A time-dependent model of pressure drop in reverse osmosis spiral wound membrane modules

Reverse osmosis (RO) is the leading technology in desalination for both, brackish and seawater. Modeling RO process is a complex task as there are a high dependence on the operating conditions and feedwater characteristics. One of the main drawbacks of this technology is the performance decay due to fouling impact. Usually, fouling make the pressure drop to increase. This increase has not been reflected in the proposed models in RO process. The aim of this work was to proposed a time-dependent model for the pressure drop in RO process. For this purposes long-term experimental data of two full-scale brackish water RO desalination plants with two stages each were used. The first desalination plant was operating along 11 years in continuous regime while the second desalination plant was in operation during 14 years in intermittent regime. In the first desalination plant, the pressure drop ranges were 75-250 kPa and 25-150 kPa in the first and second stage respectively while in the second desalination plant were 50-200 kPa and 20-125 kPa. The behavior of the experimental data in both cases was close to an exponential function. The mentioned function was fitted in time domain using the standard deviation as error function.