A solid-ejecting disc centrifuge provides intermittent solids ejection by regulating its valve — controlled peripheral ports using a timer or an automatic triggering device. The advantage of this centrifuge for algae harvesting is its ability to produce algal cake in a single step without chemical dosing (Mohn and Soeder, 1978; Mohn, 1980; Shelef et al., 1984). This centrifuge con­centrated various types of microalgae effectively, achieving algal cake of 12-25% solids (Mohn, 1980; Moraine et al., 1980). The extent of the algae suspension separation increases with increas­ing residence time (decreasing feed rate), and the ejected cake concentration is affected by the intervals between successive desludging (Shelef et al., 1984). A solid-ejecting disc centrifuge was found very reliable. The only reported setback was that solids finer than algae may be retained in the overflow, which reduces the separation efficiency (Moraine et al., 1980). High capital and energy costs render this separation method unappealing.