Since hydrogen sulfide occurs as a gas in water, h2s removal from water physically removed by injecting air into the water and allowing the gas to escape. Aeration units may work by cascading, bubbling, or stripping the gas from the water.
Aeration may be advantageous because it does not add chemicals to the water. Maintenance costs are low for aeration units but the initial purchase costs are often higher then other treatment options.
Aeration is not usually efficient enough to remove all of the offensive odor at high hydrogen sulfide concentrations; thus, it is normally not used when hydrogen sulfide concentrations exceed about 2 mg/ L. In some cases, aeration may form sulfur particles that must be filtered from the water. Disinfection of aerated water is recommended.
Ion exchange to remove hydrogen sulfide works much like a conventional water softener by exchanging one ion for another. In this case, hydrogen sulfide is removed from the water and chloride is added in its place.
The unit must be regenerated with a sodium chloride solution and the treatment will result in an increased amount of chloride in the treated water. Suspended solids and precipitated iron can also clog the IE unit and may require pretreatment.