The Application of UVC Used in Synergy with Surface Material to Prevent Marine Biofouling

UV emitting glass: A promising strategy for biofilm inhibition on transparent surfaces

Marine biofouling causes serious environmental problems and has adverse impacts on the maritime industry. Biofouling on windows and optical equipment reduces surface transparency, limiting their application for on-site monitoring or continuous measurement. This work illustrates that UV emitting glasses (UEGs) can prevent the establishment and growth of biofilm on the illuminated surfaces. Specifically, this paper describes how UEGs are enabled by innovatively modifying the surfaces of the glass with light scattering particles. Modification of glass surface with silica nanoparticles at a concentration 26.5 μg/cm2 resulted in over ten-fold increase in UV irradiance, while maintaining satisfactory visible and IR transparency metrics of over 99 %. The UEG reduced visible biological growth by 98 % and resulted in a decrease of 1.79 log in detected colony forming units when compared to the control during a 20 day submersion at Port Canaveral, Florida, United States. These findings serve as strong evidence that UV emitting glass should be explored as a promising approach for biofilm inhibition on transparent surfaces.

Investigating the Impacts of UVC Radiation on Natural and Cultured Biofilms: An assessment of Cell Viability

Biofilms are conglomerates of cells, water, and extracellular polymeric substances which can lead to various functional and financial setbacks. As a result, there has been a drive towards more environmentally friendly antifouling methods, such as the use of ultraviolet C (UVC) radiation. When applying UVC radiation, it is important to understand how frequency, and thus dose, can influence an established biofilm. This study compares the impacts of varying doses of UVC radiation on both a monocultured biofilm consisting of Navicula incerta and field-developed biofilms. Both biofilms were exposed to doses of UVC radiation ranging from 1626.2 mJ/cm2 to 9757.2 mJ/cm2 and then treated with a live/dead assay. When exposed to UVC radiation, the N. incerta biofilms demonstrated a significant reduction in cell viability compared to the non-exposed samples, but all doses had similar viability results. The field biofilms were highly diverse, containing not only benthic diatoms but also planktonic species which may have led to inconsistencies. Although they are different from each other, these results provide beneficial data. Cultured biofilms provide insight into how diatom cells react to varying doses of UVC radiation, whereas the real-world heterogeneity of field biofilms is useful for determining the dosage needed to effectively prevent a biofilm. Both concepts are important when developing UVC radiation management plans that target established biofilms.

Design and In Situ Validation of Low-Cost and Easy to Apply Anti-Biofouling Techniques for Oceanographic Continuous Monitoring with Optical Instruments

Biofouling is the major factor that limits long-term monitoring studies with automated optical instruments. Protection of the sensing areas, surfaces, and structural housing of the sensors must be considered to deliver reliable data without the need for cleaning or maintenance. In this work, we present the design and field validation of different techniques for biofouling protection based on different housing materials, biocides, and transparent coatings. Six optical turbidity probes were built using polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), PLA with copper filament, ABS coated with PDMS, ABS coated with epoxy and ABS assembled with a system for in situ chlorine production. The probes were deployed in the sea for 48 days and their anti-biofouling efficiency was evaluated using the results of the field experiment, visual inspections, and calibration signal loss after the tests. The PLA and ABS were used as samplers without fouling protection. The probe with chlorine production outperformed the other techniques, providing reliable data during the in situ experiment. The copper probe had lower performance but still retarded the biological growth. The techniques based on transparent coatings, epoxy, and PDMS did not prevent biofilm formation and suffered mostly from micro-biofouling.

Biocide vs. Eco-Friendly Antifoulants: Role of the Antioxidative Defence and Settlement in Mytilus galloprovincialis

Antifoulant paints were developed to prevent and reduce biofouling on surfaces immersed in seawater. The widespread use of these substances over the years has led to a significant increase of their presence in the marine environment. These compounds were identified as environmental and human threats. As a result of an international ban, research in the last decade has focused on developing a new generation of benign antifoulant paints. This review outlines the detrimental effects associated with biocide versus eco-friendly antifoulants, highlighting what are effective antifoulants and why there is a need to monitor them. We examine the effects of biocide and eco-friendly antifoulants on the antioxidative defence mechanism and settlement in a higher sessile organism, specifically the Mediterranean mussel, Mytilus galloprovincialis. These antifoulants can indirectly assess the potential of these two parameters in order to outline implementation of sustainable antifoulants.

Single Ultraviolet-C light treatment of early stage marine biofouling delays subsequent community development

Past studies of Ultraviolet-C (UV-C) radiation as a marine antifoulant have focused on repeated doses. However, single or very low frequency exposures of UV-C could create more plausible applications for certain marine structures. The objective of the study reported here was to apply a single treatment of UV-C radiation to an early stage marine biofouling community to observe subsequent effects on biofouling development. Biofouling formed over a 2-week field immersion received UV-C treatments of 0 (control), 4, 20, or 120 min, and subsequent progression was then monitored weekly for 16 weeks. Analysis of acute effects and later macrofouling development suggested direct toxicity of UV-C illumination to invertebrate recruits caused reduction of subsequent biofouling (compared to controls) that persisted for up to 16 weeks following the longest UV-C treatment. Thus, UV-C treatments spaced by days or even weeks could be an option for some applications of UV-C radiation as an antifoulant.