Control of biofilms with UV light: a critical review of methodologies, research gaps, and future directions

The use of UV light to prevent or mitigate the development of biofilms is an area of emerging research that spans numerous industries. We reviewed 58 papers published between 1998 and 2024 reporting UV/biofilm experiments. Unlike earlier literature reviews on this topic, we included studies from many areas of practice including water, healthcare, and food safety. We focused on experimental methods and the types of information reported in different studies. Major research gaps included a lack of comparison between different approaches to biofilm growth and/or UV exposure, poor reporting of the chemical and/or optical characteristics of the biofilm growth and UV exposure media, little to no investigation into the impact(s) of support surface characteristics on treatment efficacy, few attempts to meaningfully compare the effects of different UV wavelengths on biofilms, and limited use of advanced methods to quantify and characterize of biofilms exposed to UV light. No existing studies have explored how UV light travels through biofilms or whether existing UV characterization methods can be meaningfully applied to UV/biofilm studies. The impacts of hydraulic conditions during biofilm growth and UV exposure also remain unexplored. Through this review we determined that a prescriptive standard experimental method for UV/biofilm experiments would be unable to encompass the wide range of industries and potential applications of the technology. Instead, recommendations for minimum reporting requirements were developed and examples of advanced methods to enhance future for UV/biofilm experiments were identified along with a proposed terminology framework to improve comparability between studies.