Membrane bioreactor waste water treatment method

Abstract

The invention relates to a membrane bioreactor waste water treatment method comprising a sludge dewatering step and a step involving the recycling of the liquid effluent originating from the sludge dewatering step, which is performed at the head of the bioreactor. The invention is characterised in that: the biological sludge extracted from the bioreactor (1) is brought into contact with the liquid effluent from the sludge-dewatering step such that the residual polyelectrolyte content in said effluent, which was used for sludge conditioning during the dewatering step (4), moves towards the biological sludge; the biological sludge is separated from the liquid effluent such as to produce a polyelectrolyte-free liquid effluent and a polyelectrolyte-loaded biological sludge; the polyelectrolyte-free liquid effluent is recycled at the head of the membrane bioreactor, and the polyelectrolyte-loaded biological sludge is conveyed towards the dewatering step.

Dependencies are inferred from the claim text.