IMS Annual Conference 2019

Flocculation of particles into larger and easily removable forms is necessary for efficient separation by sedimentation, filtration, or dewatering. Three types of polymers are discussed in regards to physical form, molecular weight, charge density, and size distribution. Proper way of handling and storage of polymer is reviewed as well as its shelf-life.

Quality of dilution water including hardness has tremendous impact on the efficiency of polymer solution. With increasing trend of utilizing reclaimed water for polymer mixing at most WWTPs, chlorine level of dilution water must be carefully monitored. When reclaimed water is used, aging of polymer solution is also carefully evaluated. Chlorine, suspended solids, and dissolved ions included in reclaimed water are reacting with polymer and resulting in degraded polymer solution during aging.

Preparing efficient polymer solution is one of several key factors for successful solid-liquid separation. Due to its unique property of polymer, polymer make-down requires well established scientific understanding. It includes the concept of two-stage mixing; very high energy mixing at the first stage followed by low energy mixing to minimize damaging polymer chains. Two-step dilution and adequate residence time are also required to achieve fully extended molecular structure of polymer in solution.