ACTIFLO® Softening: Clarification plus Softening

ACTIFLO® Softening removes hardness and alkalinity to improve water quality. It combines both clarification and softening processes to achieve optimal water treatment.

Designed to further enhance water quality, ACTIFLO® Softening combines in a single compact treatment unit both clarification and softening operations to reduce water alkalinity and hardness. At the same time, the process removes other water components such as silica, heavy metals, fluorides and phosphates as well as TSS (Total Suspended Solids) and organic matter.

Rapid and efficient, ACTIFLO® Softening produces very high quality water and is a municipal application for surface and groundwater softening for drinking water production.

Process Description

The raw water is directed to the ACTIFLO® Softening train(s) consisting of a draft-tube precipitation stage and a microsand enhanced flocculation and settling stage. 

The raw water enters the reaction/softening chamber equipped with a TURBOMIX draft tube and mixer, where recycled sludge and other specified chemicals are added to precipitate calcium and magnesium. The TURBOMIX design promotes precipitation of the dissolved particles to maximize their size, resulting in faster settling rates and improved sludge handling characteristics. The rate of the sludge recirculation is variable and continuous, according to process design criteria. The rate of lime slurry and/or caustic addition is controlled by the pH measured at the reaction chamber to guarantee the complete softening reactions. 

The softened water flows from the Reaction/Softening chamber into the Coagulation chamber, equipped with a mixer, where coagulant is added for micro-flocculation. The rate of coagulant addition is paced off the total flow to the treatment train. (The microsand/sludge flocs agglomerate and grow in to high-density flocs known as microsand ballasted flocs.)

The overfow from the maturation chamber enters the lamella gravity settlers where the microsand ballasted flocs settle quickly to the bottom of the tank. The efficiency of settling is further increased by the use of the lamella tubes. The clarified water is monitored for turbidity.

Scrapers force the sludge/microsand mixture collected at the bottom of the settling tank into the center cone, from which it is continuously pumped to hydrocyclones where the sludge is separated from the microsand by the centrifugal forces generated in the hydrocyclone. The recovered microsand is continuously recycled to the maturation tank, and the separated sludge is sent to sludge handling and a portion is returned to the reaction/softening chamber to enhance the crystallization kinetics. 


  • Very small footprint: ACTIFLO® Softening is up to 10 times smaller than conventional softening processes
  • High rise rate: Up to 30 gpm/sf
  • Retrofit: Can be easily implemented in existing tanks
  • Enhanced chemical precipitation with Turbomix™ draft tube
  • Minimizes coagulant consumption due to solids precipitation with calcium carbonates
  • Sludge up to 8% dry solids; can be easily thickened and dewatered
  • Easy start-up: Within few minutes
  • Influent harness up to 500 mg/L
  • Can be used with or without microsand
  • Plant-wide automation: ACTIFLO® Softening can be fully automated and integrated into existing plants

Equipped With

  • A softening tank with TurbomixTM draft tube and recycling of carbonates sludge
  • A coagulation tank
  • A flocculation tank with TurbomixTM
  • A settling tank with lamella and scraper
  • A recirculation line with "MA" hydrocyclone