The development of systems for the onboard treatment of ballast water has been under way since the late 90’s. By water treatment process equipment standards, the market may no longer be embryonic, but it is still in its infancy. The initial offerings involved the obvious process migration from other high flow treatment applications in the industrial and municipal markets such as UV, electrochlorination, other chlorine compounds, and ozone. This was followed soon after with integrated process systems combining these and other techniques. Due to the unique operating environment onboard, other methods soon evolved that utilized process equipment from other ship applications such as inert gas and oxygen stripping systems.