Biotechnology
Parisa Tajer Mohammad Ghazvini; Zahra Shiri-Yekta; shaghayegh nasr; Narges Eslami; ,Mansoure Hosseini
Abstract
Introduction: Uranium, as one of the heavy metals, is a natural radionuclide that has harmful effects on human health and the environment due to its serious toxicity and radiation properties. Biosorption is a simple and cost-effective technique that can be used for remove of heavy metals and Radionuclides ...
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Introduction: Uranium, as one of the heavy metals, is a natural radionuclide that has harmful effects on human health and the environment due to its serious toxicity and radiation properties. Biosorption is a simple and cost-effective technique that can be used for remove of heavy metals and Radionuclides from waste waters. Material and methods: In this study, Micrococcus luteus biomass pretreated with autoclave heat was used. Then, physicochemical factor affecting the biosorption including biosorbent dose, initial uranium concentration, temperature and pH were investigated by Response Surface Methodology. Results: The results showed that the factor of initial uranium concentration, sorbent dose and pH statistically (p-value‹ 0.05) affect the uranium biosorption process. In contrast, temperature factor (p-value› 0.05) statistically have no effect on uranium removal by M. luteus. Discussion and conclusion: The results indicated that the pre-treated biomass under the conditions suggested by Design Expert software (19.75 g/liter of biomass, temperature 32.14 OC and pH 3.33) is able to remove approximately 99.98 percent of uranium from the contaminated area is 26.11 mg/liter of uranium, which shows its valuable potential in bioremediation applications of uranium from acidic wastewaters contaminated with low concentrations of uranium.
Parisa Mohammadi; Nora javanmardy; Parisa Tajer Mohammad Ghazvini
Abstract
Today bioremediation by microalga is an effective method to remove radionuclides and heavy metals from wastewater. Bioremediation of radionuclides and heavy metals is an efficient method of treating heavy metal contaminated effluents. In this study, the bioremediation of uranium from aqueous solutions ...
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Today bioremediation by microalga is an effective method to remove radionuclides and heavy metals from wastewater. Bioremediation of radionuclides and heavy metals is an efficient method of treating heavy metal contaminated effluents. In this study, the bioremediation of uranium from aqueous solutions was evaluated using live microalgae Chlorella vulgaris in a batch system. The Plackett-Burman method by Minitab statistical software was used to screen for effective factors such as initial uranium concentration, temperature, time, pH and amount of biomass on the removal of uranium by C. vulgaris. The results showed that the initial uranium concentration and pH factors were statistically effective by software. Optimization of effective factors in uranium bioremediation was evaluated by the response surface methodology (RSM). To determine the main effects and interaction of factors affecting uranium removal by C. vulgaris, central composite design (CCD) was used. The experimental data were then processed and the equation was evaluated to match the experimental data, and then the optimal removal values were determined. Finally, the results showed that C. vulgaris in optimal conditions proposed by Design-Expert software can remove 99.63% of existing uranium from aqueous solutions containing 7.1 mg / l uranium with pH 4.3.
Nessa Namdarian; Parisa Tajer Mohammad Ghazvini; Akram Sadat Tabatabaee bafroee
Abstract
The aim of this study was to evaluate the ability of treated Azolla filiculoides to uranium biosorption as a new biosorbent. In this study, uranium biosorption experiments were performed by untreated biomass and [Fe(CN)6]4--treated biomass and H2O2/MgCl2-treated biomass. Studies showed that the maximum ...
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The aim of this study was to evaluate the ability of treated Azolla filiculoides to uranium biosorption as a new biosorbent. In this study, uranium biosorption experiments were performed by untreated biomass and [Fe(CN)6]4--treated biomass and H2O2/MgCl2-treated biomass. Studies showed that the maximum uranium uptake capacity by various treated sorbents is pH 5. Freundlich isotherm was examined to evaluate the experimental data. The results showed that the treated sorbent with H2O2/MgCl2 is more efficient than other sorbents and its uranium adsorption is relatively rapid, reaching to the maximum in 60 minutes. Maximum uranium adsorption was obtained using the large adsorbent particles (2-4 mm). The maximum adsorption capacity of uranium ions by H2O2/MgCl2-treated sorbent under optimal conditions is about 42.2 mg /g dry biomass. The results showed that pretreatment can be a good way to increase the adsorption capacity of biosorbents.
Atieh Sadat Razavi; Parisa Tajer Mohammad Ghazvini; javad hamedi
Abstract
Biomineralization of selenium by bacteria not only has the potential to remove toxic selenium oxyanions from the environment, but can also produce nano- scale elemental selenium. In this work, the response surface method (RSM) based on the Box- Behnken design was used for evaluation and optimization ...
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Biomineralization of selenium by bacteria not only has the potential to remove toxic selenium oxyanions from the environment, but can also produce nano- scale elemental selenium. In this work, the response surface method (RSM) based on the Box- Behnken design was used for evaluation and optimization of the different process parameters effect on the bioreduction process of selenate. The proposed second order model with a correlation coefficient R2 = 0.96 appropriately predicted the process behavior and determined the 41.25 percent reduction of selenate by Bacillus sp. Strain TR-6 at 5.24 percent initial bacterial inoculation, process time of 24 h and 3.8 mM concentration of sodium selenate as the optimum condition. Scanning electron microscope (SEM) with the Energy Dispersive X-ray spectroscopy (EDX) confirmed the ability of the selected bacteria to produce selenium nanospheres. Finally, Bacillus sp. Strain TR-6 is determined as a valuable candidate for nano- technologies and selenium biomineralization processes.
