Water quality guidelines suspended solids

In the recommended feed water quality guidelines, McCoy notes that for modem industrial boilers, which have extremely high rates of heat transfer, the concentrations for iron should be essentially zero. Similarly, total hardness should not exceed 0.3 ppm CaC03, even at the lowest pressures suspended solids in the feed water should be zero, if possible. 

Suspended solids are typically measured using turbidity. Turbidity measures the light-scattering ability of particles in water. The water quality guidelines call for an influent turbidity of less than 1 Nephelometric Turbidity Units (NTU), which also happens to be a warranty requirement of membrane manufacturers. Exceed 1 NTU and the membrane warranty is voided. The lower the turbidity, the less likely the membranes are to foul with suspended solids. RO best practices call for feed water turbidity less than 0.5 NTU. 

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