Definition - What does Tertiary Treatment mean?
Tertiary treatment in waste water is the third and final advanced treatment process used to disinfect water that has already been treated by primary and secondary processes for removing harmful material in a waste water plant. This produces high quality, usable water. This treatment removes phosphorous, nitrogen and other nutrients, as well as any organic and other suspended material from the water.
Safeopedia explains Tertiary Treatment
This final stage of water treatment is any treatment, going beyond primary and secondary, and is often a disinfection process that can involve the use of ultraviolet (UV) light or chemicals, such as lime, to eliminate pathogens (bacteria or viruses) from the water. Although secondary treatment eliminates most of the bacteria and viruses, there can still be nitrogen and phosphorous and other solids still remaining which will also be destroyed in the final treatment.