Wastewater treatment requirements vary massively depending on the nature of the wastewater and the intended use or disposal route of the effluent. In the water industry it tends to be classified as Municipal or Industrial Wastewater Treatment.
Municipal Wastewater Treatment
Sewage treatment, or municipal wastewater treatment treats wastewater (sewage, and in combined sewer systems surface drainage) from homes, towns and cities. Traditionally the treated effluent was disposed to rivers or the sea. Increasingly means of reusing this water are being found.
Municipal wastewater treatment typically comprises up to three stages: primary, secondary & tertiary.
Primary treatment is generally a physical process in which heavy solids are allowed to settle to the bottom, and light solids (& liquids including oils and grease) are encouraged to float to the surface.
Secondary Treatment is normally a biological process in which microbes are encouraged to eat and retain nutrients found in the wastewater. The activated sludge process, and its variations, are most widely employed in secondary treatment.
Tertiary treatment is not conducted at all municipal wastewater treatment plants. It is generally considered to be any extra treatment process following primary & secondary. Processes include disinfection & chemical treatment, membrane or media filtration, or extended physico-biological treatment processes like lagoons.
Industrial Wastewater Treatment
Industrial wastewater treatment is the treatment of wastewater from industrial sources. This can employ the same techniques as municipal wastewater treatment. There are, however, often recalcitrant substances (ones that are difficult to remove) or such high concentrations of particular substances that make biological treatment difficult. As such chemical treatment is often required. The processes employed depend on the wastewater composition.
We are here to help
Aqueum’s freelance wastewater consultants can give independent advice on which processes to use & can help you design, specify or tender these systems. Feel free to contact us with any wastewater treatment queries.