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Removal and recovery of uranium from uranium-mine wastewater is beneficial to environmental protection and resource preservation. Reduction of soluble hexavalent U (U(VI)) to insoluble tetravalent uranium (U(IV)) by microbes is a plausible approach for this purpose, but its practical implementation has long been restricted by its intrinsic drawbacks. The electro-stimulated microbial process offers promise in overcoming these drawbacks. However, its applicability in real wastewater has not been evaluated yet, and its U(VI) removal mechanisms remain poorly understood. Herein, we report that introducing a weak electro-stimulation considerably boosted microbial U(VI) removal activities in both synthetic and real wastewater. The U(VI) removal has proceeded via U(VI)-to-U(IV) reduction in the biocathode, and the electrochemical characterization demonstrates the crucial role of the electroactive biofilm. Microbial community analysis shows that the broad biodiversity of the cathode biofilm is capable of U(VI) reduction, and the molecular ecological network indicates that synthetic metabolisms among electroactive and metal-reducing bacteria play major roles in electro-microbial-mediated uranium removal. Metagenomic sequencing elucidates that the electro-stimulated U(VI) bioreduction may proceed via e-pili, extracellular electron shuttles, periplasmic and outer membrane cytochrome, and thioredoxin pathways. These findings reveal the potential and mechanism of the electro-stimulated U(VI) bioreduction system for the treatment of U-bearing wastewater.

Removing and recovering uranium (U) from U-mining wastewater would be appealing, which simultaneously reduces the adverse environmental impact of U mining activities and mitigates the depletion of conventional U resources. In this study, we demonstrate the application of a constant-voltage electrochemical (CVE) method for the removal and recovery of U from U-mining wastewater, in an ambient atmosphere. The effects of operation conditions were elucidated in synthetic U-bearing water experiments, and the cell voltage and the ionic strength were found to play important roles in both the U extraction kinetics and the operation cost. The mechanistic studies show that, in synthetic U-bearing water, the CVE U extraction proceeds exclusively via a single-step one-electron reduction mechanism, where pentavalent U is the end product. In real U-mining wastewater, the interference of water matrices led to the disproportionation of the pentavalent U, resulting in the formation of tetravalent and hexavalent U in the extraction products. The U extraction efficacy of the CVE method was evaluated in real U-mining wastewater, and results show that the CVE U extraction method can be efficient with operation costs ranging from $0.55/kgU ~ $64.65/kgU, with varying cell voltages from 1.0 V to 4.0 V, implying its feasibility from the economic perspective.

Recyclable Fe in soil was prepared by using fermented food waste supernatant. The efficient cyclic oxidation of long-chain alkanes in oil-contaminated soils could be achieved by Fenton oxidation with the recyclable Fe. The oxidation efficiency of macro long-chain alkanes (C27-C30) from the first cycle (63.4%) to the last cycle (60.1%) showed no significant decrease during three-cycle Fenton oxidation with the recyclable Fe. However, for the oil-absorbing Fe prepared by HA and Fe-SOM prepared by Cs, the oxidation efficiency of C27-C30 could not be efficiently cyclic oxidized during three-cycle Fenton oxidation. Further analysis showed that the proportion of Fe(III) in the recyclable Fe was higher than that in the oil-absorbing Fe or the Fe-SOM, where the iron content was similar. Moreover, more fulvic-like acid and humic-like acid were found in the recyclable Fe, and thus many Fe(III) ions simultaneously combined with the fulvic-like acid and humic-like acid through –C–O–C and C˭O bonds in the recyclable Fe. It was the recyclable Fe with such a stable structure that could still maintain high catalytic activity and efficiently cyclic oxidize macro long-chain alkanes during three-cycle Fenton oxidation, which is valuable for its repeated use.

The female reproductive lifespan is largely determined by the size of the primordial follicle pool, which is established early in life. We previously reported that Di (2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor and a widely-spreading plasticizer, impairs primordial folliculogenesis. In the present study, we found DEHP significantly altered the number and sex ratio of the offspring of neonatal-exposed mice. Furthermore, by a neonatal exposure model and an ovary culture model, it showed that DEHP activated autophagy in the ovary, with increased autophagy-related gene expression and recognizable autophagosomes, while inhibition of autophagy by 3-MA attenuated the adverse impact of DEHP on primordial folliculogenesis. Moreover, key components of AMPK-SKP2-CARM1 signalling were up-regulated by DEHP in the ovary, and AMPK inhibitor Compound C reduced autophagy-related gene expression and partially recovered primordial follicle assembly. Collectively, this study demonstrates that DEHP induces autophagy by activating AMPK-SKP2-CARM1 signalling in mice perinatal ovaries, which results in disrupted primordial folliculogenesis and reduced female fertility.