Membrane-based liquid filtration installation and method for producing drinking water therewith without post-mineralisation

Abstract

Installation for the pressurised filtration of liquid with a view to producing drinking water, comprising at least one membrane-based drinking-water production unit (MPU), each MPU comprising: a plurality of filtration blocks each containing a bundle of pressure tubes mounted in parallel, each pressure tube accommodating at least two membrane-based filtration modules with spiral membranes or hollow-fibre membranes mounted in series, means () for feeding the liquid that is to be filtered, means for removing the filtered liquid, and means () for removing the concentrate, characterised in that the membranes of the filtration modules are of at least two different types selected from the group consisting of reverse-osmosis membranes and low-pressure reverse-osmosis membranes (-), on the one hand, and nanofiltration membranes (-) on the other hand, and in that at least one MPU comprises means (-) making it possible to alter the order in which the blocks of pressure tubes that it groups together are supplied with fluid. The method consists in supplying the filtration blocks of at least one MPU in a first order of supply in which the tubes containing nanofiltration membranes are at the head of the MPU and then in supplying the pressure tubes in a second order of supply in which the pressure tubes containing reverse-osmosis membranes or low-pressure reverse-osmosis membranes are at the head of the MPU.