Researchers conduct large-scale test of system to kill invasive species in ballast water

Researchers have conducted a large-scale test of a new system to kill invasive species hiding in the ballast water of Great Lakes freighters.

The Associated Press reports that crews recently pumped lye into two of 10 ballast tanks inside the 1,000-foot Indiana Harbor as it left Gary, Ind., treating 1.8 million gallons of ballast water. The chemical then was neutralized with carbon dioxide as the boat traveled across Lake Superior before releasing the ballast water in the Duluth-Superior harbor.

Lye, also known as sodium hydroxide, raises the pH of water to kill organisms. It is commonly used in wastewater treatment plants but had not been used in major ballast water applications before.

The Duluth News Tribune reported it's believed to be the first such major-scale test on the Great Lakes, with researchers from multiple universities and federal agencies involved along with funding from multiple state and federal grants.

The issue is important because state and federal governments are moving to require ballast treatment to help stop invasive species such as zebra mussels and nonnative fish, which cause an estimated $5.9 billion in damage to the Great Lakes every year. More than 60 percent of invasive species introduced in the Great Lakes have come from ballast water discharged by oceangoing ships.

Phyllis Green, superintendent of Isle Royale National Park and the instigator of the effort, told the News Tribune the next step will be to treat all 10 ballast tanks. Green moved earlier to ban ballast water discharges in Isle Royale National Park waters and installed a ballast treatment system onto the park's own passenger boat to avoid introducing a fish-killing disease to the park's waters.

The Superior-based Great Ships Initiative now is testing water samples drawn from the ballast tanks to see if the chemical actually killed organisms and whether the treated water was then successfully neutralized to prevent environmental harm. Results should be available next month.