Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading

Molokwane, Pulane E.; Meli, C. K.; Chirwa, Evans M.N.

doi:10.2166/wst.2008.669

Cited by 11 publications

(11 citation statements)

References 6 publications

(6 reference statements)

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“…Molokwane et al . () also demonstrated that microcosm inoculated with Cr(VI)‐reducing bacteria (R5) achieved significant removal of Cr(VI).…”

Section: Discussionmentioning

confidence: 92%

“…Similar results were found by Srivastava and Thakur (2006) testing different Cr(VI) concentrations (200 and 400 mg kg À1 ) on soil inoculated with A. niger (FK1), which indicated that lower concentration of chromate (250 ppm) was reduced (75%) at 15 days compared with the control (5%), and chromium was removed by bioaccumulation in the mycelium of the fungus. Molokwane et al (2008) also demonstrated that microcosm inoculated with Cr(VI)-reducing bacteria (R5) achieved significant removal of Cr(VI).…”

Section: Discussionmentioning

confidence: 94%

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Bioaugmentation of chromium-polluted soil microcosms withCandida tropicalisdiminishes phytoavailable chromium

et al. 2013

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Aim: Localization of Cr(VI) removal activity in Candida tropicalis strain and the study of its Cr(VI) removal capacity in soil. Methods and Results: Candida tropicalis strain HE650140 showed a remarkable capacity to completely reduce 50 mg l À1 of Cr(VI) in 48 h under aerobic conditions; however, a small change in total content of chromium in the culture liquid was detected, which can be explained by the formation of Cr (III). Fractionation of the cells showed that chromium removal activity was present in both the cytoplasm and membrane. The bioaugmentation of Cr (VI)-contaminated soil microcosms by live and dead biomass showed that yeast inoculation diminishes phytoavailable chromium from soils, improving different growth parameters of clover. Conclusion:The Cr(VI) removal activity was found in both cytoplasmic and membrane fractions. Both live and dead biomass of C. tropicalis were capable to reduce Cr(VI) in the soil and limit the toxicity of this metal to clover seedlings. Significance and Impact of the Study: This study is one of the few documents that present the ability of dead yeast to limit phytoavailability of Cr(VI) from soil. This is of great significance in bioremediation of Cr(VI)-contaminated soil.

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“…Molokwane et al . () also demonstrated that microcosm inoculated with Cr(VI)‐reducing bacteria (R5) achieved significant removal of Cr(VI).…”

Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 94%

Bioaugmentation of chromium-polluted soil microcosms withCandida tropicalisdiminishes phytoavailable chromium

et al. 2013

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“…The regeneration of adsorbent is quite crucial for the process to be cost-effective as well for the recovery of metal ions from the solution. In the present study, desorption was studied at different solution pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). The result, as can be seen from Figure 6, indicates that the maximum desorption of 82.6% occurred at a pH of 8.…”

Section: Regeneration and Reusability Of Adsorbentsmentioning

confidence: 71%

“…The batch adsorption experiments were conducted by varying several parameters, namely pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), temperature (20 C-50 C), adsorbent dosage (5 g/L-15 g/L), and initial Cr(VI) concentration (50 ppm-150 ppm), keeping the volume of the solution at 50 mL for every run. The solutions were agitated using a magnetic stirrer at 210 rpm.…”

Section: Batch Adsorption Experimentsmentioning

confidence: 99%

Red mud (aluminum industrial waste): An eco‐friendly treatment of electroplating effluent

Verma

Balomajumder

2020

Can J Chem Eng

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In this work, aluminum industrial waste, red mud (RM), was activated to verify its potential in the management of electroplating wastewater containing hexavalent chromium (Cr(VI)). A comparison between the adsorption capabilities of RM and activated red mud (ARM) towards Cr(VI) from aqueous solutions was made. The effects of several parameters were evaluated. The adsorbents were characterized by field emission scanning electron microscopy (FESEM), Fourier transmission infrared spectroscopy (FTIR), x-ray diffraction (XRD), zeta potential, and thermogravimetric analysis (TGA). The particle size was observed as 23.59 nm. The ARM demonstrated an acceptable adsorption capacity of 25.641 mg/g at a pH of 2, adsorbent dosage of 2 g/L, initial Cr(VI) concentration of 100 mg/L, at 25 C. The experimental data is in good agreement with Langmuir adsorption isotherm. The kinetic study was performed to verify that the adsorption follows pseudo-second-order kinetics. In addition, the ARM showed decent recyclability for adsorbing Cr(VI) as even after three adsorption cycles, and the adsorption capacity was reduced by 30%. The results recommend ARM to be an efficient and cost-effective adsorbent for Cr(VI) removal from industrial wastewater.

