HAL (Le Centre pour la Communication Scientifique Directe), Nov 1, 2008
Sludge drying reed beds have been used for dewatering and mineralization of sludge since the begi... more Sludge drying reed beds have been used for dewatering and mineralization of sludge since the beginning of the 90's, but their insufficient performances in terms of Dry Matter [DM] content and mineralization of the sludge have made necessary new studies. Therefore, 8 pilots of 2m² each and a full-scale plant (13 000 p.e , 8 beds of 470m² in operation for 4 years) have been monitored to examine the influence of the sludge loading rate, the sludge quality and the loading frequency on the dewatering and mineralization efficiencies. Two filtration layers (vegetal compost or sand) and two loading rhythms were tested on pilots which were fed at a loading rate of 25 kgDM.m-2 .yr-1 during the first year of operation (commissioning period). Hydraulic behaviour (infiltration rate, outflow), O 2 and CO 2 relative concentrations in the filtration media, redox potential, pollutants removal and dry matter content were assessed during all the study. The rheological quality of the extracted sludge from full scale beds were assessed and showed that it mechanical behaviour exceed those of sludge of comparable dry matter content, making its spreading easier Therefore, these sludge could easily claim the status of solid and stabilized sludge according to the French regulation. Design and management recommendations (number of beds, loading rates, feeding/rest period) gained from the experiments results are suggested.
Traitement des eaux usées domestiques par marais artificiels : état de l'art et performances des ... more Traitement des eaux usées domestiques par marais artificiels : état de l'art et performances des filtres plantés de roseaux en France a. Cemagref, UR Qualité des eaux et préventions des pollutions, 3 bis quai Chauveau, CP 220, 69336 Lyon Cedex 09 b. Cemagref, chargée de mission « Épuration des eaux usées », mission appui technique (CGGREF),
The removal of chlorinated benzenes (CBs) from the compartments and from polluted industrial site... more The removal of chlorinated benzenes (CBs) from the compartments and from polluted industrial sites is of great public interest for the decontamination of polluted water and for the protection of the environment. Biological degradation could be considered as a feasible process to eliminate these compounds from the environment as soil or groundwater. A research program in progress since the year
Effets du pcp apres une contamination ponctuelle sur le compartiment vegetal d'ecosystemes aq... more Effets du pcp apres une contamination ponctuelle sur le compartiment vegetal d'ecosystemes aquatiques, en se situant preferentiellement au niveau des productions d'energie et plus particulierement de la photosynthese. En parallele, on suit son devenir dans le miliau aquatique considere, et on montre l'importance de la photodegradation dans les processus de disparition du pcp des ecosystemes aquatiques de type lenitiques
Aquatic Ecosystem Health & Management, Oct 1, 2000
Aquatic microcosm tests are widely used to assess the toxic effects of chemical contaminants on h... more Aquatic microcosm tests are widely used to assess the toxic effects of chemical contaminants on higher pelagic and benthic organisms, but rarely take into account bacteria and other microorganisms. In this study, the bacterial compartment of freshwater/formulated sediment laboratory microcosms was monitored in 4-week tests. In a first experiment, the influence of various organic matter compositions (cellulose+TetraMin®, cellulose+spirulin+meat extract, peat moss+TetraMin®) on bacterial communities was studied. In a second experiment, the effect of fluoranthene on bacterial communities was estimated. The following bacterial parameters were measured: total bacteria counts (epifluorescence microscopy) and enzymatic activities (INT-reductase and β-glucosidase). Compared to natural sediments, the artificial sediment was a satisfactory support for bacterial development. The organic composition of the formulated sediments had no apparent influence on bacterial populations. This result could be due to the high variability of parameters, such as the using 2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazolium chloride-reductase activity, and to the C/N ratio similarity between the tested organic matters. The fluoranthene-contaminated sediment had no apparent effect on bacterial populations. The absence of toxicity could be due in part to the uncontaminated surficial sand layer of the sediment which might have protected pelagic organisms by limiting the rate of suspended contaminated particles and creating an uncontaminated refuge for benthic organisms.
