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Sewage treatment


Sewage or wastewater treatment is a process that involves removing solid material and other contaminants to make the remaining liquid (effluent) safe for return to the natural environment.

Sewage is a term used to mean raw sewage, sewage sludge or septic tank waste.

Raw sewage is mainly water containing excrement, industrial effluent and debris, such as sanitary towels, condoms, plastic, etc.

Excrement is the major source of harmful microorganisms, including bacteria, viruses and parasites.

Sewage treatment reduces the water content and removes debris, but may not remove the microorganisms.

For an example of sewage treatment with further information and diagrams, refer to the Severn Trent Water poster.

Hazards (for further information refer to National Operational Guidance: Utilities and fuel)

  • Electricity
  • Working near water
  • High-pressure water supplies
  • Water-borne contaminants
  • Chemicals
  • Confined space entry
  • Flammable or explosive atmospheres

References and further reading