Pasteurizing Ballast Water?

“Nobody thought it was possible,” commented Kim Diederichsen, CEO of BAWAT AS, a Danish company that it releasing to the shipping industry the first type-approved ballast water treatment system utilizing the pasteurization process.

In simple terms, his system cooks and then deoxygenates the ship’s ballast water to kill all the critters that enter the ballast tanks while in port.  The vast majority of other ballast water treatment systems, of which there are many, utilize in-line mechanical filtering and UV radiation to eliminate these organisms.

bawat ballast water treatment
Rendering courtesy BAWAT

As of today, there are roughly 1000 ships that have ballast water treatment systems installed on board, however companies that develop ballast water treatment systems have observed that only 1/10th of those ships are actually using these systems regularly.  Considering the Ballast Water Convention has not been ratified, there’s no requirement to use these systems unfortunately unless the ship calls on a U.S. port.

Considering the United Nations has placed invasive species as one of the top four threats to the ocean environment, using ballast water treatment systems is undoubtably the right thing to do and by 2015, the Ballast Water Convention will be ratified globally.

With this in mind, Diederichsen, a man who has had both operational experience as a merchant marine officer as well as a businessman leading successful entrepreneurial projects in the maritime industry, decided that a non-filtration ballast water treatment system was the right way to go.

Heating up tens, or hundreds of thousands of gallons of seawater to 70 degrees C is not an easy task however, nor is it cheap – or so the skeptics thought.

In reality, it’s quite a simple process and by using waste heat from the ship’s main engine, it can be quite inexpensive as well.

Diederichsen’s system, named BAWAT, involves using globally available equipment such as pumps and standard plate-type heat exchangers and a to cycle ballast water through a heat exchanger and then mixed with nitrogen for deoxygenation. The ballast water is then injected into the bottom of the tank through rotary jet heads and fixed nozzles ensuring a thorough mixing.

The BAWAT system takes approximately 24 to 96 hours of treatment time depending on the size of the ship and the capex needed for such a system varies between $250,000 and $2 million, according to Diederichsen.

Have a question?  Feel free to comment below, or email Kim Diederichsen