Sustained Phosphorus Removal and Enrichment through Off-Flow Desorption in a Reservoir of Membrane Capacitive Deionization.

In this study, we used a membrane capacitive deionization device with a reservoir (R-MCDI) to enrich phosphorus (P) from synthetic wastewater. This R-MCDI had two small-volume electrode chambers, and most of the electrolyte was contained in the reservoir, which was circulated along the electrode chambers. Compared with conventional MCDI, R-MCDI exhibited a phosphate removal rate of 0.052 µmol/(cm2·min), approximately double that of MCDI. This was attributed to R-MCDI's utilization of OH- alternative adsorption to remove phosphate from the influent. Noticing that around 73.9% of the removed phosphate was stored in the electrolyte in R-MCDI, we proposed a novel off-flow desorption operation to enrich the removed phosphate in the reservoir. Exciting results from the multicycle experiment (∼8 h) of R-MCDI showed that the PO43--P concentration in the reservoir increased all the way from the initial 152 mg/L to the final 361 mg/L, with the increase in the P charge efficiency from 5.5 to 22.9% and the decrease in the energy consumption from 28.2 to 6.8 kW h/kg P. The P recovery performance of R-MCDI was evaluated by viewing other similar studies, which revealed that R-MCDI in this study achieved superior P enrichment with low energy consumption and that the off-flow desorption proposed here considerably simplified the operation and enabled continuous P enrichment.

Emerging electro-driven technologies for phosphorus enrichment and recovery from wastewater: A review.

The recovery of phosphorus from wastewater is a critical step in addressing the scarcity of phosphorus resources. Electro-driven technologies for phosphorus enrichment have gathered significant attention due to their inherent advantages, such as mild operating conditions, absence of secondary pollution, and potential integration with other technologies. This study presents a comprehensive review of recent advancements in the field of phosphorus enrichment, with a specific focus on capacitive deionization and electrodialysis technologies. It highlights the underlying principles and effectiveness of electro-driven techniques for phosphorus enrichment while systematically comparing energy consumption, enrichment rate, and concentration factor among different technologies. Furthermore, the study provides a thorough analysis of the capacity of various technologies to selectively enrich phosphorus and proposes several methods and strategies to enhance selectivity. These insights offer valuable guidance for advancing the future development of electrochemical techniques with enhanced efficiency and effectiveness in phosphorus enrichment from wastewater.

Adaptive Laboratory Evolution Reveals the Selenium Efflux Process To Improve Selenium Tolerance Mediated by the Membrane Sulfite Pump in Saccharomyces cerevisiae.

Selenium (Se) is a micronutrient in most eukaryotes, and Se-enriched yeast is the most common selenium supplement. However, selenium metabolism and transport in yeast have remained unclear, greatly hindering the application of this element. To explore the latent selenium transport and metabolism mechanisms, we performed adaptive laboratory evolution under the selective pressure of sodium selenite and successfully obtained selenium-tolerant yeast strains. Mutations in the sulfite transporter gene ssu1 and its transcription factor gene fzf1 were found to be responsible for the tolerance generated in the evolved strains, and the selenium efflux process mediated by ssu1 was identified in this study. Moreover, we found that selenite is a competitive substrate for sulfite during the efflux process mediated by ssu1, and the expression of ssu1 is induced by selenite rather than sulfite. Based on the deletion of ssu1, we increased the intracellular selenomethionine content in Se-enriched yeast. This work confirms the existence of the selenium efflux process, and our findings may benefit the optimization of Se-enriched yeast production in the future. IMPORTANCE Selenium is an essential micronutrient for mammals, and its deficiency severely threatens human health. Yeast is the model organism for studying the biological role of selenium, and Se-enriched yeast is the most popular selenium supplement to solve Se deficiency. The cognition of selenium accumulation in yeast always focuses on the reduction process. Little is known about selenium transport, especially selenium efflux, which may play a crucial part in selenium metabolism. The significance of our research is in determining the selenium efflux process in Saccharomyces cerevisiae, which will greatly enhance our knowledge of selenium tolerance and transport, facilitating the production of Se-enriched yeast. Moreover, our research further advances the understanding of the relationship between selenium and sulfur in transport.

Biosynthesis of biocompatibility Ag2Se quantum dots in Saccharomyces cerevisiae and its application.

As fluorescence in the second near-infrared window (NIR-II, 1000-1400 nm) could image deep tissue with high signal-to-noise ratios compared with that in NIR-I (750-900 nm), Ag2Se quantum dots (QDs) with fluorescence in the NIR-II could be ideal fluorophores. Here, we described a biosynthesis method to prepare the Ag2Se QDs by using temporally coupling the irrelated biochemical reactions, whose photoluminescence (PL) emission can reach NIR-II. The nanoparticles were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results showed that the nanoparticles obtained by extracellular purification were Ag2Se QDs with a uniform size of 3.9 ± 0.6 nm. In addition, the fluorescence intensity of Saccharomyces cerevisiae was improved successfully by nearly 4-fold by constructed engineering strain. In particular, the biosynthesis of Ag2Se QDs had good biocompatibility because it was capped by protein. Furthermore, investigating the toxicity of Ag2Se on cells and NIR images of nude mice showed that the Ag2Se synthesized using S. cerevisiae had low toxicity and could be used for in vivo imaging. In this work, the synthesis pathway of biocompatible Ag2Se was broadened and laid a foundation for the enlarged applicability of bioimaging in the biosynthesis of NIR-II QDs.