Wastewater Disinfection

Wastewater contains high microbial loads which must be disinfected before being discharged into the environment. Even with modern wastewater treatment processes like MBR and UF, disinfection is still required to lower the possibilities of harmful microorganisms being released into the environment from wastewater.

Chlorine has its limitations in wastewater disinfection and costs of ozone disinfection of wastewater are prohibitive.

Limitations of Chlorine Disinfection of Wastewater

  •  Inadequate protection from chlorine resistant microorganisms like Cryptosporidium, Guardia and viruses.
  •    Corrosion of plant and buildings reduces effective plant life, making Chlorine expensive in the long term.
  •  Not suitable for wastewater reuse for applications like irrigation. Chlorine changes pH of water and affects suitability for irrigation.
  •  OH&S risks – after all Chlorine in any form is an oxidizing chemical.
  •  Difficult to measure efficacy online.

Ultraviolet disinfection of wastewater is reliable, non-chemical and can be measured online through well designed UV intensity sensors and monitors.

However, the presence of suspended matter, oily substances and humic acids in wastewater all tend to absorb UV-C energy. Selection of UV systems for wastewater disinfection depends on peak flow rate, %UVT of wastewater, hydraulic design of UV reactor, types of UV lamps, etc.