Sewage Treatment System Odors and Air Pollutants

The major air pollution problem associated with sewerage systems is odor. Sludge or screening incinerators may discharge particulate matter, incompletely combusted organic compounds, nitrogen oxides, and sulfur dioxides, all of which are air pollutants. The intensity of sewage odor production is dependent upon the following factors: organic concentration, temperature, sulfate content, detention time, agitation, microbes, pH and flow depth. Three methods of odor control are: (1) preventing the odors from forming; (2) preventing the odors from reaching the atmosphere; and (3) removing or renovating the odors which have been formed. Odors may be suppressed by the following methods: (1) sewer maintenance to remove biological slimes, grease, and silt; (2) addition of oxidation or reduction compounds; (3) precipitation of sulfides; (4) waste pretreatment to reduce waste strength; and (5) the use of perfumed masking agents. Odors can be prevented from reaching the atmosphere by sealed enclosures, and collected by a partial vacuum within the disposal facility. The odors and air pollutants such as particulate matter or nitrogen oxides can be reduced by appropriate afterburners, scrubbers, activated carbon or other specialized equipment.