Ballast water purification to protect Ecosystems

The Alfa-Laval launch of a ship’s ballast water purification system, PureBallast, took place at Greenwich – where else would it be? This is an impressive product, with an interesting future

The recent Alfa-Laval presentation and world-wide launch of a ship’s ballast water purification system, Pure Ballast, took the opportunity to really “Push the boat out” – and included all the aspects any Marketing Manager could ask for, to make a good product launch: Major life threatening problem, Large Demand, Legislative Requirement, High Technology, Patented system, Proven field trials, No significant competitors – plus a good venue, a BBC / IMO CD describing the requirement, and a receptive audience.

Not often do all these come together, after over three years of development work! The product is a water purification system to treat and purify the large volumes of water sucked in to ships for ballast, then transported around the world to be deposited in a different ecosystem.


Ballast water transported from port to port, around 7000 Million tonnes a year, by container ships, oil tankers and car transporters, transfers alien aquatic species over journeys across half the world.

Some of these species can produce devastation where they arrive.


1) Cone jellyfish from the US seaboard have colonised the Caspian Sea, where they have no predators.

They have caused the depletion of the native plankton stocks, which has decimated the local population of Kilki fish (sprats), destroying the local fishing industry therefore, but now affecting the Iranian Caviar industry because the sturgeon have no small Kilki to eat.

(A more effective economic strangulation than any politically motivated ‘nuclear activity’ sanctions!).

2) Chinese ‘Golden Mussels’ arrived in South America 5 years ago, and are invading the freshwater inland, penetrating towards the Amazon basin at 240Km a year.

The mussels coat the river beds, stopping other water life, and have killed the fishing industry again: plus blocked water extraction pumps, and are currently threatening to shut down the hydro-electric plants, having penetrated and populated the cooling systems.

3) The ‘Red Tide’ of algal bloom originating in the sea off South Africa produces a toxic, oxygen depleting layer, killing fish, but shellfish just secrete the poisons: this is now exported to China, Europe, Australia and the Caribbean, where the shellfish are poisoning local consumers.

4) This time not an organism, but a cholera outbreak in South America during the 1990s was believed to have been caused by the virus being transported in ballast water, when over 10,000 people died.

(Many of the above facts presented at the Alfa Laval launch are also reported in the film produced by BBC Worldwide and IMO entitled “Invaders from the Sea”, a joint initiative of the Global Environment Facility, United Nations Development Programme, and IMO: this is available on an IMO copyright CD.


1) The requirement is for a treatment system that can handle the volumes involved, kill the transported organisms and viruses, but leave no polluting residues, for example of toxic chemicals or disinfectants, which would equally damage the receiving port ecosystem.

2) IMO has decreed and agreed certain rules that require ballast water exchange at sea (where it is assumed the alien species will die off in the ocean), or treatment of the ballast water to stringent purification standards.

3) The ship owners and captains do not like the safety and complications of ballast water exchange at sea: it can make ships unstable, and susceptible to bad weather: already one car transporter has had a major incident resulting in the loss of the cargo.

4) Already US Coastguards inspect and sample ballast water to make sure the ships arriving have done suitable ballast water exchanges, before the ships are allowed into a US port.

5) The Alfa-Laval PureBallast system has undergone several years of practical tests, as required, and is the only system to have reached this stage.

THE PureBallast OPTION.

Alfa-Laval joined with Wallenius Water and DNV to present the PureBallast system to ship owners and journalists at the Greenwich Observatory early in December 2006, Greenwich being chosen as a major nautical scenario for such a significant development.

Wallenius Water developed the original AOT systems, (AOT is defined as Advanced Oxidation Technology), to enable systems that eliminate biofilms and hazardous bacteria from industrial water, swimming pools, cooling systems etc.

The technology is the same as that used to create the self-cleaning windows now used on skyscrapers and cars, using the reaction of UV light on titanium dioxide films.

The Alfa-Laval PureBallast AOT uses light, including ultra-violet light, to produce free OH radicals, i.e hydroxyl ions, within the water flow, in a reaction on the surface of a titanium catalyst.

These radicals are active oxidising agents over a very short spatial range, oxidising any organic material in the flow, but decaying within microseconds to leave no residual contamination of the flow stream.

(The system is NOT the same as water sterilisation by UV).

By removing the problems of bacteria without leaving any harmful residues in the ballast flow, the system is easy to employ.

The hydroxyl ions destroy the cell membrane of any Planktonic species by removing hydrogen from the structure, as would any other oxidising agent, like a chlorine based bleach, or ozone.

The main fluid interfacing problem seems to have been to create sufficient contact and turbulence within the flow stream to ensure all sections of the fluid were treated equally.

DNV were present at the launch to be able to confirm the laboratory test procedures established, which have been a major undertaking.

The basic unit shown was able to treat 250m3/hour, and uses significant power to light the lamps, around 6kW.

On-board and laboratory tests of the prototype units have met the IMO requirements for the removal of living organisms, producing lower than 10 particles per cubic metre, and reducing E.Coli to less than 250cfu per 100mL.

The on-board tests on a Wallenius car transporter will still take 6 months before final type approval can be granted.

More information can be found from Alfa Laval, on


While Alfa-Laval will have a major market demand for this technology, in satisfying the ballast water market, this is just one of the Alfa-Laval water purification products available for the marine industry.

Alfa Laval is a supplier of desalination systems for fresh water onboard ship, and sewage treatment systems for shipboard use.

Bilge water separation systems under the EcoStream brand, uses high-speed centrifugation to separate oil, water and particles prior to bilge discharges, reducing oil content of the discharge flow to less than 5ppm, to meet a different and earlier IMO requirement.

Careful design of the smooth entry to the centrifuge prevents shearing and foaming which might create a further emulsion, reducing the separation efficiency.

EcoStream is used on all types of vessels, from Queen Mary 2 to LNG tankers owned by Gaz de France.


Wallenius Water ( currently offers an AOT based system for swimming pool and other industrial treatment systems: possibly with further production volumes and the Alfa-Laval interest in wider use of this water treatment technology, we will see further industrial use of the AOT free radicals for water purification, and effective sterilisation of further effluent outflows, for polishing of other discharges before allowing them into the environment.

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