Layers of Uranium Phosphate Nanorods and Nanoplates Encrusted on Fungus Cladosporium sp. Strain F1 Hyphae.

The hyphae of Cladosporium sp. strain F1 (CFGR 2020-301-00084) were heavily encrusted with pre-synthesized uranium phosphate minerals under a wide range of pH conditions. SEM and TEM images showed that nanorods and nanoplates of uranium phosphate minerals at pH 4 and 5 and at pH 6, 7, and 8, respectively, were tightly adsorbed along the hyphae of Cladosporium sp. strain F1, while only a few uranium phosphate minerals were observed on the hyphae of Aspergillus niger VKMF 1119. Based on the physical mobility and chemical stability of uranium phosphate minerals under in situ oxidizing environmental conditions, the application of Cladosporium sp. strain F1 has potential as a novel strategy for the remediation of uranium contamination in sediments and aquifers under a wide range of pH conditions where larger amounts of phosphate are present in the environment.

Microbial removal of uranium in uranium-bearing black shale.

The effects of several conditional factors on efficiency of U bioleaching using an iron-oxidizer, Acidithiobacillus ferrooxidans, from U-bearing black shale (349 mg kg-1 of U) were investigated. When batch-type reactors containing black shale were initially inoculated with the cells, lower pH, higher redox potential and higher amount of aqueous Fe3+ than those of non-inoculated reactor were observed until 200 h. Such development of condition, which was facilitated by microbial activity, can enhance the rate and extent of U leaching from the solid substrate. However, under the condition of enough nutrients and energy source (Fe2+) supplied, indigenous Fe-oxidizers in the non-inoculated black shale were activated over time. They exerted almost same influence on the leaching efficiency with the inoculated samples after 250 h. Low initial Fe2+ supply (5 g l-1) and no addition of inorganic nutrients resulted in nearly identical extent of U leaching with that of 9 g l-1 of initial Fe2+ and nutrients supply. The results indicate that, in a practical process of bioleaching, the expenses for Fe2+ and nutrients addition can be reduced.

Sorption behaviors of heavy metals in SAT (soil aquifer treatment) system.

Degradation or detoxification of pollutants by SAT system was generally focused on organic contaminants although the regulation of water reuse has provisions of heavy metals. This study is to evaluate the feasibility of SAT for metals such as Cd, Cr and Pb with the pilot scaled column experiment. The desorption possibility of sorbed metals was also examined in the condition of continuous water and even acidic water (pH 4.3) injection. Fractional factorial analysis is a tool frequently used to identify factors or variables that have an effect on a certain response. A two-level fractional factorial analysis was planned to study the effect of four factors on Pb sorption from the experiments; soil particle size, TOC in solution, Pb concentration in solution and flow rate. The main effects among the factors were obtained by ANOVA based MINITAB software. The effects of four factors were also converted into coefficients; those values may build an empirical model to predict the metal sorption of soils.