| 摘要 |
<PICT:1082669/C1/1> Purified drinking water is obtained by removing a filter element 1 from carrying case 2, immersing it in a river and sucking water through the element and up tube 17 held in the mouth. Element 1 comprises a bacteria - removing filtering membrane of pore diameter less than 0.5 microns and a bed of sorbent material 15. The filtering membrane may be of pleated hollow form (Fig. 3, not shown), or may be a pleated membrane forming one side of a rectangular box (Figs. 4-6, not shown). The membrane may comprise a deposit of fibres of diameter 2 microns or less and/or particles of average diameter below 10 microns of glass, asbestos, plastics, rubber, metals, natural fibres, active carbon, minerals &c. (details given). Bactericides &c. such as silver halides may be included in the deposit, which is formed on porous paper or sintered metal or plastics powders, plastic foam, wire mesh, cloth, felt &c. The deposit is applied as a suspension, whose fluid part is then washed out. The sorbent 15 may be granular active carbon, glass wool or powder, chabicite, pumice, active alumina, silica gel, chromic oxide gel, quartz crystals, Fuller's earth and glaucosil. |
