tailieunhanh - Ebook Membranes for industrial wastewater recovery and Re-use: Part 2

(BQ) Part 4 book "Membranes for industrial wastewater recovery and Re-use" has contents: Computer-Aided design for reverse osmosis plant, water pinch analysis, design examples, flag fen high purity water production plant, automotive water recycling, reference material,. and other contents. | Chapter 4 System design aids Computer-aided design for reverse osmosis plant Etienne Brauns VlTO Water pinch analysis Danielle Baetens VlTO Design examples Simon Judd School of Water Sciences, Cranfield University 172 Membranes for lndustrial Wastewater Recovery and Re-use Computer-aided design for reverse osmosis plant Introduction It has already been pointed out (Section 2 . 3 . 2 ) that modelling of filtration processes is not feasible on a universal basis, and that only reverse osmosis can be modelled on the basis of solution-diffusion. In such a case, modelling is possible using simple analytical expressions provided the water can be treated as a continuum essentially free of the more complex interactions introduced by the presence of dispersed particles, solute precipitation effects (gel layer formation) and/or biological activity at the membrane-solution interface. As a result of these complicating factors, which relate largely to porous membrane processes, computer-aided design (CAD) software is currently available only for reverse osmosis membranes and modules. The software packages are based on a series of calculations that enable the estimation of the RO array design and operation. It is instructive to review these CAD packages, which are produced by RO membrane manufacturers and suppliers based on their own products, with a view to ascertaining their general usefulness and limitations (Brauns, 200 1). Key elements of the reverse osmosis process Modelling of the reverse osmosis process relies on accurate mathematical representation of 0 0 0 the osmotic pressure, concentration polarisation, and the hydraulic resistance offered by the membrane and the membrane channels. As already discussed (Section ), the pressure required to drive a reverse osmosis process relates both to the permeability of the membrane and the osmotic pressure. The osmotic pressure is solute concentration related, and can be very high for .