Filamentous fungi were used to leach heavy metals from dredged sediments in semi-pilot scale air-lift bioreactors. Prior to the bioleaching experiments, a physico-chemical characterization of the sediments comprising ...Filamentous fungi were used to leach heavy metals from dredged sediments in semi-pilot scale air-lift bioreactors. Prior to the bioleaching experiments, a physico-chemical characterization of the sediments comprising a sequential extraction study was conducted. The sediments turned out to highly contaminated with heavy metals. Most of the studied metals were found to be strongly linked to the matrix because of their association with the sulphides and with the organic matter. The conditions that favored the solubilization of heavy metals by the filamentous fungi turned out to be favorable for the activity of the sediments organotrophic bacterial microflora as well. The latter played a key role in the biosolubilization process by producing organic acids under temporary anoxic conditions. Better solubilization results (Mn: 77%, Zn: 44%, Cu: 12%, Cd and Pb: <2%) were thus obtained in the uninoculated sugar treatment in comparison to the fungal treatment. In general, organotrophic leaching was found to be limited by the poor nature of the organic acids and by their microbial consumption under sugar limited conditions. It was therefore restrained to the relatively mobile metals, namely those linked to the acid-soluble and reducible fractions of the sediments.展开更多
High silica zeolite Y has been positively evaluated to clean-up water polluted with sulfonamides, an antibiotic family which is known to be involved in the antibiotic resistance evolution. To define possible strategie...High silica zeolite Y has been positively evaluated to clean-up water polluted with sulfonamides, an antibiotic family which is known to be involved in the antibiotic resistance evolution. To define possible strategies for the exhausted zeolite regeneration,the efficacy of some chemico-physical treatments on the zeolite loaded with four different sulfonamides was evaluated. The evolution of photolysis, Fenton-like reaction, thermal treatments, and solvent extractions and the occurrence in the zeolite pores of organic residues eventually entrapped was elucidated by a combined thermogravimetric（TGA–DTA）, diffractometric（XRPD）, and spectroscopic（FT-IR） approach. The chemical processes were not able to remove the organic guest from zeolite pores and a limited transformation on embedded molecules was observed. On the contrary, both thermal treatment and solvent extraction succeeded in the regeneration of the zeolite loaded from deionized and natural fresh water. The recyclability of regenerated zeolite was evaluated over several adsorption/regeneration cycles, due to the treatment efficacy and its stability as well as the ability to regain the structural features of the unloaded material.展开更多
In order to contribute to the valorisation of the clay materials of Ivory Coast in the depollution of wastewater, the physicochemical and mineralogical characterization of three clay samples taken in Agboville (AGB), ...In order to contribute to the valorisation of the clay materials of Ivory Coast in the depollution of wastewater, the physicochemical and mineralogical characterization of three clay samples taken in Agboville (AGB), Bingerville (BIN) and Katiola (KAT) was carried out. The objective of this work was to compare the properties of the clays in order to identify the one that is likely to have interesting adsorptive capacities to clean up contaminated water. These clays were studied by chemical analysis, X-ray diffraction, scanning electron microscopy and thermal analysis. In addition, their specific surface areas and cation exchange capacities were determined. The AGB clay is composed of 75.51% kaolinite, 14.20% illite and 9.26% quartz. The BIN clay contains 52.21% kaolinite, 6.23% illite, 17.50% quartz and 15.71% goethite. As for the KAT clay, it contains 48.08% kaolinite, 3.55% illite, 20.14% smectite, 6.11% quartz and 16.86% goethite. Their thermal behavior and microstructure are in agreement with their mineralogy. The measured specific surface areas and cation exchange capacities are consistent with literature values. The KAT clay has the highest specific surface and cation exchange capacity. In the light of the results obtained, the KAT clay appears to be more effective in depolluting water than the BIN and AGB clays.展开更多
