[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.).

[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 | 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.

International audience | Barrage fishponds may represent a significant surface water area in some French regions. Knowledge on their effect on water resources is therefore necessary for the development of appropriate water quality management plans at the regional scale. Although there is much information on the nutrient removal capacity of these water bodies, little attention has been paid to other agricultural contaminants such as pesticides. The present paper reports the results of a 1-year field monitoring of pesticide concentrations and water flows measured upstream and downstream from a fishpond in North East France to evaluate its capacity in reducing pesticide loads. Among the 42 active substances that had been applied on the fishpond's catchment, seven pesticides (five herbicides, two fungicides) were studied. The highest concentration in the inflow to the pond was 26.5 mu g/L (MCPA), while the highest concentration in pond outflow was 0.54 mu g/L (prosulfocarb). Removal rates of dissolved pesticides in the fishpond ranged from 0-8 % (prosulfocarb) to 100 % (clopyralid). Although not primarily designed for the treatment of diffuse sources of pesticides, the studied fishpond had the potential to do so.

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

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | CWs for combined sewer overflow treatment (CSO CWs) are vertical flow filters with detention basin and fixed outflow rate. They receive stochastic loadsinduced by urban runoff and protect natural waters against pollutants and streambed erosion. Thefull-scale site at Marcy l‘Etoile was monitored to gain data about hydrology and to quantify NH4-N adsorption capacities and nitrification rate. The throttled outlet ensuresa uniformflow in the porous media, butonly aftersaturation. Until then,the percolation is focused to the inletzone. As only a partof the filteris water-contacted and detention times are shorter than normal, removal performances are lower. The phenomenon is referred to as shortcutting, a temporary state at commencing load, which might last at low inflow rates. Eighteen TDR probes weredug in the longitudinal section of the filter to follow changes in the water content. This enabled to createan animation of the expansion of saturated area until complete saturation. Furthermore, tracer tests were carried out to signify shortcutting at different stages in the filter (Fig. 1).The filter was fed at the inlet point at a fixed and lowrate until saturation and three fluorescein pulses were dosed withidenticaldelay.The basin was flooded after to follow tracer passage and washout. Results were used to parameterizethemodel-based design-support tool Orage [1]and to suggest an improvementof the outflow limitationstructureto minimize shortcutting.

[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 | CWs for combined sewer overflow treatment (CSO CWs) are vertical flow filters with detention basin and fixedoutflow rate. They receive stochastic loadsinduced by urban runoff and protect natural waters against pollutants and streambed erosion.However, due to the stochastic nature of flows, concentrations and periodicity, optimizing CSO CW design requires a dynamic approach.Computational tools are available but process-based models are difficult to handle [1].Moreover, the absence of user interface in design-oriented tools (e.g. RSF_Sim [2]) demands manual data handling and simulations of multiple designs. Therefore, a new tool called Orage was developed. Orage relies on a core model similar to RSF_Sim.Long-term hydraulics, COD and NH4-N were simulated with good accuracy. Filter material selection and scaling is based on inflow data series and a low number of inputs. The iterative shell calls for simulations repeatedly to (1) optimize hydraulics; (2) select the simplest material which isnecessary to satisfy emission requirements on NH4-N and (3) determine the minimalfilter area at which legislative thresholds can be met. A design is optimized if the maximum of moving average on simulated effluent concentrations (Peak_MA_cc) is at the legislative threshold (NH4N) or below (COD). Fig. 1 shows an example of the iteration process.

[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.

International audience | Pesticides have long been used as the main solution to limit agricultural pests, but their widespread use resulted in chronic or diffuse environmental pollutions, development of insect resistances, and biodiversity reduction. The effects of low residual doses of these chemical products on organisms that affect both targeted species (crop pests) but also beneficial insects became a major concern, particularly because low doses of pesticides can induce unexpected positive-also called hormetic-effects on insects, leading to surges in pest population growth at greater rate than what would have been observed without pesticide application. The present study aimed to examine the effects of sublethal doses of deltamethrin, one of the most used synthetic pyrethroids, known to present a residual activity and persistence in the environment, on the peripheral olfactory system and sexual behavior of a major pest insect, the cotton leafworm Spodoptera littoralis. We highlighted here a hormetic effect of sublethal dose of deltamethrin on the male responses to sex pheromone, without any modification of their response to host-plant odorants. We also identified several antennal actors potentially involved in this hormetic effect and in the antennal detoxification or antennal stress response of/to deltamethrin exposure