Removal of three polycyclic aromatic hydrocarbons or PAHs (fluoranthene, pyrene and benzo(k)fluor... more Removal of three polycyclic aromatic hydrocarbons or PAHs (fluoranthene, pyrene and benzo(k)fluoranthene) from two types of PAH-contaminated effluents was investigated using four laboratory columns filled with two different organic media: a green compost and a layer coming from the first stage of vertical flow constructed wetlands. Synthetic runoff polluted by polycyclic aromatic hydrocarbons were fed through the columns during a period of two months. After a period of hydrodynamic stabilisation, the results showed a great adsorption of PAHs (>95%) on the solid media due to their large adsorption capacities. Leaching of these compounds by water was monitored. The concentrations of PAHs in leaching samples indicated that PAHs were strongly adsorbed on organic substrates and that lixiviation was limited. Fluoranthene metabolites were also investigated. Accumulation of metabolites was transitory and located in the first few cm of the media, as was observed for PAH concentrations. A toxicity test of leachates based on the inhibition of the bioluminescence of luminescent bacteria Vibrio fischeri indicated a low inhibition which can be enhanced by metal traces.
Removal of pyrene, a representative PAH, was studied using laboratory tests in two different type... more Removal of pyrene, a representative PAH, was studied using laboratory tests in two different types of solid media: an organic matter collected on the surface of a vertical flow constructed wetland (VFCW) and a formulated clay silicate sand (inorganic matter). The aim of this study was to evaluate the capacity of pyrene biodegradation in these media in order to use them for treating run-off water. The sorption process, the kinetics of pyrene biodegradation and the influence of selected bacteria were also investigated. The sorption process was evaluated by adsorption isotherms and desorption kinetics using a batch equilibration method. The adsorption coefficient values of 28.8 and 2.1 for the organic and the inorganic matter respectively, confirmed the relationship of adsorption with organic carbon content. A small proportion of the sorbed pyrene was available for desorption (8% and 15% for the organic and the inorganic matter, respectively), indicating that sorption was partially irreversible, with the presence of hysteresis. For the formulated clay silicate sand inoculated with a specific bacteria (Mycobacterium sp.6PY1), selected for its ability to degrade PAHs, pyrene removal was complete in 32 days. With the organic matter, these values ranged from 40% to 95% for the different experiments, following a lag time of 3 weeks before observation of a significant degradation. Indigenous bacterial species in the organic medium had the metabolic capacity to degrade pyrene, and microbial populations pre-exposed to the PAH degraded pyrene faster than similar unexposed populations. Three metabolites of pyrene degradation by Mycobacterium were found. They accumulated in both organic and inorganic matter, indicating that the enzymes catalyzing them have slow kinetics.
The aim of this study is to assess the sustainability of two wastewater treatment systems by ener... more The aim of this study is to assess the sustainability of two wastewater treatment systems by energy and emergy analyses. The first system is a Sequencing Batch Reactor (SBR) which is a concrete and electricity dependent intensive process. The second is a constructed wetland, usually considered as an extensive process. The two studied facilities have similar treatment capacity and removal efficiencies. This study sheds new light on the comparison of wastewater treatment plants. We defined a new unit, the "Functional Efficiency Index" (or FEI) to describe the energetic efficiency of the facilities, expressed in kJ per year and per kg of removed COD. The energy analysis showed that, after its construction, the constructed wetland system uses only renewable energy, in marked contrast to the SBR, totally dependent on electricity which is considered here as a non renewable. The emergy analysis showed no significant differences between the two processes, but energy and emergy indices are in favour of the constructed wetland process and thus confirm its sustainability.
French legislation requires, the control of private on-site sanitation systems by local authoriti... more French legislation requires, the control of private on-site sanitation systems by local authorities. This will result in a large increase of the quantity of sludge from septic tanks to be treated. Nevertheless, large wastewater treatment plants are not systematically able to treat this sludge because they may have reached their nominal load or they are not so numerous in rural zone to avoid too long transportation. The study concerns both, the feasibility of sludge reed beds devoted to the treatment of septage and the assessment of a simultaneous treatment with aerated sludge. The experiments have been carried out on eight pilot-scale drying reed beds (2m²) planted with Phragmites australis. Two filtration layers of either vegetal compost or sand were tested. The study is focused on the commissioning period (first vegetative year) with a loading rate of 30 kgSS.m-2 .yr-1. According to these operational conditions, dewatering efficiencies reached approx. 30% DM during summer but less than 20%DM in winter for each filtration layer and sludge. High removal efficiencies, with an average of 96%, 92% and 89% for SS, COD and TKN respectively, were achieved with septage whereas they were lower for the mixture of aerated sludge and septage. The dewaterability of septage and its filtration behaviour were assessed by several parameters (Capillary Suction Time, bound water) which may be some interesting tools for an optimised loading strategy.
