Advances In RO System Operation & Real-Time Control

Recent advances in model-based control and energy optimization for RO desalination have made it possible to develop self-adaptive operational strategies for RO membrane desalination systems. The goal of self-adaptive operation is to enable the plant to autonomously respond to changes in water feed salinity and fouling propensity. In order to demonstrate the operational benefits of advanced membrane process control, the UCLA team developed a compact second generation RO (CoM2RO) desalination system integrated with MF-UF feed filtration. The Com2RO implements a novel feed-forward controller capable of simultaneously self-adjusting the feed flow rate and transmembrane pressure in order to maintain the desired water productivity and quality.  Real-time sensor data along with embedded computing capability allow (real-time) on-line membrane element characterization and overall system performance assessment (with appropriate data normalization) that are used for rapid control and optimization. The controller enables integration of the UF and RO systems such that the UF can directly utilize the RO concentrate for backwashing and minimizes RO energy consumption, while the RO system adapts to any changes in pressure, flow rate or salinity that result from the cyclic nature of the UF backwashing. A field evaluation of the present advanced RO/UF system control was carried out for seawater desalination. Results of the study demonstrated that the present operational approach enabled the UF/RO system to adapt to changes in feed conditions while maintaining constant RO permeate production and quality. Moreover, real-time information regarding membrane characterization enabled rapid evaluation of the impact of varying fouling conditions on the performance of both the UF and RO systems, thereby enabling adjustment of operating conditions as well as fault detection.