Particular interest is attached to the fate of nanoparticles in sewage treatment processes. There are major knowledge gaps regarding the behaviour of nanoparticles in sewage sludge and the nanoparticle exposure pathways during further usage of the sewage sludge. Together with three operators of sewage treatment plants, the project thus plans to investigate the effects of typical processes occurring during treatment of municipal and industrial wastewaters on nanoparticles and to identify the relevant substance pathways and processes.
The distribution of particles from sewage sludge in the environment is analysed based on data from possible nanoparticle uptake by plants. To that purpose the uptake of nanoparticles and the corresponding mechanisms of action at different stages of plant growth will be investigated. Besides, the availability of nanoparticles in soils is investigated by means of transport studies.
The use of radiolabeled nanoparticles in the analyses is a particular methodological feature providing considerable experimental benefits and enabling detection of nanoparticles at the expected low "real" concentrations in highly complex environments due to distinction from the background concentration. In the laboratory, the radiolabelled particles are applied to water, soil and plant samples. These samples are subjected to treatment steps identical to those they would undergo in a sewage treatment plant and subsequent processes like processing of sewage sludge, its application as fertiliser up to a possible absorption by the plants. Such procedure enables both process analyses and the development of detailed knowledge about the behaviour of nanoparticles during the different water treatment stages through to the sewage sludge – soil – plant system.
Requirements regarding environmental protection will be derived, and proposals for optimisation of the sewage treatment processes will be developed together with the operators of the sewage treatment plants. The close interdisciplinary cooperation of a research institution with two industrial partners and three municipal operators promises a successful approach to the complex problems discussed above.