noun
activated sludge
Technical term in wastewater treatment; refers to the biologically active mass of microorganisms used to break down organic matter.
活性汚泥法は下水処理で広く使われている。
The activated sludge process is widely used in sewage treatment.
Compound of 活性 (activity, active) and 汚泥 (sludge), a direct translation of the English term 'activated sludge'.