Method and system for treating ultrapure water

A water polishing system comprising:

• a source of ultrapure water (UPW);
• an ultrafiltration (UF) module having an inlet and a permeate outlet;
• a recirculation conduit communicating the permeate outlet with the inlet and forming a recirculation loop;
• a recirculation pump disposed along the recirculation conduit upstream from the inlet of the UF module and fluidly coupled to the source of UPW;
• a supply conduit fluidly coupled to the recirculating conduit and a demand source, the supply conduit positioned downstream from the permeate outlet;
• a pressure control valve disposed along the recirculation conduit downstream from the supply conduit and configured to maintain a pressure of the permeate at a predetermined value;
• and
• a pressure sensor positioned along the recirculation conduit between the supply conduit and the pressure control valve, configured to generate a pressure signal indicative of a pressure of the permeate.