In a precautionary approach and dealing with the coming International Maritime Organization (IMO) regulations on ballast water, PETROBRAS developed a new method for ballast water exchange in tankers. Differently from ordinary methods PETROBRAS' method which have been called BRAZILIAN DILUTION METHOD (BDM) involves ballast loading through the top with simultaneous unloading from the bottom of the tanks. The method proposal was firstly presented to IMO, which encouraged PETROBRAS to carry out a field trial. PETROBRAS in June 1998 carried out a trial in the product carrier M/V Lavras. A simulation study was useful to plan the trial assessing the theoretical efficiency of the method, establishing the best sampling points and comparing the BDM with the Tank Overfilling Method (TOM). Simulation showed that for the same tank shape, the water renewal in BDM is more effective than in TOM and that 90 % of water renewal could be obtained by BDM. A dye concentration variation monitoring and a biological assessment were performed and the results confirmed that over than 90 % of the ballast water was renewed after three exchanges. The method was proved safe, practical, economical and suitable to minimize the risk of exotic species transport between ports.
international approach and in 1997 proposed Ballast water has been used since the late the Resolution A.868 (20) – Guidelines for the 1870s to control the trim and increase the control and management of ships' ballast ship stability. Organisms and suspended water to minimize the transfer of harmful sediments in the water are pumped on board aquatic organisms and pathogens. into the ballast tanks1. Thus organisms A lot of effort has been applied to the occurring in the ballast water can be subject focusing in the ballast water transported worldwide and transferred from a management. Researches of technologies for place to other. ballast water treatment have been carried out.
It has been estimated that the world Ballast water exchange at high seas has shipping moves approximately 10 billion tons been pointed out as a good way to reduce the of ballast water around the globe each year risk of exotic species transference between and that on average more than 3000 species ports. of plants and animals are transported daily around the world.
