AP Environmental Science Flashcards: Sewage Treatment
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 11 cards to help you master important concepts.
What is tertiary treatment of sewage?
Tertiary treatment is the use of ecological or chemical processes to remove any pollutants left in the water after primary and secondary treatment.
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What is tertiary treatment of sewage?
Tertiary treatment is the use of ecological or chemical processes to remove any pollutants left in the water after primary and secondary treatment.
A municipality needs to remove specific chemical pollutants like pharmaceuticals from its wastewater. Which level of treatment would be necessary?
Tertiary treatment would be necessary, as it employs chemical or ecological processes to remove pollutants remaining after the first two stages.
What are the products of bacterial breakdown during secondary treatment?
During secondary treatment, bacteria break down organic matter into carbon dioxide and inorganic sludge.
A treatment facility's effluent contains high levels of organic matter, but large solids are absent. Which stage is most likely malfunctioning?
The secondary treatment stage is likely malfunctioning, as its role is to use bacteria to break down organic matter.
What is secondary treatment of sewage?
Secondary treatment is a biological process where bacteria break down organic matter into carbon dioxide and inorganic sludge in an aerated tank.
Identify three common disinfectants used in sewage treatment.
Three common disinfectants used to treat sewage water prior to discharge are chlorine, ozone, and UV light.
Why is aeration used during secondary treatment?
The tank is aerated to introduce oxygen, which increases the rate at which aerobic bacteria break down organic matter.
What is the key difference between primary and secondary sewage treatment?
Primary treatment is a physical process involving screening and settling, while secondary treatment is a biological process that uses bacteria to decompose organic matter.
Describe the overall sequence of the main stages in sewage treatment.
The sequence is primary treatment (physical removal), followed by secondary treatment (biological breakdown), then optional tertiary treatment (chemical/ecological removal), and finally disinfection.
What is the purpose of the final disinfection stage in sewage treatment?
The purpose of disinfection is to kill any remaining harmful bacteria in the treated water before it is discharged into the environment.
What is primary treatment of sewage?
Primary treatment is the physical removal of large objects from sewage, followed by the settling of solid waste in the bottom of a tank.