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Raimonet M.,CNRS Transfers and Interactions in Hydrosystems and Soils | Vilmin L.,CNRS Transfers and Interactions in Hydrosystems and Soils | Vilmin L.,MINES ParisTech | Flipo N.,MINES ParisTech | And 2 more authors.
Water Research | Year: 2015

Maintaining low nitrite concentrations in aquatic systems is a major issue for stakeholders due to nitrite's high toxicity for living species. This study reports on a cost-effective and realistic approach to study nitrite dynamics and improve its modelling in human-impacted river systems. The implementation of different nitrifying biomasses to model riverine communities and waste water treatment plant (WWTP)-related communities enabled us to assess the impact of a major WWTP effluent on in-river nitrification dynamics. The optimal kinetic parameters and biomasses of the different nitrifying communities were determined and validated by coupling laboratory experiments and modelling. This approach was carried out in the Seine River, as an example of a large human-impacted river with high nitrite concentrations. The simulation of nitrite fate was performed at a high spatial and temporal resolution (δt=10min, dx=500m) including water and sediment layers along a 220km stretch of the Seine River for a 6-year period (2007-2012). The model outputs were in good agreement with the peak of nitrite downstream the WWTP as well as its slow decrease towards the estuary. Nitrite persistence between the WWTP and the estuary was mostly explained by similar production and consumption rates of nitrite in both water and sediment layers. The sediment layer constituted a significant source of nitrite, especially during high river discharges (0.1-0.4mgNh-1m-2). This points out how essential it is to represent the benthic layer in river water quality models, since it can constitute a source of nitrite to the water-column. As a consequence of anthropogenic emissions and in-river processes, nitrite fluxes to the estuary were significant and varied from 4.1 to 5.5TNd-1 in low and high water discharge conditions, respectively, over the 2007-2012 period. This study provides a methodology that can be applied to any anthropized river to realistically parametrize autochthonous and WWTP-related nitrifier communities and simulate nitrite dynamics. Based on simulation analysis, it is shown that high spatio-temporal resolution hydro-ecological models are efficient to 1) estimate water quality criteria and 2) forecast the effect of future management strategies. Process-based simulations constitute essential tools to complete our understanding of nutrient cycling, and to decrease monitoring costs in the context of water quality and eutrophication management in river ecosystems. © 2015 Elsevier Ltd. Source

Matar Z.,University Paris Est Creteil | Matar Z.,Lebanese University | Soares Pereira C.,University Paris Est Creteil | Chebbo G.,University Paris Est Creteil | And 8 more authors.
Environmental Science and Pollution Research | Year: 2015

This study focuses on spatiotemporal variations in the type of dissolved organic matter (DOM) and copper binding ability both upstream and downstream of Paris. It also compares the relative influence of both natural DOM upstream of Paris and effluent dissolved organic matter (EfDOM) output from a wastewater treatment plant (WWTP) on trace metal speciation and bioavailability in aquatic systems. In addition to the typical high- and low-affinity binding sites, a third family of very high-affinity binding sites has been highlighted for EfDOM. In receiving waters downstream of Paris during low-flow periods, the percentage of high- and very high-affinity sites originating from EfDOM reaches nearly 60 %. According to the speciation computation, the free copper concentration upstream of Paris exceeds the downstream Paris concentration by a factor of 2 to 4. As regards copper bioavailability, the highest EC50tot values were observed for EfDOM and downstream DOM, with a very low aromaticity and low UV absorbance. This finding suggests that specific ultraviolet absorbance (SUVA) is unlikely to be useful in assessing metal speciation and toxicity in aquatic systems subject to strong urban pressures. These results also highlight that the copper speciation computation for surface water exposed to considerable human pressures should include not only the humic and/or fulvic part of dissolved organic carbon but more hydrophilic fractions as well, originating for example from EfDOM. © 2015, Springer-Verlag Berlin Heidelberg. Source

Bernier J.,Laval University | Rocher V.,Siaap Direction du developpement et de la prospective | Lessard P.,Laval University
Environmental Technology (United Kingdom) | Year: 2016

