Bioelectrochemical Characterization of Heavy Metals Resistant yeast: Hansenula fabianii Isolated from Tannery Wastewater

To date, heavy metals present a main drawback for bioelectrochemical systems (BESs) performances. Therefore, our results confirm, for the first time, that Hansenulafabianii is an electrochemical active yeast that has a potential tolerance against various heavy metals. The bioreactor inoculated by Hansenula fabianii in mediatoless conditions provided a maximum current density of 32 mA/m²; up to 300 mA/m² in the presence of methylene blue. In mediatorless conditions, cyclic voltammetry (CV) on a yeast pellet showed a single oxidative peak at 450mV and a pair peak, the CV of the supernatant confirmed that Hansenula fabianii secretedits own mediator. The obtained results proved that Hansenula fabianii based biofuel cell could be used for simultaneous current generation and heavy metal bioremediation

Low-Cost Electrode Modification to Upgrade the Bioelectrocatalytic Oxidation of Tannery Wastewater Using Acclimated Activated Sludge

Effective and eco-friendly technologies are required for the treatment of tannery wastewater as its biological toxicity and large volume leads toground water pollution. Hydrophobic (unmodified carbon felt) and hydrophilic modified carbon felt with Linde Type A zeolite (LTA zeolite) and bentonite were examined for their effects on bacterial attachment, current generation, and tannery wastewater treatment efficiency. Chronoamperometry and cyclic voltammetry confirmed the higher electron transfer obtained with modified anodes. Maximum current densities of 24.5 and 27.9 A/m² were provided with LTA zeolite and bentonite-modified anodes, respectively, while the unmodified carbon felt gave a maximum current density of 16.9 A/m². Compared with hydrophobic unmodified carbon felt, hydrophilic modified electrodes increased the exploitation of the internal surface area of the 3D structure of the carbon felt by the electroactive biofilm. The study revealed 93.8 ± 1.7% and 96.3 ± 2.1% of chemical oxygen demand (COD) reduction for LTA zeolite and bentonite, respectively. Simultaneous chromium removal was achieved with values of 94.6 ± 3.6 and 97.5 ± 2.2 for LTA zeolite and bentonite, respectively. This study shows the potential approach of carbon felt clay modification for the efficient tannery wastewater treatment using bioelectrochemicals systems (BESs) accompanied with high current recovery

Modeling and synthesis of carbon-coated LiMnPO4 cathode material: Experimental investigation and optimization using response surface methodology

Nanostructured LiMnPO4 cathode materials for lithium-ion batteries (LIBs) have been successfully prepared by a modified solvothermal method under controlled conditions. Polyethylene glycol (PEG-10000) was used as a solvent to optimize the particle size/mor­phology and as a carbon conductive matrix. In order to investigate the effect of synthesis parameters such as concentration of PEG-10000, reaction time and reaction temperature on the LiMnPO4 phase purity, Response surface methodology was carried out to find variations in purity results across the composition. The purity of all materials was checked using HighScore software by comparing the matched lines score to ones of reference data. As a result, it has been found that the pure phospho-olivine material LiMnPO4 can be syn­thesized using the following optimum conditions: PEG concentration = 0.1 mol l-1, reaction time = 180 min, and reaction temperature = 250 °C. The as-prepared LiMnPO4 under opti­mum conditions delivered an initial discharge capacity of 128.8 mAh g-1 at 0.05 C‑rate. The present work provides insights and suggestions for optimizing synthesis conditions of this material, which has been considered the next promising cathode candidate for high-energy lithium-ion batteries

Sustainable Approach for Tannery Wastewater Treatment: Bioelectricity Generation in Bioelectrochemical Systems

Treating tannery wastewater in bioelectrochemical systems (BESs) is considered as an achievable, economical and sustainable process compared to conventional methods. Two experiments with raw and pretreated tannery wastewater were operated separately to elucidate the divergence to form an efficient microbial anode under similar operating conditions [temperature (30 ± 0.1 °C); acidophilic microenvironment (pH 4.5), constant potential − 0.2 V/ECS]. In the reactor operated with raw tanneries, no microbial activity was detected due to the toxicity of the tannery effluent. While, the reactor fed by tannery wastewater that sustained electrochemical pretreatment demonstrated the ability of in situ bioelectricity generation along with wastewater treatment. Maximum current density of 11.2 A/m2 was obtained accompanied with removal of 90%, 84% and 96%, respectively, of chemical oxygen demand, biological oxygen demand (BOD5) and sulfate in addition of total removal of chromium. This study shows the potential approach of electrochemical pretreatment for the efficient tannery wastewater treatment using BESs accompanied with high current recovery

