汚泥

1. Origins, structure, and basic meaning

• Structure: 汚泥 is read as おでい and means “contaminated sludge”.
• Basic usage: It refers to polluted sediment settled in a tank and to sludge represented with brown clay in a model.

2. Common pitfalls and similar expressions

• 汚泥が / 汚泥を
  • Settled sludge is marked by 汚泥が, while sludge being represented is marked by 汚泥を.