Can UVC-LEDs mitigate biofouling in community-scale photovoltaic-powered reverse osmosis systems?

ABSTRACT The lack of safe drinking water infrastructure in off-grid communities is a significant risk to sustainable development, especially for low- and middle-income countries (LMICs). Photovoltaic-powered reverse osmosis (PVRO) has emerged as a promising method due to its performance, scalability, consistency, and the robust global supply chain of its components. However, reliability issues like biofouling can quickly reduce its performance, shorten membrane lifetime, and hinder adoption in off-grid settings. Ultraviolet light emitting diodes (UV-LEDs) ranging from 200–285 nm wavelengths reduce the number of microorganisms in water but there are mixed results about their use on mitigating biofouling in reverse osmosis systems. Herein, we aim to provide a preliminary assessment on whether UV-LED pre-treatment can mitigate biofouling in PVRO systems. Analysis of the E. coli concentration pre- and post-UV treatment for batch and flow cell experiments demonstrated reduced bacterial concentration after treatment but suggest that remaining bacteria after UV treatment can grow back over time, i.e., UV-LEDs do delay, but not completely eliminate, biofouling. These results encourage further investigation into how UV-LEDs can be optimally integrated in PVRO systems and also set the premise for controlled biofouling mitigation studies for intermittently operated, small-scale PVRO.