Biodegradation of microcystin-LR using acclimatized bacteria isolated from different units of the drinking water treatment plant

Bacterial community isolated from different units of a Drinking Water Treatment Plant (DWTP) including pre-ozonation unit (POU), the effluent-sludge mixture of the sedimentation unit (ESSU) and top-sand layer water sample from the filtration unit (TSFU) were acclimatized separately in the microcystin-leucine arginine (MC-LR)-rich environment to evaluate MC-LR biodegradation. Maximum biodegradation efficiency of 97.2 ± 8.7% was achieved by the acclimatized-TSFU bacterial community followed by 72.1 ± 6.4% and 86.2 ± 7.3% by acclimatized-POU and acclimatized-ESSU bacterial community, respectively. Likewise, the non-acclimatized bacterial community showed similar biodegradation efficiency of 71.1 ± 7.37%, 86.7 ± 3.19% and 94.35 ± 10.63% for TSFU, ESSU and POU, respectively, when compared to the acclimatized ones. However, the biodegradation rate increased 1.5-folds for acclimatized versus non-acclimatized conditions. The mass spectrometry studies on MC-LR degradation depicted hydrolytic linearization of cyclic MC-LR along with the formation of small peptide fragments including Adda molecule that is linked to the reduced toxicity (qualitative toxicity analysis). This was further confirmed quantitatively by using Rhizobium meliloti as a bioindicator. The acclimatized-TSFU bacterial community comprised of novel MC-LR degrading strains, Chryseobacterium sp. and Pseudomonas fragi as confirmed by 16S rRNA sequencing. Biodegradation of microcystin-LR by in-situ bacterial community present in the drinking water treatment plant without formation of toxic by-product.Fil: Kumar, Pratik. Université du Québec a Montreal; CanadáFil: Hegde, Krishnamoorthy. Université du Québec a Montreal; CanadáFil: Brar, Satinder Kaur. Université du Québec a Montreal; CanadáFil: Cledón, Maximiliano. Universidad Nacional del Comahue; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kermanshahi-pour, Azadeh. Dalhousie University Halifax; CanadáFil: Roy-Lachapelle, Audrey. University of Montreal; CanadáFil: Galvez-Cloutier, Rosa. Laval University; Canad

Agro-industrial residues as a unique support in a sand filter to enhance the bioactivity to remove microcystin-Leucine aRginine and organics.

In the past, the versatility of a biosand filter has been successfully checked to counter suspended solids, metals, dissolved organic carbon (DOC), coliforms and other water quality parameters (WQPs) from the drinking water sources. In this study, cyanotoxin in the form of microcystin-LR (MC-LR) along with above-mentioned WQPs including nitrate, nitrite, and ammonia are analyzed for their removal using agro-residue based biosand filters (ARSFs) for 49 days (7 cycles). Three different agro-residue materials (ARMs) viz. deinking sludge (DSF), hemp fiber (HFF) and paper-pulp dry sludge (PPF) were used as the support material (top 5 cm) along with sand (49 cm) as the primary filter media to enhance the overall bioactivity. This enhancement in bioactivity is hypothesized to remove more MC-LR, DOC, coliform along with efficient nitrification/denitrification. Native bacterial community isolated from the filtration unit of a drinking water treatment plant (Chryseobacterium sp. and Pseudomonas fragi = X) along with the MC-LR-degrader: Arthrobacter ramosus (which was screened as the best biofilm-former among two other MC-LR-degraders tested) were used to inoculate the filters (all three ARSFs). Overall, DSF performed the best among all the ARSFs when compared to the sand filter (SFI) inoculated with the same bacterial strains (A + X). An increase in the bioactivity for ARSFs, particularly DSF was evident from the DOC removal (44 ± 11%, 15% more than SFI), coliform removal (92.7 ± 12.8%, 24% more than SFI), MC-LR removal (87 ± 14%, 13% more than SFI) and an effective nitrification/denitrification, reducing ammonia, nitrate and nitrite level to below guideline values. Toxic assessment using bioindicator (Rhizobium meliloti) revealed safe filter water only in case of DSF

