The contribution deals with the following topics: --Microbiological in situ investigations of polluted ground water aquifers in order to develop a concept for biological remediation. --Removal of organic and halogenated organic compounds from ground water using methods which are common in the drinking water treatment (sand-fastfiltering, immobilized reactors). --Removal of organic and halogenated organic compounds from ground water using methods which are common in sewage treatment (activated sludge, suspension reactors). The conclusion has been drawn that there are many microbiological methods existing which can be used to remove the above contaminants from soil and ground water environments.