Dissolved air flotation unit Cylindrical & rectangular
The SERDAF dissolved air flotation unit is a wastewater treatment equipment enabling pollution reduction by injecting microbubbles of air into the effluent. By upward movement, these microbubbles drive the particles contained in the effluent to the surface, where they are evacuated by a scraping device.
The dissolved air float sieve SERDAF is used in the treatment of wastewater, urban effluents (wastewater treatment plants), industrial effluents (food industry: canneries, slaughterhouses, dairy / cheese factories, washing of fruits and vegetables, fish industry- chemicals / pharmaceuticals – mechanical and paper industry – agricultural sector: breeding, wineries – hotels / restaurants – etc) and processes.
Chemistry - Pharmacy
Flotation is a separation process consisting in the generation and injection of microbubbles of gas into a liquid containing particles: bubbles attach to the particles and, like buoys, drag them to the surface to form a foam which is scraped off.
The principle is simple. Putting it in practise much less.
We started to study this process in 1991 to finally design a unit that now meets, as far as possible the expectations in terms of:
Easy, minimal and safe operator work
Durability of the various components
and of course by trying to offer it at an affordable price.
This was obtained after a great deal of research and testing on all the stages of the process:
Air dissolution in water, then precipitation
The search for the most suitable components, and the pressurization pump in particular
The bubbles / particles contact and their fixation
The hydrodynamics of circulation in the flotation tank
The system optimization and the extraction sequences of the different separate phases.
Our range of flotation units SERDAF includes the following models:
Rectangular R with sediment reception hoppers
Rectangular with Archimedes’ screw extraction of sediment RS
Rectangular with lamellar pack FP
All our models are equipped with the air dissolution system and micro bubble generator SERKIT assembly
This SERKIT can be sold separately to transform any static separator, equipped with a surface scraper and a bottom purge, into a dissolved air flotator.
These kits SERKITgenerate air microbubbles of 10 and 100 microns in diameter that cling to the particles contained in the water to be treated, to drive them to the surface.
They are designed to dissolve as much air as possible in the water and form bubbles as small as possible, while requiring minimum maintenance.
A pressurization pump sucks up part of the clean water leaving the flotation unit. Precisely dosed air is injected at the pump outlet. The rise in pressure causes the air to dissolve in the water. The flow passes through a reservoir in which the dissolution continues and where the excess air is purged.
The pressurized water is sent to the raw water inlet line in the flotation unit, where sudden depressurization generates what is known as “white water”. This milky appearance is the result of the appearance of myriads of microbubbles which allow the separation of the particles.
The choice of the model, the sizing of the flotation unit and the pressurization kit are made by our engineers in agreement with the customer, according to the flow rate of the water to be treated, the nature and the load of suspended solids and the BOD (Biological Demand in Oxygen).
The particularity of our dissolved air flotation units SERDAF are their efficacy, fiability and minimal operation requirements.
From a hydrodynamic point of view each of the models is made up of 3 zones:
A high turbulence contact zone in which pressurized water is mixed with raw water to promote contact between bubbles / drops of grease or materials to float.
A separation zone in which a white water mattress forms and where the flotation of light particles and the sedimentation of heavy particles take place.
The areas of accumulation of separated materials at the surface and at the bottom of the flotator
The Extraction of the “floating”
The surface foams are swept up by scraping into a recovery chute, ie:
In the cylindrical CYfloats, by a geared motor bearing 2, 4 or 8 arms with articulated scrapers
In the rectangular models R, RSand FP,by two side chains carrying the scrapers.
The operating time of the scraping can be adjusted by time delay in order, if necessary, to act on the dryness of the floats.
In every DAF model, sediments accumulate in the bottom hoppers of the flotation tanks.
They are extracted:
Either by opening a purge valve, under the hydrostatic head pressure, in the models CY, R and FP
Or, in the model RS, when the presence of sediment is significant in the raw water, by scraping a bottom trough, with an Archimedes’ screw to a collection pot, then flushed out by opening a purge valve.
These products could be associated with Dissolved Air Flotation units