ABSTRACT
The most common use of chlorine in wastewater treatment is for disinfection. Other uses include odor control and activated sludge bulking control.
Chlorine may also be used for nitrogen removal, through a process called breakpoint chlorination. For nitrogen removal, enough chlorine is added to the wastewater to convert all the ammonium nitrogen to nitrogen gas. To do this, approximately 10 mg/L of chlorine must be added for every 1 mg/L of ammonium nitrogen on the wastewater.
For disinfection, chlorine is fed manually or automatically into a chlorine contact tank where it contacts flowing wastewater for at least 30 minutes to destroy disease causing microorganisms (pathogens) found in treated wastewater.
Chlorine may be applied either as a gas or as a solid or liquid hypochlorite form.
