Predicting Antiscalant Dosages in RO/NF Feedwater With High Ferric Iron Concentrations

This paper discusses certain aspects of iron behavior, the developed computer model, and its application and validation using a pilot system at the Florida RO plant. Speciating the hydrolysis states of ferric iron with respect to pH, ionic strength, and temperature, is essential to predicting the concentration factor as well as the scaling potential. The solubility of iron is highly dependent on the types of counterions that are present in solution. The iron dosage model worked well in a pilot trial for a feed water with high iron. However, later work suggested that the model could be further improved by accounting for the deprotonation states of the components within the antiscalant.

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