LAND-BASED EVALUATION OF THE EFFECTIVENESS OF THE OPTIMARIN BALLAST SYSTEM IN THE GREAT LAKES

Abstract

This technical report presents the land-based evaluation of the Optimarin Ballast System, Model 334/340FX2. This work was conducted to evaluate the potential of the system to be used as a flow-through water treatment method for the Laurentian Great Lakes, treating via filtration and UV exposure on uptake and UV exposure again on discharge. The evaluation began September 2021 and ended October 2021. All analyses were conducted at either the Montreal Pier Facility or the Lake Superior Research Institute (LSRI) at the University of Wisconsin-Superior (UWS), both located in Superior, Wisconsin, USA. Biological effectiveness was examined during a commissioning trial and five efficacy trials with overnight retention of harbor water at the Montreal Pier Facility that was amended to achieve ETV Protocol challenge conditions. Effectiveness was assessed in terms of remaining live organisms in three size classes per unit volume: organisms ≥50 µm in minimum dimension (nominally zooplankton), organism entities ≥10 µm in any dimension and with cell sizes <50 µm in minimum dimension (nominally protists), and organisms <10 µm in minimum dimension (e.g., total culturable heterotrophic bacteria, total coliform bacteria, Escherichia coli, Enterococcus spp., and toxigenic Vibrio cholerae O1 and O139). Samples were compared to the United States Coast Guard’s (USCG) Standards for Living Organisms in Ships’ Ballast Water Discharged in U.S. Waters (USCG, 2012) with a focus on the reduction in the number of propagules in treated water versus control water. The Optimarin system was found to be highly effective at reducing the densities of organisms in all three regulated size classes. In particular, the USCG ballast water discharge standard (BWDS) was met in the bacteria size class in all trials. The density of zooplankton in treated discharge was below the USCG BWDS in all but one of the test cycles. Protist densities were greater than USCG BWDS in all test cycles but densities of protists in treatment discharge were decreased by >95% compared to control discharge samples.