Volatile organic contaminants (VOCs) emitted from sewer networks during wastewater collection and transport.

Presence of volatile organic compounds (VOCs) in sewer networks is a concern due to exposure of workers during maintenance at manholes and repairs of wastewater pipes, and hazard potential for gas explosion. Occurrence, types, and levels VOCs present at the wastewater treatment plant influents in municipalities in Florida (USA) were compared. Gas phase concentrations were estimated by the Henry's law. In addition, gas samples were collected from the sewer lines at one municipality (City of Hallandale Beach, Florida). Comparison of the gas phase concentrations estimated from the liquid influent samples at the wastewater treatment plants with the gas samples collected from the sewer lines showed that gas concentrations estimated by the Henry's law from the influent liquid concentrations underestimate the gas phase VOC levels. The VOCs detected in gas samples collected at the manholes (City of Hallandale Beach) were acetone (11-75.5 μg/m3), chloroform (15-117 μg/m3), chloromethane (1.6-5.6 μg/m3), dichlorodifluoromethane (2.5-4.5 μg/m3), 1,4-dichlorobenzene (2.5-57 μg/m3), ethanol (7.5-329 μg/m3), methylene chloride (0.6-3.2 μg/m3), pentane (4.7-43.9 μg/m3), propane (1.0-2.7 μg/m3), tetrachloroethene (0.88-2410 μg/m3), trichloroethene (0.23-4.4 μg/m3), toluene (5.3-43 μg/m3), and total xylenes (0.48-4 μg/m3).