Numerical Studies of Design, Operation, and Maintenance for Reverse Osmosis Process

Abstract

Seawater reverse osmosis (SWRO) is one of the widely employed technology among the previously developed desalination process. A great deal of research has been conducted to improve its performance. Although the SWRO process has been significantly advanced since its first introduction to the water treatment industry, there are several problems to prevent further reduction of energy consumption. The SWRO process utilizes a semi-permeable membrane to filtrate high salinity water. Therefore, the performance of the process mainly depends on membrane performance. It means that the maintenance of the membrane state during operation plays a vital role in the SWRO process. In this study, numerical studies of design, operation, and maintenance for the SWRO process were conducted to develop the performance improvement methods by simulating the SWRO process. In the design stage, improvement methods of the process stability and the process flexibility were proposed by using internally staged design and two types of pump-train configurations under the seasonal fluctuation of feedwater. An optimization algorithm was employed to decide the membrane element configuration in a pressure vessel. Process performances were assessed according to the pump-train configuration. The flexibilities of the separated feed lines design and pump station design were compared to determine optimum design configuration. In the operation and maintenance stage, membrane fouling was predicted, and the process performance after cleaning and replacement of the membrane was evaluated. The hybrid machine learning algorithm was employed to predict membrane fouling and to increase prediction accuracy. The optimum cleaning and replacement criteria were determined by estimating the operating costs. At the end of this study, optimization methods were proposed to improve the SWRO process performance. The results of this study could be used to design a new SWRO plant or to enhance the process performance and flexibility during operation.