THMs and Chlorination

• THMs
• Chloroform
• DDT
• PCBs
• Dioxin

Terms

• Chlorine dose: amount Cl2 added
• Chlorine demand: amount CL2 consumed
• Chloring residual: amount CL2 remaining
  • Concerns
    • taste and odor (ppb thresholds)
    • toxicity (formation of THMs)

Alternatives to Chlorination

• Chlorine dioxide
  • expensive, can't be stored
• Ozone
  • expensive, smog component
• UV radiation
  • colored material and organics must be absent