In a system and process for ultrasonically treating a liquid and delivering the liquid as a spray of liquid droplets, liquid is directed to flow along a flow path over a first ultrasonic waveguide, with the first ultrasonic waveguide having at least one agitating member extending outward therefrom and into the flow path. The first ultrasonic waveguide and agitating member(s) are excited to agitate the liquid as the liquid flows along the flow path. The liquid is further directed to flow along the flow path over a second waveguide, with the second waveguide having a terminal end adjacent an exit of the flow path. The second ultrasonic waveguide is ultrasonically excited at least at its terminal end to ultrasonically energize the liquid just prior to the liquid exiting the flow path such that the liquid exits the flow path as a spray of liquid droplets.
