Vigneswaran, S & Chang, JS 1989, 'Experimental testing of mathematical models describing the entire cycle of filtration', Water Research, vol. 23, no. 11, pp. 1413-1421.
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Two mathematical models developed based on different concepts to describe the entire cycle of filtration were tested with experimental results. The concept of Model I is based on the detachment of deposited particles. The degree of detachment was assumed proportional to the hydraulic gradient and number of particles already retained on the filter grain. Model II is based on the concept that there exists a maximum limit on particle deposition on the filter grain. It was found that Model I, based on the detachment assumption, can simulate better than Model II does. This may be an experimental proof for the concept of detachment which is now agreed by most of the researchers. The ultimate specific deposit was estimated experimentally for different filtration velocities to give a qualitative justification on the applicability range of the proposed models. © 1989.
Vigneswaran, S & Mora, JC 1989, 'Energy recovery considerations for membrane separation process', RERIC International Energy Journal, vol. 11, no. 1, pp. 1-15.
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This paper gives an overview of different membrane processes like reverse osmosis ultrafiltration with direct and indirect energy recovery systems. The feasibility of using direct and indirect energy recovery in each membrane process and a few examples are presented. The importance of cogeneration technology and pervaporation, and principles and examples are also introduced.
Vigneswaran, S, Muttamara, S & Srianandakumar, K 1989, 'Low waste technologies in selected industries', ENVIRON. SANIT. REV., no. 27, pp. 1-86.
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Expectations of increasingly higher living standards along with rapid industrial developments have resulted in a dramatic rise in the level of pollution of the natural environment. At the same time it is generally accepted that a healthy life requires good quality environment and hence the control of pollution. Today, environmental scientists are in the process of combining all these three aspects (industrialization, clean environment and healthy life) based on the principle of using low and non-waste technology. The philosophy behind this is 'to produce better while polluting less'. In practice, this technology and its application go by many names such as low and non-waste technology (LNWT), clean technology, pollution prevention, waste reduction, waste recycling, resource utilization, etc. The basic goal of LNWT is to eliminate the by-product formation that is discarded as waste. The objectives of LNWT are therefore to avoid inefficiencies in production which result in excess of waste and to recover the useful components of the waste in such a way that they can either be reused or recycled to minimize the emission of pollutants to the environment. LNWT alleviates disposal costs, liability risk and resource cost.
Vigneswaran, S, Muttamara, S, Srianandakumar, K & Ben Aim, R 1989, 'Low waste technologies in selected industries', Environmental Sanitation Reviews, no. 27.
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The paper examines the need for low and non-waste technology. The methods to achieve low-waste technology are given. Selected unit operations are discussed for suspended solids removal and dissolved solids removal. The applications in selected industries include: pulp and paper mill industry; tapioca starch industry; palm oil refinery wastewater treatment; food industry; textile industry; electroplating industry; distillery industry.
Visvanathan, C, Aim, RB & Vigneswaran, S 1989, 'Application of cross-flow electro-microfiltration in chromium wastewater treatment', Desalination, vol. 71, no. 3, pp. 265-276.
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Cross-flow microfiltration (CFMF) was experimentally studied for the separation of precipitates of chromium hydroxide. Although this process enables one to obtain chromium-free filtrate, a disadvantage is that the filtration flux declines rapidly due to membrane fouling. In order to avoid this fouling problem and increase the filtration flux, an electric field was applied across the membrane as an antifouling technique (cross-flow electro-microfiltration-CFEMF). The surface charges of the precipitates were modified by adding a dispersant. The experimental results indicate that this modified process of CFEMF is highly effective in reducing the membrane fouling, which eventually leads to a remarkable filtration flux increase. The application of this antifouling technique of CFEMF is cited only for the suspensions containing charged particles and colloids. Nevertheless, the process of modification of surface charge with a dispersant permits us to use this technique with a wide variety of suspensions. © 1989.