Treatment Technologies for Chromium(VI)

Hawley, Elisabeth L.; Deeb, Rula A.; Kavanaugh, Michael C.; Jacobs, James A.

doi:10.1002/chin.200614270

Cited by 43 publications

(65 citation statements)

References 49 publications

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“…Similarly, the presence of other microorganisms could exert some influence, since the role bacteria can play in reductions of Cr +6 to Cr +3 has been documented [33]. While the direct effect of the microalgae on the concentration of chromium seems to be evident, it may also be indirect.…”

Section: +3mentioning

confidence: 99%

Using Scenedesmus sp. for the Phycoremediation of Tannery Wastewater

et al. 2016

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Wastewater from the leather tannery industry contains high concentrations of heavy metals, especially chromium, as well as high values of inorganic nutrients and organic matter which, if not treated prior to discharge, may alter the quality of surface water bodies. As an alternative treatment to these industrial effluents, we propose the use of microalgae, due to their ability to remove contaminants. This study evaluates the growth of the microalga Scenedesmus sp. in three different dilutions of wastewater (20%, 50%, and 100%) at a tannery in Bogotá, Colombia, for a period of 15 days. We assess the removal of hexavalent chromium, nutrients (nitrites, nitrates, phosphates and sulfates), and Biochemical Oxygen Dilution (BOD). Results indicate a growth of Scenedesmus proportional to the dilution of the effluent, with greater biomass in undiluted wastewater. This biomass achieved the removal of Cr+6 (>98%), nitrates (>90%) and phosphates (>99%), and BOD (>88%) which can be attributed to a shared microalgae-bacteria effect. Thus, we conclude that the microalgae Scenedesmus sp. Used the waste effluent as a growth substrate, improving its effect during a phycoremediation process.Keywords: Phycoremediation, Scenedesmus, Tanneries, Chromium. ResumenLas aguas residuales de la industria del curtido de pieles (curtiembres) presentan elevadas concentraciones de metales pesados, especialmente de cromo, así como altos valores de nutrientes inorgánicos y materia orgánica, que de no ser tratados previa a su descarga puede alterar la calidad de los cuerpos de agua superficiales. Como un tratamiento alternativo a estos efluentes industriales, se propone el uso de microalgas, debido a su capacidad de remoción de contaminantes. En el presente trabajo se evaluó el crecimiento de la microalga Scenedesmus sp. en tres diluciones diferentes de una agua residual (20%, 50% y 100%) de una Curtiembres del Barrio San Benito de la ciudad de Bogotá, por un periodo de 15 días, valorando la remoción de cromo hexavalente (Cr+6), nutrientes (nitritos, nitratos, fosfatos y sulfatos) y reducción de la demanda bioquímica de oxigeno (DBO). Como resultado se obtuvo un crecimiento de Scenedesmus que proporcional a la dilución del efluente, con mayor obtención de biomasa en el agua residual sin diluir. Esta biomasa redujo la concentración de Cr+6 (>98%) así como los nitratos (>90%) y fosfatos (>99%) los cuales pudieron ser tomados por la microalga para su crecimiento, pero adicionalmente se observó una reducción de nitritos (>98%), sulfatos (>92%) y DBO (>88%) que puede ser atribuible a un efecto compartido microalga-bacteria. De esta forma se puede concluir que la microalga utilizo el efluente residual como un sustrato de crecimiento, mejorando la calidad del mismo en un proceso de ficorremediación.

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Section: +3mentioning

confidence: 99%

Using Scenedesmus sp. for the Phycoremediation of Tannery Wastewater

et al. 2016

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“…The batch experiments were performed to evaluate the Cr removal efficiency of CSO-INPs at different pH (2,3,5,8,10), for different doses of CSO-INPs (0.1, 0.3, 0.5, 0.9, 1.0 mg/ml) at different temperatures (28, 38°C) and for different initial pollutant (Cr) concentrations (10, 20 ppm). Once the ANN model has been prepared and validated as discussed in ''ANN modelling and validation'' section, the ANN simulation has been carried out to obtain the Cr removal efficiency for varying inputs pH (2, 3, 4, 5, 6, 7, 8, 9, 10), CSO-INPs doses (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 mg/ml), initial pollutant concentrations (10, 15, 20, 25, 30, 35 ppm), temperatures (20, 25, 28, 30, 35, 38, 40, 45°C).…”

Section: Batch Experiments and Ann Model To Evaluate Cr Removal Efficmentioning

confidence: 99%

“…The relative concentration of the various Cr(VI) species depends on the pH and the total Cr(VI) concentration within the normal pH range in natural waters (i.e. [6][7][8], and the CrO 4 2-, HCrO4 -and Cr 2 O 7 2-ions are the forms expected [5]. Above a pH of about 6, CrO 4 2-generally dominates.…”

Section: Introductionmentioning

confidence: 99%

An artificial neural network (ANN)-based framework for the Cr removal from the spiked water samples by chitosan oligosaccharide-coated iron oxide nanoparticles

Shukla

Kumar

Prakash

et al. 2017

Nanotechnol. Environ. Eng.

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Chromium contamination in water has become a major concern worldwide due to its adverse health effects. Chitosan oligosaccharide-coated iron oxide nanoparticles (CSO-INPs) were used in the present study for the magnetic separation of chromium from a chromium spiked water samples. Transmission electron microscope-energydispersive X-ray spectroscopy elemental mapping and scanning electron microscope-energy-dispersive X-ray spectroscopy elemental analysis were carried out to confirm the successful removal of the contaminant (total Cr) from the spiked water samples. A feedforward artificial neural network (ANN) model has been developed to predict the optimum efficiency of chromium ions removal from aqueous solution by CSO-INPs. Both the batch experiments and the ANN have been applied to assess the impact of various factors such as pH, nanoparticles dose, temperature, and time influencing the Cr removal efficiency of CSO-INPs. Removal efficiency has been found to be higher at low pH, with higher dose of nanoparticles at higher temperature. The ANN simulation further gives us a set of desired conditions (pH 3, CSO-INPs dose 0.7 mg/ml, temperature 28-30°C, time 60 min) to achieve an optimum Cr removal efficiency of CSO-INPs. Graphical AbstractKeywords Chromium Á Chitosan oligosaccharide Á Iron nanoparticles Á Artificial neural network (ANN)

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“…Proper contact between the reagents can be ensured by mixing in a turbulent sump pump or agitated vessel. The Cr(III) precipitates that form as a result of the reduction reactions are Cr(OH) 3 (s), FeCr 2 O 4 (s) and Fe x Cr y (OH) 3 (s) (Hawley, et al, 2005).…”

Section: Figure 19mentioning

confidence: 99%