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Related to activated sludge: Trickling filter, activated sludge method
activated sludge[′ak·tə‚vād·əd ′sləj]
A semiliquid mass removed from the liquid flow of sewage and subjected to aeration and aerobic microbial action; the end product is dark to golden brown, partially decomposed, granular, and flocculent, and has an earthy odor when fresh.
Sewage sediment that has been subjected to vigorous aeration and the action of microorganisms.