Treatment of maceration water in the collagen industry by flotation DAF

Characteristics of the effluents to be treated

Description of supply

The company ROUSSELOT gelatin S.L., dedicated to the manufacture of food gelatines, incorporated a flotation equipment for the treatment of collagen maceration in its industry located in Cervià de Ter (Girona).                                                          

The scope of supply includes: A SIGMADAF FAPC50 assembly consisting of the metal body, float scraper system, recirculation pumping assembly with pressurized air injection manifold. A pneumatic control panel, a power and control panel, a preparation equipment and a PFL contact coil are provided. Engineering documentation and installation manuals are also provided. The expected performance of the equipment supplied achieves reductions of >90% of TSS and >90% for oils and greases, operating under correct conditions and with proper chemical conditioning.

Basic features

• Equipment: SIGMADAF FPAC50
• Materials: AISI 316 /AISI 304                          
• Dimensions: 8.000 x 2.400 x 2.300 mm (L x W x H)                
• Design flow rate: 20 ^m3/h
• Free area: 13^m2
• Air consumption: 15 Nl/min.
• Power consumption: 12 kW
• Surface scraper system with 0.37 kW motor
• Sediment extraction system with 0,37 kW motor
• Pumping, pressurization and recirculation with 7.5 kW motor

The dissolved air flotation (DAF) technique allows the separation of suspended solids, oils and fats, thanks to the recirculation of part of the treated wastewater, to which pressurized air is injected and then depressurized in the liquid, thus creating a stream of micro air bubbles (30 - 50 µm) that adhere to the particles, causing them to rise as they lose apparent density. This system is equipped with a static surface grid for sludge thickening.

DAF FPAC flotation equipment with large surface area and crossflow separation                                              

The DAF FPAC is ideal for working with small and medium flows, containing high pollutant loads (up to 40 kg of ^MS/m2). They are also the most suitable model for sludge thickening. They have a large free surface to accumulate the floated sludge.                                   

The FPAC model includes a single motion separator that rotates against the hydraulic current helping to minimize the distance the floated sludge travels and eliminating solids carryover in the effluent. This solution creates a sludge with a dry solids content 3 to 4 times higher than a conventional system. This results in a simplification of possible subsequent treatments, such as dewatering or drying, which reduces operating costs.                                                                                                         

Main features of DAF FPAC equipment

• Compact and customizable system.
• Treatment of high loads of TSS and other contaminants.
• Efficient laminar regime.
• Low maintenance and easy to operate.

Heavy sludge, which settles to the bottom of the system, is retained, concentrated and partially dewatered by the shaftless conveyor system. This allows the operator to control the concentration of the sludge and reduce its accumulation. The residual sludge is conveyed to the central discharge point and removed through an automatic pneumatic valve. This discharge cycle has a self-cleaning effect, which facilitates any particles adhering to the walls of the system to be released and removed with the rest of the waste.       

This case is a clear example of treatment of liquids loaded with high concentrations of TSS, oils and fats, and COD.