Chemical and Physical Characterization of Ballast WaterPart 1:
Effects on Ballast Water Treatment Processes
D.J. Oemcke and J(Hans) Van Leeuwen
The translocation of marine species around the world via ships’ ballast water is a serious threat to fisheries, ecosystems and even human health. One of the options for controlling the movement of organisms in ballast water is disinfection using techniques common in municipal water and waste-water treatment. There is a paucity of data on the composition of ballast water that can be used to predict the effects of water quality on disinfection, however. In this research on the characterization of ballast water we sampled ballast water, sludge and sediment from ten ships that were visiting ports in North Queensland, Australia and analyzed those components that would affect filtration, ultraviolet irradiation and ozonation. Filtration was also assessed by reviewing the sizes of organisms that could be removed directly. Ozonation will be limited by the presence of bromide in seawater, high pH levels and is likely to be affected by corrosion and reducing conditions if it is applied to water in ballast tanks. Ozone will react rapidly with bromide in seawater to form hypobromous acid, a weaker, but more stable disinfectant. Ultraviolet irradiation will be affected by the presence of iron but only for treatment conducted after deballasting. Screens with apertures of about 20 mm will be effective for the direct removal of several species of concern. An analysis of the iron levels demonstrated a significant effect of sample location and collection method.