As the quantity and quality of inland water sources decline, more coastal municipalities are looking at seawater desalination as a potential source of drinking water. The Long Beach Water Department (LBWD) developed an alternative technology to desalt seawater by using dual-staged nanofiltration (NF2). This novel NF system treats the first-stage permeate through a second stage in order to produce finished water with salinity levels that meet drinking water standards.
Focusing on the application of membranes in an engineering context, this hands-on computational guide makes previously challenging problems routine. It formulates problems as systems of equations solved with MATLAB, encouraging active learning through worked examples and end-of-chapter problems. The detailed treatments of dead-end filtration include novel approaches to constant rate filtration and filtration with a centrifugal pump. The discussion of crossflow microfiltration includes the use of kinetic and force balance models. Comprehensive coverage of ultrafiltration and diafiltration processes employs both limiting flux and osmotic pressure models. The effect of fluid viscosity on the mass transfer coefficient is explored in detail, the effects of incomplete rejection on the design and analysis of ultrafiltration and diafiltration are analysed, and quantitative treatments of reverse osmosis and nanofiltration process analysis and design are explored. Includes a chapter dedicated to the modelling of membrane fouling.
Treated wastewater effluents contain high concentrations of particles; many of these particles are large (with diameters greater than 100 m) and consist of densely-packed bacterial cells. Microorganisms occluded in wastewater particles can be difficult to inactivate in chlorine disinfection systems, as the chlorine must first diffuse through the macro- and microscopic pore spaces prior to inactivating the occluded microorganisms. The impact of microorganisms occluded in particles is evident in disinfection, where reduced inactivation rates occur even with increasing doses of the disinfectant. Reduction of occluded microorganisms in plant effluents can be accomplished using filtration to remove the total number of particles, and disinfection to ensure that intra-particle chlorine concentrations are sufficient to inactivate the occluded microorganisms.
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