During the period from 20 November to 19 December 2023, DHI conducted an anonymized scientific investigation in Danish, German and Swedish ports to test if the water discharged from the Ballast Water Management Systems (BWMS) installed on board eight different vessels were in compliance with the D-2 discharge standard. According to the D-2 standard the number of organisms ≥50 μm shall be less than 10 organisms/m3, and the number of organisms ≥10 and <50 μm shall be less than 10 organisms/mL.
All BWMS investigated were treating ballast water with filtration and UV. The Treatment Rated Capacity (TRC) varied from 500 m3/h to 1040 m3/h. The installation year of the BWMS varied from 2014 to 2023.
While four out of eight tests showed compliance with the D-2 standard, the remaining four tests did not. The investigation showed no correlation between performance efficiency and installation date or TRC.
Interviews were performed with the crew operating the BWMS on board the ships. During this investigation, it was noted that crew members seemed well trained in operating the BWMS and were aware of the Operation Maintenance and Safety Manual (OMSM) and the Type Approval Certificate.
The most important observation from the survey is that though the operation of the BWMS seems to be working within performance limits, and no alarms are observed, there is still a risk that the BWMS do not comply with the D-2 discharge standard.
Link to publication "Scientific investgation of ballast water discharge compliance to D-2