Ballast Water Systems

Ballast Water Treatment Systems

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There are several types of treatment systems available on the market or currently in development. They work on the principles of one or a combination of mechanical, physical and chemical.

Common Methods

  • Filter and ultraviolet: systems filter the particulates and bigger organisms followed by UV disinfection.
  • Filter and electrolysis: systems filter the particulates and the bigger organisms followed by injection of active substances generated from the electrolysis.
  • Filter and chemical injection: systems filter the particulates and the bigger organisms followed by injection of a chemical solution.
  • Ozone: disinfection through injection of O3.
  • Inert gas and ultrasonic: diffusing inert gas directly into the ballast tank to deoxygenate the water and using ultrasonic shockwaves to treat anaerobic organisms and bacteria.

Choosing the right treatment system is not going to be simple.

With the limited number of currently available treatment systems to achieve both IMO and USCG type approval, shipowners have a very difficult decision to make. There is a serious risk that when selecting and installing an IMO compliant system it might not gain type approval by the USCG.

Discharge performance standards

The discharge standards for the USCG are similar to IMO BWM Convention D-2 standards. The numerical values for organisms and microorganisms are the same.

However, prior to VIDA, there was a significant difference between the two standards. The USCG regulation stated that organisms must not be “living”. This was in contrast to IMO international ballast water regulations which refer to “viable” organisms (their ability to reproduce).

VIDA amended the USCG regulations by accepting that organisms that cannot reproduce (“non-viable”) are not considered “living”, therefore aligning with IMO discharge standards.


Organisms surviving the treatment process can find themselves in an environment without predators and an abundance of food. This can lead to accelerated growth and multiplication.

Concerns on this potential for regrowth within the ballast tank have been raised by a number of parties. The most prominent fear is that for vessels fitted with systems that do not have secondary disinfection (i.e. treatment when deballasting), the scale of regrowth during a voyage will result in discharged ballast water failing the regulatory discharge performance standard.

What are the penalties for non-compliance?

The IMO BWM Convention states in Article 8 that a vessel violating the convention could be subject to action by both the Flag State and the country in which it took place. Penalties and sanctions will therefore be determined by the relevant jurisdiction.

In the United States, federal penalties are addressed in 33 CFR Part 151 (Subpart D) and states that a person who violates is liable for a civil penalty not to exceed $35,000. Each day of a continuing violation constitutes a separate violation. Also, any persons who knowingly violate the regulations are guilty of a class C felony.

A vessel could very well be subject to additional penalties imposed by the US State in which the violation occurred.


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