Facebook logo Twitter logo YouTube logo Podcast logo RSS feed logo

Ballast Water Filtering Project Comes to Minnesota

ballast water tanks

Donald Reid, Great Lakes Ballast Technology Demonstration Project consultant, releases filtered water back into the Duluth-Superior harbor from containers that simulate a ship’s ballast tanks.

You’ve heard the story: many of our exotic species — Eurasian ruffe, round gobies, and zebra mussels — apparently hitched a ride on ocean-going vessels, hiding in the ship’s ballast water and then gained a foothold in the Great Lakes after the water was released. Each day during the shipping season, cargo vessels load and discharge about 2 million gallons of ballast water in the Great Lakes. This ballast water is used to stabilize an empty or partially-loaded ship. If Allegra Cangelosi of the Northeast Midwest Institute and Richard Harkins of the Lake Carriers’ Association succeed, aquatic organisms may no longer get such an easy ride from their homes in Europe to America.

In 1996, Cangelosi and Harkins teamed to examine ways of removing aquatic organisms from ballast water. They developed the Great Lakes Ballast Technology Demonstration Project to test the feasibility of filtering lake and sea water before it enters a ship’s ballast tanks. The aim of the ballast water project is to develop an effective, durable, and economical way to prevent aquatic creatures from accidentally arriving in ecosystems where they are not native.

According to Cangelosi, many ships already filter ballast water through coarse screens to remove incoming debris and fish, but the filters they are testing can remove particles and plankton down to 25 microns. Even the minute larvae of zebra mussels would not pass through such a small mesh.

During the 1997 shipping season, the filter system rode aboard the Algonorth, a commercial carrier that shuttled grain and iron ore through the Great Lakes and the St. Lawrence Seaway.

The next phase of the Great Lakes Ballast Technology Demonstration Project now sits aboard a barge in Duluth’s harbor. This fall, project consultant Donald Reid and his co-workers collected pre-filtered and post-filtered samples of water pumped from 23 feet below the surface of the Duluth-Superior harbor, approximately the same depth at which cargo vessels acquire their ballast. “After the water is pumped up to the deck of the barge, it passes through one or two filters ranging in mesh size from 25 microns to 300 microns,” said Reid. “We collect subsamples of the filtered water from the three holding tanks then separate organisms and particles from the water in our field laboratory.” Era Laboratories in Duluth and the University of Wisconsin-Superior biology department will examine the zooplankton content of the different filtering regimes. Bacteria and viruses are being examined by a network of labs led by a James Madison University researcher.

Results of both the Algonorth and stationary barge tests will be combined into a report expected to be completed in the spring.

Along with biological questions, Cangelosi, Harkins, and project sponsors (including Sea Grant’s parent agency, the National Oceanic and Atmospheric Administration; other U.S. and Canadian federal agencies, the Great Lakes Protection Fund, the State of Minnesota, and shipping companies) are addressing mechanical considerations such as the practicalities of keeping the two back-flush filters from clogging, the frequency of backflush cycles in relation to different mesh sizes, and other industry concerns.

Based on the preliminary results of the Great Lakes Ballast Technology Demonstration Project, Cangelosi thinks filtering ballast water could be a viable first line defense against future invasions of aquatic life but it might not be the last. To purge bacteria, microbial organisms, and viruses from ballast water, secondary measures such as ultraviolet or chemical treatment might be necessary.

Most nations understand the importance of keeping aquatic organisms where they belong. “In general, the world maritime community wants to continue to make shipping one of the more environmentally-friendly modes of transportation,” says Ray Skelton from the Seaway Port Authority of Duluth, another agency supporting the filtration project. The U.S. and Canada require ocean-going vessels bound for the Great Lakes to exchange ballast water in mid-ocean. Mid-sea ballast exchange can be dangerous, ineffective, and at times impossible.

Over 130 non-native species have survived long enough to be found in the Great Lakes during the last 200 years. North American businesses, governments, and researchers continue to fight the zebra mussel, ruffe, lamprey, and other non-native species in an effort to prevent them from irrevocably altering Lake Superior’s ecosystem and fisheries. Similarly, nations bordering the Black Sea fight to prevent North America’s comb jellyfish from destroying their anchovy fishery.

Because it’s a prototype, the experimental filter floating on the barge in Duluth’s harbor is smaller and slower than the type that may eventually prevent tiny stowaways from boarding ships. However, it represents a promising step towards solving the global problem of aquatic invasions of non-native species.

By Sharon Moen
September 1998

Return to September 1998 Seiche

This page last modified on March 01, 2018     © 1996 – 2019 Regents of the University of Minnesota     The University of Minnesota is an equal opportunity educator and employer.
Facebook logo Twitter logo YouTube logo Podcast logo RSS feed logo
Logo: NOAA Logo: UMD Logo: University of Minnesota Logo: University of Minnesota Extension