Options for Phosphorus Removal on Trickling Filter Plants

Abstract

Chemical precipitation was evaluated for phosphorus removal on trickling filter plants to assess suitability for meeting the requirements of the EC Urban Wastewater Treatment Directive. Pre-, simultaneous and post-precipitation options have all been shown to be capable of meeting the 2mg/l standard. Pre- and post-precipitation options can meet the 1mg/l standard. For the lower standard careful attention needs to be paid to the rapid mixing and subsequent flocculation of the coagulant. The phosphorus solubility equilibrium has been shown to be an important source of additional load from the primary settlement tanks if they are used for sludge storage.