There is a need for quality control of wastewater introduced into drainage systems. Physical and chemical analyses of wastewater inform only about the situation existing at the moment of sampling. The analysis based on bioindication methods allows to evaluate the existing state before sampling and so to recognize a drop of excessive loads or harmful substances for activated sludge. This refers to the moment preceding the sample taking at least by the generation time of the species with the lowest reproduction rate. For these reasons, the possibility of using microfauna representatives (feeding on organic pollutions) for bioindication was evaluated. The estimation was made of the usefulness of indicator species from the Kolkwitz-Marssori system, the Shannon-Wiener index based on species abundance and the latter based on abundances of morphological-functional organism groups. The study results showed that the ShannonWiener index calculated for morphological-functional groups (easiest to determine) was accurate enough for bioindication.

The present work focuses on problems connected with the location and sampling method for pecton (biofilm) in sewage treatment plants. We also discuss the amount and quantity of pecton necessary to compose a representative sample. Comparisons of other selected contamination indicators in place of pecton sampling, are also presented. Research carried out at the WWTP "Hajdow" demonstrated that everything (starting from grid chambers), coming into contact with sewage surfaces is covered with biofilm This biological formation does not cause any significant changes in sewage quality due to its relatively small surface compared to the sewage flux. As presented in the following analysis, pecton can be used for bioindication of sewage quality. This is possible because the organisms forming these communities use substances contained in flowing sewage as nutritional substrates. In such cases the wastewater purification level in biological sewage treatment plants can, in a way similar to rivers, be determined based on bioindication methods using existing similarities between the prevailing processes and organisms.