Fluid treatment

Abstract

Abstract <PICT:0985940/C6-C7/1> <PICT:0985940/C6-C7/2> A dialysis or electrodialysis device comprises membranes, at least some of which are ionselectively permeable, having gaskets interspersed between the membranes securing only a portion of each membrane so that each membrane has at least one unsecured movable edge extending beyond one side of the gaskets, which gaskets define liquid flow paths between the membranes and have liquid flow passages communicating between the membranes. Fig. 1 shows an electrodialysis stack comprising end plates 26, 27, electrodes 51, 52, membranes 30, 31 which are selectively permeable to cations and anions respectively, gaskets 28, 32, 33, 29 holding the membranes at one end, and membrane spacers 55. The stack is mounted in a container 21 and liquid to be diluted is supplied to diluting cells D1 between the membranes via tube 46 and passages 37 and 40. The stack width is substantially equal to that of the container so that there is little or no cross-leakage between the sides of the cells and flow between cells is at the right hand end as viewed in Fig. 1. Liquid is further diluted in cells D2 and is finally withdrawn at 48. Liquid is concentrated in cells C and a concentrated product is withdrawn at 49. Liquid which has flowed past the electrodes is withdrawn at 47 and 50. In modifications to prevent cross-leakage between cells the stack is surrounded by a plastic sheath 58, Fig. 7 (not shown) or, as shown in Fig. 8, has sponge elements 60, 61 held by elastic bands 62. Fig. 9 shows an electrodialysis stack in a shallow cylindrical container 20C, the stack <PICT:0985940/C6-C7/3> <PICT:0985940/C6-C7/4> having curved membranes 30, 31, an end plate 74 with large openings 75, and a central electrode 78 but otherwise similar to the device shown in Fig. 1. In a further modification, the membrane may be spirally arranged in a cylindrical container. In the various embodiments, the membrane spacers may comprise expanded plastic, Fig. 10 (not shown), or ribs 87, Fig. 12, joined by thin transverse members 88. Specifications 863,396 and 926,595 are referred to.

Inventors

• 👤 Nellen William Joseph

Bibliographic Details