For drastic reduction of energy necessary to thermal treatment of ballast water, a heat retrieving type ballast-water treatment system (BWTS), Thermal Aqua-Filtration (TAF) system, has been under development. The land-based plant (15 m3/h for TOR), consisting mainly of a plate-type heat exchanger (HX) and a Thermal-treatment Tank with electric heaters for sub-heating, showed to meet D-2 regulation with 70 °C and 5 minutes treatment. By using the land-based plant (15 m3/h for TOR), consisting mainly of a plate-type heat exchanger and a Thermal-treatment Tank with electric heaters for sub-heating, it was confirmed that 70 °C and 5 minutes treatment meet D-2 regulation. The heat-retrieving ratio became over 95 %, which reduces the operation cost of an ocean friendly BWTS to the realistic level. The bio-fouling on the plates of heat exchanger, which has been one of the key technical issues, could well be overcome.
