OVER 30% of all ballast water treatment systems (BWTS) fail port state compliance inspections, according to new information submitted to the International Maritime Organization (IMO).

This is despite 95% of BWTS having passed commissioning tests, according to analysis submitted by Global TestNet, an association of testing organisations, to the IMO’s recent MEPC 82 meeting.

Between 29% and 44% of BWTS are failing to remove invasive species in the over 50 microns (µm) range, with reportedly more than 100 organisms of this size routinely found in every 1 cubic metre of treated water.

Ships are required to discharge ballast water with less than 10 viable organisms per cubic metre that are at least 50µm in size.

Global TestNet, an association of testing organisations set up in 2010 under the GloBallast Partnership, also reported instances where more organisms were found in discharged water than in inlet water.

“These results show that even if a vessel with a type-approved ballast water treatment system passes initial commissioning tests, the BWM system alone cannot assure against non-compliance,” said BIO-UV Group’s BWT project manager, Charlène Ceresola.

According to the findings, the most common reasons for non-compliance were;

  • Contamination of the ballast water tank from mixing treated and untreated waters or improperly opening/closing valves
  • Organism regrowth due to insufficient and infrequent cleaning of the ballast water tanks, and
  • Human error due to insufficient system knowledge, maintenance, and training

“When a BWMS is properly installed, a high efficacy in removing organisms is achieved but IMO MEPC reports have acknowledged that this efficacy may not be sufficient to constantly meet the D-2 discharge standard,” Ceresola said.

“If operators do not fully understand the impacts of Ballast Water Management on board, and if bypassing cleaning procedures for ballast tanks occurs frequently, non-compliance will be unavoidable.

Maintenance and crew training are also areas where ships can be detained, according to Ceresola;

“There is certainly a need for strengthening maintenance and system knowledge, and this will be part of the package of amendments IMO is preparing,” she said.

“Shipowners want their systems to be in good working order but how do you ensure this once the manufacturer has installed the system and left the ship, or is no longer in the market?”