dross vs sewage

dross

noun
  • Waste or impure matter. 

  • Worthless or trivial matter. 

  • The impurities in metal. 

  • Residue that forms on the surface of molten metal from oxidation. 

  • A waste product from working with metal. 

verb
  • To remove dross from. 

sewage

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

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