[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.

International audience | Antibiotic use in the early 1900 vastly improved human health but at the same time started an arms race of antibiotic resistance. The widespread use of antibiotics has resulted in ubiquitous trace concentrations of many antibiotics in most environments. Little is known about the impact of these antibiotics on microbial processes or “non-target” organisms. This mini-review summarizes our knowledge of the effect of synthetically produced antibiotics on microorganisms involved in biogeochemical cycling. We found only 31 articles that dealt with the effects of antibiotics on such processes in soil, sediment, or freshwater. We compare the processes, antibiotics, concentration range, source, environment, and experimental approach of these studies. Examining the effects of antibiotics on biogeochemical processes should involve environmentally relevant concentrations (instead of therapeutic), chronic exposure (versus acute), and monitoring of the administered antibiotics. Furthermore, the lack of standardized tests hinders generalizations regarding the effects of antibiotics on biogeochemical processes. We investigated the effects of antibiotics on biogeochemical N cycling, specifically nitrification, denitrification, and anammox. We found that environmentally relevant concentrations of fluoroquinolones and sulfonamides could partially inhibit denitrification. So far, the only documented effects of antibiotic inhibitions were at therapeutic doses on anammox activities. The most studied and inhibited was nitrification (25–100 %) mainly at therapeutic doses and rarely environmentally relevant. We recommend that firm conclusions regarding inhibition of antibiotics at environmentally relevant concentrations remain difficult due to the lack of studies testing low concentrations at chronic exposure. There is thus a need to test the effects of these environmental concentrations on biogeochemical processes to further establish the possible effects on ecosystem functioning

Passive sampling devices (PS) are widely used for pollutant monitoring in water, but estimation of measurement uncertainties by PS has seldom been undertaken. The aim of this work was to identify key parameters governing PS measurements of metals and their dispersion. We report the results of an in situ intercomparison exercise on diffusive gradient in thin films (DGT) in surface waters. Interlaboratory uncertainties of time-weighted average (TWA) concentrations were satisfactory (from 28% to 112%) given the number of participating laboratories (10) and ultra-trace metal concentrations involved. Data dispersion of TWA concentrations was mainly explained by uncertainties generated during DGT handling and analytical procedure steps. We highlight that DGT handling is critical for metals such as Cd, Cr and Zn, implying that DGT assembly/dismantling should be performed in very clean conditions. Using a unique dataset, we demonstrated that DGT markedly lowered the LOQ in comparison to spot sampling and stressed the need for accurate data calculation.

The effects of polystyrene microbeads (micro-PS; mix of 2 and 6 μm; final concentration: 32 μg L−1) alone or in combination with fluoranthene (30 μg L−1) on marine mussels Mytilus spp. were investigated after 7 days of exposure and 7 days of depuration under controlled laboratory conditions. Overall, fluoranthene was mostly associated to algae Chaetoceros muelleri (partition coefficient Log Kp = 4.8) used as a food source for mussels during the experiment. When micro-PS were added in the system, a fraction of FLU transferred from the algae to the microbeads as suggested by the higher partition coefficient of micro-PS (Log Kp = 6.6), which confirmed a high affinity of fluoranthene for polystyrene microparticles. However, this did not lead to a modification of fluoranthene bioaccumulation in exposed individuals, suggesting that micro-PS had a minor role in transferring fluoranthene to mussels tissues in comparison with waterborne and foodborne exposures. After depuration, a higher fluoranthene concentration was detected in mussels exposed to micro-PS and fluoranthene, as compared to mussels exposed to fluoranthene alone. This may be related to direct effect of micro-PS on detoxification mechanisms, as suggested by a down regulation of a P-glycoprotein involved in pollutant excretion, but other factors such as an impairment of the filtration activity or presence of remaining beads in the gut cannot be excluded. Micro-PS alone led to an increase in hemocyte mortality and triggered substantial modulation of cellular oxidative balance: increase in reactive oxygen species production in hemocytes and enhancement of anti-oxidant and glutathione-related enzymes in mussel tissues. Highest histopathological damages and levels of anti-oxidant markers were observed in mussels exposed to micro-PS together with fluoranthene. Overall these results suggest that under the experimental conditions of our study micro-PS led to direct toxic effects at tissue, cellular and molecular levels, and modulated fluoranthene kinetics and toxicity in marine mussels.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | Constructed wetlands for combined sewer overflow treatment (CSO CWs) are variably saturated vertical flow filters in France. The design-support software Orage aims to facilitate engineering work by optimizing filter area and material sitespecifically which was otherwise encumbered by the stochasticity of CSO flows and concentrations. The optimization process relies on measured or simulated CSO series and a low number of input parameters. The iterative shell calls the core model repetitively. During the process, effluent flows and concentrations are simulated from a range of CW domains and compared to legislative thresholds. The iterative shell was tested both with measured and simulated inflows. First, key parameters of the hydraulic optimization were fixed. Large and underscaled designs are excluded this way and succeeding optimizations for pollutant removal are more efficient. Then, the optimization functions were verified using inflow and available land from an existing CSO CW. At third, the automatizations were used to test model predictions in the function of legislative thresholds. Zeolite-enriched media ensures high NH4-N removal at hydraulic loads exceeding the recommendations of present guidelines, marking clogging as an issue for further research. In summary, the demonstrated simulation experiments verified the optimization approach of the dynamic design tool Orage.

