“It is important that all three fractions and especially those greater than 50 µm are considered when testing ballast water, as experience proves that if a system fails it is most likely in this category,” said Carine Magdo, Business Development Manager for Ballast Water Monitoring Solutions, LuminUltra.
Indeed, zooplankton is the most difficult fraction to treat in order to achieve compliance with D2 discharge requirement. Blooms of zooplankton can also clog up BWTS filters. If filters fail, then this can pose a significant challenge to system performance during the approval process and later then in actual operation. Meanwhile the presence of phytoplankton and bacteria, is generally seasonal and dependent on the region, so checking for these organisms alone is not a fair indicator of a BWMS’s efficacy. Furthermore, the ecosystem in a ballast tank can change between ports, with the >50µm fraction potentially increasing and the 10-50µm fraction potentially decreasing. One of the reasons is because Zooplankton can survive in the ballast tank without light, whereas phytoplankton dies or is eaten. “IMO has made remarkable progress in regulating ships’ ballast water,” Magdo said.
“The Ballast Water Management Convention, still fairly new to the industry, continues to evolve as more technology and expertise is developed. A number of next steps have been identified, which LuminUltra is involved with, including verification of the indicative analysis instruments required to measure the different levels across the fractions.”