effluent

The term "effluent" originates from the Latin word "effluere," meaning "to flow out." Historically, it referred to a stream flowing from a larger body of water. Today, "effluent" primarily denotes waste products that are discharged into the environment, such as liquid factory waste, smoke, or sewage.1

Wastewater treatment systems are designed to purify these waste products before they are released. The level of treatment varies based on local environmental conditions and governmental standards, with three main stages: primary, secondary, and tertiary. Tertiary treatment is the most advanced, capable of producing effluent of nearly drinking-water quality, though it is often expensive. Disinfection is a crucial final step in all treatment levels to eliminate pathogens and protect public health. Effluent standards set specific limits on pollutants in the treated wastewater discharged from treatment plants.23