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PlanktonTrap - Ballast Water Treatment
Ballast Water Do You Know What's in it ?
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Ballast water treatment is a challenging issue.

wendy Laursen,

The wording of the compliance date requirements specified in the 2004 Ballast Water Convention differs from most other IMO conventions. Although the convention will enter into force 12 months after it is ratified, as it stands today, the vessel construction dates that control compliance are specifically defined as 1 January 2009 and 1 January 2012, depending on ballast capacity. They will not shift forward to follow a future ratification date. This means that vessels being built now may have to comply as early as 2012 so designers should already be incorporating enough space and power for a ballast water treatment system. An amendment to the dates might yet be made since ultimately the convention will affect at least 50,000 existing ships and hundreds of newbuildings each year but the environmental imperative for taking immediate action on the issue is clear. The US/Canadian Great Lakes already have more than 180 invasive species, many attributed to ballast water, and Australia has at least 250. The Chinese mitten crab is just one example of the global problem. This species has caused more than €85 million of damage in German waters alone through the destruction of infrastructure such as fishing nets, pumping stations, dykes and river banks. The first mitten crab was found in Germany in 1912 and it spread throughout Europe during the 1920s and 1930s. It is now a pest in the US too. IMO continues to engage with the industry to bring about ratification. The GloBallast initiative, first established in 2000, has been successful in raising awareness of the issues and the way forward in less-industrialised regions of the world. The establishment of the Global Industry Alliance in 2009 will likewise focus on education and also on furthering technological solutions. The US is also set to play an important role in global politics as it is considering the introduction of tougher requirements for the number of viable organisms in ballast water than IMO.

New technologies will be needed for compliance testing since it can be difficult to tell if a phytoplankton cell is alive or dead when testing the efficacy of a treatment system. In current shipboard trials, some resting cells are being grown out in nutrient-rich culture to confirm their viability. Authorities responsible for testing compliance will need a more expedient method but just how and when compliance will be tested once systems are installed on board is still to be clarified. IMO is working with regulatory authorities to determine the necessary protocols and to ensure they are based on sound statistical principles but owners should be aware of how the need to provide suitable sampling strategies could affect their operations. A range of onboard ballast water treatment systems are entering the marketplace, and portable systems are being developed too – including one that uses a ship’s fire hydrant system. So far, only a few have gained the necessary type approval. This is a stringent process requiring much time and money, and most of the systems progressing through the necessary land and sea trials have had to employ a number of different technologies in combination to achieve the standards defined by the convention in a time and space efficient manner.

Complex processes are involved in the operation of treatment systems. Potential pests can survive for months in ballast tanks and could be discharged along any coastline or in any port. Even vessels reporting no ballast on board pose a risk. The intricacy of the internal structure of ballast tanks presents a challenge to exchange protocols and treatment systems alike. It is possible that the first generation of treatment solutions will need refining in some way. Although many are based on land-based water sanitisation technologies, they are new to the marine environment. Owners are naturally placing a lot of confidence in type approval but questions have been raised about the consistency of the IMO approval process with respect to corrosion testing. In theory at least, changing the characteristics of ballast water represents a potential corrosion risk. Manufacturers with systems that reduce the oxygen content of ballast water are claiming a corrosion advantage but other systems should at least be coating friendly and corrosion neutral. No single manufacturer will be able to provide the best solution for every vessel. Owners must sift through the market offerings to find the system that best suits their ship type, size and voyage pattern. Pump pressure limitations, operational costs and stray current generation are just a few of the considerations and, for most owners, it will be a multi-million dollar decision. In the longer term, an alternative is to invest in one of the innovative ship designs now being investigated in several countries; these could avoid the problems of treatment altogether. Will all the effort being directed at the problem of invasive species pay off? Only time will tell whether or not onboard treatment systems provide a reliable and workable solution. Given that hull fouling is another major potential source of invasive species from shipping, we may never know for sure if they have.

 BALLAST WATER STANDARDS 

 organism   Regulation
 plankton, >50μm in minimum dimension  < 10 cells/m3
 plankton, 10-50μm  < 10 cells/ml
 toxicogenic Vibrio cholera (O1 and O139)  < 1 cfu/100ml
 escherichia coli  < 250 cfu/100ml
 intestinal enterococci  < 100 cfu/100ml

cfu = colony forming unit
source: Ballast Water Treatment Technology, published by Lloyd’s Register in September 2008


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