Study of heavy metal accumulation mechanisms in the Lachine Canal sediments

Due to industrialization over the past 100 years, the sediments at the bottom of the Lachine Canal and Bay have become contaminated. This study investigated the heavy metal accumulation mechanisms within the Lachine Canal sediments and was carried out in three phases. Laboratory analytical and instrumental work were included.During Phase I, 28 parameters were measured on 44 samples collected along the Lachine Canal and Bay. The results revealed the presence of a wide variety of both organic and inorganic contaminants. Heavy metals such as Zn $>$ Pb $>$ Cr $>$ Ni $>$ Cu $>$ Cu (in order of decreasing abundance) in addition to organic contaminants (PAH $>$ MAH $>$ PCBs) were found in high concentrations exceeding background concentrations and various quality criteria levels. The total load of both organic and inorganic contaminants was found to be higher in the canal than in the bay zone. Although a positive correlation existed in between % mineral clay fraction or TOC and the total cumulative load of heavy metals, the correlation could not be assessed as conclusive.Further study on the association heavy metal-sediment constituents (Phase II and III) was carried on the canal zone. X-ray diffraction, Transmission Electron Microscopy and other geochemical analysis revealed that the sediments consisted mainly of silt and clay size fractions composed of: illite, kaolinite and chlorite, calcite and dolomite and minor amounts of Fe- minerals, organic matter and amorphous metal oxides. Each of these constituents bound heavy metals at varying degrees as assessed by a sequential extraction (SE) protocol. The partition distribution pattern was ruled by the geochemical setting. The associations with each phase were (in order of decreasing significance): (1) residual phase Pb (50%) = Cd (50%) $>$ Cr (49%) $>$ Zn (20%), (2) oxide phase Zn (33%) $>$ Pb (32%) $>$ Cr (28%) $>$ Cd (10%), (3) carbonate phase Zn (38%) $>$ Cd (26%) $>$ Pb (13%) $>$ Cr (5%), (4) the organic phase Cr (14%) $>$ Zn (8%) $>$ Cd (6%) $>$ Pb (5%) and (5) the exchangeable phase Cd (8%) $>$ Cr (4%) $>$ Zn (1%) = Pb (1%). The order of abundance in terms of total concentration was 1300 mg Zn/kg, 500 mg Pb/kg, 90 mg Cr/kg and 10 mg Cd/kg.According to the cation exchange capacity (CEC), carbonate and oxide content measurements, the heavy-metals occupied a minor fraction of the total capacity to retain metals by these mechanisms. The SE results revealed that the partition patterns varied with pH. The phases associated to the carbonate and the exchangeable phases were the most sensitive to a change in pH with the residual phase being almost unchanged. The Zn and Cd were sensitive to release when the conditions drifted to acidic conditions. Towards basic conditions no change in the metal distribution was observed.The partition patterns for various grain size fractions (${}175 mu$m) revealed that no particular fraction accumulated a certain heavy metal. However, a small increment of heavy metal content with decreasing grain size was found for Zn, Pb and Cd while the contrary was found for Cr. The metal distribution of each grain size fraction followed the pattern under unsieved conditions.Additionally, it was found that the geotechnical behaviour of sediments was influenced by the chemical composition of the sediments specially with respect to water retention

Modification du transfert de trois métaux lourds (Zn, Pb et Cd) dans un sol issu d'un dépot fluvio-glaciaire carbonate par l'introduction de geotextiles

