Abstract: This invention relates to improved apparatus and to an improved process for the treatment of liquids, and particularly water for domestic consumption. The improved process for treating water to remove hydrogen sulfide and soluble mineral compounds while saturating the water with oxygen comprises feeding the liquid through a nozzle and contacting the liquid with an oxygen containing gas, e.g., air comprises utilizing a venturi nozzle having a nozzle extension that retains the water and air in the form of a confined stream as it is discharged therefrom. The nozzle extension preferably is equipped with restrictor means for directing water from the interior walls of the nozzle chamber toward the center and the nozzle extension directed so that the stream of water containing air is directly discharged from the nozzle extension into the water retained within the tank.