Research reveals filtration favored over disinfection when treating ballast water
When treating ships' ballast water, new research conducted by the Analytical BioGeoChemistry research unit at the Helmholtz Zentrum München in Germany shows that filtration -- rather than disinfection -- can potentially serve as a more efficient method.
July 31, 2015 -- When treating ships' ballast water, new research conducted by the Analytical BioGeoChemistry (BGC) research unit at the Helmholtz Zentrum München in Germany, working in close collaboration with colleagues in the United States, shows that filtration -- rather than disinfection -- can potentially serve as a more efficient method.
In order to prevent the transfer of harmful organisms, ships' ballast water is often subjected to electrochemical disinfection. "However, our analyses show that electrochemical disinfection creates numerous so-called disinfection by-products (DBPs)," explained Professor Philippe Schmitt-Kopplin, who led the study.
He and his team at the BGC compared samples of treated and untreated ballast water. Using high-resolution mass spectrometry, they discovered that treatment led to the formation of 450 new, diverse compounds -- some of which had not previously been described as disinfection products or been structurally categorized.
"Until the toxicological features of these compounds are fully clarified, we recommend a cautious approach to disinfecting ballast water," Schmitt-Kopplin said. According to the scientists, the study -- the first in-depth analysis of DBPs in ballast water -- revealed the high degree of complexity of the resulting products. As an alternative, he recommends the use of physical processes such as filtration or adsorption.
In addition, the Helmholtz researchers point out the broader significance of their findings: As a result of the increasing dissemination of goods around the world, a growing number of ever-larger ships are being used. These vessels take on correspondingly large and increasing amounts of ballast water in order to stabilize their position in the water and to balance out any changes in the weight of goods or fuel during the journey.
Experts worldwide are now discussing ways of dealing with this water, as discharging untreated ballast water will be prohibited in the future. The alternative method of choice at present is electrochemical disinfection, according to the study.
"Large volumes of disinfected ballast water are distributed daily in coastal waters, but as yet, their impact on the environment cannot be foreseen," said First Author Michael Gonsior of the University of Maryland's Center for Environmental Science. "In future studies, we want to find out what influence the DPSs have on coastal ecosystems."