Les géotextiles sont des géomatériaux fibreux de plus en plus utilisés au sein des bassins d'infiltration d'eaux pluviales, sans faire l'objet d'un questionnement particulier par rapport à leur influence sur le devenir des contaminants transportés par ces eaux. Cette étude vise à caractériser, à l'aide de colonnes de laboratoire, la modification du transfert simultané de trois métaux lourds (Zn, Pb et Cd) induite par l'introduction de géotextiless dans un sol saturé et soumis à un écoulement unidirectionnel et permanent. Ce sol est issu d'un dépôt fluvio-glaciaire carbonaté qui sert de support à plusieurs bassins d'infiltration de l'Est lyonnais (France). Cette modification a été caractérisée pour différentes conditions hydriques de mise en place (géotextiles mis en place secs ou saturés) et pour deux vitesses d'écoulement, pour un géotextile aiguilleté. La rétention des métaux a ensuite été optimisée par le choix du type de géotextile (aiguilleté, thermolié) et par le nombre de géotextiles introduits. L'écoulement a été caractérisé au niveau de son homogénité à l'aide de traçages. Des essais colonnes complémentaires spécifiques ont été réalisés pouur l'observation au microscope électronique à balayage du sol et des géotextiles après contamination. Les résultats mettent en évidence que les géotextiles introduits secs induisent une augmentation de la rétention des métaux, différant selon le type de géotextiles (aiguilleté ou thermolié). S'ils n'induisent aucune rétention particulière en leur sein, ils favorisent la rétention des métaux dans le sol avoisinant. L'augmentation de la rétention résulte d'un meilleur contact entre la solution métallique et les particules solides réactives du sol (carbonates) du fait d'une homogénéisation de l'écoulement au voisinage des géotextiles. Les géotextiles régulent la rétention des métaux dans le sol en modifiant l'écoulement.Geotextiles are fibrous materials that are more and more employed for the design of infiltration basins. And yet, their influence on the transfer of contaminants carried by stormwater has not been fully investigated. This study, based on leaching experiments, was aimed at characterising the modification of the transfer of three heavy metals (Zn, Pb and Cd), due to the introduction of geotextiles in a saturated soil under steady state and unidirectional flow. The soil was collected in a carbonated fluvio-glacial deposit on which several infiltration basins were constructed in the Eastern region of Lyon (France). This modification was characterised in different installation hydric conditions (the geotextiles were put either wet or dry) and at two flow-rates. The retention of heavy metals was then optimised thanks to the kind of geotextiles (needle-punched or heat-bonded) and the number of geotextiles put in the soil. The flow was characterised by tracer experiments. Specific leaching experiments were monitored for the observation of the soil and the geotextiles after contamination with a scanning electron microscope. The results show that the geotextiles which were dry when placed triggered an increase in the retention of the heavy metals and that this increase depended on the kind of geotextiles (needle-punched or heat-bonded). While there was no specific retention inside geotextiles, they increased the retention in the neighbouring soil. This increase was due to a better contact between the metallic solution and the reactive particles of the soil (carbonates) thanks to a local homogenisation of flow in the neighbouring of geotextiles. The geotextiles ruled the retention of heavy metals in soil by modifying the flow.VILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceCanadaFRC

Modifications hydrodynamiques du comportement des métaux lourds dans un sol hétérogène présentant une contamination résiduelle en NAPL (étude sur la contamination mixte des sols)