Lubricants are very often found in nature under waste-oil forms and represent for the environment a real danger of pollution due to the difficulty of their biodegradation. The situation is especially worrying in most ...Lubricants are very often found in nature under waste-oil forms and represent for the environment a real danger of pollution due to the difficulty of their biodegradation. The situation is especially worrying in most developing countries in particular those of Sub-Saharan Africa due to the absence of regulation or control. The present work aims to isolate bacterial strains able to degrade hydrocarbons which can later be used in biotechnology for environments depollution. Oil-contaminated wastewater samples were collected in Ouagadougou city (Burkina Faso) and then used as source of bacterial isolation. Appropriate amounts of samples were inoculated to a mineral salt medium (MS) with Total Quartz 9000 oil as sole carbon and energy source and then incubated for enrichment, prior to microbe isolation. Two bacterial strains namely S2 and S7 were isolated from the enrichment cultures. The strains were tested for their ability to degrade other hydrocarbons (i.e. gasoline, diesel oil, brake oil) and for temperature, pH and salt concentration ranges for growth before their biochemical characteristics were defined. Based on their morphological, physiological and biochemical traits, strains S2 and S7 belong to Acinetobacter and Pseudomonas genera, respectively.展开更多
In this work, the authors made aquatic filters according to the formulation “clay stabilized at 4% of cement mixed with 4% of kambala sawdust and 10% of white sand” then heated to 1050°C to decontaminate the wa...In this work, the authors made aquatic filters according to the formulation “clay stabilized at 4% of cement mixed with 4% of kambala sawdust and 10% of white sand” then heated to 1050°C to decontaminate the waters of gutters and wells. The authors carried out geotechnical, geochemical, thermal, infrared spectroscopy, and scanning electron microscopy that analyzed the clay material. Geotechnical analyzes have shown that this material is made up of 22% thin sand, 22% of silt, and 56% of clay with 26 plasticity index. The geochemical analysis showed the presence of trace elements shared out as follows: 3% of alkaline metals, 24% of alkaline earth metals, 46% of transition metals, 10% of metal, 16% of lanthanides, 1% of actinides. The most abundant trace elements are barium (19%), vanadium (12%), chromium (11%) and zinc (9%). The thermal and microscopic analyzes revealed the kaolinitic nature of materials. The chemical depollution studies have shown elimination yields of 50% - 52.38% of sulphates;77.33% - 85.19% of phosphates;34.85% - 88.49% nitrates;91.3 - 100 of sulphides;The removal of bacteriological pollution are 92.8% - 98% of total germs;94% - 97% of total coliform and 95% - 98% of <em>E. coli</em>.展开更多
This article highlights an optimal robust control technique called H-infinity, which thanks to a particular algorithm offers several solutions in the experimental implementation of harmonic compensators of systems wit...This article highlights an optimal robust control technique called H-infinity, which thanks to a particular algorithm offers several solutions in the experimental implementation of harmonic compensators of systems with API-siemens modules. This control and command technique is directly tested on a TLC adaptive hybrid filter topology that provides benefits, such as reduced switching losses when injecting currents in the network, limitation of resonance problems and above all low power consumption at the DC bus level, thus allowing us to obtain results for 105 V to be compared with existing models in the literature which require 600 V for the same performance. This article therefore simultaneously offers two essential contributions to the optimization of harmonic pollution control. A first contribution is essentially based on the H-infinite algorithm and its particularity in its implementation on our TLC hybrid model. The second is on the advantages offered by the TLC-HAPF hybrid topology. The results obtained with this algorithm give us THDs conforming to the IEEE 519-1996 and which are very meaningful compared to the results obtained with other robust and stochastic control algorithms taken under the same conditions.展开更多
In the recent years, photocatalytic self-cleaning and ＂depolluting＂ materials have been suggested as a remediation technology mainly for NOx and aromatic VOCs in urban areas. A number of products incorporating the a...In the recent years, photocatalytic self-cleaning and ＂depolluting＂ materials have been suggested as a remediation technology mainly for NOx and aromatic VOCs in urban areas. A number of products incorporating the aforementioned technology have been made commercially available with the aim to improve urban air quality. These commercial products are based on the photocatalytic properties of a thin layer of TiO2 at the surface of the material （such as glass, pavement, etc.） or embedded in paints or concrete. The use of TiO2 photocatalysts as an emerging air pollution control technology has been reported in many locations worldwide. However, up to now, the effectiveness measured in situ and theexpected positive impact on air quality of this relatively new technology has only been demonstrated in a limited manner. Assessing and demonstrating the effectiveness of these depolluting techniques in real scale applications aims to create a real added value, in terms of policy making （i.e., implementing air quality strategies） and economics （by providing a demonstration of the actual performance of a new technique）.展开更多