The headloss prediction capability of a wastewater biofiltration model is evaluated on data from a full-scale tertiary nitrifying biofilter unit located in the Paris conurbation (Achères, France; 6,000,000 population equivalent). The model has been previously calibrated on nutrient conversion and TSS filtration observations. In this paper the mass of extracted biofilm during biofilter backwash and the headloss value at the start of an operation cycle are first calibrated on sludge production estimations and relative pressure measurements over the year 2009. The calibrated model is then used on two one-month periods in 2012 for which hourly headloss measurements were acquired. The observed trends are correctly predicted for 2009 but the model exhibits some heavy daily variation that is not found in measurements. Hourly predictions stay close to observations, although the model error rises slightly when the headloss does not vary much. The global model shows that both nutrient conversion and headloss build-up can be reasonably well predicted at the same time on a full-scale plant. © 2015 Taylor & Francis. Source

Lucas F.S.,University Paris Est Creteil | Therial C.,University Paris Est Creteil | Goncalves A.,Siaap Direction du developpement et de la prospective | Servais P.,Free University of Colombia | And 2 more authors.
Environmental Science and Pollution Research | Year: 2014

The microbiological quality of urban wastewaters presents important environmental, sanitary, and political challenges. However, the variability of untreated wastewater quality is seldom known when it comes to microbial parameters. This study aims to evaluate the variability of microbiological quality in wastewater influents from different wastewater treatment plants connected to combined and partially separate sewer networks in the Parisian area and to evaluate the impact of this variability on the treatment efficiency and on the accuracy of wastewater effluent monitoring. The densities of fecal indicator bacteria (FIB), Escherichia coli and intestinal enterococci, and their partitioning on settleable particles were analyzed at the inlet of two wastewater treatment plants during dry weather (130 composite samples and 7 days sampled every 2 hours) and storm events (39 composite samples, and 7 rain courses) from 2008 to 2012. The results showed that fecal indicator densities vary according to the network characteristics and according to the meteorological conditions. During storm events, a significant dilution of E. coli and enterococci was observed, as well as a decrease in the settleable fraction of E. coli during the maximal impact of the storm. However, storm events did not significantly impact the regular FIB monitoring. FIB removals by primary and secondary treatment were significantly correlated with FIB densities in influent wastewater; however, meteorological conditions also influenced the removal of FIB. © 2013 Springer-Verlag Berlin Heidelberg. Source

Berge A.,Laboratoire Central Of La Prefecture Of Police | Gasperi J.,University Paris Est Creteil | Rocher V.,Siaap Direction du developpement et de la prospective | Gras L.,SEVESC | And 2 more authors.
Techniques - Sciences - Methodes | Year: 2013

Wastewaters carry a large number of pollutants including substances called "emerging" as phthalates and alkylphenols. The risk associated with these compounds is the most widely recognized undoubtedly in their estrogenic activity, that is to say, their ability to mimic natural estrogen hormones. If the data collected in the environment has started to be substantial, especially for alkylphenols and to a lesser extent for phthalates, information about the different sources of contamination (industrial waste, domestic waste, discharges from wastewater treatment plants, etc.) is too limited to define priority actions to reduce these compounds. Among the sources of contamination, industrial discharges are often considered as a vector of urban pollution. A total of 101 samples distributed over 33 sites and classified in 11 sectors were collected. Thus discharges of industrial laundries, industries, surface treatment, pharmaceutical and cosmetic industries, etc. were sampled. The samples were analyzed for the following compounds: diethyl phthalate, di-n-butyl phthalate, butyl benzyl phth-alate, di-(2-ethylhexyl) phthalate, nonylphenol and 4-tert-octylphenol. Phthalates and nonylphenol were measured at high concentrations (up to 1.200 ug/L). Finally, after pollutant load estimation, it appears that there is little contribution of industrial wastewater on total flux entering the wastewater treatment plants of Paris and its conurbation (less than 3% for all compounds). Source

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