Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Built Environment (hierarchy name)
4. Single Built Works (hierarchy name)
5. single built works (built environment)
6. [single built works by specific type]
7. [single built works by function]
8. hydraulic structures
9. [hydraulic structures by function]
10. water distribution structures
11. water treatment plants
12. sewage treatment plants

Anotations

Scope note:

Components of modern sewage-treatment systems where waste water is passed through a series of tanks following coarse screening to remove large objects. Grit chambers settle out sand and cinders; primary settling tanks remove heavy organic solids; and aeration tanks mix the incoming sewage with activated, bacteria-rich sludge and fine air bubbles, causing the rapid oxidation of organic matter. Final settling tanks remove the remaining suspended solids from the mixture.