[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 French Overseas Territories experience big sanitations problems and have to comply with both French and EU regulations. Vertical flow constructed wetland (VFCW) appear well adapted to the context of these regions, but their adaptation to tropical climate requires new guidelines to be defined (area needed, number of filters, species of plants, material to be used …). To this end ATTENTIVE project was build up in the French Antilles with local water offices and supported by the national water authorities. Three different VFCW fed with raw wastewater were built in Martinique and Guadeloupe and are now under monitoring. While the 3 plants are actually in operation, this paper will focus on Taupinière plant (Martinique), sized for 900 p.e., in operation since October 2014. The treatment plant is composed of aunsaturated/saturated vertical flow constructed wetland, receiving raw domestic wastewaters, followed by a simplified trickling filter.The first stage is 0,8m²/p.e. with two filters in parallel (360 m² each), with a 40 cm unsaturated first layer of 2/4 mm gravel, a 15 cm transition layer of 11/22 with intermediate passive aeration pipes and a 60 cm saturated layer at the bottom made of 20/40 pea gravel. The trickling filter(116 m²)is composed of 150 cm of pumice stones. The sludge accumulated at the bottom of the trickling filter is sent back to the first stage.A recirculation loop is implemented on the trickling filter. Before the outlet, effluent passes through UV. The regulationobjectives is to achieve 90% removal for COD, BOD5 and TSS, 80% for TKN, and less than 1000 unit per 100 mL for E.coli and intestinal streptococcus. Nevertheless, the monitoring look after optimal operation to increase TN removal rates as well as the maximum loads that can be treated. The monitoring consists on classical daily composite samples at each treatment stages (30 campaigns) as well as online measurements. The later aim at measuring flows, climatic conditions, and COD, BOD5, and Nitrate (UV/visible analysis) at each treatment stages. Three different loading phases has been implemented from 30 % of the nominal load to 150 %. The paper will present performances of this compact (less than 1 m²/p.e.) treatment system in both dry and rainy season and discuss the optimization of TN removal as well as the footprint reduction with the high loads that can be implemented.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | In recent years, unsaturated/saturated vertical flow constructed wetlands(VFCW) treating raw wastewateraregradually considered as apromising solution for their adaptation under various climatic conditions. These facilities provide surface optimization but alsobetter treatment efficiencies compare to classical French VFCW.The main performance improvements are: SS entrapment and carbon consumption for denitrification within saturated layer.When total nitrogen, by nitrification and denitrification,istargeted in the two successive zones, a design compromise has to be fund between nitrification efficiency and available carbon source for denitrification. As performance largely depends on unsaturated and saturated layers depths,a better understanding of their quantitative effects on treatment performance is essential for the adaptation of this system under various installation conditions. The aim of this study was to estimate the influence of these two linked design parameters onN efficiency with a focus onremoval limitations in regard to nitrogen loads. For this purpose, two different pilot-scale experimental configurations were designed: (i) 45 cm of unsaturated and 25 cm of saturated layers and (ii) 55 cm of unsaturated and 35 cm of saturated layers. The mature pilots were operated over 5 months using real wastewater with a feeding/resting period cycle of 3.5/3.5 days with a daily hydraulic load of 0.36 m d-1.In order to vary inlet nitrogen loads, ammonium nitrogen enrichments were added to vary loads from 10 to 40 g N m-2 d-1.24h flow composite samples at inlet and outlet of each pilot were semiweekly collected and analyzed for the following parameters: total suspended solids (TSS), total and dissolved chemical oxygen demand (COD), Kjeldahl nitrogen (TKN), ammonium, nitrate, phosphate and sulfate. Online measurement on a minute time step were done for inlet/outlet flows, oxygen content at three different depths, outlet ammonium and nitrate concentrationsby ion specific probes, and temperature. The paper will present the performance and limitations ofthe two configurations.Dynamics of nitrogen removal processes will be discussed in relation to physicochemical conditions (temperature, oxygen content, hydraulic retention time, carbon sources, etc.).

International audience | In estuarine ecosystems, metallic and organic contaminants are mainly associated with fine grain sediments which settle on mudflats. Over time, the layers of sediment accumulate and are then transformed by diagenetic processes mainly controlled by microbial activity, recording the history of the estuary's chemical contamination. In an environment of this specific type, we investigated the evolution of the chemical contamination and the structure of both total and active microbial communities, based on PhyloChip analysis of a 4.6-m core corresponding to a 40-year sedimentary record. While the archaeal abundance remained constant along the core, a decrease by one order of magnitude in the bacterial abundance was observed with depth. Both total and active microbial communities were dominated by Proteobacteria, Actinobacteria, and Firmicutes in all sediment samples. Among Proteobacteria, alpha-Proteobacteria dominated both total (from 37 to 60 %) and metabolically active (from 19.7 to 34.6 %) communities, including the Rhizobiales, Rhodobacter, Caulobacterales, and Sphingomonadales orders. Co-inertia analysis revealed a relationship between polycyclic aromatic hydrocarbons, zinc and some polychlorobiphenyls concentrations, and the structure of total and active microbial communities in the oldest and most contaminated sediments (from 1970 to 1975), suggesting that long-term exposure to chemicals shaped the structure of the microbial community.