Final Report of the Land-Based, Freshwater Testing of the Lye (NaOH) Ballast Water Treatment System

Abstract

The Great Ships Initiative (GSI) provides independent, no-cost performance verification testing services to developers of ballast water treatment systems (BWTSs) and processes at a purposebuilt, land-based ballast treatment test facility located in the Duluth-Superior Harbor of Lake Superior (Superior, WI). The GSI is capable of performing testing fully consistent with the requirements of the International Maritime Organization’s (IMO’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 International, 2010). GSI procedures, methods, materials and findings are also publicly accessible on the GSI website (www.greatshipsinitiative.org). In July 2010, GSI conducted a land-based performance evaluation test of a proposed BWTS developed by researchers from the U.S. Geological Survey’s Leetown Science Center in Kearneysville, West Virginia. The proposed system involved application of sodium hydroxide (NaOH, in the same formulation used for lye or caustic soda) to ballast water to raise pH, followed by application of carbon dioxide (CO2) as a neutralization step prior to discharge of the ballast water to the receiving system. The purpose of the land-based test of this system, consisting of four trials, was status testing for research and development. As such, the testing was based on, though not strictly consistent with, the IMO’s G8 Guidelines for Approval of Ballast Water Management Systems (IMO, 2008a), the IMO’s G9 Guidelines for Approval of Ballast Water Management Systems that make use of Active Substances (IMO, 2008b), and the USEPA’s ETV Program Generic Protocol for the Verification of Ballast Water Treatment Technology, v.5.1 (NSF International, 2010). During the test, the NaOH BWTS was evaluated for its ability to: (a) successfully treat ballast water without interruption, (b) successfully neutralize treated ballast water to achieve Wisconsin Department of Natural Resources (WIDNR) permitting levels for harbor discharge (i.e., pH 6-9), (c) meet discharge target values for water chemistry/quality and biology that are approximately consistent with the IMO Convention’s Annex D-2 discharge standards, and (d) discharge water after two- or three-day retention periods that is environmentally benign (i.e., no residual toxicity) pursuant to USEPA water quality criteria. The NaOH BWTS performed very well operationally and well enough biologically to warrant additional testing at the bench, land and ship-based scales. The system successfully treated ballast water without interruption, and successfully neutralized treated ballast water to achieve WIDNR permitting levels for harbor discharge (i.e., pH 6-9). The BWTS also significantly reduced live organism densities in treated discharge relative to control discharge in all size classes of organisms. Finally, in these tests, the BWTS performance met discharge target values that were approximately consistent with the IMO Convention’s Annex D-2 discharge standards, though precision in this estimate was not possible given the research and development testing parameters. The only possible problem that this testing revealed was that the water discharged after two- or three-day retention periods was not entirely environmentally benign (i.e., with no residual toxicity at the 100 % effluent dilution), though the level of residual toxicity in 100 % effluent evident from these tests may not be of regulatory concern.