Phosphate Removal at Baltimore, Maryland

by Marion R. Scalf,
Fred M. Pfeffer,
Lawrence D. Lively,
Jack L. Witherow,
Charles P. Priesing,

Serial Information: Journal of the Sanitary Engineering Division, 1969, Vol. 95, Issue 5, Pg. 817-828

Document Type: Journal Paper


The removal of phosphate by activated sludge at Baltimore, Maryland, was a function of mixed liquor dissolved oxygen concentration, BOD loading, and soluble phosphorus loading. Plant research demonstrated greater than 90% soluble phosphorus removal coinciding with plug flow conditions in the aeration tanks and high dissolved oxygen concentrations in the mixed liquor and final clarifiers. Pilot studies using aerated jugs of mixed liquor containing plant return sludge and primary effluent predicted the response of the plant activated sludge process. Pilot study revealed that 1,200 mg per l is the minimum mixed liquor suspended soilds concentration resulting in over 99% phosphate removal at Baltimore. Using mixed liquor suspended solids concentrations similar to plant conditions, pilot investigations showed that: (1) Increased orthophosphate load required greater aeration time for phosphate removal; (2) increased BOD load resulted in higher initial phosphate concentrations; and (3) increased aeration rates resulted in less time required for phosphate removal.

Subject Headings: Phosphate | Dissolved oxygen | Concentrated loads | Aeration | Suspended loads | Activated sludge | Solubility | Phosphorus | Maryland | United States | Baltimore

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