A simple and efficient feedback control strategy for wastewater denitrification

Due to severe mathematical modeling and calibration difficulties open-loop feedforward control is mainly employed today for wastewater denitrification, which is a key ecological issue. In order to improve the resulting poor performances a new model-free control setting and its corresponding "intelligent" controller are introduced. The pitfall of regulating two output variables via a single input variable is overcome by introducing also an open-loop knowledge-based control deduced from the plant behavior. Several convincing computer simulations are presented and discussed.Comment: IFAC 2017 World Congress, Toulouse, Franc

An environmentally friendly surrogate method for measuring the soluble chemical oxygen demand in wastewater: use of three-dimensional excitation and emission matrix fluorescence spectroscopy in wastewater treatment monitoring

International audienceGaining rapid knowledge of dissolved organic matter (DOM) proves to be decisive for wastewater treatment plant operators in efforts to achieve good treatment efficiency in light of current legislation. DOM can be monitored by application of fluorescence spectroscopy both online and in real time in order to derive an assessment of DOM oxidation potential. This work presents an eco-friendly alternative method for measuring the soluble chemical oxygen demand (COD) in raw sewage by means of three-dimensional fluorescence spectroscopy. A peak-picking approach has been developed based on a previous parallel factor analysis (PARAFAC) model dedicated to Paris raw sewage. Fluorescence spectroscopy parameters were used to obtain a good prediction model of soluble COD (r(2) = 0.799; p < 0.0001; n = 80) for raw sewage. The approach employed in this study serves as a guideline for purposes of implementing online wastewater monitoring and conducting environmentally friendly soluble COD measurements in the laboratory

Inhibition de la digestion anaérobie : cas de l'acide propionique

International audienceEn réponse à la loi relative à la transition énergétique pour la croissance verte (17/08/2015),imposant une valorisation des résidus d’épuration des eaux usées (boues urbaines), c’est la digestion anaérobie qui est souvent choisie. Cette transformation microbienne de matières organiques en absence d’oxygène, conduit principalement à l’obtention de méthane (CH4), dioxyde de carbone (CO2) et digestats. De nombreux micro-organismes parmi les bactéries et les archées la catalysent et elle peut être mise en œuvre relativement aisément à échelle industrielle.Du fait de la composition intrinsèque des boues urbaines, des inhibitions peuvent êtreobservées, et ce, simultanément à une accumulation de l’acide propionique, lui-même sousproduit de la digestion anaérobie. L’objectif de ce travail était de quantifier l’effet de l’acide propionique sur la digestion anaérobie.Des incubations en microcosmes de digestion anaérobie ont été menées, avec ajout d’acide propionique à concentrations croissantes (de 31 à 6000 mg/L) au point de temps initial. Lesvolumes de CH4 produit ainsi que la composition des communautés microbiennes par metabarcoding d’ARNr 16S ont été déterminés. A partir d’une concentration de 1000 mg/L, la production de méthane était retardée mais augmentée par rapport au contrôle. L’ajout de la concentration la plus élevée s’est révélétoxique et a stoppé la production de CH4. De plus, un effet sur la composition des communautés microbiennes a pu être observé dans le cas d’une inhibition légère. Des taxons bactériens étaientfavorisés par les concentrations importantes d’acide propionique. C’est notamment le cas de bactéries acétogènes productrices obligatoires d’hydrogène, OHPA. En revanche, d’autrestaxons archées étaient défavorisés, tel que Methanosfastidiosum. Ces résultats encouragent à poursuivre les investigations pour définir des bio-indicateurs d’inhibition de la digestion anaérobie

