Activated Sludge 1 : A microbial mass grown in aeration tanks, subsequently separated from treated wastewater by sedimentation, and wasted or returned to the process as needed
NFPA 820 Standard for Fire Protection in Wastewater Treatment and Collection Facilities, 2008 ed. http://www.nfpa.org/codes-and-standards/document-i nformation-pages?mode=code&code=820, (Std: Fr Prac in Wastewater Treatment and Collection Fcilty - Amer) {351 NFC}