Abstract
The separation characteristics of high-concentration magnetic sludge were studied using magnetic activated sludge, and the basic strategy for designing a magnetic separator using a permanent magnet was proposed. During the experiment, magnetic sludge was stuck on the magnet for only several seconds, until half the value of the saturation. The maximum magnetic compaction effect of the sludge was obtained when the concentration ratio of magnetite to activated sludge was from 1~3. The magnetic compaction was roughly twice that of gravitational settling in the experiment, and only several seconds was sufficient for the process. When the concentration ratio of separated sludge to suspended sludge is nearly 1, separated water can hardly be obtained from the magnetic separator. It is assumed that the concentration ratio of separated sludge to suspended sludge should be considerably smaller than 1. Under such condition, shortening of the scraping cycle seems to be effective for improving magnetic separator performance. It is believed that this basic strategy is useful to design a magnetic separator using a permanent magnet, electromagnet or superconductive magnet to separate high-concentration magnetic sludge.
