
In the activated sludge wastewater treatment process of many metazoan scrubbers are associated to organic colloids and organ metallic present in wastewater. Some agencies may use the carbon and the nitrogen component drugs to feed or use it as a source of energy. The study of the biological degradation of micro pollutants (secondary pollution), including the pharmaceutical compound reveals a great importance for the process of degradation and environmental. In this work we are interested in the study of the effect of three drugs (NSAIDs, hormone and a corticosteroid) rejected at the same time, in wastewater on the most abundant metatozoans according to the method of the design of experiments (23 factorial) and study some parameters directly linked pollution has this kind of micro-organisms. The results obtained show that: studied medicines interfere with the process of nitrification and they have an adverse effect, in certain doses, on the metazoan present.