[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).

National audience

The Athabasca's oil sands exploitation is controversial due to its potential risks to water quality but little is known about the temporal changes in the most bioavailable fraction of metal, the free/labile species. In this study, diffusive gradient in thin films (DGT) and the Windermere Humic Aqueous Model (WHAM VII) equilibrium model were used to examine the temporal changes in free/labile metal (Cu, Ni, Zn, Pb) species in three tributaries of the north-flowing Athabasca River in the Athabasca oil sands region (AOSR). The influence of dissolved organic matter (DOM) composition (i.e. fulvic: humic ratio) on modeled Cu and Ni speciation showed a negligible effect on the labile concentration. The best agreements (92 ± 8%) between DGT-labile and WHAM calculated labile concentrations were found assuming the formation of iron oxyhydroxides (FeO(OH)). The agreement was only 70 ± 7% in the presence of inorganic colloidal aluminum oxyhydroxides (AlO(OH)) and in the absence of any inorganic colloids. Together these results suggest that a change in DOM composition had limited impacts on modeled free metal ion concentrations. Although the concentration of the main metal ligand (i.e. DOM), varied from 9 to 40 ppm, no significant temporal differences in the abundance of WHAM-modeled labile species were found, suggesting mobility and bioavailability of Cu, Ni, Pb and Zn were comparable over the 2003–2012 period.

Engineered Nanoparticles (ENPs) present novel/added challenges to the established effect assessment modus operandi, requiring an update of used methods. ENPs are dimensionally and physically different from conventional chemicals, which imply that the metrics with which we relate effect and the type of effect responses are different from that of the conventional approach. Effects on organisms are often preceded by changes on the sub-organismal level (cell, genes), dedicated tools have vast potential to detect earlier (and link to) effects on higher levels of organization. High-throughput screening (HTS) is rapid, cost-effective and specific. One way forward is to link HTS to population outcomes, targeting a systems toxicology approach. Although the benefits of integrating various levels of information may seem obvious, this is an even more decisive aspect when rapid answers are needed for ENPs. Here we rank the available tools/methods, highlight main study gaps and list priority needs and the way forward.

Transition metals in the fourth period of the periodic table of the elements are widely widespread in aquatic environments. They could often occur at certain concentrations to cause adverse effects on aquatic life and human health. Generally, parametric models are mostly used to construct species sensitivity distributions (SSDs), which result in comparison for water quality criteria (WQC) of elements in the same period or group of the periodic table might be inaccurate and the results could be biased. To address this inadequacy, the non-parametric kernel density estimation (NPKDE) with its optimal bandwidths and testing methods were developed for establishing SSDs. The NPKDE was better fit, more robustness and better predicted than conventional normal and logistic parametric density estimations for constructing SSDs and deriving acute HC5 and WQC for transition metals in the fourth period of the periodic table. The decreasing sequence of HC5 values for the transition metals in the fourth period was Ti > Mn > V > Ni > Zn > Cu > Fe > Co > Cr(VI), which were not proportional to atomic number in the periodic table, and for different metals the relatively sensitive species were also different. The results indicated that except for physical and chemical properties there are other factors affecting toxicity mechanisms of transition metals. The proposed method enriched the methodological foundation for WQC. Meanwhile, it also provided a relatively innovative, accurate approach for the WQC derivation and risk assessment of the same group and period metals in aquatic environments to support protection of aquatic organisms.

Freely dissolved polycyclic aromatic hydrocarbons (PAHs) were monitored in seven inland lakes of Antarctica by a polyethylene (PE)-based passive sampling technique, with the objective of tracking human footprints. The measured concentrations of PAHs were in the range of 14–360 ng L−1 with the highest values concentrated around the Russian Progress II Station, indicating the significance of human activities to the loading of PAHs in Antarctica. The concentrations of PAHs in the inland lakes were in the upper part of the PAHs levels in aquatic environments from remote and background regions across the globe. The composition profiles of PAHs indicated that PAHs in the inland lakes were derived mainly from local oil spills, which was corroborated by a large number of fuel spillage reports from ship and plane crash incidents in Antarctica during recent years. Clearly, local human activities, rather than long-range transport, are the dominant sources of PAH contamination to the inland lakes. Finally, the present study demonstrates the efficacy of PE-based passive samplers for investigating PAHs in the aquatic environment of Antarctica under complex field conditions.

Illicit drugs have been recognized as a group of emerging contaminants. In this work, occurrence of common illicit drugs and their metabolites in Chinese surface waters was examined by collecting samples from 49 lakes and 4 major rivers across the country. Among the drugs examined, methamphetamine and ketamine were detected with highest frequencies and concentration levels, consistent with the fact that these are primary drugs of abuse in China. Detection frequencies and concentrations of other drugs were much lower than in European lakes and rivers reported in the literature. In most Chinese surface waters methamphetamine and ketamine were detected at concentrations of several ng L−1 or less, but in some southern lakes and rivers, these two drugs were detected at much higher concentrations (up to several tens ng L−1). Greater occurrence of methamphetamine and ketamine in southern surface waters was attributed to greater abuse and more clandestine production of the two drugs in southern China.

Reconstructing the history of metal deposition in Singapore lake sediments contributes to understanding the anthropogenic and natural metal deposition in the data-sparse Southeast Asia. To this end, we present a sedimentary record of Pb, Pb isotopes and eleven other metals (Ag, As, Ba, Cd, Co, Cr, Cu, Ni, Tl, U and Zn) from a well-dated sediment core collected near the depocenter of MacRitchie Reservoir in central Singapore. Before the 1900s, the sedimentary Pb concentration was less than 2 mg/kg for both soil and sediment, with a corresponding 206Pb/207Pb of ∼1.20. The Pb concentration increased to 55 mg/kg in the 1990s, and correspondingly the 206Pb/207Pb decreased to less than 1.14. The 206Pb/207Pb in the core top sediment is concordant with the 206Pb/207Pb signal of aerosols in Singapore and other Southeast Asian cities, suggesting that Pb in the reservoir sediment was mainly from atmospheric deposition. Using the Pb concentration in the topmost layer of sediment, the estimated atmospheric Pb flux in Singapore today is ∼1.6 × 10−2 g/m2 yr. The concentrations of eleven other metals preserved in the sediment were also determined. A principal component analysis showed that most of the metals exhibit an increasing trend towards 1990s with a local concentration peak in the mid-20th century.