Effect of operating conditions and solution chemistry on model parameters in crossflow reverse osmosis of natural organic matter

Abstract

This paper describes the effect of operating conditions and solution chemistry on model parameters in crossflow reverse osmosis of natural organic matter. Mathematical fouling model based on the combined osmotic pressure and cake filtration model was used to evaluate model parameters (i.e. steady-state flux, J* and specific cake resistance, α cake). In addition, the empirical equation for steady-state flux ( J* = 9.12 × 10 − 8 Δ P 1.04 v 0.223 R − 1.18 I − 0. 590) was successfully determined to characterize reverse osmosis operation. Steady-state flux increased with increased operating pressure, indicating a pressure-dependent steady-state flux under laminar flow condition. The specific cake resistance ( α cake = 7.943 × 10 12Δ P − 2.03 v − 0.739 R 6.29 I 1.37) was inversely related to increased operating pressure and crossflow velocity, while the specific cake resistance increased linearly with recovery effects and ionic strength. Recovery effects with high ionic strength resulted in the highest flux decline, corresponding to high specific cake resistance (i.e. lowering cake porosity) due to combined salt concentration polarization and NOM cake compaction near the membrane surface.