Impact of intermittent operation on reverse osmosis membrane fouling for brackish groundwater desalination systems

Solar powered reverse osmosis systems are a promising technology for remote communities facing water insecurity. These systems are often operated intermittently with extended shutdown periods to reduce energy storage requirements and system cost. This article experimentally evaluates the effect of intermittent operation on membrane fouling with brackish groundwater. Lab-scale results show that the use of anti-scalant during operation and a rinse with clean water before shutting down the system results in high membrane permeability, above 70% of the initial membrane permeability after seven days of operation. Without rinsing, the lab-scale results showed the membrane permeability dropped to less than 50% of the initial permeability. Membrane autopsy using scanning electron microscopy for mineral deposits and adenosine triphosphate for quantifying biofouling revealed the fewest deposits when anti-scalant and a rinse were performed. To show scalability, pilot-scale studies were conducted and showed similar permeability declines and fouling structures in membrane autopsy. These results will help inform the advancement of reliable solar powered reverse osmosis systems for remote areas.