Disinfection is a process by which microorganisms present in the wastewater are killed using chlorine, Ultraviolet light or Ozone.
The secondary effluent is pretty clean, but it still contains large number of invisible harmful microorganisms that need to be destroyed before discharge into the Neosho River. To destroy the microbes, The City of Miami currently practices disinfection using Ultraviolet light.
The effluent (treated water) is decanted to an Ultra Violet light system. The Southeast Wastewater Treatment Plant uses the UV system instead of chlorine for water disinfection. The effluent then passes through a set of steps (cascade) to bring up the oxygen levels. All effluent discharged into the Neosho River must meet National Pollutant Discharge Elimination System (NPDES) criteria which include DO (dissolved oxygen), BOD (biochemical oxygen demand), Fecal Coliform (disease causing bacteria), and many others.