Disinfection of wastewater is defined as the addition of sufficient chlorine so that a free chlorine residual of between 0.5 ppm and 0.7 ppm exists after a 30 minute contact time. The amount of chlorine required to maintain the residual varies greatly depending upon the composition, temperature, and flow rate of the wastewater. Frequent monitoring and adjustment of chlorine flow is needed to maintain uniform results. Other chemicals are occasionally used as disinfecting agents in wastewater treatment processes. These include bromine, iodine, and ozone.
Chlorine is still the most effective way of disinfecting domestic wastewater.
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