Abstract: A liquid or water treatment apparatus comprising one or both of an electrodialysis cell and a cavitation unit. The cavitation unit generates cavitation in the liquid by flow of the liquid into a constriction where cavitation bubbles are formed and then to an outlet where cavitation bubbles implode, and the constriction includes an aperture formed by walls which are long and narrowly spaced in a plane normal to the flow direction. The electrodialysis cell is arranged with an inlet flow path for directing only part of a quantity of water to be treated through the electrodialysis cell, and an outlet flow path for returning a product of the electrodialysis cell to the remainder of the water.

Abstract: A system and method for treatment of water contaminated with organisms, in particular ballast water in ships, the system including a pump (5) pumping water from the sea trough a cavitation unit (7) and into one or more ballast tanks. The cavitation unit (7) will introduce a strong cavitation in the water, the cavitating action destroying any organic tissue and cell membranes of organisms present in the water. In the cavitation unit (7) hydrogen and steam are added to the water, while oxygen is removed. The oxygen-depleted water will exhibit a reduced corrosive effect on the ballast tanks.