sewage works
noun /ˈsuːɪdʒ wɜːks/
  /ˈsuːɪdʒ wɜːrks/
(also sewage treatment works, sewage disposal works)
 (all British English) (also sewage plant especially in North American English)
 [countable + singular or plural verb]- a place where chemicals are used to clean sewage so that it can then be allowed to go into rivers, etc. or used to make manure