Abbreviations COP Conference of Parties GA Genetic algorithms MVS Mechanical Ventilation System N... more Abbreviations COP Conference of Parties GA Genetic algorithms MVS Mechanical Ventilation System NZEB Nearly Zero Energy Building STT Solar Thermal Tree Variables A Area of the tree (m²) CHM Hess-Murray coefficient (-) Cp Specific heat capacity of the heat transfer fluid (J.Kg-1 .K-1) D Diameter of the absorber pipes (m) E Solar irradiance (W.m-2) f Friction factor (-) hc Convective heat transfer coefficient (W.m-2 .K-1) k Thermal conductivity (W.m-1 .K-1) L Length of the pipes (m) • m Masse flow rate of the heat transfer fluid for a single pipe (kg.s-1) N Number of ramification levels (-) Ngen Number of generations (-) Npop Number of individuals (-) Nu Nusselt number (-) Nx Number of branches at the level x, for a single ramification (-) Nx,TOT Total number of branches at the level x (-) QV Volumetric flow rate per square meters of the tree area A (m 3 .h-1 .m-2) P Pressure (Pa) Pmut Mutation probability rate (-) Pr Prandtl number (-) Re Reynolds number (-) • S Entropy production (W.K-1) T Temperature (K) Text External temperature (K) Ts Surface temperature of the absorber (K) U Fluid velocity (m.s-1) Ue Heat loss coefficient between absorber and exterior (W.m-2 .K-1) V Total pipe volume of the solar tree (m 3)
International Journal of Chemical Engineering, 2010
In constructed wetlands, microorganisms associated with plants are assumed to play a major role. ... more In constructed wetlands, microorganisms associated with plants are assumed to play a major role. A one-year survey was conducted in five vertical flow constructed wetland systems that had been operating from 2 months to 8 years in small French villages (100-500 People Equivalent) to provide a better understanding of microbiological activity. The objective of our study was to highlight the most important factor generating variability between microorganisms communities compared to treatment performances. Results of community level physiological profiling using Biolog Ecoplates were analyzed using principal component analysis. The greatest microbial activity was observed in the oldest wetland during summer. Profiles of fed and rest bed were differentiated by the nature of the main carbon source metabolized. Whereas carbohydrates and carboxylic acids appeared to be better assimilated with fed beds, it seemed that phosphate compounds as well as amines allowed better growth in the plates inoculated with samples of rest beds. In all fed beds, the most important parameters affecting the diversity were the season and the age of the wetlands. There were only slight profile differences between surface and subsurface samples and between the first and second stage samples.
Investigation on the sensivity to temperature variations has been achieved on a full-scale experi... more Investigation on the sensivity to temperature variations has been achieved on a full-scale experimental dairy wastewater treatment plant including an unheated but insulated upflow anaerobic sludge blanket. A simple steady-state heat transfer model based on energy balance has been designed to forecast the biogas production depending on ambient air and dairy wastewater temperatures variations. Energy balance has been described for any part of the digestion plant. Calculated heat losses were in the same range than observed losses with an uncertainty of about 10%. From the equalization tank to the digester the average heat loss under cold period was close to 10°C due to convection and conduction. Mesophilic conditions are not respected for couples of ambient air and wastewater temperatures ranging respectively from 8-35 to 35-29°C. Technical solutions are suggested to increase the biogas production.
Chlorinated Benzenes (CBs) that were released into the environment contaminate groundwater at man... more Chlorinated Benzenes (CBs) that were released into the environment contaminate groundwater at many existing and former industrial sites. A research program was initiated to investigate the ecoremediation of CBs contaminated groundwater using subsurface flow constructed wetlands. Four lab-scale experiments were performed to evaluate removal efficiency with different operation conditions. The first experiment was achieved with two different solid-state materials: a peat and a lava stone (pozzolana). In order to stimulate biological activity, organic matter coming from an aged Vertical Flow Constructed Wetlands (VFCW) was added to the media. Mass balance was determined to assess the fate of these pollutants in this system. The biofiltres of the second experiment were constructed with the same materials but bioaugmentation was realized by adding organic matter of VFCW or by bacteria inoculums. Peat and pozzolana biofiltres planted with Phragmites australis constituted the third experiment to evaluate the effect of plants. Bioaugmentation was constituted by the addition of OM coming from aged VFCW. Compost mixed with pozzolana was the solid-state material of the fourth experiment. Columns were made of two stages. The first stage was unplanted and the second stage was planted with Phragmites. Peat has been replaced by compost, a renewable material. Lab-scale biofiltres remove CBs with an efficiency of 70%-99%, depending on studied media and conditions. Greater efficiency was observed with bioaugmented media. Volatilization was very low (<0.2%) and the detection of chlorides in water indicated the occurrence of biodegradation. The experiments have shown that organic solid-state materials (compost or peat) are useful for groundwater remediation, with higher treatment efficiency than pozzolana material. Bioaugmentation increased biological activity. Clogging of biofiltres have been observed and can be reduced by the presence of plants or by a resting period of 14-21 days (requiring alternative feedings on several filters).
