Water Quality, The Forgotten Secret to System Optimization

When reverse osmosis (RO) and nanofiltration (NF) systems are designed, the water quality is the most crucial piece of information. It is the deciding factor for which membranes will be used, what pretreatment will need to be installed, how much water can be recovered and the cost of energy that will be required to run the system. However, after the initial design, many systems neglect to monitor water quality unless there is a problem with the system. When an issue arises, system operators often only monitor a limited number of parameters, such as chlorine, conductivity/total dissolved solids, flow or individual ions (e.g. silica, iron, calcium) and many times the need to conduct a periodic ìwell roundedî water analysis is overlooked. Case studies involving system audits and laboratory analysis have shown that systems could be missing out on large economic benefits such as a reduction in consumables (i.e. pretreatment chemicals and cartridge filter replacement), increase in water production (recovery) and optimization of pretreatment requirements by not closely monitoring water quality. This paper describes how water quality monitoring can mitigate fouling and scaling before it occurs while lowering operational costs.