Method for treating ballast water and device for treating ballast water

A device for treating ballast water, comprising

• a housing having
• an axially arranged ballast water inlet on the top thereof and
• a ballast water outlet arranged on the bottom thereof,
• a hydrocylone connected to the ballast water inlet having
• a particle outlet arranged on the bottom of the housing, which outlet discharges particles from the device, and
• an outlet carrying particle-depleted ballast water,
• a filter surrounding the hydrocyclone, which filter divides the device into an intermediate chamber arranged between the hydrocyclone and the filter and an outer chamber arranged between the filter and the housing, wherein the intermediate chamber is communicatively connected to the outlet of the hydrocyclone carrying particle-depleted ballast water, and
• an ultrasound generator acting on the outer chamber and/or the filter,
• a UV light generator acting on the outer chamber and/or the filter, and
• a gas inlet for introducing gas into the outer chamber of the device.