[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | French vertical flow constructed wetlands (VFCW) treating raw wastewater have been developed successfully over the last 30 years. The highly aerobic treatment observed on these two-stages of filter allows an almost complete nitrification and accepts high hydraulic loads with seasonal variations. Nevertheless, the French two-stage VFCWs need a total filtration area of 2-2.5 m2/PE and the use of sand on the second stage. Furthermore, it is not always economically competitive and their high removal efficiencies are not systematically needed. In this context, implementing a one-stage system allowing reaching standard requirements is of interest. One of the solutions developed in France is to use a vertical flow system with an unsaturated layer at the top and a saturated layer at the bottom. It is proposed by Epur Nature as Biho-Filter®. The aim of this study was to assess the potential of this new configuration, in order to optimize the design and operating conditions (bottom saturation layer depth, recirculation rate, etc.). The study consisted in hydraulic and removal assessment of 3 different Biho-Filter® plants. It presents the results regarding outflow concentrations that can be achieved (15 mg.L -1 in TSS, 70 mg.L -1 in COD, 15 mg.L -1 in BOD5, 25 mg.L -1 in TKN and 70% in TN removal) as well as the impact of the operation conditions on treatment performances and the limits of the systems.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU | International audience | Pesticide pollution is one of the main current threats on water quality. This paper presents the potential and functioning principles of a "Wet" forest buffer zone for reducing concentrations and loads of glyphosate, isoproturon, metazachlor, azoxystrobin, epoxiconazole, and cyproconazole. A tracer injection experiment was conducted in the field in a forest buffer zone at Bray (France). A fine time-scale sampling enabled to illustrate that interactions between pesticides and forest buffer substrates (soil and organic-rich litter layer), had a retarding effect on molecule transfer. Low concentrations were observed for all pesticides at the forest buffer outlet thus demonstrating the efficiency of "Wet" forest buffer zone for pesticide dissipation. Pesticide masses injected in the forest buffer inlet directly determined concentration peaks observed at the outlet. Rapid and partially reversible adsorption was likely the major process affecting pesticide transfer for short retention times (a few hours to a few days). Remobilization of metazachlor, isoproturon, desmethylisoproturon, and AMPA was observed when non-contaminated water flows passed through the forest buffer. Our data suggest that pesticide sorption properties alone could not explain the complex reaction mechanisms that affected pesticide transfer in the forest buffer. Nevertheless, the thick layer of organic matter litter on the top of the forest soil was a key parameter, which enhanced partially reversible sorption of pesticide, thus retarded their transfer, decreased concentration peaks, and likely increased degradation of the pesticides. Consequently, to limit pesticide pollution transported by surface water, the use of already existing forest areas as buffer zones should be equally considered as the most commonly implemented grass buffer strips.

International audience | Today, urban runoff is considered as an important source of environmental pollution. Roofing materials, in particular, the metallic ones, are considered as a major source of urban runoff metal contaminations. In the context of theEuropean Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required on thecity scale, and therefore the development of assessment tools is needed. However, on this scale, there is an important diversity of roofing materials. In addition, given the size of a city, a complete census of the materials of the different roofing elements represents a difficult task. Information relating roofing materials and their surfaces on an urban district do not currently exist in urban databases. The objective of this paper is to develop a new method of evaluating annual contaminant flow emissions from the different roofing material elements (e.g., gutter, rooftop) on the city scale. This method is based on using and adapting existing urban databases combined with a statistical approach. Different rules for identifying the materials of the different roofing elements on the city scale have been defined. The methodology is explained through its application to the evaluation of zinc emissions on the scale of the city of Créteil.

7th International PCB Workshop - Chemical mixtures in a complex world, Arcachon, FRANCE, MAY 27-31, 2012 | International audience | Human activities are emitting persistent organic pollutants (POPs) to the environment. These compounds have raised concerns about the risk of transfer through the food chain via animal products. They are characterized by a strong persistence in environmental matrices and a lipophilicity which may lead to their accumulation in fat tissues. In EU Regulations (no. 1881/2006, 1259/2011), maximum acceptable levels for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), and dioxin-like or nondioxin-like polychlorinated biphenyls (PCBs) in food of animal origin have been set. Transfer rates from contaminated fodder to milk have been established: for PCBs, the rate of transfer varies from 5 to 90 % and for PCDD/Fs from 1 to 40 %. The differential transfer of the compounds towards milk is related to the hydrophobicity of the pollutants and to their metabolic susceptibility. According to numerous authors, soil is the major reservoir for POPs, and its involuntary ingestion by farm animals reared outdoors may be the main cause of animal product contamination (meat, milk, or eggs). Recent studies seem to indicate that soil is a real risk matrix in terms of transfer of pollutants to the food chain. A POP crisis management is extremely difficult, since it impacts many farmers located in the contaminated area. The question arising is to know if livestock contaminated by POPs may be decontaminated and further used for their initial purpose. Recent data demonstrate that the decontamination process appear feasible and depends on initial level of contamination or the physiological status of the animals.

