AWWA MTC93052

The approach to process design is similar for reverse osmosis and nanofiltration facilities. Although basically a low pressure version of RO, NF plants tend to be slightly different in scope, and in the opinion of some, offer a somewhat greater opportunity for design creativity. This paper covers certain ground rules pertaining to: basis of design (feed water quality, plant and train capacity and blending, type of plant, and recovery); and selection of operating characteristics (membrane flux, system pressure, and membrane assemblies). Having developed a number of equations and rules of thumb to perform hand calculations to predict and confirm membrane system process parameters, it will no doubt come as a relief that computer software is available from several membrane manufacturers, including Hydranautics, Fluid Systems, Dow, TriSep, and others. The concluding section of the paper offers brief reviews of each manufacturer's software.