New publication: Dissipation of micropollutants in a rewetted fen peatland – a field study using treated wastewater

A mixture of treated wastewater and surface water was used to rewet a degraded fen peatland site during a three-year rewetting experiment. Behaviour and effects of micropollutants were studied using hydrological, physico-chemical, microbiological and ecotoxicological monitoring. The highest concentrations of micropollutants in the treated wastewater were found for the pharmaceuticals carbamazepine and diclofenac, some metabolites, the sweetener acesulfame, tolyl- and benzotriazole and diatrizoate. In the underlying, shallow groundwater, where treated wastewater application for rewetting had been expected to have the greatest impact due to seeping and evapotranspiration processes, only a sporadic occurrence of micropollutants was found. The influence of dilution by groundwater movements was examined by applying a geohydrological model. The sorption of micropollutants onto the peaty soil also played a role, as found for carbamazepine. Further processes such as photolysis, microbial decay under low redox conditions and plant uptake can be assumed to be relevant for the removal of many substances. Ecotoxicity tests with the soil before and after rewetting did not indicate any negative impact of the wastewater application, but clearly pointed at ecotoxicologically relevant geogenic arsenic concentrations at the study site. Although a positive effect on receiving surface water systems is expected, if wastewater is applied onto land instead of discharged to water bodies, the rewetted soil may turn into a sink for micropollutants in the long term. The findings of the present field study encourage further investigations to identify the processes governing the elimination of micropollutants in rewetted peatlands flooded with treated wastewater.

For additional information, see the publication in Water:

Maassen, S., Richter, E., Coors, A., Guimarães, B., Balla, D. (2017). Dissipation of micropollutants in a rewetted fen peatland: a field study using treated wastewater. Water 9:449.

The study was performed within the project ELaN (FKZ 033L025) that was funded by the German Federal Ministry of Education and Research (BMBF).

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