Ballast water is used to stabilise vessels and compensate for changes in their weight as a result of cargo loading and discharging, and fuel and water consumption. The international shipping community has long been aware that ballast water can be the cause of serious ecological and health problems.
The International Maritime Organisation (IMO) has submitted “The International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM)”. The Convention obliges vessels to have an approved ballast-water plan, and in the course of the next few years they will also need to implement a Ballast Water Treatment System (BWTS). We can therefore expect that by 2019, as many as 50,000 vessels will be equipped with BWTS.
The Wilhelmsen Technical Solutions system, Unitor BWTS, combines four cleansing technologies: cavitation, electrochlorination, ozone (O3) oxidation and self-cleaning mechanical filtration. MARINTEK and SINTEF ICT have analysed this system, putting particular emphasis on computational fluid dynamics (CFD) aspects. Our studies enabled Wilhelmsen Technical Solutions to validate and document its design.