Correlation between cell surface physicochemical properties of bacterial strains and their chromium removal potential

Physicochemical characterization of microbes has gained recently a great interest by scientific community. It is proved of extreme importance in several fields of science and technology applications such as bioremediation. In this work, we investigated the establishment of a possible correlation between chromium removal capacity of seven bacterial strains isolated from contaminated sites with industrial wastes including tanning processing and their cell surface physicochemical properties. Thus, hydrophobicity and donor/acceptor electrons character were obtained using contact angle measurements. Statistical analysis showed a high significant positive correlation between hexavalent chromium (Cr(VI)) removal by the strains and their acceptor electron character γ+(r = 0.90). While significant negative correlation between the Cr(VI) removal potential and the ΔGiwi value (r = −0.844) and also with their donor electron character γ− (r = −0.746) were observed. These results may contribute to determine a selectrion criteria of bacteria that can be operated in bioremediation applications

Challenges of Microbial Fuel Cell Architecture on Heavy Metal Recovery and Removal From Wastewater

Being constituents of the effluents of many industries, heavy metals cause severe environmental pollution given the fact that they are recalcitrant and persistent in the environment. Conventional remediation strategies used to treat heavy metals loaded wastewater are neither economical nor environmentally friendly. To overcome these challenges, the rise of a new process that combines energy conservation and recovery was mandatory. Microbial fuel cells have emerged as a promising technology to mitigate environmental pollution; it provides a solution to wastewater treatment and the removal and/or recovery of heavy metals. They are bioelectrochemical systems that utilize the catalytic activity of microorganisms organized in biofilms to oxidize organic or inorganic compounds by producing electric current, thus providing a new opportunity for sustainable energy production and bioremediation. The removal and recovery of metals, such as Cr(VI), V(V), and Cu(II) have been evaluated using both single and double chambered MFCs. The fact that some heavy metals have high redox potential makes it possible to utilize them as effective electron acceptors instead of oxygen in the cathodic chamber of microbial fuel cells. Biotic/Abiotic cathode chambers can not only remove but also recover heavy metals. However, a number of challenges such us: low production rates and limited efficiencies make the application of this technology restricted to lab scale only. In this chapter, we review the removal/recovery of metals from effluents using the microbial fuel cells technology. We'll first summarize the principle of metal removal/recovery in microbial fuel cells, and then provide an overview of literature that attempted to treat metal loaded effluents in both single and double chambered microbial fuel cells while discussing power output, heavy metal removal efficiency and mechanisms involved in the process. Furthermore, the main challenges facing microbial fuel cells and their future applications in the treatment of heavy metals contaminated wastewater will be outlined

Quantitative assessment of the relative impacts of different factors on flood susceptibility modelling: case study of Fez-Meknes region in Morocco

The mapping and assessment of flood susceptibility is an integral component of flood mitigation and prevention programs, by determining the most vulnerable regions and the associated characteristics that influence the flood susceptibility. Hence, the aim of the present study is to identify flood-prone areas in the Fez-Meknes region (Morocco) for the first time using a multicriteria approach, in particular the Analytical Hierarchy Process (AHP) technique and Geographic Information Systems (GIS). A total of fifteen conditioning factors for flooding were selected: distance to rivers, river network density, precipitation, flow accumulation, elevation, slope, plane curvature, TWI, aspect, NDVI, LULC, TRI, geology, soil type, and SPI. All factors were defined as raster data sets with a resolution of 30 x 30 m. The results showed that, the efficiency tests of the flood susceptibility map show a good accuracy using an area under the curve (AUC) by remarkably good number (0.90).in addition, LULC was recognized as the most significant factor, which is followed by the stream power index that affect the flood map

Theoretical and experimental adhesion of yeast strains with high chromium removal potential