Constructed wetland hydrodynamics were modeled using mathematical tools generally employed in che... more Constructed wetland hydrodynamics were modeled using mathematical tools generally employed in chemical engineering processes. The hydraulic residence time (HRT) distributions of the subsurface horizontal flow constructed wetland from Curienne (France) were estimated using the impulsion tracer method. A non-ideal flow wetland was first modeled by classical method: the dispersion plug flow model (DPFM), which gives a constant ratio to axial dispersion (the Peclet number Pe), and the stirred tanks in series model (STSM), which gives a number of stirred tank in series (NSTS). Six experimental HRTs were monitored to determine flow characteristics. Several periods were monitored to represent different seasons. It was found that evapotranspiration played a major role in summer by improving HRT.
Twenty-five landfill leachates were tested using duckweed and the contribution of ammonia and alk... more Twenty-five landfill leachates were tested using duckweed and the contribution of ammonia and alkalinity to their acute toxicity was studied by means of the following experiments: bioassays with ammonium sulphate (@R&SO,) and sodium bicarbonate (NaHCO,) and tests on one sample following ammonia stripping. The results show that un-ionized ammonia is the toxic form of ammonia. Furthermore, this compound appears to be the major toxicant for most leachates from landfills receiving household refuse. Alkalinity is not directly toxic to duckweed, but enhances ammonia toxicity by controlling the pH of the samples. These results are discussed regarding the regulations in France of landfill leachate monitoring.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Ecotoxicology and Environmental Safety, Jun 1, 1994
The goal of this work was to study the fate of dichloromethane in indoor aquatic microcosms after... more The goal of this work was to study the fate of dichloromethane in indoor aquatic microcosms after a sublethal and static exposure to simulate the accidental contamination of a lenitic ecosystem such as littoral lake zone or a pond. This kind of ecosystem is characterized by high productive capacity and rich biocoenose, and are usually first affected by acute or chronic pollution. Microcosms containing immersed bryophytes (Fontinalis antipyretica), macrophytes (Lemna minor, Groenlendia densa, Elodea canadensis), molluscs (Physa fontinalis), crustaceans (Daphnia magna), and unicellular green algae (Scenedesmus subspicatus) were contaminated with sublethal concentrations of dichloromethane or [14C]dichloromethane. The initial mean concentration was 9.9 +/- 3.7 microM. The mean concentration exposure for organisms was 4.5 +/- 1.5 microM. The fate of 14C radioactivity was monitored by measuring the radioactivity of the sediment, water, macro- and microorganism, and atmospheric compartments. Radioactivity in the water disappeared quickly from the microcosms, most likely as [14C]dichloromethane (t1/2 = 5.31 +/- 0.41 days). At the end of the experiments, radioactivity was mainly located in the atmosphere, with traces remaining in the biomass. Under static conditions, the bioaccumulation of 14C radioactivity from the radiolabeled dichloromethane was negligible.
This work focuses on the segregation of microbial populations in Electrochemically Active Biofilm... more This work focuses on the segregation of microbial populations in Electrochemically Active Biofilms (EAB) fed by glucose under continuous flow, simulated with a 2D bioanode model. In the model several reactions take place in parallel (fermentation, electroactivity, methanogenesis), performed by four microbial metabolic groups. Bioconversion yields and rate parameters were estimated by a thermodynamic approach. The model results include biomass segregation according to metabolic activity, distribution of concentrations of solutes and current production along the anode. This numerical tool exhibits an acceptable numerical cost (7000 nodes and below 35000 degrees of freedom) to evaluate innovative designs for enhancing the bioelectrochemical reactor efficiency using a multicriteria approach. Therefore, a multi-objective optimization (coulombic efficiencies and organic removal rates) was achieved and highlights a Pareto front, showing that relatively high coulombic
HAL (Le Centre pour la Communication Scientifique Directe), Nov 1, 2008
Sludge drying reed beds have been used for dewatering and mineralization of sludge since the begi... more Sludge drying reed beds have been used for dewatering and mineralization of sludge since the beginning of the 90's, but their insufficient performances in terms of Dry Matter [DM] content and mineralization of the sludge have made necessary new studies. Therefore, 8 pilots of 2m² each and a full-scale plant (13 000 p.e , 8 beds of 470m² in operation for 4 years) have been monitored to examine the influence of the sludge loading rate, the sludge quality and the loading frequency on the dewatering and mineralization efficiencies. Two filtration layers (vegetal compost or sand) and two loading rhythms were tested on pilots which were fed at a loading rate of 25 kgDM.m-2 .yr-1 during the first year of operation (commissioning period). Hydraulic behaviour (infiltration rate, outflow), O 2 and CO 2 relative concentrations in the filtration media, redox potential, pollutants removal and dry matter content were assessed during all the study. The rheological quality of the extracted sludge from full scale beds were assessed and showed that it mechanical behaviour exceed those of sludge of comparable dry matter content, making its spreading easier Therefore, these sludge could easily claim the status of solid and stabilized sludge according to the French regulation. Design and management recommendations (number of beds, loading rates, feeding/rest period) gained from the experiments results are suggested.
Traitement des eaux usées domestiques par marais artificiels : état de l'art et performances des ... more Traitement des eaux usées domestiques par marais artificiels : état de l'art et performances des filtres plantés de roseaux en France a. Cemagref, UR Qualité des eaux et préventions des pollutions, 3 bis quai Chauveau, CP 220, 69336 Lyon Cedex 09 b. Cemagref, chargée de mission « Épuration des eaux usées », mission appui technique (CGGREF),
The removal of chlorinated benzenes (CBs) from the compartments and from polluted industrial site... more The removal of chlorinated benzenes (CBs) from the compartments and from polluted industrial sites is of great public interest for the decontamination of polluted water and for the protection of the environment. Biological degradation could be considered as a feasible process to eliminate these compounds from the environment as soil or groundwater. A research program in progress since the year
Effets du pcp apres une contamination ponctuelle sur le compartiment vegetal d'ecosystemes aq... more Effets du pcp apres une contamination ponctuelle sur le compartiment vegetal d'ecosystemes aquatiques, en se situant preferentiellement au niveau des productions d'energie et plus particulierement de la photosynthese. En parallele, on suit son devenir dans le miliau aquatique considere, et on montre l'importance de la photodegradation dans les processus de disparition du pcp des ecosystemes aquatiques de type lenitiques
Aquatic Ecosystem Health & Management, Oct 1, 2000
Aquatic microcosm tests are widely used to assess the toxic effects of chemical contaminants on h... more Aquatic microcosm tests are widely used to assess the toxic effects of chemical contaminants on higher pelagic and benthic organisms, but rarely take into account bacteria and other microorganisms. In this study, the bacterial compartment of freshwater/formulated sediment laboratory microcosms was monitored in 4-week tests. In a first experiment, the influence of various organic matter compositions (cellulose+TetraMin®, cellulose+spirulin+meat extract, peat moss+TetraMin®) on bacterial communities was studied. In a second experiment, the effect of fluoranthene on bacterial communities was estimated. The following bacterial parameters were measured: total bacteria counts (epifluorescence microscopy) and enzymatic activities (INT-reductase and β-glucosidase). Compared to natural sediments, the artificial sediment was a satisfactory support for bacterial development. The organic composition of the formulated sediments had no apparent influence on bacterial populations. This result could be due to the high variability of parameters, such as the using 2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazolium chloride-reductase activity, and to the C/N ratio similarity between the tested organic matters. The fluoranthene-contaminated sediment had no apparent effect on bacterial populations. The absence of toxicity could be due in part to the uncontaminated surficial sand layer of the sediment which might have protected pelagic organisms by limiting the rate of suspended contaminated particles and creating an uncontaminated refuge for benthic organisms.
Removal of three polycyclic aromatic hydrocarbons or PAHs (fluoranthene, pyrene and benzo(k)fluor... more Removal of three polycyclic aromatic hydrocarbons or PAHs (fluoranthene, pyrene and benzo(k)fluoranthene) from two types of PAH-contaminated effluents was investigated using four laboratory columns filled with two different organic media: a green compost and a layer coming from the first stage of vertical flow constructed wetlands. Synthetic runoff polluted by polycyclic aromatic hydrocarbons were fed through the columns during a period of two months. After a period of hydrodynamic stabilisation, the results showed a great adsorption of PAHs (&gt;95%) on the solid media due to their large adsorption capacities. Leaching of these compounds by water was monitored. The concentrations of PAHs in leaching samples indicated that PAHs were strongly adsorbed on organic substrates and that lixiviation was limited. Fluoranthene metabolites were also investigated. Accumulation of metabolites was transitory and located in the first few cm of the media, as was observed for PAH concentrations. A toxicity test of leachates based on the inhibition of the bioluminescence of luminescent bacteria Vibrio fischeri indicated a low inhibition which can be enhanced by metal traces.
Removal of pyrene, a representative PAH, was studied using laboratory tests in two different type... more Removal of pyrene, a representative PAH, was studied using laboratory tests in two different types of solid media: an organic matter collected on the surface of a vertical flow constructed wetland (VFCW) and a formulated clay silicate sand (inorganic matter). The aim of this study was to evaluate the capacity of pyrene biodegradation in these media in order to use them for treating run-off water. The sorption process, the kinetics of pyrene biodegradation and the influence of selected bacteria were also investigated. The sorption process was evaluated by adsorption isotherms and desorption kinetics using a batch equilibration method. The adsorption coefficient values of 28.8 and 2.1 for the organic and the inorganic matter respectively, confirmed the relationship of adsorption with organic carbon content. A small proportion of the sorbed pyrene was available for desorption (8% and 15% for the organic and the inorganic matter, respectively), indicating that sorption was partially irreversible, with the presence of hysteresis. For the formulated clay silicate sand inoculated with a specific bacteria (Mycobacterium sp.6PY1), selected for its ability to degrade PAHs, pyrene removal was complete in 32 days. With the organic matter, these values ranged from 40% to 95% for the different experiments, following a lag time of 3 weeks before observation of a significant degradation. Indigenous bacterial species in the organic medium had the metabolic capacity to degrade pyrene, and microbial populations pre-exposed to the PAH degraded pyrene faster than similar unexposed populations. Three metabolites of pyrene degradation by Mycobacterium were found. They accumulated in both organic and inorganic matter, indicating that the enzymes catalyzing them have slow kinetics.
The aim of this study is to assess the sustainability of two wastewater treatment systems by ener... more The aim of this study is to assess the sustainability of two wastewater treatment systems by energy and emergy analyses. The first system is a Sequencing Batch Reactor (SBR) which is a concrete and electricity dependent intensive process. The second is a constructed wetland, usually considered as an extensive process. The two studied facilities have similar treatment capacity and removal efficiencies. This study sheds new light on the comparison of wastewater treatment plants. We defined a new unit, the "Functional Efficiency Index" (or FEI) to describe the energetic efficiency of the facilities, expressed in kJ per year and per kg of removed COD. The energy analysis showed that, after its construction, the constructed wetland system uses only renewable energy, in marked contrast to the SBR, totally dependent on electricity which is considered here as a non renewable. The emergy analysis showed no significant differences between the two processes, but energy and emergy indices are in favour of the constructed wetland process and thus confirm its sustainability.
French legislation requires, the control of private on-site sanitation systems by local authoriti... more French legislation requires, the control of private on-site sanitation systems by local authorities. This will result in a large increase of the quantity of sludge from septic tanks to be treated. Nevertheless, large wastewater treatment plants are not systematically able to treat this sludge because they may have reached their nominal load or they are not so numerous in rural zone to avoid too long transportation. The study concerns both, the feasibility of sludge reed beds devoted to the treatment of septage and the assessment of a simultaneous treatment with aerated sludge. The experiments have been carried out on eight pilot-scale drying reed beds (2m²) planted with Phragmites australis. Two filtration layers of either vegetal compost or sand were tested. The study is focused on the commissioning period (first vegetative year) with a loading rate of 30 kgSS.m-2 .yr-1. According to these operational conditions, dewatering efficiencies reached approx. 30% DM during summer but less than 20%DM in winter for each filtration layer and sludge. High removal efficiencies, with an average of 96%, 92% and 89% for SS, COD and TKN respectively, were achieved with septage whereas they were lower for the mixture of aerated sludge and septage. The dewaterability of septage and its filtration behaviour were assessed by several parameters (Capillary Suction Time, bound water) which may be some interesting tools for an optimised loading strategy.
