On the importance of mixing characterization and application in the water treatment process

Floc properties can be controlled only by selecting a coagulant type and adjusting mixing parameters. However, optimization of mixing is widely overlooked. Well-chosen mixing conditions increase floc separation efficiency, which decreases the operating costs of drinking water treatment plants (DWTPs). This paper presents guidelines for designing mixing parameters in water treatment. Special attention is paid to the determination of mixing intensity and the purpose of different mixing intensities with respect to the subsequent separation. For instance, single-stage separation by filtration must be preceded by homogenization and rapid flocculation mixing. Double-stage separation by sedimentation and filtration should be preceded by homogenization, rapid flocculation mixing and slow flocculation mixing.