In the Mezquital valley, untreated wastewater (45 m(3) s(-1)) from Mexico City is used for the irrigation of around 900 km(2) of agricultural soil. High concentrations of metals including methylmercury (3.8+/-2.5 ng l(-1)) and lead (0.16+/-0.05 mg l(-1)) were measured in anoxic wastewater canals. Downstream, dissolved, and particulate polymetallic (Hg, Pb, Cr.) concentrations decreased by factors 10 to 1,000 in the Tula River (which received a mix of fresh and wastewater) due to the dilution and oxidation of surface water, and to the decrease of contaminants concentration in wastewater downstream irrigated soils. However, dissolved and particulate methylmercury concentrations (0.06 to 0.33 ng l(-1) and 1.6 to 4.5 g kg(-1), respectively) remained elevated in comparison to other natural hydrosystems. The monitoring of an irrigation event and the distribution of metals in a soil profile irrigated for more than 80 years showed that metals were retained in the draining tilled layer. The oxic conditions and slightly acidic pH (similar to 6.5) in this layer were found favorable for metal adsorption and co-precipitation with redox-sensitive elements (Fe, Mn) and suggestively for mercury demethylation. In the downstream Tula River and groundwater, almost all metallic concentrations remained below guideline thresholds. Only, dissolved As and Pb concentrations remained two to five times above thresholds for drinking water, highlighting a potential health risk for approximately 500,000 people who use groundwater as water supply.

Intra-specific variability of root biomass production (RP) of six rooted macrophytes, i.e. Juncus effusus, Phragmites australis, Schoenoplectus lacustris, Typha latifolia, Phalaris arundinacea, and Iris pseudacorus grown from clones, in response to Cu exposure was investigated. Root biomass production varied widely for all these macrophytes in control conditions (0.08 μM) according to the sampling site. Root biomass production of T. latifolia and I. pseudacorus in the 2.5–25 μM Cu range depended on the sampling location but not on the Cu dose in the growth medium. For P. australis, J. effusus, S. lacustris, and P. arundinacea, an intra-specific variability of RP depending on both the sampling location and the Cu-dose was evidenced. This intra-specific variability of RP depending on the sampling location and of Cu-tolerance for these last four species suggests that Cu constitutive tolerance for all rooted macrophytes is not a species-wide trait but it exhibits variability for some species.

International audience

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | Buffer zones between wastewater treatment plants and receiving water bodies have recently gained interest in France. These Planted Discharge Areas (PDAs) receive treated wastewater, and may have various designs aiming to mimic “natural” kinds of wetlands. Research is needed to assess the treatment efficiency of such systems: a comprehensive study is carried out to understand the fate of water, conventional pollutants (suspended solids, organic carbon, ammonium, and phosphates), micro pollutants that are refractory to up-stream biological treatment, and pathogens. Special attention must be paid to understand the fate of the infiltrated treated wastewater in the field where PDAs are built, in order to ensure their long-term operation (system scale) and to protect the underground water bodies (site scale). To address these issues, the authors propose a comprehensive strategy combining successive stages using either geological or hydrological methods. These techniques provide the following prominent information for a proper design of PDAs: (1) the number and the location of the different soil layers; (2) the infiltration capacity of each layers; (3) the water table (height of the groundwater). Furthermore, the seasonal variation (if any) of the land characteristics are also determined. The proposed strategy successfully determined the fate of the infiltrated treated wastewater on the land considered before the implementation of the semi-industrial scale PDAs in Bordeaux. Besides, methods used for long-term PDA efficiency assessment are presented.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA [TR2_IRSTEA]TED | Five estrogenic hormones (unconjugated+conjugated fractions) and 10 beta blockers were analyzed in three wastewater treatment plant (WWTP) effluents and receiving river waters in the area of Lyon, France. In the different samples, only two estrogens were quantified: estrone and estriol. Some beta blockers, such as atenolol, acebutolol, and sotalol, were almost always quantified, but others, e.g., betaxolol, nadolol, and oxprenolol were rarely quantified. Concentrations measured in river waters were in the nanogram per liter range for estrogens and between 0.3 and 210 ng/L for beta blockers depending on the substance and the distance from theWWTP outfall. The impact of the WWTP on the receiving rivers was studied and showed a clear increase in concentrations near the WWTP outfall. For estrogens, the persistence in surface waters was not evaluated given the low concentrations levels (around 1 ng/L). For beta blockers, concentrations measured downstream of the WWTP outfall were up to 16 times higher than those measured upstream. Also, the persistence of metoprolol, nadolol, and propranolol was noted even 2 km downstream of the WWTP outfall. The comparison of beta blocker fingerprints in the samples collected in effluent and in the river also showed the impact of WWTP outfall on surface waters. Finally, a tentative environmental risk evaluation was performed on 15 sites by calculating the ratio of receiving water concentrations to predicted non-effect concentrations (PNEC). For estrogens, a total PNEC of 5 ng/L was considered and these substances were not linked to any potential environmental risk (only one site showed an environmental risk ratio above 1). Unfortunately, few PNECs are available and risk evaluation was only possible for 4 of the 10 beta blockers studied: acebutolol, atenolol, metoprolol, and propranolol. Only propranolol presented a ratio near or above 1, showing a possible environmental risk for 4 receiving waters out of 15.

Effets des pollutions atmosphériques sur les cultures et la forêt. Journée scientifique sur la pollution atmosphérique et les impacts sanitaires