. The new directions are shown by considering the progress made in membrane manufacturing and membrane processes. Thus, the combined efforts of the researchers who are engaged in membrane and membrane process design with those who are engaged in nuclear waste treatment near the plant sites were highlighted.
134 citations
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TL;DR: In this paper, the boundary value problem of steady, symmetric and one-dimensional electro-osmotic flow of a micropolar fluid in a uniform rectangular microchannel, under the action of a uniform applied electric field, was formulated and solved.
Abstract: We have formulated and solved the boundary-value problem of steady, symmetric and one-dimensional electro-osmotic flow of a micropolar fluid in a uniform rectangular microchannel, under the action of a uniform applied electric field. The Helmholtz–Smoluchowski equation and velocity for micropolar fluids have also been formulated. Numerical solutions turn out to be virtually identical to the analytic solutions obtained after using the Debye–Huckel approximation, when the microchannel height exceeds the Debye length, provided that the zeta potential is sufficiently small in magnitude. For a fixed Debye length, the mid-channel fluid speed is linearly proportional to the microchannel height when the fluid is micropolar, but not when the fluid is simple Newtonian. The stress and the microrotation are dominant at and in the vicinity of the microchannel walls, regardless of the microchannel height. The mid-channel couple stress decreases, but the couple stress at the walls intensifies, as the microchannel height increases and the flow tends towards turbulence.
24 citations
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TL;DR: In this paper, the initial boundary value problem of non-steady electro-osmotic flow of a micropolar fluid in a rectangular microchannel of height much larger than the Debye length and length much larger the height was formulated.
Abstract: We formulated the initial-boundary-value problem of non-steady electro-osmotic flow of a micropolar fluid in a rectangular microchannel of height much larger than the Debye length and length much larger the height. Solving the governing differential equations numerically when a spatially uniform electric field is applied as an impulse of finite magnitude, we found that the effect is instantaneous on the flow, just as for simple Newtonian fluids. The decay times of the fluid velocity and the microrotation, however, are smaller in micropolar fluids than in simple Newtonian fluids. The maximum magnitude of microrotation decreases as the micropolarity increases. The effect of microrotation on the stress tensor is more dominant than that of the fluid speed, and a threshold effect with respect to the magnitude of the zeta potential is evident in the spatial profile of the couple stress tensor. We expect similar trends even when the applied electric field varies over some finite interval of time.
9 citations
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TL;DR: In this paper, the authors derived analytical expressions for speed, flux, microrotation, stress, and couple stress in a micropolar fluid exhibiting a steady, symmetric, and one-dimensional electro-osmotic flow in a uniform cylindrical microcapillary.
Abstract: Analytic expressions for speed, flux, microrotation, stress, and couple stress in a micropolar fluid exhibiting a steady, symmetric, and one-dimensional electro-osmotic flow in a uniform cylindrical microcapillary were derived under the constraint of the Debye-Huckel approximation, which is applicable when the cross-sectional radius of the microcapillary exceeds the Debye length, provided that the zeta potential is sufficiently small in magnitude. Since the aciculate particles in a micropolar fluid can rotate without translation, micropolarity affects the fluid speed, fluid flux, and one of the two non-zero components of the stress tensor. The axial speed in a micropolar fluid intensifies when the radius increases. The stress tensor is confined to the region near the wall of the microcapillary, while the couple stress tensor is uniform across the cross-section.
7 citations
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TL;DR: In this paper, the electro-osmotic flow of a physiological fluid with prominent micropolar characteristics, flowing over a microchannel has been analyzed for a situation, where the system is subject to the action of an external AC electric field.
Abstract: Electro-osmotic flow of a physiological fluid with prominent micropolar characteristics, flowing over a microchannel has been analyzed for a situation, where the system is subject to the action of an external AC electric field. In order to account for the rotation of the micro-particles suspended in the physiological fluid, the fluid has been treated as a micropolar fluid. The microchannel is considered to be bounded by two porous plates executing oscillatory motion. Such motion of the plates will normally induce oscillatory flow of the fluid. The governing equations of the fluid include a second-order partial differential equation depicting Gauss’s law of electrical charge distributions and two other partial differential equations of second order that arise out of the laws of conservation of linear and angular momenta. These equations have been solved under the sole influence of electrokinetic forces, by using appropriate boundary conditions. This enabled us to determine explicit analytical expressions for the electro-osmotic velocity of the fluid and the microrotation of the suspended micro-particles. These expressions have been used to obtain numerical estimates of important physical variables associated with the oscillatory electro-osmotic flow of a blood sample inside a micro-bio-fluidic device. The numerical results presented in graphical form clearly indicate that the formation of an electrical double layer near the vicinity of the wall causes linear momentum to reduce. In contrast, the angular momentum increases with the enhancement of microrotation of the suspended microparticles. The study will find important applications in the validation of results of further experimental and numerical models pertaining to flow in micro-bio-fluidic devices. It will also be useful in the improvement of the design and construction of various micro-bio-fluidic devices.
6 citations
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