Success Story – Ballast Water Treatment Study Released
Wisconsin Great Lakes Protection Strategy Includes Treatment of Ballast Water
President Bush signed the Great Lakes Compact on October 3, 2008, with an effective date of December 8, 2008. This historic agreement seeks to address managing water quantity and promoting water conservation and efficiency throughout the Great Lakes Basin. Wisconsin’s Great Lakes Strategy takes a further step with protecting Great Lakes water by controlling the spread of aquatic invasive species (AIS). The key to preventing new AIS introductions is by controlling the transport mechanisms or pathways of release of AIS from the shipping industry into Lakes Michigan and Superior. The highest prevention priority is the control of ballast water from ships from foreign ports. A study released by the DNR in September 2008, Port of Milwaukee Off-Ship Ballast Water Treatment Feasibility Study Report, Phase 2 (PDF), evaluates the wastewater treatment options for ballast water. The report was prepared for the DNR by Brown and Caldwell Environmental Engineers and Scientists and Bay Engineering, Inc.
What is Ballast Water and Why is it a Problem?
Ballast water is used to balance a ship when it loads and unloads cargo and to stabilize it during transit through rough water. Ships take in ballast water when cargo is unloaded and discharge it when cargo is loaded. The volume of ballast water carried on-board a ship varies depending on the type of load that it is transporting and the ship’s capacity for storing ballast water. Research has shown that ballast water of ships engaged in international trade have transferred AIS species from locations such as the Baltic, Black, and North Seas across the Atlantic Ocean to the freshwater ecosystem of the Great Lakes. The Transportation Research Board of the National Academies noted in it report, Great Lakes Shipping, Trade, and Aquatic Invasive Species, issued July 2008, that an estimated 55 to 70 percent of all AIS introductions in the Great Lakes Basin are attributed to ballast water discharges.
Aquatic Invasive Species are Costly to Control
The zebra mussel, Eurasian ruffe, round goby, and quagga mussel are all AIS thought to have entered the Great Lakes Basin through the discharge of ballast water of ocean going ships. Major economic and ecological impacts on the Great Lakes region have resulted from the introduction of AIS.
The ecological impacts of zebra mussels are well documented. The explosive growth of the zebra mussel populations in underwater utility infrastructure clogs intake and distribution pipes for water treatment plants and power generation facilities. Financial impacts from zebra mussels have been significant to Wisconsin's water utilities and power plants. In 2001, Wisconsin Electric Power Company reported spending $1.2 million per year in the control of zebra mussels on the submerged infrastructure of their Lake Michigan power plants. The estimated annual cost of controlling zebra mussels in the Great Lakes now range from $100 to $400 million, according to the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory Director, Dr. Stephen Brandt.
Ballast Water Treatment Study Recommendations
Ships can potentially transport AIS from any oceanic location in the world into the Great Lakes Basin unless the ballast water is treated prior to discharge. There are currently no shore-based ballast water treatment facilities available to vessels operating on the Great Lakes. Seeing the need for research on this topic, the DNR funded the Port of Milwaukee study to evaluate the feasibility of developing wastewater treatment facilities in port areas.
The feasibility study contains a conceptual design for retrofitting a barge to collect ballast water from ships from foreign ports. In order to effectively transfer ballast water from the ship to the barge, a modification to the ship would need to be made. The ship modification consists of inserting a tee into the existing ballast piping inboard of the sea valve on the shell of the vessel, closing the sea valve, and then sending the ballast water up through new piping (called the off-ship connection branch) to the deck of the ship.
The conceptual treatment system on the barge would consist of a cloth media disk filter, followed by ultra-violet (UV) disinfection. The report includes estimated capital costs, operation and maintenance costs, ship retrofitting considerations, ballast water transfer issues, and wastewater treatment options. Future actions recommended include performing a wastewater characterization study of ballast water; pilot testing of the ship modifications; pilot testing of the wastewater treatment system; and determining costs for residuals handling.
RSS