[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | According to French standards, constructed wetlands treating combined sewer overflow (CSO CWs) are vertical flow filters with detention basin and outflow limitation. Their purpose is to treat rapid loads of wastewater with stochastic volumes, concentrations and periodicity. The first full-scale CSO CW at Marcy l‘Etoile was monitored to provide in-depth understanding of hydraulics and nitrogen dynamics. Monitoring lasted for three years incl. online equipment. The water content in the media was visualized along the longitudinal section of the filter to follow hydraulics in the fill stage. Tracer tests showed shortcutting at this stage weakening as the filter saturated which tallied with peaks of NH4-N concentrations diminishing at the outflow side. Adverse shortcutting effects can be diminished by minimizing fill time of the media. As for nitrogen dynamics, adsorption capacities showed no difference in the two filter sides, one with a sand-zeolite mixture and the other with pozzolana. An equation was fitted to temperature and adsorbed NH4-N mass measurements to calculate inter-event nitrification. The rate was found to double with every 5.7 °C. The results helped to calibrate the design-support software Orage. Finally, the washout dynamics of NO3-N were analysed to consider the possibility of a second filter stage for denitrification.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | The scope of this study is to research the removal of NH4 +-N from domestic wastewater using different porous and reactive materials by 1) increasing biological activity and 2) adsorption process. Experimental setup consisted of pilot scale VFCW (2.3 m2), which were put in operation in August 2014 receiving real raw domestic wastewater near a vertical flow wastewater treatment plant in the central region of France (L‘Encloitre, 37360). Two types of filtration media were tested 1) Leca® (L30M) and 2) natural zeolite (Z10M). Pilots were fed under regular feeding/resting periods (3´/7 days) and the nominal loading rate was of 300 g COD m-2 d-1 and 33 g.N.m2.d-1 in the operating filter. Results show a good treatment efficiency of domestic wastewater by the two French-Vertical Flow constructed Wetland (VFCWs) with more than 94% and 85% removal rate for TSS and COD for both filters respectively. Results also showed an increase of the NH4 +-N with the use of natural zeolite. The overall removal of more than 80% observed for Z10M seems to be linked to the effect of the ion exchange and adsorption properties of zeolite.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | Plants are essential in Constructed Wetland (CW) functioning. When implementing systems in tropical area, Phragmites autralis cannot be always selected because of its invasive characteristics. In Vertical Flow Constructed Wetland (VFCW) fed with raw wastewater, the main role of plant is their mechanical action that avoids clogging of the deposit organic matter. If alternative species have already been used in some tropical climate studies, it is generally not for such systems and without trying to do a real screening of numerous alternatives species. This paper presents a methodology to select species among a hundred studied, as well as promising plants that have been tested in batch and in full scale. Species from Zingiberales order showed strong adaptation to the main stresses generated by VFCW. They have long vegetative cycle that may require weed growth control after plantation but low harvesting frequency. Root system with long rhizomes like Heliconia psittacorum should have priority to ensure homogeneous growth and avoid clumps. To limit phytosanitary risk with Musaceæ (Banana tree) Canna indica or Canna glauca must be preferred. Species from the Cyperus genus demonstrate good adaptation too and might be interesting, especially when a high stems density is required (planted sludge drying bed).

International audience | Remediation of colored wastewater loaded with dyes and metal ions is a matter of interest nowadays. In this study, 220 bacteria isolated from textile wastewater were tested for their potential to decolorize each of the four reactive dyes (reactive red-120, reactive black-5, reactive yellow-2, and reactive orange-16) in the presence of a mixture of four different heavy metals (Cr, Zn, Pb, Cd) commonly found in textile effluents. Among the tested bacteria, the isolate ZM130 was found to be the most efficient in decolorizing reactive dyes in the presence of the mixture of heavy metals and was identified as Pseudomonas aeruginosa strain ZM130 by 16S rRNA gene analysis. The strain ZM130 was highly effective in simultaneously removing hexavalent chromium (25 mg L-1) and the azo dyes (100 mg L-1) from the simulated wastewater even in the presence of other three heavy metals (Zn, Pb, Cd). Simultaneous removal of chromium and azo dyes ranged as 76.6-98.7 % and 51.9-91.1 %, respectively, after 180 h incubation. On the basis of quadratic polynomial equation and response surfaces given by the response surface methodology (RSM), optimal salt content, pH, carbon co-substrate content, and level of multi-metal mixtures for decolorization of reactive red-120 in a simulated textile wastewater by the strain ZM130 were predicted to be 19.8, 7.8, and 6.33 g L-1 and a multi-metal mixture (Cr 13.10 mg L-1, Pb 26.21 mg L-1, Cd 13.10 mg L-1, Zn 26.21 mg L-1), respectively. Moreover, the strain ZM130 also exhibited laccase and nicotinamide adenine dinucleotide (reduced)-dichlorophenolindophenol reductase (NADH-DCIP reductase) activity during the decolorization of reactive red-120. However, the laccase activity was found to be maximum in the presence of 300 mg L-1 of the dye as compared to other concentrations. Hence, the isolation of this strain might serve as a potential bio-resource required for developing the strategies aiming at bioremediation of the wastewater contaminated with dyes and heavy metals.

