It is inevitable that during normal operations, some ballast systems will suffer malfunctions. Some of these may be minor irritations but on occasions it is likely that the system will become incapable of treating ballast at all. Under such circumstances, a contingency plan is an essential element that should be incorporated into the ship’s Ballast Water Management Plan (required as part of the IMO convention regulations) and into the ship’s standard operating procedures.
For ships engaged on long ocean voyages, there will be at least some opportunity to carry out ballast exchange using the IMO D-1 standard. However, while there is now an international convention in force requiring ships to treat ballast to a standardised level, port states are free to set their own regulations covering discharge into territorial waters. This is not so much a failing of the convention itself but of the system and charter under which the IMO operates and where it is powerless to regulate for states as it does for ships.
In the early days of the convention’s development, it was suggested that it would make practical and economic sense for ballast water to be treated ashore rather than onboard. The argument was that there are far fewer ports in the world than ships and a system ashore would have a much longer lifespan, be easier to maintain and could be a revenue stream for ports. There is some merit to the argument although in some ports ballast has to be taken or discharged at places away from the berths so as to allow the ship to manoeuvre safely and avoid hazards such as bars or shoals in the port.
A small number of system makers and engineering companies have developed port-based systems that can be housed on barges, trucks or even temporarily placed on a ship. Some of these use type-approved systems modified so as to be housed in a standard ISO container.
One such system is the Damen InvaSave produced by Damen Green Solutions. The system has already been demonstrated in the Netherlands and in January, a system was sent to the Canary Islands to be demonstrated there, treating ballast from a ship in the port. The system is type-approved and has a 300m3/h capacity.
Another emergency system was demonstrated in the Great Lakes last year by two Seattle-based organisations – Global Diving & Salvage and marine engineering specialist Glostens.
Known as Ballast Responder, the mobile ballast water treatment system was developed by Glosten in cooperation with Global, the US Geological Survey and the US National Park Service. The small mobile system is designed to be easily transported to any location to treat vessels that have unmanaged or untreated ballast water in port, or have grounded or are in some other emergency situation. It is a chemical dosing system using a biocide such as sodium hypochlorite. It doses the ship’s ballast tanks directly and the water is regularly tested until it reaches the D-2 standard. Before discharge, the water is neutralised using the same chemicals as most shipboard systems. Unlike the Damen InvaSave, the Ballast Responder is not a type-approved system but is not meant for permanent installation.
There is currently no pressure on ports to make emergency treatment systems available but that is something that may change in the future. The probability of it happening may increase after the results of the IMO’s experience building phase which ends in 2022 are known. If it is demonstrated that there is a high degree of non-compliant samples taken from ships that are employing best practices, that may add credence to shipowners’ claims that a high number of systems do not perform in practice as well as they should. There would then be a need for some recognition of the fact that, with the best will in the world, shipowners cannot always meet their obligations under the convention.