[Biotechnological principles and environmental hygiene aspects of in situ sanitation methods in soil and groundwater areas].

Biotechnological in situ measures can become a suitable mean to compete with a broad spectrum of mainly organic contaminants in soil and ground water environments. They can partly follow the spread of the contaminants, are ecologically safe and economically reasonable. Their application, however, is less effective at high concentrations of the contaminants, in the presence of toxicants and also under hydraulically unsuitable conditions. Care must be taken to avoid possible side-effects of the nutrient added, enriched microbial biomass, and some metabolical products. Long-term effects of in situ remediation techniques, and especially in connection with the possible use of added microorganisms, are not well known, yet. There is a need for further research in this complex field, in order to establish a scientific base because until now these remediation techniques were mainly based on empirical views.