Ballast treatment commission system for improved efficiency

Malcolm Latarche

Malcolm Latarche · 18 November 2019

ShipInsight


It is generally accepted that the implementation of the 2004 Ballast Convention was not well handled and that many challenges and obstacles were not foreseen at the time of its adoption. For that reason, the IMO at MEPC71 in November 2017, adopted resolution MEPC.290(71) establishing an Experience Building Phase. It also adopted a new timetable for installing systems in existing ships which is now under way.

The following year at MEPC 73, the IMO decided that testing ballast treatment systems on commissioning was a desirable development. The main objective of commissioning testing is not to validate the Type Approval but to demonstrate that the principle treatment methods of the system are capable of functioning as installed and in accordance with several of the requirements of the Ballast Convention itself.

Thus, new guidelines on compliance testing were issued as Guidance for the commissioning testing of ballast water management systems (BWM.2/Circ.70). Implementation of these will be required by the Flag State of the vessel or the Recognised Organizations (RO’s) acting on their behalf.

At MEPC 74 in May 2019, it was agreed that commissioning testing should begin as soon as possible in accordance with guidance circular with amendments to rules mandating this done to be confirmed at MEPC 75 in March 2020. As an interim measure, MEPC urged flag states to provide the ROs which acted on their behalf with written and clear instructions in relation to the conduct of indicative analysis testing of BWMS at the time of their commissioning on board ships flying their flag, including what actions were to be taken in the event of this testing demonstrating non-compliance .

In most of Europe this will be done by October 2021 and elsewhere around the globe other flag states are adopting the rules early and issuing instructions on compliance testing although some are treating the requirements under the guidelines as voluntary.

Liberia has released the following instructions to all its RO’s:

“Pending entry into force of the draft amendment to regulation E-1 of the BWM Convention, please note that the BWM.2/Circ.70 on validation testing during commissioning of BWMS installed on ships is guidance only and may be voluntarily applied by owners/operators/recognized organizations/shipyards until entry into force of the draft amendment to regulation E-1 of the BWM Convention.
In case owners voluntarily carry out validation testing during commissioning, then we have provided guidance:
In this regard, the arrangement for conducting the test and commercial dealings pertaining to the commissioning test should be between the shipowners/manager/shipyard/contractor and the manufacturer. The persons collecting and conducting the test should be independent of the BWMS manufacturer and accepted by the RO which issues the IBWMC.
A written report including methods and detailed results of the commissioning testing should be provided by the shipyard/manufacturer to the attending RO surveyor for verification before an IBWMC may be issued. The RO is authorized to issue a statement of fact in this regard."

Meanwhile Singapore by way of Shipping Circular No. 9 of 2019 allows only ships under 400gt to treat the guidance as voluntary. Larger vessels must follow the guidance.

Most ROs are class societies and they will have to develop procedures for the commissioning process even if the guidelines themselves provide most of the information. It is also recognised that the installer and the system manufacturer also need to be involved.

The leading class societies will be involved in developing the IMO regulations through IACS which is the source of most technical input. In fact, it was IACS which at MEPC 72, describing the lack of a commissioning process as “a fundamental problem”. That was followed by the Bahamas proposing an amendment to regulation E-1 in the BWMC to specifically mention the commissioning test and an indicative analysis, both for initial and additional surveys when a BWMS is installed on an existing ship.

IACS has said it will develop resolutions for its members relating to commissioning and some members are already preparing texts for this.

Manufacturers of systems generally have their own commissioning practices and will either offer the services of an independent laboratory to confirm the performance standard once a system is installed or else provide the shipowner and crew with the means for testing themselves. What options will be acceptable to the flag state and RO will need to eb ascertained first.

The installation of the ballast treatment system serves a specific purpose. This is the vessels’ compliance according to IMO and USCG discharge standards. Despite the rigorous and strict type approval schemes available, there is still uncertainty on the shipowners' side on the equipment performance. That is particularly true of in line systems that do not include a complete treatment process such as filtration and disinfection. For those cases the compliance testing at commissioning can prove or not the integrity of the chosen technology.

With the entry into force of the convention, there are two discharge standards, D1 and D2 that are enforced on ships based on the applicability regime. For those vessels which should comply with the D2 standards, the performance of their ballast treatment system can only achieve that. Therefore, an operational, efficient ballast treatment system capable to operate in real harbour water conditions with minimum system design limitations is requested. When a ballast treatment system has repeatedly proven to be non-compliant then the risk of not allowing the vessel to discharge ballast water is high.

To tackle such situations, port authorities have requested vessels to leave the terminal for conducting ballast water exchange in the open sea prior to discharging ballast water in their territorial waters. Such options impose significant delays and costs on the shipowner or vessels’ manager.

Choosing a system with a proven track record and robust technology as well as conducting a successful compliance test at commissioning eliminates such risks. Following the guidance from flag states, class societies and others such as P&I clubs is also recommended. It is, however, possible that conditions when commissioning a system are not conducive to showing that the requirements of the convention can be met.