Inhibition de la digestion anaérobie : cas de l'acide propionique

International audienceEn réponse à la loi relative à la transition énergétique pour la croissance verte (17/08/2015),imposant une valorisation des résidus d’épuration des eaux usées (boues urbaines), c’est la digestion anaérobie qui est souvent choisie. Cette transformation microbienne de matières organiques en absence d’oxygène, conduit principalement à l’obtention de méthane (CH4), dioxyde de carbone (CO2) et digestats. De nombreux micro-organismes parmi les bactéries et les archées la catalysent et elle peut être mise en œuvre relativement aisément à échelle industrielle.Du fait de la composition intrinsèque des boues urbaines, des inhibitions peuvent êtreobservées, et ce, simultanément à une accumulation de l’acide propionique, lui-même sousproduit de la digestion anaérobie. L’objectif de ce travail était de quantifier l’effet de l’acide propionique sur la digestion anaérobie.Des incubations en microcosmes de digestion anaérobie ont été menées, avec ajout d’acide propionique à concentrations croissantes (de 31 à 6000 mg/L) au point de temps initial. Lesvolumes de CH4 produit ainsi que la composition des communautés microbiennes par metabarcoding d’ARNr 16S ont été déterminés. A partir d’une concentration de 1000 mg/L, la production de méthane était retardée mais augmentée par rapport au contrôle. L’ajout de la concentration la plus élevée s’est révélétoxique et a stoppé la production de CH4. De plus, un effet sur la composition des communautés microbiennes a pu être observé dans le cas d’une inhibition légère. Des taxons bactériens étaientfavorisés par les concentrations importantes d’acide propionique. C’est notamment le cas de bactéries acétogènes productrices obligatoires d’hydrogène, OHPA. En revanche, d’autrestaxons archées étaient défavorisés, tel que Methanosfastidiosum. Ces résultats encouragent à poursuivre les investigations pour définir des bio-indicateurs d’inhibition de la digestion anaérobie

Temperature, turbidity, and the inner filter effect correction methodology for analyzing fluorescent dissolved organic matter in urban sewage

International audienceDissolved organic matter (DOM) will be increasingly monitored by means of in situ fluorescence spectroscopy devices in order to supervise wastewater treatment plant efficiency, due to their ease of implementation and high-frequency measurement capacity. However, fluorescence spectroscopy measurements are reported to be sensitive to the sample matrix effects of temperature, the inner filter effect (IFE), and turbidity. Matrix effect estimation tests and signal correction have been developed for DOM (tyrosine-like, tryptophan-like, and humic substances-like fluorescent compounds) fluorescence measurements in unfiltered urban sewage samples. All such tests are conducted in temperature, absorbance, and turbidity ranges representative of urban sewage. For all fluorophores studied, an average of 1% fluorescence intensity decrease per degree (degrees C) of temperature increase could be observed. Protein-like fluorescent compound signals were found to be significantly affected by turbidity (0 to 210 NTU) and IFE (absorbance 254 nm > 0.200). Only temperature needs to be corrected for humic substances-like fluorescent compounds since other effects were not observed over the studied ranges of absorbance and turbidity. The fluorescence intensity correction method was applied first to each matrix effect separately and then combined by using a sequential mathematical correction methodology. An efficient methodology for determining the matrix effect correction equations for DOM fluorescence analysis into unfiltered urban sewage samples has been highlighted and could be used for in situ fluorescence measurement devices

New outlook in BOD measurement and bioprocess management: the Enverdi® kit

Knowing the quantity and biodegradability of wastewater organic matter (OM) is really essential for the optimization of modern biological treatment processes, particularly when considering the highly challenging context for sewage treatment plant operators. However, the current standard methods for wastewater characterisation, as for 5-days biochemical oxygen demand (BOD5) measurement, OM fractionation analysis and bacterial inhibitor detection, show very poor suitability for routine operational use. In this paper, the efficiency of the commercial Enverdi® method (fluorimetric respirometry) for such analytical applications is investigated, especially for the BOD5-equivalent measurement in municipal wastewater samples. The result of numerous experiments showed that the BOD5 values obtained from the alternative Enverdi® method and the main standard methods are statistically equivalent. The analytical performances of the Enverdi® method was found similar to the standard BOD5 method specifications and perfectly matched the French regulatory requirements in force. The regulatory acceptance of this method is presently under consideration. Such an outlook would be really valuable for end-users given the main advantages of this analytical solution which is time- and space-saving, user-friendly and financially competitive. In addition to BOD5 measurement, the fluorimetric respirometry displayed very promising abilities for the OM fractionation and the detection of bacterial inhibitors in wastewater

Horse Manure and Lignocellulosic Biomass Characterization as Methane Production Substrates

