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The ultimate clarifier

ACTIFLO® is a high rate clarifier exclusively developed and patented by Veolia Water Technologies.

With more than 1,000 references all over the world, ACTIFLO® has been in use for municipal and industrial water and wastewater treatment for more than 25 years.

ACTIFLO® is a high rate compact water clarification process in which water is flocculated with microsand and polymer in a Turbomix® draft tube. The microsand enhances the formation of robust flocs and acts as ballast, significantly increasing their settling velocity. The unique characteristics of the resulting microsand ballasted flocs allow for clarifier designs with very short retention times, high rise rates and extremely compact system footprints that are up to 50 times smaller than other clarification processes of similar capacity.


  • High treatment efficiency: Eliminates up to > 99% turbidity, suspended solids and associated pollutants
  • Extremely small footprint: The process requires little space; it is especially suited for use in restricted areas and ideal for retrofitting existing basins while expanding treatment capacity
  • Reduced civil costs: Thanks to its extremely small footprint, significant savings in civil costs are achieved
  • Few minutes of hydraulic residence time: Rapid start-up and quick treatment optimization
  • Unique process stability, also in the event of sudden flow and/or load variations
  • Ideal for automatic and remote operation, including frequent shut-downs & re-starts
  • User friendly process: Easy operation, requires minimum operator attention
  • Minimum equipment maintenance; easy to access
  • 20+ years of operating experience with more than 800 ACTIFLO® references worldwide



ACTIFLO® is for: Drinking and process water applications for the production of consistently high treated water quality, with removal efficiencies up to > 99% for Turbidity, Iron, Color, Algae, Arsenic, etc. ; Wastewater applications, consistently achieving high effluent quality with removal efficiencies of up to > 99% for Total Suspended Solids (TSS), Total Phosphorus, Heavy Metals, Total Coliforms, etc.


ACTIFLO® applies to surface, ground and karstic water for the production of the highest settled water quality.

It is ideally suited for the treatment of:

  • Rapidly fluctuating raw water sources
  • High turbidity river water or very low turbidity reservoir water
  • Warm surface water or very low temperature spring run-off water (0°C)
  • Brackish and/or seawater
  • Filter backwash water for recycling or discharge

Thanks to the use of microsand, ACTIFLO® achieves better treatment performance than all existing clarification processes on the market, displaying consistent and up to > 99% removal efficiencies of:

  • High or low turbidity, flocculable Natural Organic Matter (NOM) and Total Organic Carbon (TOC)
  • Algae, particle counts, Crypto Oocysts, Giardia and other pathogens/parasites
  • Iron, Manganese, Arsenic...

ACTIFLO® is particularly efficient in treating algal bloom and hence reducing taste & odor that are associated with algae.

It can also be used for the recovery and recycle of filter backwash water for the purpose of reducing water losses and associated operating costs while preserving water resources.


ACTIFLO® can be used in all municipal wastewater treatment applications:

  • Primary Clarification: Before Activated Sludge Basins (AS), Biological Aerated Filters (BAF) or Moving Bed Biological Reactors (MBBR)
  • Secondary Clarification: After Activated Sludge whenever space is tight or not available for large footprint conventional secondary clarifiers, after MBBR or as secondary clarifier in BIOACTIFLO®
  • Tertiary Clarification: For effluent polishing and phosphorus precipitation. With up to >95% removal of total phosphorus and up to >99% removal of total suspended solids, ACTIFLO® performance exceeds most water quality discharge or reuse standards

Stormwater/Combined or Sanitary Sewer Overflow Treatment (CSO/SSO):

  • With its very short hydraulic residence time and quick treatment within few minutes, ACTIFLO® easily handles rapid raw water load and/or flow fluctuations.
  • It treats stormwater peak flows "online" as they occur with > 90% removal of total suspended solids and associated BOD & COD
  • Thanks to a solids pre-contact tank, BIOACTIFLO® treats CSOs according to US EPA discharge standards
  • Combined with downstream UV disinfection, ACTIFLO® treated effluents are compliant with most bathing and shellfish water directives.

Biofilter Backwash Water Treatment: Due to ACTIFLO®'s very short hydraulic residence time, biological sludge is unlikely to go septic; it is clarified extremely efficiently, with superior removal levels as compared with flotation.

Treatment of Trickling Filter effluents, in replacement of conventional clarifiers.

Water Reuse for agricultural irrigation and/or aquifer recharge, optionally in combination with further polishing with downstream Discfilters (Actiflo® Disc)


ACTIFLO® is ideally suited for industrial water and wastewater applications. It has reduced costs, increased operating efficiency and improved system reliability for customers in all industrial market segments:

Surface water and ground water pre-treatment

  • Process water production
  • Wastewater treatment
  • Reuse and recycle
  • Stormwater run-off treatment

ACTIFLO® is an ideal solution for:

Process water production:


  • Boiler demineralised water supply
  • Cooling tower make-up
  • Water softening
  • Silica removal

Wastewater treatment:

  • Removal of suspended solids, fines and associated BOD & COD
  • Heavy metals removal
  • Removal of dispersed and emulsified oil & grease
  • >95% removal of total phosphorus in tertiary polishing

Reuse and recycling:

  • Treatment of industrial effluents and recycling back to production
  • Treatment of municipal secondary effluents for industrial make-up water

Stormwater run-off treatment:

  • High and efficient removal of total suspended solids, fines, heavy metals, oil & grease and other run-off associated pollutants


ACTIFLO® Brochure (1.37 MB)


BIOACTIFLO™ is a process designed for treatment of stormwater and reduction of its soluble BOD.
Clarification and Flotation

ACTIFLO® Softening

ACTIFLO® Softening removes hardness and alkalinity to improve water quality for municipalities and industries.


Actilfo® Pack, a complete range of pre-engineered and standardized ACTIFLO® units. ACTIFLO® package unit treatment capacities can be as high as 2,500 m3/h.


Designed to reduce the amount of sludge produced and related water losses, Actiflo® HCS (for High Concentration Sludge) is an Actiflo system equipped with an outside recycling loop.
Clarification and Flotation


Actiflo® Duo is a two in one ready-to-use system designed to adjust to substantial fluctuations in wastewater flows to be treated.
Clarification and Flotation


ACTIFLO® Disc is a polishing solution designed to achieve high removal levels of suspended solids and phosphorus in municipal and industrial wastewater for water reuse.


The ACTIFLO® CARB process combines the features and the efficiency of ACTIFLO® with the adsorption qualities of activated carbon to remove compounds that are refractory to water clarification.