Disclosed is an improve aeration system. The aeration system of the present invention more efficiently removes contaminates, such as hydrogen sulfide, from water. The increased efficiency is achieved by adjusting the pH level of the water in between sequential mass transfer media stages within the aerator. The present invention also relates to an aeration system wherein the forced or induced air is used to strip contaminants from the processed water is reutilized by one or more aeration towers connected in series.