Advanced studies of ballast water treatment with UV radiation

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Treatment of ships' ballast water to prevent species introductions is governed by regulations from the International Maritime Organization (IMO) and, by default, the US Coast Guard. Treatment with ultraviolet radiation (UV) is a proven technology for wastewater sterilization, an application led by Trojan Technologies (London, Ontario). UV is demonstrably effective for killing ballast water organisms. However, the current standard for validating treatment technologies is based on vital stains - an indirect assessment of viability - and alternative tests can be used only if they can be proved to work. This is critical to application of UV, because significant numbers of cells that are inactivated by UV appear to be alive when tested with vital stain assays that are currently being used by regulators to validate treatment technologies. In the absence of more accurate alternative tests, these misleading results would necessitate expensive and unnecessary over-treatment when UV is used for treatment. That in turn would prevent Trojan from competing effectively for a potential annual market share estimated at c. $1 billion annually for the next 6 years. We will determine the appropriate UV dose for killing a variety of phytoplankton, with an emphasis on species that can form ecologically-damaging or toxic blooms if introduced. This will define the minimum exposures required to confidently reduce the number of viable cells to the levels mandated by the IMO, thereby avoiding costly over-treatment. Viability will be determined directly with time- and effort-intensive grow-out procedures. We will also test optical techniques to assess the effectiveness of treatment in near-real time as a potential alternative to vital stains, which will tested in parallel. The results would allow Trojan to optimize treatment protocols and to develop rapid viability assays independent of the use of vital stains. Both are critical to compete effectively in a vast potential market.