Abbreviations COP Conference of Parties GA Genetic algorithms MVS Mechanical Ventilation System N... more Abbreviations COP Conference of Parties GA Genetic algorithms MVS Mechanical Ventilation System NZEB Nearly Zero Energy Building STT Solar Thermal Tree Variables A Area of the tree (m²) CHM Hess-Murray coefficient (-) Cp Specific heat capacity of the heat transfer fluid (J.Kg-1 .K-1) D Diameter of the absorber pipes (m) E Solar irradiance (W.m-2) f Friction factor (-) hc Convective heat transfer coefficient (W.m-2 .K-1) k Thermal conductivity (W.m-1 .K-1) L Length of the pipes (m) • m Masse flow rate of the heat transfer fluid for a single pipe (kg.s-1) N Number of ramification levels (-) Ngen Number of generations (-) Npop Number of individuals (-) Nu Nusselt number (-) Nx Number of branches at the level x, for a single ramification (-) Nx,TOT Total number of branches at the level x (-) QV Volumetric flow rate per square meters of the tree area A (m 3 .h-1 .m-2) P Pressure (Pa) Pmut Mutation probability rate (-) Pr Prandtl number (-) Re Reynolds number (-) • S Entropy production (W.K-1) T Temperature (K) Text External temperature (K) Ts Surface temperature of the absorber (K) U Fluid velocity (m.s-1) Ue Heat loss coefficient between absorber and exterior (W.m-2 .K-1) V Total pipe volume of the solar tree (m 3)
International Journal of Chemical Engineering, 2010
In constructed wetlands, microorganisms associated with plants are assumed to play a major role. ... more In constructed wetlands, microorganisms associated with plants are assumed to play a major role. A one-year survey was conducted in five vertical flow constructed wetland systems that had been operating from 2 months to 8 years in small French villages (100-500 People Equivalent) to provide a better understanding of microbiological activity. The objective of our study was to highlight the most important factor generating variability between microorganisms communities compared to treatment performances. Results of community level physiological profiling using Biolog Ecoplates were analyzed using principal component analysis. The greatest microbial activity was observed in the oldest wetland during summer. Profiles of fed and rest bed were differentiated by the nature of the main carbon source metabolized. Whereas carbohydrates and carboxylic acids appeared to be better assimilated with fed beds, it seemed that phosphate compounds as well as amines allowed better growth in the plates inoculated with samples of rest beds. In all fed beds, the most important parameters affecting the diversity were the season and the age of the wetlands. There were only slight profile differences between surface and subsurface samples and between the first and second stage samples.
Investigation on the sensivity to temperature variations has been achieved on a full-scale experi... more Investigation on the sensivity to temperature variations has been achieved on a full-scale experimental dairy wastewater treatment plant including an unheated but insulated upflow anaerobic sludge blanket. A simple steady-state heat transfer model based on energy balance has been designed to forecast the biogas production depending on ambient air and dairy wastewater temperatures variations. Energy balance has been described for any part of the digestion plant. Calculated heat losses were in the same range than observed losses with an uncertainty of about 10%. From the equalization tank to the digester the average heat loss under cold period was close to 10°C due to convection and conduction. Mesophilic conditions are not respected for couples of ambient air and wastewater temperatures ranging respectively from 8-35 to 35-29°C. Technical solutions are suggested to increase the biogas production.
Chlorinated Benzenes (CBs) that were released into the environment contaminate groundwater at man... more Chlorinated Benzenes (CBs) that were released into the environment contaminate groundwater at many existing and former industrial sites. A research program was initiated to investigate the ecoremediation of CBs contaminated groundwater using subsurface flow constructed wetlands. Four lab-scale experiments were performed to evaluate removal efficiency with different operation conditions. The first experiment was achieved with two different solid-state materials: a peat and a lava stone (pozzolana). In order to stimulate biological activity, organic matter coming from an aged Vertical Flow Constructed Wetlands (VFCW) was added to the media. Mass balance was determined to assess the fate of these pollutants in this system. The biofiltres of the second experiment were constructed with the same materials but bioaugmentation was realized by adding organic matter of VFCW or by bacteria inoculums. Peat and pozzolana biofiltres planted with Phragmites australis constituted the third experiment to evaluate the effect of plants. Bioaugmentation was constituted by the addition of OM coming from aged VFCW. Compost mixed with pozzolana was the solid-state material of the fourth experiment. Columns were made of two stages. The first stage was unplanted and the second stage was planted with Phragmites. Peat has been replaced by compost, a renewable material. Lab-scale biofiltres remove CBs with an efficiency of 70%-99%, depending on studied media and conditions. Greater efficiency was observed with bioaugmented media. Volatilization was very low (<0.2%) and the detection of chlorides in water indicated the occurrence of biodegradation. The experiments have shown that organic solid-state materials (compost or peat) are useful for groundwater remediation, with higher treatment efficiency than pozzolana material. Bioaugmentation increased biological activity. Clogging of biofiltres have been observed and can be reduced by the presence of plants or by a resting period of 14-21 days (requiring alternative feedings on several filters).
