Facultative means being able to exist in more than one state. In the absence of sufficient oxygen the bacteria derives oxygen from any source available, generally sulphur compounds. When the bacteria are forced to derive the needed oxygen from sulphur compounds, hydrogen sulfide, methane and other compounds are produced as a byproduct. The hydrogen sulfide combines with water to made sulfuric acid. In the aerobic state, no sulfides are generated and no odors are present.
Aerobic bacteria produce carbon dioxide and nitrogen as byproducts.
The corrosion associated with hydrogen sulfide is eliminated. About 9 parts per million of oxygen can be dissolved in water, thus air must be continually bubbled through the waste or the bacteria will quickly become anaerobic. The nutrients supplied are not in the form of dissolved oxygen, but as molecular nutrients. This allows the facultative bacteria to become and remain aerobic. This effectively eliminates sulfide production and actually prevents odors from existing.