Since the early days of shipbuilding, the need for ballast has been understood. The nature of mechanics on the water makes it so that having a certain amount of weight on a ship, properly positioned, makes it ride properly, avoid capsizing, and become more maneuverable. Ballast was once provided by heavy objects, such as rocks, or cargo served the purpose on merchant vessels, but that was from a time when the “fuel” for a ship was the wind. As ships developed that experienced significant weight loss while out at sea due to burning fuel, the most prevalent resource available was put to action to provide ballast: water.
The problem is that when one is taking on water from around them in order to provide ballast, it often means also taking in the life that lives in it. It wasn’t long before ship captains discovered that bacteria, microbes, small invertebrates, eggs, cysts and larvae of various species were sneaking on board the ship with the ballast water, sometimes staying put and forming colonies that could seriously damage the ship or cause injury to the crew. Eventually, however, ballast water treatment systems were created.
Treating ballast water is no simple task. It took about 70 years just to figure out how, and even then it took much longer to find a way to do so that was safe for both the ship and the waterways it sailed on. The first step in correctly managing ballast water is filtration. Ships started employing a variety of advanced filtration materials, such as 40 micron wire weaves and backwash flow control. There are also often bio-fouling controls to take care of various microbes, which also makes system maintenance less necessary.
Another technique that can be used is electrochlorination. Electrochlorination is a fascinating process that combines the use of safe chemicals with electricity in order to eliminate or at least significantly reduce the amount of aquatic invasive species (AIS) in ballast water. Often the process is based around sodium hypochlorite (NaOCl), which has been used for years in order to prevent AIS from invading underwater piping and the like. This particular molecule is produced on demand in the water by the use of electricity through a Concentric Tube Electrode, which takes the elements already present in the water and starts a chemical reaction that results in the production of NaOCl, which in turn makes the water into an environment unsuited to the majority of AIS that may have made it past the filtration system.
There are many ways to go about treating a ballast system, and engineers around the world like the folks @Cathodicme.com are always looking for better, more efficient, more environmentally sound ways of going about it. Working on the water is no easy job, and it’s made even harder by problems in the ballast system caused by unwanted visitors. That’s why managing that system and keeping it free of AIS is of paramount importance. It’s not only good for the people on board, it’s good for the oceans as well.