Treatment of ballast water with screens can remove dinoflagellate cysts, so the failure of a treatment to inactivate these cysts does not mean that it should be rejected as a treatment option. The ballast water project of the CRC Reef Research Centre and the Ports Corporation of Queensland started in 1995. The first component of the project was the measurement of physical and chemical characteristics of ballast water to determine characteristics which may affect screening, filtration, ultraviolet irradiation or ozonation, and to examine the potential of chemical characterisation to determine if ballast had been exchanged at sea. The second component of the program is testing the efficacy of ultraviolet and ozonation for their use as ballast disinfectants. The third phase is to assess the results and recommend a design for a pilot treatment plant.
Screens have excellent potential as a primary ballast water treatment.
For ship-based treatment during ballasting, for example, screens of between approximately 10 and 50 micrometres are likely to be appropriate for primary treatment. The actual size of screen which could be used can only really be determined by pilot testing. Experiments on ultraviolet irradiation have been very promising and have demonstrated considerable potential for ultraviolet irradiation as a ballast water treatment. Ultraviolet has been demonstrated to be effective for the control of the dinoflagellate alga Amphidinium sp. and vegetative cells of Gymnodinium catenatum under conditions approximating those in ships ballast tanks. Research is continuing into the use of ultraviolet on these, and other species.