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The cleaning or regeneration of fouled membrane modules is an essential procedure in the membrane equipment operation. Despite the development of some successful cleaning techniques, the predictions of the membrane separation process operation parameters after regeneration is still an unsolved problem. In our previous works, the attempt to develop the methodology of estimating the membrane productivity after the regeneration of the fouled spiral wound membrane modules by cleaning the subatmospheric pressure has been made. However, this methodology requires some improvement, including the correction of the dimensionless equation to calculate the mass transfer coefficient. In this work, a set of additional experiments was carried out, and the corrections of the mass transfer correlation were done using both new and previously obtained experimental data. As a result, the improved dimensionless equation was contained as Sh = 0.00045Re0.8Sc0.33(de/l). This equation is valid in the range of Reynolds number variation of 0.4–60.0 for the case of the regeneration of spiral wound modules and can be used for the prediction of the permeate flux after the regeneration procedure.

The experimental determination of concentration polarization layer resistance during reverse osmosis of mineral salts solutions was carried out with the aim to estimate the influence of solution composition on the value of mentioned resistance. In experimental conditions, the membrane resistance remains constant (the mean value was 0.534·1014 m-1) which means that the membrane compaction was not observed. Moreover, under experimental conditions, the hypothesis about linear dependence between the concentration polarization layer and applied pressure was confirmed for all solutions under investigations. It was defined that value of concentration polarization layer resistance different salt solutions was varied less than 10 % although under experimental conditions the diffusion coefficient values of magnesium sulfate were more than three times higher than corresponded values for other salts. The increasing of solutions concertation determines the increasing of concentration polarization layer resistance. At the same time, in previous study it was defined that changes in hydrodynamic regime in membrane module under similar conditions could determine the change in concentration polarization layer resistance in 3–5 times, while in both studies the trends of impact of hydrodynamic conditions still similar to the value of considered resistance decrease with Reynolds number increasing. Such results showed that in considered range of concentrations the hydrodynamic conditions have a lower influence on concentration polarization layer resistance than solution composition. The obtained results are in agreement with the film theory of concentration polarization.