Learning to live with ballast treatment

Malcolm Latarche

Malcolm Latarche · 15 May 2020

ShipInsight


When the IMO revisited its G8 type approval procedures and issued new guidelines in 2016 that were later made mandatory, it did so because of reported difficulties with systems not operating as intended. With the impending coming into effect of the treaty the following year, the IMO could not ignore the issue any longer.

The anecdotal evidence of systems failure was well publicised but until a survey carried out by the classification society ABS in 2018 was published in 2019 the true extent had never been quantified.

The report found issues with more than half of the systems included in the survey. Some of the common problems included unstable sensors, frequent failing of UV lamps, filter clogging and issues when operating in low-salinity waters. The ABS report also stated that most IMO and USCG type-approved systems are, to date, not suitable for use when gravity-discharging topside tanks which is a particular problem for bulk carriers.

Aside from filter clogging which would require regular flushing and consequent time delays for the ship, none of the problems would necessarily impact the ballasting or deballasting process nor affect the stability of the ship. The problem of a non-performing system only arises for enforcement and contractual matters.

Experience building underway

With regard to enforcement, currently the IMO is in the data gathering stage of its Experience Building Phase (EBP) and should be moving to the data analysis stage before any changes to the 2004 convention are considered and enacted. During EBP the IMO recommends that ships should not be penalised for not meeting the convention requirements with regard to discharge standards except in specific circumstances.

Very little official information as to system performance is available as yet and could be further delayed due to cancellation of IMO meetings during 2020. Singapore has carried out a short study involving the performance of eleven vessels and found that three did not meet the standard for large organisms above 50μm and one failed on the requirements for smaller organisms between 10μm and 50μm.

The sampling test was as much to gauge the performance of various testing methods and systems as to register compliance with the D2 standard. Interestingly none of the test systems performed faultlessly when compared to a detail analysis of the samples. This was particularly true in the case of larger organisms where all methods produced false negatives on some ships.

With such a small sample of vessels, it is hard to know if the results are truly representative. More to the point, some of the ballast treatment systems on the vessels were of the first generation and installed before the G8 guidelines were revised. With the days of these systems numbered by the new rules, it would be hoped that a similar survey taken in the future might show less system failures. Although older systems will not be outlawed and ships can continue to use them, it might be that they will fall foul of a more aggressive PSC regime in future.

The Singapore survey does show that the issue of regrowth – whereby organisms supposedly made non-viable by the treatment do in fact survive and the ‘kill rate’ of the system being lower than anticipated – is a real problem. Some treatment systems operate with a secondary treatment on discharge which partially addresses this problem but if a sample is taken of discharged ballast immediately after this treatment and shows that the D2 standard has not been reached, the ship may be prevented from further discharging of ballast.

If the port has no facility to take and treat the ballast on board, the ship may be asked to re-treat the ballast at the berth before further discharge is allowed, be order to move and treat outside territorial waters or if neither of those are possible to sail with the ballast still on board. The latter might affect the quantity of cargo that could be loaded.

Any ship with a ballast treatment system that is found to be problematic is bad news for the owner. When operating on the owner’s own services it is bad enough but if the ship is on time charter, such a failing would be sufficient for the ship to be declared unseaworthy. That could lead to additional costs for the owner in damages, offhire time and difficulty in obtaining future employment.

Power and performance

Ships being retrofitted with ballast treatment systems may need some thought as to additional demands on their power supply. On older ships, generating capacity may be limited and the power demands of the system may cause auxiliary engines to struggle.

Previously ballast water would not be filtered to the extent that some systems require, and the additional pressure may cause the pumps to struggle or fail. Installing a system may be an opportune moment to replace pumps with better performing models which may benefit the power demand aspect as well. The greater power demands of a treatment system may result in an increased fuel consumption and that is something that may mean a rewriting of the ship’s time charter description is called for.

Some of the UV systems on the market have two modes of operation. One for when operating under IMO discharge standards and another for use when calling to US ports. The US type-approval process includes operational limitations on the intensity or dose of the UV reactor. In part this is to satisfy the US requirement for organisms to be killed whereas under IMO rules the target is to make them unviable. This subtle difference has caused many problems for makers of UV systems in obtaining USCG type-approval.

Although ballast treatment systems have been in use now for around a decade, the number of ships fitted with them is still probably less than half of the existing world fleet. Since September 2017, all new ships have been required to have a ballast system on delivery and some of the existing fleet have been retrofitted already.

It is believed that many of the systems fitted before the convention came into force have rarely if ever been operated because the ship has not yet reached the point in time where treatment to D2 standards is mandatory for it. Conceivably some of these will experience issues when brought into service so it may be a wise move to begin operating them well before the vessels IOPP needs renewing triggering the ship’s need to comply.

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