Identification modeling and control of continuous desalination process using reverse osmosis

Abstract

newline Water scarcity due to global warming and seasonal anomaly has led newlineprocess industries to reuse utility (water) to the maximum extent. If the wastewater newlinecan be reused, both the demand for water and the amount of waste newlinewater can be reduced. Generally, desalination is done by distillation (multistage- newlineflash (MSF), multiple effect, evaporation and vapour compression), or newlinemembrane processes (electro dialysis reversal, nano filtration, membrane newlinedistillation, forward osmosis and reverse osmosis). Out of all these, reverse newlineosmosis (RO) using cellulose acetate or polyamide membranes, is widely newlinechosen, as the cost of production is reduced by the use of energy efficient newlinetechniques. Because of the energy efficiency of the process, RO has been newlineused commercially since 1982. RO enables more environment-friendly newlineoperations like demineralisation of water, to clean brackish water or to desalt newlineseawater. Fresh water is generally considered to be that which has less than newline1000 mg/L of total dissolved solids (TDS), whereas sea water typically has newline35000 mg/L of TDS. Brackish and saline water, fall between these values. newlineAccording to WHO s guidelines, drinking water should not contain more newlinethan 500 ppm (mg/L) of TDS. Desalination has lumped nature of dynamics, newlinethough pretreatment and post-membrane processes are easy to understand, newlinedynamics through porous membrane gave most of the complexities of proper newlinecontrolling the desalination process. The concentration polarisation along the newlineboundary wall of membranes are yet to be understood, for the mechanism of newlinethe building of a boundary layer of solute along the walls of membrane, acts newlineas a barrier to the percolation process and prohibits the transport of the solute through the membrane. In order to solve the above problems, operational newlinecontrol strategy is to be formulated through the estimation of the transfer newlinefunctions, and feedback control of the multivariable process. So the objective newlineof the desalination process is to increase the production of permeates, at a newlinespecified salinity,