sewage vs tailings

sewage

noun
  • A suspension of water and solid waste, transported by sewers to be disposed of or processed. 

tailings

noun
  • The waste that remains after the minerals have been extracted from an ore by ore dressing. 

  • The feints, the last fraction of product obtained at the end of distillation. 

How often have the words sewage and tailings occurred in a corpus of books? (source: Google Ngram Viewer )