| 摘要 |
A membrane separation process and apparatus uses two different semi-permeable membranes to remove inorganic ions and low molecular weight species from high molecular weight species. The first semi-permeable membrane has a pore size to allow mainly diffusive transport of species across the membrane and a preferred pore size is 20-40 angstroms. The second semi- permeable membrane has a pore size to allow mainly convective transport of species across the membrane and a suitable pore size is between 60-120 angstroms. A stripping fluid contacts the other side of the semi- permeable membranes to carry away any species which pass across the membranes. The stripping fluid of the second semi-permeable membrane can be further treated by nanofiltration and/or ion exchange to remove ions from the stripping fluid. The method and apparatus is suitable for demineralisation of concentrated whey solutions. <IMAGE> |