This is foreseen in some of the advice given by flag states. For example Singapore’s Shipping Circular 09 of 2019 says ‘In case D-2 is enforced at the time of commissioning for a ship, and validation testing using indicative analysis cannot be completed for reasons such as system design limitations (SDL); other valid reasons such as this, then RO should issue a short term IBWMC for D-2 for 3 months. This is to allow time for the validation test to be carried out to the satisfaction of the attending RO surveyor and the attending RO surveyor ensures the following:

  • Reasons for the commissioning test not being completed successfully are recorded in the ballast water record book;
  • The attending RO surveyor is provided with new arrangements for the commission test (e.g. date, time, location);
  • The ship’s ballast water management plan (BWMP) has incorporated appropriate contingency measures in line with the “Amendments to the Guidelines for ballast water management and development of ballast water management plans (G4)” (Resolution MEPC.306(73));
  • The ship’s Master and the designated ballast water management officer are aware of the “Guidance on contingency measures under the BWM Convention”, BWM.2/Circ.62, as may be amended, in particular on the communication between the ship and the port State; and
  • The ship’s Master and the designated ballast water management officer are aware of the reporting requirements to the competent port Authority as per regulation E1.7 of the BWM Convention when the vessel is calling a foreign port and shall comply with any additional requirements that the port State may impose.

Filtration Benefits and Shortcomings

Most of the research from academic institutions and the majority of ballast treatment system manufacturers (more than 70%) concludes that mechanical separation is essential to in line ballast water treatment systems. Although the true figure may never be known, it has been estimated that between 10 and 12 billion tonnes of ballast water is transferred around the globe each year. With that comes the potential to carry bacteria, plankton, viruses, small fish, crabs or jellyfish into other ecosystems.

In the early days of ballast water treatment, it was assumed that a simple filter/strainer on the intake would prevent the majority of organisms entering the ballast tanks. Nevertheless, research has proved that the mesh required would have to be much finer, down to 40μm. That should mean that less energy is required for disinfection to take place as less disinfectant concentration is produced. Organisms larger than 50μm are generally in their adult stage of life and as a result they may have developed resistance mechanisms such as hard shells against any form of water disinfection.

Consequently, no-filter in line ballast treatment system that utilise active substances require increased Total Residual Oxidants demand and holding time in order to avoid any non-compliancy risks.

There are no tricks to compromise technology. For meeting D2 standards without a filter using electrolysis, the TRO production should be increased to high levels (>31mg/l) which can be achieved via one or a combination of the below methods:

Erma first 2

Terms such as electrophoresis to all ballast water do not exist or are not supported by any scientific or engineering document. It is the chlorine which oxidises the bacteria and the pathogens and not special environment within the electrolyzers. Organisms larger than 40 microns are insensitive to acute chlorine dosage. As such the only elimination method is either the use of filter, or the extremely high TRO concentration or a long holding time. The later will kill such insensitive organisms due to starvation and not due to TRO.

Moreover, the absence of filter leads to a high solid material concentration in ballast water that consumes the chlorine at a very fast rate. Of course, an accountable percentage of seawater sediment has size smaller than 40 microns but the remaining consumes the majority of the TRO. As such, minimised or no holding time creates question over disinfection efficacy and compliant operation in real circumstances of high sediments and turbid sea water.

In addition, a filter protects components’ internal, wetted parts. Unfiltered water, which contains various sized solids / debris (consisting of both organic and inorganic material), has a detrimental effect on the lifetime of the anode electrodes which are the heart of the electrolysis technology. These anodes consist usually of a precious metal oxide mixture coating applied on a titanium substrate and are highly susceptible to mechanical wear caused by unfiltered water at high velocities.

Besides, taking into consideration that in some no-filter ballast treatment system, the electrolyser housing is made of metal, the debris passing through in combination with the high-water velocity effectively sandblasts the housing causing accelerated mechanical wear. This wear in combination with the produced oxidants on site could prove to have a catastrophic effect on the structural integrity of the electrolysers.

Equally important is the ballasting sequence: ballast treatment systems without filters typically come with a strainer with a mesh filter of approximately 3000μm retention capacity. If the strainer is clogged, then ballasting operation must be stopped for manual cleaning of the internal mesh. This involves the crew opening the strainer, extract the filtering mesh and cleaning it manually to bring it back to its initial clean condition.

Last but not least, is the TRO sampling: With no filter, there will be challenging TRO sampling and analysis procedures, due to the existence of large solids in seawater that will result in frequent sensor filter clogging. Moreover, solids affect the efficiency of the photometric sensor measurements.

Conclusions

The quest for a reduced overall equipment cost needs to be bound by performance and endurance requirements. The initial savings from the purchase and installation of a ballast treatment system can be easily lost in covering operation delays, charges or fines. The correct process design and engineering combined with a proper material selection are the cornerstones for high performance and durability of a ballast treatment system in the demanding marine environment. Performing compliance testing during commissioning will ensure that the shipowners’ investment is successful and hopefully will act as a screen to keep the type-approved but poorly designed systems out of the market.

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