Roquette Planta LESTERM (Francia)

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SIGMADAF was contracted by ROQUETE LESTREM to supply two FPHF-750 DAF units to clarify the effluent from the biological treatment to remove TSS and Phosphates. Prior to the DAF units a phisico-chemical treatment with coagulation and flocculation tanks and chemical dosing (Ferric Chloride 2 – 20 ppm and Polyelectrolite 1 -3 ppm) is required. 

The technology used in the DAF is the PACK LAMELAR that use a combination of counter-current and cross water flow in the tank through the lamellas, to assure an even uniform water distribution and facilitate the water outlet through lateral pipes along the tank length. The lamellas are counter-current type with 60 mm separation between plates and 60º inclination. The heavier particles are separated with a relative high efficiency in the lamellas, whereas the lighter suspended matter is floated to the surface and extracted with the top scrapper.

 Year construction 


  Nº of units  


  DAF model  




Pack lamelar 

YES (PP with supports in AISI316)

 Unitary daf flow  

 725 m3/h

  TSS max in / out 

 200 / 10 ppm

 Phosphore max. in / out.  

 20 / 2 ppm


the wastewater treatment equipment supplied by SIGMA to the LESTERM plant in France: flocculation tanks and DAF-FPHF.

Suspended solids are aggregated in flocs in the flocculation tank and as they enter into the DAF unit, air-bubbles adhere to the flocs and enhance their buoyancy and separation process. The use of micro-bubble flotation technology (30 to 50-micron range) increases the float efficiency, as smaller bubbles easily adhere to equal-sized or larger particles, boosting the overall effectiveness of the system. The SIGMADAF air aerator generates the required amount of air to be injected in small size bubbles in quantity and well distributed in the full tank volume. 

The DAF units have dimensions of L 10 x W 3 m, with a useful vertical flotation surface of 24 m2 and projected lamella surface of 400 m2, designed to operate at hydraulic flow rate of 1.81 m3/m2-h and mas load rate of < 6 kg/m2-h.

Rendering of the DAF FPHF equipment supplied to clarify the biological treatment effluent and remove TSS at the Lesterm Water Plant (Francia).

To generate the air bubbles a recirculation of clarified water (15-20%) is taken from the DAF outlet with a centrifugal pump and air is injected up to its saturation point. The mixture air dissolved and water at 6 bar is then depressurized in the saturation vessel or manifold with multiple depressurization valves and added to the DAF tank inlet through multiple hose pipes for missing with the feed water. 

Photo detail of the manifold of one of the DAF-FPHF 750 equipment supplied by SIGMADAF to ROQUETTE LESTERM and installed in a plant in France.

Floated sludge is swept from the tank water surface with a chain type scrapper and extracted through a collection hopper. The scrapper is constructed in AISI316/ Neoprene (paddles, shaft) and POM (chain, bearings) with a drive motor of 0,53 kW provided with VFD for speed adjustment. Solids which sediment in the tank bottom are extracted through a shaft-less screw device in AISI316 and drive motor of 0,37 kW. 

The DAF units are packed in SIGMADAF workshop and protected for transportation to the site by truck, where they are installed in place. 

SIGMADAF order for the DAF units included the design-fabrication of the complete units with instrumentation and supervision services on site for the erection, installation, start-up and training. 

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