Avec nos remerciements à Jodie Thénard, Virginie Grondin, Jean-Pierre Pétraud, Amélie Trouvé, Christelle Marrauld et Françoise Poiroux | Earthworms play a key role in agroecosystem soil processes. This study aims to assess the effects of different doses of a commercial formulation of epoxiconazole (Opus®), a persistent and widely used fungicide, on the earthworm Aporrectodea icterica. A laboratory study was conducted in a natural soil in order to measure effects of Opus® on earthworm mortality, uptake, weight gain, enzymatic activities (catalase and glutathione-S-transferase), and energy resources (lipids and glycogens). The estimated LC50 was 45.5 mg kg−1, or 268 times the recommended dose. Weight gains were 28, 19, and 13 % of the initial weight after 28 days of exposure in the control and D1 and D10 (1 and 10 times the recommended dose) treatments, respectively. No difference was observed for catalase activity between the three treatments, at 7, 14, or 28 days. The glutathion-S-transferase (GST) activity was two times as high in D1 as in D0 at 14 days. At 28 days, glycogen concentration was lower in D10 than in the D1 treatment. This study highlighted moderate sublethal effects of the commercial formulation Opus® for earthworms. Considering that these effects were observed on a species found in cultivated fields, even at recommended rates, much more attention should be paid to this pesticide.

International audience | Jérémie Sage, Elissar El Oreibi, Mohamed Saad, Marie-Christine Gromaire (2016). Modelling the temporal variability of zinc concentrations in zinc roof runoff – Experimental study and uncertainty analysis, Environmental Science and Pollution Research, pp. 1-15. The final publication is available at Springer via http://dx. ABSTRACT This study investigates the temporal variability of zinc concentrations from zinc roof runoff. The influence of rainfall characteristics and dry period duration is evaluated by combining laboratory experiment on small zinc sheets and in-situ measurements under real weather conditions from a 1.6 m² zinc panel. A reformulation of a commonly used conceptual runoff quality model is introduced and its ability to simulate the evolution of zinc concentrations is evaluated. A systematic and sharp decrease from initially high to relatively low and stable zinc concentrations after 0.5 to 2 millimetres of rainfall is observed for both experiments, suggesting that highly soluble corrosion products are removed at early stages of runoff. A moderate dependence between antecedent dry period duration and the magnitude of zinc concentrations at the beginning of a rain event is evidenced. Contrariwise, results indicate that concentrations are not significantly influenced by rainfall intensities. Simulated rainfall experiment nonetheless suggests that a slight effect of rainfall intensities may be expected after the initial decrease of concentrations. Finally, this study shows that relatively simple conceptual runoff quality models may be adopted to simulate the variability of zinc concentrations during a rain event and from a rain event to another.

The present study investigates the effect of metals on the secretion of enzymes from12 fungal strains maintained in liquid cultures. Hydrolases (acid phosphatase, β-glucosidase, β-galactosidase, and N-acetyl-β-glucosaminidase) and ligninolytic oxidoreductases (laccase, Mn, and lignin peroxidases) activities, as well as biomass production, were measured in culture fluids from fungi exposed to Cu or Cd. Our results showed that all fungi secreted most of the selected hydrolases and that about 50 % of them produced a partial oxidative system in the absence of metals. Then, exposure of fungi to metals led to the decrease in biomass production. At the enzymatic level, Cu and Cd modified the secretion profiles of soil fungi. The response of hydrolases to metals was contrasted and complex and depended on metal, enzyme, and fungal strain considered. By contrast, the metals always stimulated the activity of ligninolytic oxidoreductases in fungal strains. In some of them, oxidoreductases were specifically produced following metal exposure. Fungal oxidoreductases provide a more generic response than hydrolases, constituting thus a physiological basis for their use as biomarkers of metal exposure in soils.