This paper aimed to study the value of horse manure through anaerobic digestion. The study involved characterization of different components of horse waste and the evaluation of their biochemical composition, physicochemical characterization and the influence of the composition of horse waste on biochemical methane potential. More specifically, two bedding mixtures were studied: the first one was composed of wheat straw (WS), wood chips (WC) and horse manure (HM) with a volumetric composition of 85%, 14% and 1%, respectively; and the second one was a mixture of WS and HM with a volumetric composition of 99% and 1%, respectively. The analysis was carried out on the two bedding mixtures and on each substrate separately with 406 samples from May 2017 to October 2019. Biochemical methane potential tests conducted on these samples showed that the composition and structure of the substrate influenced the BMP. WS had the highest mono-digestion methane production with 176.1 NmL·gVS−1. The second bedding mixture (99% WS, 1% HM) showed a production of 189.4 NmL·gVS−1 compared to 127 NmL·gVS−1 by bedding mixture 1 (85% WS, 14% WC, 1% HM). The difference was due to a dilution effect on methane production caused by the presence of WC rich in lignin

Pilot-Scale Anaerobic Co-Digestion of Wastewater Sludge with Lignocellulosic Waste: A Study of Performance and Limits

The effects of co-digesting sewage sludge (SS) and horse waste (HW), the composition of HW, and the ratio of HW:SS were studied using two semi-continuous digesters of 9.5 L of working volume. These digesters were operated in parallel with the mono-digestion of SS in digester 1 (D1) and the co-digestion of SS and HW in digester 2 (D2). In digester 2, there were two phases of digestion (durations of 40 and 43 weeks, respectively). The composition of HW in the first phase was 85% wheat straw (WS), 14% wood chips (WC), and 1% horse manure (HM), with 99% wheat straw (WS) and 1% horse manure (HM) in the second phase. Variable ratios of HW:SS were studied in the digesters. The co-digestion of sewage sludge (SS) and horse waste (HW) produced more biogas than the mono-digestion of SS alone, with a maximum of 15.8 L·d−1, compared to 9 L·d−1 at the end of the experiment. When comparing the results obtained in both phases, the production of methane in phase 2 was 18 NmL·gVS−1 higher than in phase 1. This slight increase in methane yield could be linked to the absence of wood chips (WC), which is considered to have a diluting effect on methane production. Therefore, this study shows that an organic loading rate (OLR) of 4.8 kgVS·m−3·d−1, a ratio of HW:SS of 3, and a composition of HW (99% WS, 1% HM) should be respected in the actual experimental conditions for a well-functioning anaerobic digestion

Bactéries indicatrices fécales dans les effluents urbains- focus sur les rejets d’au traitée et déversement de temps de pluie

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Bioaccumulation of per- and polyfluoroalkyl substance in fish from an urban river: Occurrence, patterns and investigation of potential ecological drivers

International audiencePer- and polyfluoroalkyl substances (PFAS) are ubiquitous in aquatic environments and a recent shift toward emerging PFAS is calling for new data on their occurrence and fate. In particular, understanding the determinants of their bioaccumulation is fundamental for risk assessment purposes. However, very few studies have addressed the combined influence of potential ecological drivers of PFAS bioaccumulation in fish such as age, sex or trophic ecology. Thus, this work aimed to fill these knowledge gaps by performing a field study in the Seine River basin (France). Composite sediment and fish (European chub, Squalius Cephalus) samples were collected from four sites along a longitudinal transect to investigate the occurrence of 36 PFAS. Sediment molecular patterns were dominated by fluorotelomer sulfonamidoalkyl betaines (i.e. 6:2 and 8:2 FTAB, 46% of ∑PFAS on average), highlighting the non-negligible contribution of PFAS of emerging concern. C9–C14 perfluoroalkyl carboxylic acids, perfluorooctane sulfonic acid (PFOS), perfluorooctane sulfonamide (FOSA) and 10:2 fluorotelomer sulfonate (10:2 FTSA) were detected in all fish samples. Conversely, 8:2 FTAB was detected in a few fish from the furthest downstream station only, suggesting the low bioaccessibility or the biotransformation of FTABs. ∑PFAS in fish was in the range 0.22–3.8 ng g−1 wet weight (ww) and 11–140 ng g−1 ww for muscle and liver, respectively. Fish collected upstream of Paris were significantly less contaminated than those collected downstream, pointing to urban and industrial inputs. The influence of trophic ecology and biometry on the interindividual variability of PFAS burden in fish was examined through analyses of covariance (ANCOVAs), with sampling site considered as a categorical variable. While the latter was highly significant, diet was also influential; carbon sources and trophic level (i.e. estimated using C and N stable isotope ratios, respectively) equally explained the variability of PFAS levels in fish