Utilization of phosphate rock as a sole source of phosphorus for uranium biomineralization mediated by Penicillium funiculosum.

Nan Hu,Zhongran Dai,Dianxin Li,Ke Li,Nieying Wang,Yang Sui,Hui Zhang,Dexin Ding

doi:10.1039/c8ra01344f

Nan Hu, Zhongran Dai + Show 6 more

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https://doi.org/10.1039/c8ra01344f

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Journal: RSC advances	Publication Date: Jan 1, 2018
Citations: 12	License type: CC BY 3.0

Affiliation: University of South China, 58.com (China)

Abstract

In this work, uranium(vi) biomineralization by soluble ortho-phosphate from decomposition of the phosphate rock powder, a cheap and readily available material, was studied in detail. Penicillium funiculosum was effective in solubilizing P from the phosphate rock powder, and the highest concentration of the dissolved phosphate reached 220 mg L−1 (pH = 6). A yellow precipitate was immediately formed when solutions with different concentrations of uranium were treated with PO43−-containing fermentation broth, and the precipitate was identified as chernikovite by Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray powder diffraction. Our study showed that the concentrations of uranium in solutions can be decreased to the level lower than maximum contaminant limit for water (50 μg L−1) by the Environmental Protection Agency of China when Penicillium funiculosum was incubated for 22 days in the broth containing 5 g L−1 phosphate rock powder.

Highlights

Uranium-containing wastewaters were produced in the process of uranium mining, uranium processing, uranium hydrometallurgy, and nuclear facilities operation.[1]
The China National Environmental Protection Agency stipulates that the concentration of uranium in the charged wastewater must be below 50 mg LÀ1 (GB 23727-2009), and the U.S Environmental Protection Agency requires that the concentration of uranium in drinking water should be below 20 mg LÀ1.3,4 remediation of uranium wastewaters has become the focus of research in environmental problems
The results showed that phosphate rock powder could be dissolved by organic acid and phosphatase secreted by Penicillium funiculosum, giving soluble ortho-phosphate (PO43À);[32] and the phosphorus concentration could reach 220 mg LÀ1 a er 22 days

Summary

Introduction

Uranium-containing wastewaters were produced in the process of uranium mining, uranium processing, uranium hydrometallurgy, and nuclear facilities operation.[1]. There are four kinds of mechanisms for the remediation of uranium wastewaters by microorganism: (1) the reduction of aqueous U(VI) into insoluble U(IV) by bacteria (Nitrate-reducing bacteria, sulfate-reducing bacteria, iron-reducing bacteria) in anaerobic reduction environment; (2) the uranyl precipitation due to the interaction of aqueous U(VI) with ligands (SO42À, PO43À, CO32À, OHÀ) released by microbial metabolism products; (3) the adsorption of positively charged uranyl ions onto the negatively charged functional groups on the surface of microbial cells; (4) the entrance of uranium into the cells due to the increase of the permeability of the cells by uranium toxicity.[12]. The U(IV) can be reoxidized into soluble U(VI) when exposed to oxidation environment, and the uranium pollution will be restored due to the reoxidation of U(IV) to U(VI).[14,15] the method of transformation of U into stable uranyl phosphate by the interaction of U(VI) with PO43À is a good strategy for remediation of uranium wastewaters because uranyl phosphate cannot be reoxidized.[16,17]

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Conclusion