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Ballast Water Treatment - Time to Take Action

Cathelco BWT system 2

Over the coming months owners of superyachts will be looking very closely at the latest developments in the introduction of legislation from the International Maritime Organisation (IMO) concerning the discharge of ballast water.

The IMO have been debating the convention since 2004, but ratification is now drawing closer. It will come into force 12 months after 30 states representing 35% of the world’s gross tonnage have put their signature to it. Currently, 44 states have ratified representing 32.86% of the world merchant fleet tonnage, just 2.14% short of the percentage which will trigger implementation.

Things have moved more quickly in the USA, where the US Coast Guard ‘Ballast Water Discharge Final Rule’ came into effect in March 2012 and it is now illegal to discharge untreated ballast water in US territorial waters.

Do I need to install a ballast water treatment system?

As far as the IMO rules are concerned, the regulations only apply to superyachts. These are vessels with a length of over 50 metres and a ballast water capacity larger than 8 cubic metres. It is estimated that there are approximately 100 yachts of this size operating around the world. Smaller yachts travelling from one ocean to another will still have to comply with the discharge standards, but this could be achieved by other methods such as ballast water exchange.

Under the U.S. Coast Guard legislation superyachts are defined in a number of different ways depending on the size and number of passengers. However, to come within the scope of the legislation, the vessel would have to be at least 100 gross tonnes and be capable of carrying more than 12 people.

There are four ways of meeting the U.S. legislation: Ballast water exchange, retaining ballast water, using municipal water or installing a ballast water treatment system. In the latter case, the equipment must be certified as an Alternative Management System (AMS) by the U.S. Coast Guard or have received US Type Approval.

Close up of filter area2

What does a ballast water treatment system do?

The IMO regulations for the treatment of ballast water state that the system must discharge less than 10 viable organisms per cubic metre greater than 50 microns and less than 10 viable organisms per millilitre in the size range of 10-50 microns.

Most BWT systems involve primary and secondary treatment stages. The first stage is to remove suspended material using filtration or cyclonic separation. The waste material is back flushed and discharged at the point of origin.

The secondary treatment can be chemical using biocides, chlorine, ozone or a number of other organic agents. Alternatively, the physical approach can involve UV radiation, deoxygenation, heat treatment, ultrasound or magnetic/electrical fields.

Choosing a ballast water treatment system

The main consideration on a superyacht will be space availability in the engine room.

In most cases, the best solution will be to select a BWT system where the major components can be installed in available spaces, rather than having them all grouped together.

Worldwide there are more than 50 manufacturers of BWT systems using various technologies to treat ballast water. Many of the systems are designed for large commercial vessels and cannot be scaled down to the relatively small flow rates of superyachts.

It’s also worth considering having a ‘chemical free’ system as these do not involve the production, handling or storage of chemicals. Also, systems with chemicals tend to be larger because they entail a neutralisation process requiring additional plant.

Engineer UV chamber and UVI meter

Another question which should be kept in mind is whether the system will operate effectively in all water conditions – fresh, brackish and salt. For instance, electrochlorination systems do not work in fresh water without extra equipment.

As the market for BWT systems for superyachts is relatively small in comparison with the commercial shipping sector, very few manufacturers have decided to enter it. This also relates to the matter of having ‘scalable’ technology which has previously been mentioned.

One of the exceptions is Cathelco, a British company who are already well acquainted with the specialised requirements of the superyacht industry having supplied their seawater pipework anti-fouling systems and ICCP hull corrosion protection systems to yachts for more than 30 years.

The BWT system is based on a combination of filtration and UV irradiation which lends itself to the production of smaller units. The Cathelco units are designed to handle flow rates between 34m3/hr and 1,200m3/hr, significantly smaller at the lower end than most of their competitors, making them an attractive choice for yachts.

The reduction in the overall size of the system has been achieved in a number of ways, principally by using a small, but highly efficient filter.

The UV chamber is also 50% shorter than Cathelco’s commercial shipping counterpart, saving space and making it easier to remove the UV lamps when replacement or servicing is necessary.

cathelco flowdiagram

Cathelco have also built in some innovative technical features. The ballast water passing through the UV chambers travels in a ‘helix’ which maximises the exposure to the UV light making the process more effective. They have also incorporated a unique foam ball cleaning system to remove residue from the quartz sleeves surrounding the UV tubes as well as the inside of the reactor. This is completely chemical free as is the rest of the system.

The Cathelco system is IMO approved and has received U.S. Coast Guard AMS certification. The AMS approval recognises that it will continue to disinfect heavily silted water where UV light transmittance values are as low as 45% (75% being the value for normal sea water).

It is only a matter of time before the IMO convention is ratified and therefore superyacht owners and engineers should be entering into a dialogue with a BWT system manufacturer to discuss the implications of having the equipment installed.

One of the things to consider is the available power supply. A BWT system may require a peak power supply of 30kW. If your power supply is less than this it will be necessary to upgrade the generator or run two generators when ballasting is in progress.

Another factor is the capacity of existing ballast water pumps. This can vary considerably from yacht to yacht with some only having a capacity of 20m3/hr. As the minimum flow requirement for a BWT system is currently 34m3/hr, it might be necessary to look at replacements.

These are just a couple of many questions which should be raised in preparation for a trouble free installation rather than waiting until the rush after ratification.



About Cathelco HEM:

Cathelco produce a portfolio of products for commercial vessels and the superyacht market, one of the latest being an innovative ballast water treatment system. Formed in 1956, the company originally built its reputation on the manufacture of seawater pipework anti-fouling systems which prevent blockages in engine cooling lines caused by the growth of barnacles and mussels. They remain the world leader in this field with over 50,000 installations on vessels of every size.

In the 1990s, Cathelco diversified into the production of impressed current cathodic protection (ICCP) systems to safeguard hull surfaces against corrosion. Miniaturised systems were soon developed for the luxury yacht market with the introduction of the Minitek system to protect steel hulls and the Alutek system for aluminium hulls.

More recently, the company has entered the reverse osmosis desalinator (watermaker) market, beginning with the acquisition of Seafresh Desalinators in 2010.

In April of this year, Cathelco acquired Hydro Electrique Marine (HEM), based near Antibes in France, whose desalinators have been installed on some of the most prestigious yachts in the world. The company also produces an extensive range of water treatment systems including filtration, sterilisation and water softening equipment.

Cathelco employs almost 100 people at its headquarters in Chesterfield, United Kingdo and is represented by a network of more than 40 agent/installers based in ports and yachting centres worldwide.

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