| 摘要 |
<p>A dispersion having an aqueous continuous phase is membrane filtrated in one or more membrane filtration steps, where a feeding dispersion fed to a filtration membrane is separated in each step into a retentate retained by the filtration membrane and a permeate passing through said filtration membrane, whereby the retentate from one step can be used, if desired, as a feeding dispersion or a portion thereof in one or more succeeding steps. The permeate resulting from one or more steps is subjected to a concentration to form a concentrated fraction containing an increased concentration of the dry matter or a portion thereof present in the permeate, and this concentrated fraction is returned as a portion of the feeding dispersion in one or more membrane filtration steps. A system for membrane filtration of such dispersion comprises one or more membrane filtration units each associated with a feeding pipe, a retentate exit pipe, and a permeate exit pipe, one or more of the permeate exit pipes (8<n-1>, 8<n>, 8<n+1>, ...) being coupled to one or more concentrating units (10<n-1>, 10<n>, 10<n+1>, ...) adapted to separate the permeate into a diluted fraction and a concentrate, each concentrating unit being provided with an exit (12<n-1>, 12<n>, 12<n+1>, ...) for the diluted fraction and a concentration exit pipe (14<n-1>, 14<n>, 14<n+1>, ...) for the concentrate, said concentration exit pipe being coupled to a return pipe (16<n-1>, 16<n>, 16<n+1>, ...) opening on to one or more of the feeding pipes (2<n-1>, 2<n>, 2<n+1>, ...) of the membrane filtration units.</p> |
