Physical-chemical process optimization for phosphorus removal from domestic wastewater by chemical precipitation with ferric chloride

Abstract

Since chemical coagulation processes are very promising for wastewater treatment, this work looked into phosphorus removal from aerobic and anaerobic systems treating domestic wastewater. It was possible to reach phosphorus removal efficiencies in the order of 90 % for coagulant dosages in the range 60 to 100 mg of ferric chloride per liter. Dissolved organic carbon (DOC) removal in parallel with phosphorus removal was observed for the previously mentioned treatment system effluents. The coagulant dosages for optimized phosphorus removal also led to optimum DOC removal. The removal of organic phosphorus fractions as polyphosphates was justified due its association with the DOC removal by chemical precipitation.