Strict environmental regulations over the cleaning of ballast water means that ship owners and operators may have to adopt new technologies says Mathias Rusch, Director Marine Business Unit at SKF.

Vessels such as cargo ships are designed to operate with a full load. If they run ‘empty’ they are likely to be unstable. To remedy this, they routinely take on ballast water in order to maintain their balance. 

However, rules governing the discharge standard of ballast water – defined by the concentration and size of organisms per cubic metre - before it is discharged could cause problems for ship owners and operators, unless they are prepared. 

Ballast water is typically taken on board in one region, when a ship is empty, and discharged elsewhere when the ship takes on a new load. This means that water from one region ends up being discharged in another. There are strict rules over how this water must be cleaned before it is discharged. 

These rules are in place to prevent ‘invasive species’ spreading from one region to another. This was first noted more than a century ago, after a mass occurrence of the Asian phytoplankton algae Odontella (Biddulphia sinensis) in the North Sea in 1903. One notable and more recent, incident has seen a mitten crab native to Asia being transferred to Europe, where it has since multiplied. These days, larger species such as crabs can easily be ‘filtered out’ of ballast water before it is taken on board. However, the rules about invasive species apply to all organisms living in the water, right down to plankton and microbes. 

Water treatment
There are three most widely used ways to treat ballast water to remove all organisms: electrolysis; chemical injection; and ultraviolet (UV) light. In each case, the method treats the ballast water before it is discharged. Each has its own advantages and shortfalls. 

Electrolysis and chemical injection can both treat high volumes of water and are typically used for larger vessels such as tankers. While they are both effective, they can have a downside: chemical treatment will result in chemicals being discharged along with the ballast water which will haven a negative effect on the environment and have to be safely stored on board.; and electrolysis also generates hydrogen, which is dangerous on ship, as it is potentially explosive. With both neutralising agents may be injected to neutralise residual oxidants, therefore reducing risk but at the same time increasing the amount of added chemicals. 

UV treatment is not suitable for such high volume flow: it works because UV light kills microbes but they must be exposed to it for a certain length of time in order to receive a high enough ‘dose’. Speeding up the flow will simply result in microbes remaining in the water. In this type of system, the UV light is generated by UV lamps. These lamps often become dirty, due to the formation of a biofilm on the surface, so they must be cleaned in order to maintain performance. This is normally done with chemicals, which could have a detrimental impact on the environment and therefore must be safely stored on board and processed afterwards. 

SKF has developed a new UV-based system called BlueSonic BWMS, which uses ultrasound to clean the lamps. This ensures constant operation, as there is no need to stop and clean the lamps, and a more environmentally friendly performance, as no chemicals are discharged along with the ballast water. Ultrasound is commonly used as a cleaning method and is routinely used by opticians on new glasses. 

The new system can be used at flowrates of up to 1500 cubic metres per hour, meaning it can be applied to many different types of vessel. SKF is confident that the efficiency of this system, coupled with a greater environmental awareness on the part of ship owners and operators, will make it an attractive option. 

Tough regulations
The overarching regulation that covers treatment of ballast water is issued by the International Maritime Organization (IMO), which specifies that all vessels built since 2017 must be fitted with a ballast water management system (BWMS). For those vessels built before 2017, owners and operators must have a plan to install such a system no later than 2024. This rule affects around 47,000 vessels, while fewer than 7,000 have been retrofitted to date. 

However, the US Coastguard currently has rules of its own in place that go further than those of the IMO. While the IMO would seem to take precedence, ships that want to enter US waters must also meet the tougher rules set by the US Coastguard. 

While the IMO specifies that organisms must not be ‘viable’ (that is, unable to replicate in future), the US Coastguard’s regulations go further, insisting that organisms must have been completely destroyed before the water is discharged.

But recently, the US Senate passed the Vessel Incidental Discharge Act (VIDA), which now means that organisms that cannot reproduce are considered as being dead for the purposes of the regulation. This paves the way for UV-based ballast water treatment systems to gain US type approval and will harmonize the USCG’s approach with that of the IMO. It should also help “streamline a broken regulatory system” where vessels in the US are “subject to inconsistent and duplicative vessel discharge regulations from 25 states and two federal agencies." 

It is the pre-2017 vessels where SKF sees an urgent need for ballast water management systems. SKF’s BlueSonic BWMS just passed land-based tests and is now being prepared for tests at sea. Both are needed for type approval by IMO and US Coastguard. Full certificatation and commercialization is expected for early 2020. This will be in plenty of time for the 2024 cut-off date for retrofitting a BWMS. 

Only a limited number of systems currently have the relevant approval. Of these,as of today there are only six UV-based systems currently approved by the US Coastguard, plus five more that are under review. UV systems account for around 50% of the market: they are relatively easy to install, have very low safety concerns and work independently of salinity and temperature. 

As well as offering a new way of working, which ensures constant operation, and has no need for chemical cleaning, the new SKF system has a further advantage: it is backed by their worldwide support network, with guaranteed quick service when required. 

This, combined with an increasing environmental awareness among ship owners and operators, suggests that the future for UV treatment systems is bright.