LAND-BASED EVALUATION OF THE EFFECTIVENESS OF THE OPTIMARIN DN100 AND DN150 BALLAST SYSTEMS IN THE GREAT LAKES

Abstract

This technical report presents the land-based evaluation of two Optimarin Ballast System models. The focus was primarily on the Model 68/340FX2 using a DN100 chamber but also includes data for one trial using the Model 334/340FX2 with a DN150 ultraviolet (UV) chamber. This work evaluated the potential of the systems to be used as a flow-through water treatment methods for the Laurentian Great Lakes, treating via filtration and UV exposure on uptake and UV exposure again on discharge. The evaluation began August 2022 and ended October 2022. 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 five efficacy trials, which included overnight retention of treated harbor water at the Montreal Pier Facility that had been amended to achieve ETV Protocol challenge conditions (NSF International, 2010). Trial 1 assessed performance of both systems consecutively during a short timeframe to ensure water quality was as similar as possible. In Trials 2-5, the Model 68/340FX2 with a DN100 UV chamber was tested. Biological effectiveness was assessed in terms of remaining live organisms in three size classes per unit volume: • Organisms ≥50 µm in minimum dimension (nominally zooplankton), • organisms ≥10 µm and <50 µm in minimum dimension (nominally protists), • and organisms <10 µm in minimum dimension (nominally bacteria; e.g., total culturable heterotrophic 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 (U.S. Coast Guard, 2012) with a focus on the reduction in the number of propagules in treated water versus control water. The Model 68/340FX2 Optimarin system using a DN100 UV chamber was found to be effective at reducing the densities of organisms in all three regulated size classes. The densities of zooplankton in treatment discharge samples did not meet the USCG Ballast Water Discharge Standard (BWDS) but were >98% lower than control discharge in all trials. The densities of protists in the treatment discharge samples were above the USCG BWDS in all trials but had decreased by >84% when compared to control discharge samples. All indicator bacteria (i.e., E. coli, Enterococcus spp., and Vibrio Cholerae) were below the USCG BWDS on uptake and discharge and decreased to less than the limit of detection after treatment. The Optimarin system Model 334/340FX2 using a DN150 ultraviolet (UV) chamber showed very similar trends to in all size classes when compared to testing completed in 2021 (Polkinghorne et al., 2022) and when compared to testing completed in 2022 with Model 68/340FX2 Optimarin system using a DN100 UV chamber