Process and apparatus for treatment of backwash water from a filter

Treating water backflushed through a drinking water or waste water filter to regenerate the filter comprises moving backflushed water to a settling tank (1) in which it is separated into a part containing the sediment and a clear aqueous phase. The aqueous and/or sediment phase pass through ≥ 1 submerged membrane filter (8) or membrane filter unit (18) and separated into clear permeate and concentrated sediment phases. The clean permeate is then used as a consumable medium, while the concentrate is further thickened. The submerged membrane surface is kept clear of sedimentary deposits by a continual stream of bubbles. The aqueous phase from the settlement tank (1) may be surrendered to a separate membrane filter unit (18) at a rate which depends upon the turbidity, the Redox potential and/or Zeta potential in the aqueous phase, the flow of water returning to the filter, the level of water in the settlement tank (1), or the operating time for the membrane filter units (18) and the submerged membrane filters (8).