AWWA ACE95091

This paper is intended to provide a broader understanding of the use of dual coagulants (ferric salts and cationic polymers in this paper) and address the deficiencies in our understanding of this use. Specifically, the following points are addressed: delineate the conditions under which the use of dual coagulants is the preferable alternative; study the effect of cold temperature on flocculation kinetics using dual coagulants, and investigate whether the combined use of Iron (III) and cationic polymers is better suited for the coagulation of particles at cold water temperatures than the sole use of only these coagulants; identify the optimum addition sequence for dual coagulants under different suspension characteristics; and study the effect of rapid mixing on flocculation kinetics for the combined use of Iron (III) and cationic polymers both at room temperature and low water temperature.