APPARATUS AND METHOD FOR TREATING BALLAST WATER BY USING ELECTROLYSIS

Provided is an apparatus for treating ballast water by using electrolysis. The apparatus includes a plurality of ballast tanks into which ballast water is introduced; a first pipe for a main stream of the ballast water supplied to the ballast tanks; a second pipe for a side stream of the ballast water branched from the main stream of the ballast water; an electrolytic cell configured to perform electrolysis of the side stream of the ballast water; a first salinity measuring unit configured to measure a salinity of the side stream of the ballast water introduced into the electrolytic cell; a second salinity measuring unit configured to measure a salinity of ballast water introduced into at least one of the ballast tanks; and a controller configured to control to supply the ballast water to the electrolytic cell from one of the plurality of ballast tanks based on the salinity of ballast water measured by the second salinity measuring unit, when the salinity of the side stream of the ballast water measured by the first salinity measuring unit is less than a threshold value.