In this study the effect of pH, adsorption behavior and the chemical struc-tures of two dyes (Methyl Orange and Bromothymol Blue) on the photo-degradation rate constant, was investigated. Adsorption isotherm shows tha...In this study the effect of pH, adsorption behavior and the chemical struc-tures of two dyes (Methyl Orange and Bromothymol Blue) on the photo-degradation rate constant, was investigated. Adsorption isotherm shows that the adsorption amount of dyes on TiO2 surface is highly related to the pH of the solution and to the pKa of each dye. In acidic medium the adsorption percentage of Methyl Orange on TiO2 surface was 76% facing 5% for Bromothymol Blue. The kinetic study shows compatibility between the degradation rate constant and the adsorption percentage on the surface. In basic medium the adsorption percentage of Methyl orange and Bromothymol Blue is similar while the degradation rate of Methyl orange is two times faster than that of Bromothymol Blue which reveals the role of chemical structure in the photodegradation rate.展开更多
文摘Filamentous fungi were used to leach heavy metals from dredged sediments in semi-pilot scale air-lift bioreactors. Prior to the bioleaching experiments, a physico-chemical characterization of the sediments comprising a sequential extraction study was conducted. The sediments turned out to highly contaminated with heavy metals. Most of the studied metals were found to be strongly linked to the matrix because of their association with the sulphides and with the organic matter. The conditions that favored the solubilization of heavy metals by the filamentous fungi turned out to be favorable for the activity of the sediments organotrophic bacterial microflora as well. The latter played a key role in the biosolubilization process by producing organic acids under temporary anoxic conditions. Better solubilization results (Mn: 77%, Zn: 44%, Cu: 12%, Cd and Pb: <2%) were thus obtained in the uninoculated sugar treatment in comparison to the fungal treatment. In general, organotrophic leaching was found to be limited by the poor nature of the organic acids and by their microbial consumption under sugar limited conditions. It was therefore restrained to the relatively mobile metals, namely those linked to the acid-soluble and reducible fractions of the sediments.
基金co-funded by the Italian Ministry of Education, University, and Research (No. PRIN 2008 BL2NWK: Zeolites as nano-reactors for the environment: efficiency, selectivity and stability in the adsorption of drugs from contaminated waters)
文摘High silica zeolite Y has been positively evaluated to clean-up water polluted with sulfonamides, an antibiotic family which is known to be involved in the antibiotic resistance evolution. To define possible strategies for the exhausted zeolite regeneration,the efficacy of some chemico-physical treatments on the zeolite loaded with four different sulfonamides was evaluated. The evolution of photolysis, Fenton-like reaction, thermal treatments, and solvent extractions and the occurrence in the zeolite pores of organic residues eventually entrapped was elucidated by a combined thermogravimetric（TGA–DTA）, diffractometric（XRPD）, and spectroscopic（FT-IR） approach. The chemical processes were not able to remove the organic guest from zeolite pores and a limited transformation on embedded molecules was observed. On the contrary, both thermal treatment and solvent extraction succeeded in the regeneration of the zeolite loaded from deionized and natural fresh water. The recyclability of regenerated zeolite was evaluated over several adsorption/regeneration cycles, due to the treatment efficacy and its stability as well as the ability to regain the structural features of the unloaded material.
文摘In order to contribute to the valorisation of the clay materials of Ivory Coast in the depollution of wastewater, the physicochemical and mineralogical characterization of three clay samples taken in Agboville (AGB), Bingerville (BIN) and Katiola (KAT) was carried out. The objective of this work was to compare the properties of the clays in order to identify the one that is likely to have interesting adsorptive capacities to clean up contaminated water. These clays were studied by chemical analysis, X-ray diffraction, scanning electron microscopy and thermal analysis. In addition, their specific surface areas and cation exchange capacities were determined. The AGB clay is composed of 75.51% kaolinite, 14.20% illite and 9.26% quartz. The BIN clay contains 52.21% kaolinite, 6.23% illite, 17.50% quartz and 15.71% goethite. As for the KAT clay, it contains 48.08% kaolinite, 3.55% illite, 20.14% smectite, 6.11% quartz and 16.86% goethite. Their thermal behavior and microstructure are in agreement with their mineralogy. The measured specific surface areas and cation exchange capacities are consistent with literature values. The KAT clay has the highest specific surface and cation exchange capacity. In the light of the results obtained, the KAT clay appears to be more effective in depolluting water than the BIN and AGB clays.
