A Reaction Vessel Assembly with ambient gas exchange enhancing me comprising:a vessel containing therein a liquid phase and a gas phase interfacing with the liquid phase; a gas intake passage allowing a gas to flow from outside the vessel to the gas phase in the vessel; a stirring me for stirring the liquid phase to cause the gas in the gas phase to be continuously mixed into the liquid phase, forming gas bubbles in the liquid phase; and a gas venting passage shielded from the gas phase, said gas venting passage allowing the gas bubbles in the liquid phase to vent from the liquid phase to outside the vessel without passing through the gas phase.