Scientists in Louisiana are reporting development and successful testing of a new cost-effective system to kill unwanted plants and animals that hitch a ride to the United States in the ballast water of merchant ships.
These so-called “invasive species,” such as the notorious zebra mussel, devastate native organisms and infrastructure and cost taxpayers billions of dollars annually. The study is scheduled for the June 1 issue of ACS’ Environmental Science & Technology.
In the study, Dorin Boldor and colleagues point out that invasive species often travel in ballast tanks of international cargo ships. Ships pump sea water into these tanks for stability when a vessel leaves port with little or no cargo. They dump the water at their destination — along with zebra mussels, Asian clams and other organisms that may pose environmental risks.
The new study describes development and laboratory-scale tests of a continuous microwave system which, much like a kitchen microwave oven, used heat to inactivate zooplankton, algae, and oyster larvae in salt water.
Researchers found that a 30-second zap, followed by a 200-second holding period, removed all marine life. Boldor noted that the high heating rates, low operating costs, and effectiveness in hazy water distinguish it from conventional heating methods.