A strategy of membrane cleaning and replacement schedule for spiral-wound SWRO system

Membrane fouling is the chief culprit of the degradation of membrane performance. To reduce the operation cost, a new membrane cleaning and replacing strategy is addressed here. After establishing the SWRO performance model according to the fouling process mechanism, an optimization problem is founded with minimizing the daily operation cost as target, membrane cleaning and replacing time and frequency as optimizing variables, open equations as constraints. And then, the complicated optimization is solved by simultaneous method quickly and easily. Based on these techniques, case study on SWRO system is carried out and the solutions indicates that: 1). The proposed optimization strategy has a great potential to reduce the operation cost while obtaining the optimal membrane cleaning and replacing time and membrane cleaning frequency; 2). Feed water temperature has a significant impact on the optimal cleaning and replacing strategy. And the composition of the optimal cost and the curves of the optimal operation pressure and flow rate, which is of great significance to the further study of the system operation and analysis.