This Test Guideline describes a method to assess effects of a test chemical on the phagocytotic activity of activated sludge containing protozoan organisms under defined conditions in the presence of different concentrations of the test chemical. The principle of biological sewage-treatment plants (STP) is to transform the organic matter of incoming waste-water in microbial biomass, which in turn is separated from the liquid yielding a purified effluent. The purpose of the test is to provide a means to record effects of test chemicals on ciliated protozoa in sewage treatment plants, which due to their grazing on bacteria considerably contribute to the functioning of STPs.
Test No. 244: Protozoan Activated Sludge Inhibition Test
OECD Guidelines for the Testing of Chemicals, Section 2
