acid sludge
type: Concept
broader: sludge
preferred label: لجن اسیدی @fa

activated sludge
type: Concept
broader: sludge
preferred label: لجن فعال @fa

sludge
type: Concept
broader: analytical chemistry
narrower: activated sludge
narrower: acid sludge
preferred label: لجن @fa

analytical chemistry
type: Concept
narrower: sludge
preferred label: شیمی تجزیه @fa