Vorticella as an Indicator Organism for Activated Sludge

Abstract

IT has been recognized for a number of years that the type of protozoan fauna inhabiting activated sludge in a sewage purification plant of this type affords a useful indication of the condition of the sludge. In 1936, Ardern and Lockett¹ stated that they considered this test as the most useful in determining the activity of sludge and listed the common types associated with varying conditions. More recently, Barritt² has further enlarged their general findings. It has been concluded that the presence of ciliates and particularly the peritriches to the exclusion of other classes of Protozoa generally indicates a ripe active sludge. But the scope of the utility of this test has been limited by the fact that they were usually qualitative and therefore complementary only to the quantitative chemical analyses.