La contamination mixte des sols par les dérivés organiques pétroliers et les métaux lourds est une situation répandue et problématique dans les zones urbaines et industrialisées. Toutefois, aucun travail ne s'était penché, à ce jour, sur le rôle joué au sein de ce type de contamination par les interactions entre les métaux lourds et les liquides organiques non miscibles (NAPL). Les objectifs de la présente étude ont été de 1) vérifier la présence d'une influence des NAPL résiduels sur le transfert métallique dans les sols, 2) déterminer la nature de cette influence et 3) caractériser les mécanismes qui la déterminent. Les travaux entrepris ont permis d'identifier et de mesurer à l'échelle du laboratoire, à l'aide de colonnes de sol, les mécanismes d'interaction NAPL-métaux dans les sols. Un premier volet expérimental a servi à identifier la nature des interactions NAPL-métaux et à proposer leurs mécanismes sous-jacents. Un second volet expérimental a permis de quantifier les mécanismes d'influence du NAPL résiduel sur l'écoulement aqueux par modélisation mathématique. Les résultats de modélisation de l'écoulement aqueux ont ensuite été utilisés afin d'analyser les modifications du transfert des métaux lourds. Les résultats ont montré que les NAPL résiduels peuvent modifier le transfert des métaux lourds en altérant les conditions hydrodynamiques au sein du sol. La présence de NAPL résiduel a accentué l'hétérogénéité du réseau poreux en déconnectant les chenaux préférentiels et les micropores. Ceci a eu pour résultat de confiner la phase aqueuse au sein des chenaux préférentiels. En conséquence, ceci a modifié la capacité du sol à atténuer le flux métallique infiltrant. Les résultats ont aussi souligné le rôle de certains paramètres importants sur l'impact des NAPL résiduels sur le transfert des métaux lourds, notamment la viscosité du NAPL, les conditions hydriques initiales du sol et de la vitesse d'écoulement aqueux.Mixed soil contamination by petroleum hydrocarbons and heavy metals is a common occurrence in urban and industrial localities. However, there is no reported study on the impact of interactions between heavy metals and non-aqueous phase liquids (NAPL) on contaminant mobility. The objectives of this study were to 1) verify the possibility of an influence of residual NAPL on heavy metal transfer in mixed contaminated soils, 2) determine the nature of this influence, and 3) characterize the mechanisms underlying this influence. Experimental work at the laboratory scale using soil columns was used to identify and measure the interaction mechanisms between NAPL and heavy metals in soils. A first experimental phase was used to identify the nature of the NAPL-heavy metal interactions and to propose their possible mechanisms. A second experimental phase was used to quantify, using mathematical modeling, the mechanisms controlling the influence of residual NAPL on water flow. The modeling results were then used to analyze the modifications of heavy metal transfer. Results have shown that residual NAPLs can modify heavy metal transfer by changing the hydrodynamic regime in the soil. Residual NAPL increased the heterogeneity of the void network by decreasing the connectivity between preferential channels and micropores. This confined the infiltrating water to the preferential channels, which in turn modified the soil's capacity to attenuate the heavy metal flux. Results have also outlined the role of important parameters on the impact of residual NAPLs on heavy metal transfer, such as NAPL viscosity, initial soil water saturation and water flow velocity.VILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceCanadaFRC

Concomitant Zn-Cd and Pb retention in a carbonated fluvio-glacial deposit under both static and dynamic conditions

The chemical and physical processes involved in the retention of 10_2 M Zn, Pb and Cd in a calcareous medium were studied under saturated dynamic (column) and static (batch) conditions. Retention in columns decreased in order: Pb _Cd _ Zn. In the batch experiments, the same order was observed for a contact time of less than 40 h and over, Pb_ Cd > Zn. Stronger Pb retention is in accordance with the lower solubility of Pb carbonates. However, the equality of retained Zn and Cd does not fit the solubility constants of carbonated solids. SEM analysis revealed that heavy metals and calcareous particles are associated. Pb precipitated as individualized ZnCdCa free carbonated crystallites. All the heavy metals were also found to be associated with calcareous particles, without any change in their porosity, pointing to a surface/lattice diffusion-controlled substitution process. Zn and Cd were always found in concomitancy, though Pb fixed separately at the particle circumferences. The Phreeqc 2.12 interactive code was used to model experimental data on the following basis: flow fractionation in the columns, precipitation of Pb as cerrusite linked to kinetically controlled calcite dissolution, and heavy metal sorption onto proton exchanging sites (presumably surface complexation onto a calcite surface). This model simulates exchanges of metals with surface protons, pH buffering and the prevention of early Zn and Cd precipitation. Both modeling and SEM analysis show a probable significant decrease of calcite dissolution along with its contamination with metals

Modélisation du transfert de trois métaux Zn, Pb et Cd dans un dépôt fluvio-glaciaire carbonaté

