| 摘要 |
The invention pertains to a method for removing phosphate from a phosphate-containing water fraction comprising the steps of a) continuously providing a phosphate-containing water fraction to a holding tank comprising an adsorbent in the form of a suspension, b) continuously withdrawing a purified water stream through an ultrafiltration membrane and passing a water stream over the ultrafiltration membrane and recycling it to holding tank, wherein the volume ratio between the volume of the water stream withdrawn through the ultrafiltration membrane per second and the volume of the water stream passed over the ultrafiltration membrane per second is at least 4:1 and less than 20:1, c) periodically stopping step b), and providing a water stream through the membrane, countercurrent to the withdrawal direction in step b) to form an adsorbent-containing water stream, d) collecting the adsorbent-containing water stream in a collection vessel, wherein the adsorbent concentration in the adsorbent collection vessel is at least 3 and at most 100 times the adsorbent concentration in the holding tank. It has been found that the specific combination of an adsorbent in the form of a suspension in a holding tank, the use of an ultrafiltration membrane with a limited amount of recycle, and a specific membrane cleaning operation makes it possible to combine efficient operation and low water circulation with obtaining a low phosphate content in the product. |
