||Combined Biological and Chemical Treatment for Phosphorus Removal.
Mulbarge, Michael C. ;
Shifflet, Donald G. ;
||Robert A. Taft Water Research Center, Cincinnati, Ohio.
( Sewage treatment ;
Chemical removal(Sewage treatment)) ;
( Chemical removal(Sewage treatment) ;
( Alums ;
Sewage treatment) ;
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
Liquid alum and sodium aluminate were utilized for phosphorus removal at 1.0 and 0.2 million gal./day activated sludge municipal wastewater treatment plants. Phosphorus removals were determined at aluminum to phosphorus ratios up to a limiting point which exhibited a minimum total soluble phosphorus residual of about 1.0 mg./liter. More efficient use of chemical and higher phosphorus removal efficiencies are obtained in a multistage activated sludge system. The type of activated sludge system also influenced chemical phosphorus removals. Excessive effluent suspended solids were found to be more a function of the volatile solids produced to aluminum added ratio than of exceeding a given aluminum to phosphorus ratio or aluminum dosage. Batch studies indicate that aluminum as alum will outperform iron as ferric chloride on a performance/cost basis and that the best point of addition is just before solids-liquid separation. The considerations involved in this type of phosphorus removal system are discussed. (Author)