Constructed wetland hydrodynamics were modeled using mathematical tools generally employed in che... more Constructed wetland hydrodynamics were modeled using mathematical tools generally employed in chemical engineering processes. The hydraulic residence time (HRT) distributions of the subsurface horizontal flow constructed wetland from Curienne (France) were estimated using the impulsion tracer method. A non-ideal flow wetland was first modeled by classical method: the dispersion plug flow model (DPFM), which gives a constant ratio to axial dispersion (the Peclet number Pe), and the stirred tanks in series model (STSM), which gives a number of stirred tank in series (NSTS). Six experimental HRTs were monitored to determine flow characteristics. Several periods were monitored to represent different seasons. It was found that evapotranspiration played a major role in summer by improving HRT.
Twenty-five landfill leachates were tested using duckweed and the contribution of ammonia and alk... more Twenty-five landfill leachates were tested using duckweed and the contribution of ammonia and alkalinity to their acute toxicity was studied by means of the following experiments: bioassays with ammonium sulphate (@R&SO,) and sodium bicarbonate (NaHCO,) and tests on one sample following ammonia stripping. The results show that un-ionized ammonia is the toxic form of ammonia. Furthermore, this compound appears to be the major toxicant for most leachates from landfills receiving household refuse. Alkalinity is not directly toxic to duckweed, but enhances ammonia toxicity by controlling the pH of the samples. These results are discussed regarding the regulations in France of landfill leachate monitoring.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Ecotoxicology and Environmental Safety, Jun 1, 1994
The goal of this work was to study the fate of dichloromethane in indoor aquatic microcosms after... more The goal of this work was to study the fate of dichloromethane in indoor aquatic microcosms after a sublethal and static exposure to simulate the accidental contamination of a lenitic ecosystem such as littoral lake zone or a pond. This kind of ecosystem is characterized by high productive capacity and rich biocoenose, and are usually first affected by acute or chronic pollution. Microcosms containing immersed bryophytes (Fontinalis antipyretica), macrophytes (Lemna minor, Groenlendia densa, Elodea canadensis), molluscs (Physa fontinalis), crustaceans (Daphnia magna), and unicellular green algae (Scenedesmus subspicatus) were contaminated with sublethal concentrations of dichloromethane or [14C]dichloromethane. The initial mean concentration was 9.9 +/- 3.7 microM. The mean concentration exposure for organisms was 4.5 +/- 1.5 microM. The fate of 14C radioactivity was monitored by measuring the radioactivity of the sediment, water, macro- and microorganism, and atmospheric compartments. Radioactivity in the water disappeared quickly from the microcosms, most likely as [14C]dichloromethane (t1/2 = 5.31 +/- 0.41 days). At the end of the experiments, radioactivity was mainly located in the atmosphere, with traces remaining in the biomass. Under static conditions, the bioaccumulation of 14C radioactivity from the radiolabeled dichloromethane was negligible.
This work focuses on the segregation of microbial populations in Electrochemically Active Biofilm... more This work focuses on the segregation of microbial populations in Electrochemically Active Biofilms (EAB) fed by glucose under continuous flow, simulated with a 2D bioanode model. In the model several reactions take place in parallel (fermentation, electroactivity, methanogenesis), performed by four microbial metabolic groups. Bioconversion yields and rate parameters were estimated by a thermodynamic approach. The model results include biomass segregation according to metabolic activity, distribution of concentrations of solutes and current production along the anode. This numerical tool exhibits an acceptable numerical cost (7000 nodes and below 35000 degrees of freedom) to evaluate innovative designs for enhancing the bioelectrochemical reactor efficiency using a multicriteria approach. Therefore, a multi-objective optimization (coulombic efficiencies and organic removal rates) was achieved and highlights a Pareto front, showing that relatively high coulombic
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