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“…isolated from environment [104]. A bacterial strain of the genus Microbacterium was able to reduce Cr(VI), included in a mixed culture [105], moreover, immobilized cells of a strain Microbacterium sp. showed the capability to reduce Cr(VI) [106] [56].…”

Section: Resultsmentioning

confidence: 99%

Microbial Reduction of Hexavalent Chromium as a Mechanism of Detoxification and Possible Bioremediation Applications

Focardi¹,

Pepi²,

Focardi³

2013

Biodegradation - Life of Science

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that Cr III is involved in the tertiary structure of proteins and in the conformation of cell RNA and DNA [ , ]. . . Toxicity of chromiumCr VI exposure in humans can induce allergies, irritations, eczema, ulceration, nasal and skin irritations, perforation of eardrum, respiratory track disorders and lung carcinoma [ , , ]. Moreover, Cr VI evidences the capability to accumulate in the placenta, damaging fetal development [ ]. Cr VI pollution in the environment alters the structure of soil microbial communities [ ], reducing microbial growth and related enzymatic activities, with a consequent persistence of organic matter in soils and accumulation of Cr VI [ ].The toxic action of Cr VI is due to its capability to easily penetrate cellular membranes, and cell membrane damages caused by oxidative stress induced by Cr VI have been extensively reported, both in eukaryotic and prokaryotic cells, with effects such as loss of membrane integrity or inhibition of the electron transport chain [ , ]. Moreover, Cr VI enters cells using the sulfate transport system of the membrane in cells of organisms that are able to use sulfate [ , , , , , ].Once Cr VI entered into cells, spontaneous reactions occur with the intracellular reductants as ascorbate and glutathione, generating the short-lived intermediates Cr V and/or Cr IV , free radicals and the end-product Cr III [ , , ]. In the cytoplasm, Cr V is oxidized to Cr VI and the process produces a reactive oxygen species, referred as ROS, that easily combines with DNA-protein complexes. On the other hand, Cr IV is able to bind to cellular materials, altering their normal physiological functions [ , ]. It is known that Cr VI species and hydroxyl radicals cause DNA lesions in vivo [ ]. The intermediates that originated from the action of Cr VI are dangerous to cell organelles, proteins and nucleic acids [ , , ]. Cr VI is a very dangerous chemical form on biological systems as it can induce mutagenic, carcinogenic and teratogenic effects. Moreover, Cr VI is able to induce oxidative stress in cells, damaging its DNA [ ]. Inside of cells, the Cr III -DNA adducts and related hydroxyl radical oxidative DNA damages have a central role in originating the genotoxic and mutagenic effects [ ]. Moreover, the formation of Cr III -DNA binary adducts and L-cysteine-Cr III -DNA and ascorbateCr III -DNA ternary adducts likely increase both genotoxicity and mutagenicity in human cells [ , ]. Again the formation of DNA protein cross-linking, a process favoured by Cr VI , induces a significant promutagenic effect [ ].Considering the dangerous effects Cr VI can cause to human health, Cr VI has been comprised among priority pollutants and listed as a class A human carcinogen by the US Environmental Protection Agency USEPA [ ].The cell membrane is nearly impermeable to Cr III , Cr III has thus only about one thousandth of the toxicity of Cr VI [ , ]. Taking into account these considerations, it is possible to conclude that, depending on its oxidation state, chromium can have different biological effects,...

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Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading

Cited by 11 publications

References 6 publications

Bioaugmentation of chromium-polluted soil microcosms withCandida tropicalisdiminishes phytoavailable chromium

Bioaugmentation of chromium-polluted soil microcosms withCandida tropicalisdiminishes phytoavailable chromium

Red mud (aluminum industrial waste): An eco‐friendly treatment of electroplating effluent

Microbial Reduction of Hexavalent Chromium as a Mechanism of Detoxification and Possible Bioremediation Applications

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