The Great Ships Initiative (GSI) provides independent, no-cost performance verification testing services to developers of ballast treatment systems and processes at a purpose-built, land-based ballast treatment test facility located in the Duluth-Superior Harbor of Lake Superior (Superior, WI). GSI test protocols are consistent with the requirements of the International Maritime Organization’s International Convention for the Control and Management of Ships Ballast Water and Sediments (IMO, 2004) and the United States Environmental Protection Agency’s (USEPA’s), Environmental Technology Verification Program (ETV; NSF, 2010). GSI procedures, methods, materials and findings are also publicly accessible on the GSI website (www.greatshipsinitiative.org).
In August through October 2010, GSI conducted freshwater, land-based tests on three versions of the AlfaWall PureBallast® ballast water treatment system (BWTS). One version (hereafter referred to as v.1) of the PureBallast® BWTS received Type Approval by Det Norske Veritas (DNV) on behalf of the Norwegian Administration in June of 2008, following successful land-based testing at the Norwegian Institute of Water Research (NIVA). The second version (v.2), designed to conserve power relative to the first, was still undergoing IMO certification testing, and had completed successful land-based tests at NIVA immediately prior to testing at GSI during early summer 2010. The third version was a hybrid of versions 1 and 2, hereafter referred to as version 3 (v.3). The BWTS v.3 combined the 40 μm filtration of PureBallast® BWTS v.2 with the advanced oxidation system of PureBallast® BWTS v.1.
The GSI Test Plan for the AlfaWall PureBallast® BWTS, hereafter referred to as the GSI Test Plan, called for evaluation the PureBallast® BWTS v.2 consistent with IMO G8 and G9 guidelines for its ability to: (a) successfully treat ballast water without interruption, (b) meet IMO D-2 discharge standards after a five day holding time, and (c) discharge water after the five day retention period that is environmentally benign (i.e., no residual toxicity). Additional research and development testing of v.1 was also planned. However, the PureBallast® BWTS (both v.1 and v.2) encountered mechanical filter failures such that no valid trials (i.e. meeting IMO and ETV threshold conditions) were completed. Instead, GSI tested the hybrid version of the AlfaWall BWTS (v.3) under a set of GSI source water conditions less challenging than those required by IMO and ETV, strictly for research and development purposes. As an addition to the research and development trials of the PureBallast® BWTS v.3 at the GSI Land-Based RDTE Facility, a set of observations on living organisms in sample water 24 hours post discharge from treatment and control retention tanks was incorporated into the revised test protocol to detect any delayed effects of the BWTS.The PureBallast® BWTS v.3 performed without interruption during the first two trials under less challenging conditions than required by IMO and ETV. During the third and final trial, the PureBallast® BWTS v.3 encountered a filter failure, and the trial was stopped and restarted under ambient Duluth-Superior Harbor conditions. No residual toxicity was detected in the discharge waters of the PureBallast® BWTS v.3. The BWTS did not effectively reduce live organism densities in the two regulated size classes despite the fact that ambient densities were well below IMO and ETV testing intake thresholds. Part of the problem likely resided with filter ineffectiveness given filamentous algal forms in Duluth-Superior Harbor water. At the same time, very low ambient UV transmittance of Duluth-Superior Harbor water (naturally caused by tannins) during these tests likely impeded effectiveness of the advanced oxidation system. These two conditions also likely account for discrepancies between performance outcomes at GSI versus NIVA. Globally, the risk of very low UV transmittance conditions is not unique to Duluth-Superior Harbor, but it is relatively rare and can be anticipated in advance. Thus, this problem could be mitigated with management practices such as open ocean BWE in combination with treatment. Conditions present in Duluth-Superior Harbor likely leading to filter malfunction, on the other hand, may be relatively common to many fresh water and brackish water harbors.
Final Report of the Land-Based, Freshwater Testing of the AlfaWall AB PureBallast(R) Ballast Water Treatment System.
University of Minnesota Duluth.
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