Abstract: A ballast water treatment device includes an oxidant supply amount control device in which a storage unit stores a relationship between an absorbance of a raw water for a ballast and a dissolved organic carbon concentration thereof and another relationship between the dissolved concentration and a residual oxidant concentration required after a predetermined time from an oxidant supply, to kill organisms and to suppress their regrowth in the ballast. A calculation unit derives the required residual oxidant concentration corresponding to the absorbance measured by a meter by referring to the relationships and calculates a target oxidant supply amount using the required residual oxidant concentration. For the target, a control unit controls an oxidant supply device.

Abstract: A ballast water treatment device includes an oxidant supply amount control device in which a storage unit stores a relationship between an absorbance of a raw water for a ballast and a dissolved organic carbon concentration thereof and another relationship between the dissolved concentration and a residual oxidant concentration required after a predetermined time from an oxidant supply, to kill organisms and to suppress their regrowth in the ballast. A calculation unit derives the required residual oxidant concentration corresponding to the absorbance measured by a meter by referring to the relationships and calculates a target oxidant supply amount using the required residual oxidant concentration. For the target, a control unit controls an oxidant supply device.

Abstract: The present invention relates to an apparatus for treating ballast water, the apparatus being capable of treating ballast water so as to meet the ballast water standard established by the IMO exactly at low costs. The treatment apparatus of the present invention comprises a filter (4) that filters sea water to trap aquatic organisms, a bactericide supply apparatus (5) that supplies bactericide to the filtrate sea water, and a venturi tube 7 that introduces the sea water to which the bactericide is added, to produce cavitation in the sea water, thereby diffusing the bactericide and also damaging and destroying aquatic organisms in the sea water.

Abstract: The present invention relates to an apparatus for treating ballast water, the apparatus being capable of treating ballast water so as to meet the ballast water standard established by the IMO exactly at low costs. The treatment apparatus of the present invention comprises a filter (4) that filters sea water to trap aquatic organisms, a bactericide supply apparatus (5) that supplies bactericide to the filtrate sea water, and a venturi tube 7 that introduces the sea water to which the bactericide is added, to produce cavitation in the sea water, thereby diffusing the bactericide and also damaging and destroying aquatic organisms in the sea water.

Abstract: A method for treating waste water and a plant designed for preventing the precipitation of carriers under the air blower installed for reaction tank or aeration tank, wherein the plant comprises an aeration tank 1 containing the carriers 2 for growing microorganism for biological treatment of waste water or the subunit 1a joined with the aeration tank through a partition wall 4 including the screen capable of separating the carriers 2, air blower 3 provided for the aeration tank or the subunit of the aeration tank, air bubble generator 5 or submerged stirrer provided under the air blower 3 for creating the flow of water so that the carriers 2 under the blower 3 can be liquidized by the flow of water created by the air bubble generator or the submerged stirrer to prevent the precipitation of the carriers 2 under the air blower 3, whereby not only the precipitation of the carriers under the air blower 3 can be prevented but also the water treatment efficiency and capacity meeting the designed numerical requirem

Abstract: A ship's rudder has a main rudder body with a cross-sectional shape that is streamlined and symmetrical relative to the vertical center plane of the rudder. A pair of fins extend horizontally from opposite vertical surfaces of the rudder body, symmetrically arranged relative to the center plane of the rudder. The chord length of each fin decreases from a root of the fin toward the tip of the fin. The leading edges of the fins coincide at the center plane of the main rudder body, and are located at the same level as the center line of a propeller of the ship. The fins have winglets on their tip ends. One of the winglets is directed upwardly and the other winglet is directed downwardly.