Cette étude s'inscrit dans le contexte général de la compréhension du transfert de polluants en fond de bassin d'infiltration d'eaux pluviales. Elle porte en particulier sur le transfert de trois métaux lourds (zinc, plomb et cadmium) dans un dépôt fluvio-glaciaire servant de support à divers bassins d'infiltrations en région lyonnaise. Elle repose sur des études expérimentales précédentes, de caractérisation de la rétention et du transfert des trois métaux (zinc, plomb et cadmium) dans le dépôt en conditions statiques (essais en réacteur fermés) et dynamiques (colonnes de laboratoire). Une analyse poussée des résultats expérimentaux et la microanalyse ont permis de proposer les mécanismes de rétention spécifiques. La modélisation numérique et l'ajustement aux données expérimentales de très bonne qualité ont permis de valider les mécanismes réactionnels proposés. D'un point de vue scientifique et méthodologique, cette étude illustre l'intérêt d'associer une étape d'observation fine à petite échelle (microanalyse) à la modélisation numérique pour aboutir à la compréhension du transfert réactif en milieux poreux à macro-échelle

Modélisation du transfert de trois métaux Zn, Pb et Cd dans un dépôt fluvio-glaciaire carbonaté

Cette étude s'inscrit dans le contexte général de la compréhension du transfert de polluants en fond de bassin d'infiltration d'eaux pluviales. Elle porte en particulier sur le transfert de trois métaux lourds (zinc, plomb et cadmium) dans un dépôt fluvio-glaciaire servant de support à divers bassins d'infiltrations en région lyonnaise. Elle repose sur des études expérimentales précédentes, de caractérisation de la rétention et du transfert des trois métaux (zinc, plomb et cadmium) dans le dépôt en conditions statiques (essais en réacteur fermés) et dynamiques (colonnes de laboratoire). Une analyse poussée des résultats expérimentaux et la microanalyse ont permis de proposer les mécanismes de rétention spécifiques. La modélisation numérique et l'ajustement aux données expérimentales de très bonne qualité ont permis de valider les mécanismes réactionnels proposés. D'un point de vue scientifique et méthodologique, cette étude illustre l'intérêt d'associer une étape d'observation fine à petite échelle (microanalyse) à la modélisation numérique pour aboutir à la compréhension du transfert réactif en milieux poreux à macro-échelle

An evaluation of several in-lake restoration techniques to improve the water quality problem (eutrophication) of Saint-Augustin Lake, Quebec, Canada

Increasing phosphorus (P) content and decreasing water quality of Saint-Augustin Lake, Quebec City, Canada, has led to implementation of an Integrated Watershed Management Plan to restore the lake. As a part of the plan, the effects of different restoration techniques on lake water quality and biological community (i.e., biological compatibility) were assessed during an isolated water enclosure study and laboratory microcosm assay, respectively. The restoration techniques include: (i) coagulation of P by alum only (20 mg L 121), (ii) active capping of sediments using a calcite layer of 10 cm, and (iii) a complete method involving both alum coagulation and calcite capping. The results showed that the total P (TP) was greatly decreased (76\u201395 %) by alum + calcite, followed by calcite only (59\u201384 %). Secchi depth was 106 % greater and chlorophyll a concentrations were declined by 19\u201378 % in the enclosure which received both alum and calcite. Results of the biological compatibility test showed that total phytoplankton biomass declined by 31 % in microcosms composed of alum + calcite. No significant (P > 0.05) toxic effect was found on the survival of Daphnia magna and Hyalella azteca in both alum only and alum + calcite microcosms. Although the alum + calcite technique impaired the survival of Chironomus riparius, the midge emergence was much higher compared to alum only and control. Overall, the alum + calcite application was effective in controlling P release from sediment and lowering water column P concentrations, and thus improving the water quality and aquatic life of Saint-Augustin Lake. However, the TP concentrations are still higher than the critical limit (20 \u3bcg L 121) for aquatic life and the water column remained in the eutrophic state even after treatment. Increased TP concentrations, to higher than ambient levels of the lake, in the water column of all four enclosures, due to bioturbation artefact triggered by the platform installation, likely cause insufficient dosages of alum and/or calcite applied and reduced their effectiveness.Peer reviewed: YesNRC publication: Ye