Due to the high concentrations of bacteria and other microbiological organisms in waste water, commensurate high concentrations of chlorine are necessary for proper disinfection. Treated waste water is discharged to tributaries through NPDES (National Pollutant Discharge Elimination System) outfalls, and an NPDES permit restricts the allowable chlorine concentration of the discharged water. Sulfonators are used to inject measured amounts of sulfur dioxide into chlorinated waste water for the purpose of dechlorination.
Sulfur Dioxide Safety Precautions:
Sulfur dioxide gas is not considered to be toxic, but it is a respiratory, eye, and possible skin irritant. It can cause breathing difficulties similar to the symptoms of a chest cold.
All forms of sulfur dioxide gas must be used and handled with appropriate knowledge, care, and respect in order to eliminate the potential for unsafe conditions.
Sulfur dioxide gas is colorless and therefore is not easy to visually identify. It has a distinctive pungent odor that will alert the user of a leak in ample time before irritation can occur. It is somewhat denser then air and will sink to low-lying spaces.
Because of the density and expansion factors, sulfur dioxide containers should never be placed in direct sunlight or exposed to other direct or indirect heating sources!
It should also be noted that sulfur dioxide is corrosive to many common metals and other substances.