International audienceBiofilm-based bioprocesses are increasingly used in wastewater treatment. Microbial adhesion constitutes the key step in stability of these depollution systems. For adhesion studies, physicochemical characterization of microbial cells and supports has proved to be of extreme importance. In this work, estimation of interaction between five yeast strains with a high potential for Cr (VI) removal using extended Derjaguin–Landau–Verwey and Overbeek (XDLVO) theory as a powerful predictive tool of adhesion was investigated. Predictions showed that wood husk could be a good support for the formation of tested yeast biofilm, beech and oak exhibit better properties than other wood species studied with 100% of potential for adhesion. From a thermodynamic point of view, pine and teak woods are not suitable for biofilm formation for all tested yeast strains, presenting positive values of free energy adhesion (ΔGXDLVO). Environmental scanning electronic microscopy (ESEM) and Matlab® image analysis confirmed that all tested yeast strains were able to adhere to pine wood and, except for Wickerhamomyces anomalus they were unable to adhere to oak wood. Adhesion experiments were found to be well related to the theoretical prediction. To our knowledge, this is the first study dealing with biofilm-mediated depollution from an adhesion point of view aiming to optimize the stability of the system. It allows expanding knowledge about adhesion phenomena of yeast strains on wooden surface and contributes to select the best biofilm-support combination that would be used in a performant biological system for chromium removal

Delivery system for berberine chloride based on the nanocarrier ZnAl-layered double hydroxide: Physicochemical characterization, release behavior and evaluation of anti-bacterial potential

International audienceLayered double hydroxide (LDH) has attracted major interest as one of the most versatile drug delivery systems especially for adsorption capacity and/or controlled delivery property of bioactive agents owing to their combining features of biohybrid. ZnAl synthesized layered double hydroxide can offer a platform to immobilize various types of bioactive compounds, particularly berberine chloride (BBC). However, the immobilization reaction of berberine chloride into ZnAl-LDH was performed by direct co-precipitation method at different ratios of BBC/LDH. BBC-ZnAl-LDH biohybrids were characterized in terms of structure, surface morphology, in vitro drug release profile and antibacterial assay against various bacterial cells. The BBC biomolecules were attached by coordinate bond. Structural and microstructural characterization confirms that interaction of BBC with ZnAl-LDH occurs by adsorption rather than intercalation of BBC within LDH layers. The BBC release profiles from BBC-ZnAl-LDH had a longer release duration compared to the physical mixture, and the drug release seemed faster with the low ratio of BBC/LDH. BBC - ZnAl-LDH can be internalized into bacterial cells. In vitro experiments in PBS medium showed that BBC - ZnAl-LDH biohybrid had higher cytotoxicity and inhibitory effects against three pathogenic bacteria; Staphylococcus aureus CIP 543154, Pseudomonas aeruginosa A22 and Bacillus subtilus ILP 1428B upon the drug release profiles and its destructive potential depends on the loading BBC on the LDH layers. Nonetheless these results prove that the prepared BBC-ZnAl-LDH biohybrids retain the anti-bacterial character of the BBC molecules and are therefore potential modified drug delivery system (DDS)

Wicherhamomyces anomalus biofilm supported on wood husk for chromium wastewater treatment

A Wickeramomyces anomalus biofilm supported on wood husk was used to remediate water bodies contaminated with chromium (Cr), in batch and open systems. The favorable adhesion ability of the chromium-resistant yeast strain on the wood husk was predicted by XDLVO theory and confirmed by environmental scanning electronic microscopy. The chromium decontamination was then optimized in a batch mode using a central composite design (CCD). Analysis of variance (ANOVA) showed a high coefficient of determination (R2) value of 0.93 0.91 for Cr(VI) and total Cr removal, respectively, ensuring a satisfactory fitting of the second-order regression model to the experimental data. In batch system, the concentration of biomass exhibited the minimal effect on the process. An acidic pH of 3.72 and 5.48, an initial chromium concentration of 10 and 16.91mg/L and a support dose of 6.95 and 8.20g/L were optimal for Cr(VI) and total Cr removal, respectively. The breakthrough curves were determined in open system for different initial chromium concentrations. The study of glucose concentration effect on the yeast extracellular polymeric substances (EPS) production showed that a medium exempt of glucose allowed maximal EPS production and minimal chromium removal efficiency, while 20g/L glucose concentration of presented the optimal condition for chromium removal.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the research project PTDC/ AAG-TEC/5269/2014, the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio