Modeling chlorine-produced oxidant demand and dilution in chlorinated combined sewer overflow discharges

Austin Taterka, Robert Miskewitz, Robert R. Sharp, Jurek Patoczka

Research output: Contribution to journalArticlepeer-review


Combined sewer overflow (CSO) water introduces pathogens to receiving waters. To control pathogenic releases, chlorine may be added to disinfect CSO water. The added chlorine may react with water constituents to form oxidative species known as chlorine-produced oxidants (CPO). CPO are the sum of free and combined oxidative species that form upon adding free chlorine-bearing compounds (e.g. gaseous chlorine or hypochlorite) to water. CPO discharge is often regulated by governing agencies. Current methods to model CPO behavior do not account for CPO decay and dilution simultaneously in receiving water. This study creates a novel model for CPO demand and dilution in receiving water from chlorinated effluent in order to determine site-specific practices for implementation of a CSO water disinfection regime. To do this, representative receiving water was collected and dosed with 1, 2, and 4 mg/L chlorine. The residual chlorine was measured at intervals up to 30 min after dosing. The immediate and subsequent chlorine demand was calculated, with the subsequent demand modeled by simultaneous application of dilution and decay using pseudo-first-order decay kinetics. A comparison of model calculations indicates that application of dilution before decay underestimates CPO demand, while application of decay before dilution overestimates CPO demand.

Original languageEnglish (US)
Pages (from-to)266-274
Number of pages9
JournalJournal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering
Issue number3
StatePublished - Feb 23 2020

All Science Journal Classification (ASJC) codes

  • Environmental Engineering


  • Combined sewer overflow (CSO)
  • chlorine decay and dilution model
  • chlorine decay kinetics
  • chlorine-produced oxidants (CPO)
  • pseudo-first-order decay


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