文摘Lubricants are very often found in nature under waste-oil forms and represent for the environment a real danger of pollution due to the difficulty of their biodegradation. The situation is especially worrying in most developing countries in particular those of Sub-Saharan Africa due to the absence of regulation or control. The present work aims to isolate bacterial strains able to degrade hydrocarbons which can later be used in biotechnology for environments depollution. Oil-contaminated wastewater samples were collected in Ouagadougou city (Burkina Faso) and then used as source of bacterial isolation. Appropriate amounts of samples were inoculated to a mineral salt medium (MS) with Total Quartz 9000 oil as sole carbon and energy source and then incubated for enrichment, prior to microbe isolation. Two bacterial strains namely S2 and S7 were isolated from the enrichment cultures. The strains were tested for their ability to degrade other hydrocarbons (i.e. gasoline, diesel oil, brake oil) and for temperature, pH and salt concentration ranges for growth before their biochemical characteristics were defined. Based on their morphological, physiological and biochemical traits, strains S2 and S7 belong to Acinetobacter and Pseudomonas genera, respectively.
文摘In this work, the authors made aquatic filters according to the formulation “clay stabilized at 4% of cement mixed with 4% of kambala sawdust and 10% of white sand” then heated to 1050°C to decontaminate the waters of gutters and wells. The authors carried out geotechnical, geochemical, thermal, infrared spectroscopy, and scanning electron microscopy that analyzed the clay material. Geotechnical analyzes have shown that this material is made up of 22% thin sand, 22% of silt, and 56% of clay with 26 plasticity index. The geochemical analysis showed the presence of trace elements shared out as follows: 3% of alkaline metals, 24% of alkaline earth metals, 46% of transition metals, 10% of metal, 16% of lanthanides, 1% of actinides. The most abundant trace elements are barium (19%), vanadium (12%), chromium (11%) and zinc (9%). The thermal and microscopic analyzes revealed the kaolinitic nature of materials. The chemical depollution studies have shown elimination yields of 50% - 52.38% of sulphates;77.33% - 85.19% of phosphates;34.85% - 88.49% nitrates;91.3 - 100 of sulphides;The removal of bacteriological pollution are 92.8% - 98% of total germs;94% - 97% of total coliform and 95% - 98% of <em>E. coli</em>.
文摘This article highlights an optimal robust control technique called H-infinity, which thanks to a particular algorithm offers several solutions in the experimental implementation of harmonic compensators of systems with API-siemens modules. This control and command technique is directly tested on a TLC adaptive hybrid filter topology that provides benefits, such as reduced switching losses when injecting currents in the network, limitation of resonance problems and above all low power consumption at the DC bus level, thus allowing us to obtain results for 105 V to be compared with existing models in the literature which require 600 V for the same performance. This article therefore simultaneously offers two essential contributions to the optimization of harmonic pollution control. A first contribution is essentially based on the H-infinite algorithm and its particularity in its implementation on our TLC hybrid model. The second is on the advantages offered by the TLC-HAPF hybrid topology. The results obtained with this algorithm give us THDs conforming to the IEEE 519-1996 and which are very meaningful compared to the results obtained with other robust and stochastic control algorithms taken under the same conditions.
文摘In the recent years, photocatalytic self-cleaning and ＂depolluting＂ materials have been suggested as a remediation technology mainly for NOx and aromatic VOCs in urban areas. A number of products incorporating the aforementioned technology have been made commercially available with the aim to improve urban air quality. These commercial products are based on the photocatalytic properties of a thin layer of TiO2 at the surface of the material （such as glass, pavement, etc.） or embedded in paints or concrete. The use of TiO2 photocatalysts as an emerging air pollution control technology has been reported in many locations worldwide. However, up to now, the effectiveness measured in situ and theexpected positive impact on air quality of this relatively new technology has only been demonstrated in a limited manner. Assessing and demonstrating the effectiveness of these depolluting techniques in real scale applications aims to create a real added value, in terms of policy making （i.e., implementing air quality strategies） and economics （by providing a demonstration of the actual performance of a new technique）.
文摘In this study the effect of pH, adsorption behavior and the chemical struc-tures of two dyes (Methyl Orange and Bromothymol Blue) on the photo-degradation rate constant, was investigated. Adsorption isotherm shows that the adsorption amount of dyes on TiO2 surface is highly related to the pH of the solution and to the pKa of each dye. In acidic medium the adsorption percentage of Methyl Orange on TiO2 surface was 76% facing 5% for Bromothymol Blue. The kinetic study shows compatibility between the degradation rate constant and the adsorption percentage on the surface. In basic medium the adsorption percentage of Methyl orange and Bromothymol Blue is similar while the degradation rate of Methyl orange is two times faster than that of Bromothymol Blue which reveals the role of chemical structure in the photodegradation rate.
