Anaerobic sludge flotation works particularly effective in case of fat, oil and grease (FOG) containing wastewaters or in case of salt rich wastewater.

The FLOTAMET™ process is therefore mainly used for:

  • FOG rich wastewaters: dairy, meat and fish processing, biodiesel production
  • Salt rich wastewater: molasses based distilleries
  • High COD – high solids wastewaters from food and beverage industry.

The FLOTAMET™ process consists of a mixed anaerobic reactor (GWE’s ANAMIX™) followed by a sludge flotation stage.

It is suited for wastewaters with COD values up to about 100,000 mg/l and more, and wastewaters containing medium to large amounts of suspended solids, FOG, and/or salt.

In the ANAMIX™ reactor the actual anaerobic purification takes place. This is a completely mixed reactor, equipped with an agitation system to prevent sludge settling or flotation.

Dissolved and suspended organic matter is largely degraded by anaerobic bacteria (sludge), and converted into biogas. Only little sludge growth takes place during this process.
The effluent from the digester flows via an effluent collection tank to a special Dissolved Biogas Flotation cell, called SUPERFLOT™-Biogas unit.

In the SUPERFLOT™-Biogas, the anaerobic sludge flocs escaping the anaerobic reactor are separated from the treated wastewater by flotation and returned to the digester.

From time to time some excess sludge is evacuated.

The principle of the SUPERFLOT™-Biogas is similar to Dissolved Air Flotation, but uses biogas instead of air.

In this highly efficient solids separation process fine biogas bubbles, needed for a good flotation, are created by recycling clean effluent through a saturator in which biogas is dissolved under pressure.

After injection of the recycle flow in the SUPERFLOT™-Biogas, the sudden pressure release results in the formation of fine biogas bubbles, which float to the surface, dragging the sludge flocs with them and separating the sludge from the anaerobic effluent.