Why BWMS commissioning testing can fail

In theory, there should be no failure of a ballast water treatment system commissioning test – it is in the interest of the manufacturer, the installation yard, the shipowner and all stakeholders – for the test to be a success.

But as the first speaker in the Navigating ballast water commissioning testing requirements and potential pitfalls webinar, held 9 April 2024, global testing company SGS EMEA’s marine business manager Ersi Zacharopoulou revealed, failures do happen.

Speaking of SGS’s experiences to the end of 2023, Ms Zacharopoulou said, “We have tested around 677 systems of 30 different makers, and this was happening in 28 different countries. What we have seen is that 13% of the systems have failed.”

Ms Zacharopoulou noted that where ATP was used as a primary method for assessing compliance, in 23% of cases, discharges failed to meet the ATP criteria for the size fraction ≥50 µm (ie they were in the ’Close to compliance’ or ’Likely not in compliance’ categories).

Failure to meet the ATP criteria was much lower for the other groups: 2% for organisms in the ≥10 µm and <50 µm size class (n=12), and 5% for indicator microbes (n=32).

Regarding total residual oxidant (TRO) discharge compliance, the failure rate decreased dramatically from about 30% of failures in early testing to a constant failure rate around 9%, consistent with the improvement observed over time in meeting the discharge standard. There has been a rapid improvement in ships meeting the MADC of 0.1 mg L-1 for TRO (expressed as Cl2).

Wärtsilä Water & Waste proposals engineer Michelle Guy explained the distinct parts of commissioning. “There is commissioning of the system itself and commissioning testing. These make up a very important part of the installation phase of the project. Both are needed to incur the satisfaction of the recognised organisation and the flag administration prior to the issuance of the ballast water certificate. Without commissioning testing, that certificate will not be possible.”

She added that commissioning testing is to validate the installation of the ballast water management system (BWMS) in accordance with the BWM Convention.

What are the issues that hinder a successful commissioning test?

There is a long list of possible reasons for failure. One is the build up of sediment in the ballast tanks and it should be noted, remarked Ms Guy, that the full name of the BWM Convention is ’International Convention for the Control and Management of Ships’ Ballast Water and Sediments.’

Leaky valves and poor installation is another issue, to which Ms Zacharopoulou noted that in some cases, SGS has not been able to reach the sample valve due to obstructions, the valve was not suitable, or even missing.

These instances can be remedied but larger issues remain, such as testing in a shipyard which has challenging water conditions.

The takeaways from the webinar were that although the industry has the means at its disposal to ensure correct installation, such as 3D modelling before installation, the same failure points occur. Ms Zacharopoulou noted crew training is important as is correct calibration to prevent TRO discharge failure.

Ms Guy added that manufacturers, installers, flag and testing companies are all concerned to produce a commissioning test success and long-term compliance, but planning is the key.