Commissioning sampling for ballast water treatment systems: purpose and implementation

Posted on:

The following is an extract from a white paper examining the background, procedures and issues related to commissioning sampling for ballast water treatment systems. Click here to read the full white paper.


Water sampling in connection with commissioning testing – more simply expressed as commissioning sampling – is being introduced for newly installed ballast water treatment systems. The IMO requirement was laid out at MEPC 74 in an amendment to the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention).

At present, commissioning sampling is not mandatory for the vast majority of vessels. Nor will it become a global requirement before early 2022. Nonetheless, there is already immense confusion on the market regarding the purpose and procedures for it.

This paper clarifies the new requirement, explaining not only what commissioning sampling is, but also why, how and when it should be done.

The commissioning sampling regulation

In fact, a demand to perform water sampling as part of ballast water treatment system commissioning first arose with Resolution A.1120(40) under the Harmonized System of Survey and Certification (HSSC). The demand was not part of the BWM Convention, however, which is why it was addressed at the MEPC 74 meeting in May 2019. There it was approved as a draft amendment to Regulation E-1 of the BWM Convention, with adoption expected at the next MEPC meeting.

The amendment requires sampling to take place as part of the operational testing of the ballast water treatment system once the installation is complete and finalised. The sampling is to be performed according to BWM.2/ Circ.70, Guidance for the commissioning testing of ballast water management systems.

The amendment’s entry into force has an uncertain timetable, due to the indefinite postponement of MEPC 75. Originally to begin in March 2020, MEPC 75 may simply be merged with MEPC 76 in October 2020. This would put entry into force no earlier than April 2022, which means compliance sampling would not become globally mandatory before that date.

Although the MEPC encourages flag states to implement the requirement today, only a handful have chosen to do so thus far. (See later section, Implementation of commissioning sampling, in the full version of this white paper.)

What commissioning sampling is – and is not

Commissioning sampling is a response to demands from the market. Shipowners have requested proof that their installed ballast water treatment systems will perform according to type approval and meet the IMO D-2 discharge standard. It is important, however, to understand what commissioning sampling actually validates.

Commissioning sampling does not validate the ballast water treatment solution as such. That validation is provided by the type approval, which is an approval of the standard ballast water treatment system design. The design itself has already been shown to meet the IMO D-2 discharge standard – so this is not in question.

Rather, commissioning sampling verifies that the specific installed system replicates the performance defined in the type approval. It is a tool for spotting deviation from the type-approved performance, perhaps caused by a manufacturing defect or an installation error. The sampling is part of the wider commissioning testing that ensures all mechanical, physical, chemical and biological processes are working properly within the system.

The sampling and the testing as a whole are overseen by the flag state or by a classification society authorized by the flag state, to whom any discrepancies must be reported.

The commissioning sampling procedure

Commissioning sampling is a straightforward procedure that is defined step-by-step in BWM.2/Circ.70, Guidance for the commissioning testing of ballast water management systems. The steps can be summarised as follows.

  1. Sampling of ambient waters
    A sample characterising the ambient water should be collected during ballast water uptake. This can be done by any means practical, e.g. using an inline sample port or taking a sample directly from the harbour. The ambient water should be accepted for testing, regardless of the level of challenge it poses to the ballast water treatment system. (NB! See also the next section in the full version of this white paper, Considering System Design Limitations.)
  2. Sampling of ballast water discharge
    A sample of the corresponding ballast water discharge should be collected after full treatment has been applied, in accordance with the Guidelines on ballast water sampling (G2). The sample should be representative of the whole discharge of ballast water from any single tank or combination of tanks being discharged. It should be collected as close as possible to the overboard discharge point and during ballast water discharge whenever feasible.
  3. Evaluation of compliance with IMO D-2
    The respective samples should be analysed to confirm ballast water treatment performance that indicates compliance with the IMO D-2 discharge standard. Using reliable and accurate indicative* analysis methods, all size classes included in the standard need to be evaluated:
    – Organisms ≥50 μm
    – Organisms ≥10 μm and <50 μm
    – Vibrio cholerae, Escherichia coli and Enterococci

    * Note that none of the indicative methods defined in Table 3 of BWM.2/Circ.42/Rev.1 have been fully evaluated thus far. Because the specified indicative methods are not yet validated, test organizations may instead recommend detailed methods they know to be reliable and accurate.
  4. Reporting
    The sampling methods and analysis results should be documented for the flag state administration or the classification society authorised by the flag state as part of the written report on the wider commissioning testing.

Curious to read more?

The remainder of this white paper comprises the following sections:

  • Considering System Design Limitations
  • Implementation of commissioning sampling
  • Responsibilities associated with commissioning sampling

The full paper is available for free download from Alfa Laval here.