Effects of feed composition on the fouling on cation-exchange membranes desalinating polymer-flooding produced water

Hypothesis: Cation exchange membranes (CEMs) are subject to fouling when utilized to desalinate wastewater from the oil and gas industry, hampering their performance. The kind and extent of the fouling are most likely dependent on the composition of the stream, which in practical applications can vary significantly. Experiments: Fouling experiments were performed on commercial cation exchange membranes, which were used in electrodialysis runs to desalinate solutions of varying composition. The variations included ionic strength, type of ions, amount of viscosifying polyelectrolyte (partially hydrolyzed polyacrylamide), presence of crude oil, and surfactants. Performance parameters, like electric potential and pH, were monitored during the runs, after which the membranes were recovered and analyzed. Findings: Fouling was detected on most CEMs and occurred mainly in the presence of the viscosifying polyelectrolyte. Under normal pH conditions (pH similar to 8), the polyelectrolyte fouled the concentrate side of the CEMs, as expected due to electrophoresis. However, by applying a current in the opposite direction, the polyelectrolyte layer could be removed. Precipitation occurred mostly on the opposite side of the membrane, with different morphology depending on the feed composition. Published by Elsevier Inc.

Automated summary

The hypothesis states that cation exchange membranes (CEMs) face fouling issues when used in desalination of wastewater from the oil and gas industry, affecting their performance. Fouling experiments were conducted on commercial CEMs with varying solutions, demonstrating that fouling primarily occurs in the presence of polyelectrolytes. The study found that changing the direction of current could remove the polyelectrolyte fouling layer, with precipitation occurring on the opposite side of the membrane.