The fate of glyphosate and its metabolite AminoMethylPhosponic acid (AMPA) was followed at the catchment of the Sûre river, mainly characterized by small population density and small and medium-sized wastewater treatment plants (WWTPs). A high concentration of AMPA was found in water samples collected in inlet from different wastewater streams, the industry being the main contributor, while glyphosate resulted mainly in domestic origin. The two molecules were also monitored in the anaerobic digestion as in the supernatant produced after centrifugation (reject water). A total of 0.0713 and 2.24 g/d of glyphosate and AMPA respectively were regularly returned to the activated sludge tank (AST) indicating a 20% impact of the sludge management line on the global wastewater mass balance. Finally, the use of Constructed Wetlands (CWs) in Vertical Flow (VF) configuration was tested as a suitable technology to retain both glyphosate and AMPA (90 and up to 50% elimination respectively) and minimize their discharge into surface water.

Pharmaceuticals are normally barely removed by conventional wastewater treatments. Advanced technologies as a post-treatment, could prevent these pollutants reaching the environment and could be included in a centralized treatment plant or, alternatively, at the primary point source, e.g. hospitals. In this study, the environmental impacts of different options, as a function of several advanced treatments as well as the centralized/decentralized implementation options, have been evaluated using Life Cycle Assessment (LCA) methodology. In previous publications, the characterization of the toxicity of pharmaceuticals within LCA suffers from high uncertainties. In our study, LCA was therefore only used to quantify the generated impacts (electricity, chemicals, etc.) of different treatment scenarios. These impacts are then weighted by the average removal rate of pharmaceuticals using a new Eco-efficiency Indicator EFI. This new way of comparing the scenarios shows significant advantages of upgrading a centralized plant with ozonation as the post-treatment. The decentralized treatment option reveals no significant improvement on the avoided environmental impact, due to the comparatively small pollutant load coming from the hospital and the uncertainties in the average removal of the decentralized scenarios. When comparing the post-treatment technologies, UV radiation has a lower performance than both ozonation and activated carbon adsorption.

Background: Micropollutants in bodies of water represent many challenges. We addressed these challenges by the application of constructed wetlands, which represent advanced treatment technology for the removal of micropollutants from water. However, which mechanisms specifically contribute to the removal efficiency often remains unclear. Methods: Here, we focus on the removal of 27 micropollutants by bioremediation. For this, macrophytes Phragmites australis, Iris pseudacorus and Lythrum salicaria were taken from established wetlands, and a special experimental set-up was designed. In order to better understand the impact of the rhizosphere microbiome, we determined the microbial composition using 16S rRNA gene sequencing and investigated the role of identified genera in the micropollutant removal of micropollutants. Moreover, we studied the colonization of macrophyte roots by arbuscular mycorrhizal fungi, which are known for their symbiotic relationship with plants. This symbiosis could result in increased removal of present micropollutants. Results: We found Iris pseudacorus to be the most successful bioremediative system, as it removed 22 compounds, including persistent ones, with more than 80% efficiency. The most abundant genera that contributed to the removal of micropollutants were Pseudomonas, Flavobacterium, Variovorax, Methylotenera, Reyranella, Amaricoccus and Hydrogenophaga. Iris pseudacorus exhibited the highest colonization rate (56%). Conclusions: Our experiments demonstrate the positive impact of rhizosphere microorganisms on the removal of micropollutants.

The present research aims at giving an approach to the issue of surface water contamination due to micropollutants in rural areas. The catchment of the Sûre river was selected as a reference case for the Greater Region, characterized mainly by settlements with low population density, small water bodies and small- to medium-sized wastewater treatment plants (WWTPs). For these WWTPs, conventional technical solutions for micropollutant elimination are not suitable; therefore, an adapted mitigation strategy is needed to prevent the impact of micropollutants, especially during the dry season. As a suitable alternative to more intensive technologies, Constructed Wetlands (CW) in Vertical Flow (VF) configuration have been successfully tested over a 1-year period and the elimination rate of 27 micropollutants was quantified. Emission reduction by VF was then considered in a static mass balance model that calculates the longitudinal concentration profile for the entire river catchment. The EmiSûre approach, which focuses on river quality (concentrations of pollutants) instead of emitted loads, effectively allowed simulation of adopted measures a priori and resulted in efficient support for decision-makers with WWTP upgrade scenarios.

This study aimed to evaluate the suitability of biochar produced by pyrolysis from recovered wastewater cellulose and activated biologically as an admixture in Constructed Wetlands (CWs) when applied as a post-treatment step to remove micropollutants (MPs) from municipal wastewater effluent. Two planted vertical flow mesocosm CWs with cellulose-based admixtures of different origins (plant residue and recovered toilet paper) were fed with a municipal wastewater effluent representative for rural catchments. The results showed an average MPs elimination of 89.1 % for the activated biochar produced from recovered cellulose when 15 relevant compounds are considered and a reduction of the risk from compounds cocktail below the maximum acceptable level having diclofenac, carbamazepine, PFOS, ciprofloxacin and clarithromycin as main risk drivers (Risk Quotient > 1). The implementation of a circular approach to reduce MPs was finally conducted for the Blies catchment (Saarland region in Germany) characterized by low population density and small, sensitive water bodies. This approach demonstrates the feasibility of combining cellulose recovery with a fine sieve in large wastewater treatment plants (WWTPs) and providing biochar produced from recovered cellulose as an admixture to small WWTP where CW is an affordable solution for MP mitigation.