A subsea fluid treatment system for use in treating seawater for injection into a subterranean formation, comprising: a fluid treatment module comprising a fluid inlet, a first fluid outlet for treated seawater with a reduced concentration of a selected component, and a second fluid outlet for treated seawater with an increased concentration of the selected component; a pump having an inlet and an outlet; and an eductor having a motive fluid port, a delivery port, and a suction port, wherein the suction port of the eductor is configured to receive ambient seawater from the ambient sea and the delivery port of the eductor is in fluid communication with the fluid inlet of the fluid treatment module; wherein the second fluid outlet of the fluid treatment module is configured for disposal of the treated seawater with the increased concentration of the selected component into the ambient sea, and wherein the pump inlet is in fluid communication with the first fluid outlet of the fluid treatment module for receiving the treated seawater with the reduced concentration of the selected component; and wherein the subsea system is configured for communication of the treated seawater with the reduced concentration of the selected component from the pump outlet to a subterranean formation and for communication of the treated seawater with the reduced concentration of the selected component from the pump outlet to the motive fluid port of the eductor so as to entrain seawater from the ambient sea through the suction port of the eductor for delivery through the delivery port of the eductor to the fluid inlet of the fluid treatment module at a pressure which is greater than a pressure of the ambient sea resulting in a first pressure differential between the fluid inlet and the first fluid outlet of the fluid treatment module and a second pressure differential between the fluid inlet and the second fluid outlet of the fluid treatment module. a fluid treatment module comprising a fluid inlet, a first fluid outlet for treated seawater with a reduced concentration of a selected component, and a second fluid outlet for treated seawater with an increased concentration of the selected component; a pump having an inlet and an outlet; and an eductor having a motive fluid port, a delivery port, and a suction port, wherein the suction port of the eductor is configured to receive ambient seawater from the ambient sea and the delivery port of the eductor is in fluid communication with the fluid inlet of the fluid treatment module; wherein the second fluid outlet of the fluid treatment module is configured for disposal of the treated seawater with the increased concentration of the selected component into the ambient sea, and wherein the pump inlet is in fluid communication with the first fluid outlet of the fluid treatment module for receiving the treated seawater with the reduced concentration of the selected component; and wherein the subsea system is configured for communication of the treated seawater with the reduced concentration of the selected component from the pump outlet to a subterranean formation and for communication of the treated seawater with the reduced concentration of the selected component from the pump outlet to the motive fluid port of the eductor so as to entrain seawater from the ambient sea through the suction port of the eductor for delivery through the delivery port of the eductor to the fluid inlet of the fluid treatment module at a pressure which is greater than a pressure of the ambient sea resulting in a first pressure differential between the fluid inlet and the first fluid outlet of the fluid treatment module and a second pressure differential between the fluid inlet and the second fluid outlet of the fluid treatment module.