● n-DAMO achieves simultaneous nitrogen removal and methane emission reduction.

Wastewater treatment plants are the major energy consumers and significant sources of greenhouse gas emissions, among which biological nitrogen removal of wastewater is an important contributor to carbon emissions. However, traditional heterotrophic denitrification still has the problems of excessive residual sludge and the requirement of external carbon sources. Consequently, the development of innovative low-carbon nitrate removal technologies is necessary. This review outlines the key roles of sulfur autotrophic denitrification and hydrogen autotrophic denitrification in low-carbon wastewater treatment. The discovered nitrate/nitrite dependent anaerobic methane oxidation enables sustainable methane emission reduction and nitrogen removal by utilizing available methane in situ. Photosynthetic microorganisms exhibited a promising potential to achieve carbon-negative nitrate removal. Specifically, the algal-bacterial symbiosis system and photogranules offer effective and prospective low-carbon options for nitrogen removal. Then, the emerging nitrate removal technology of photoelectrotrophic denitrification and the underlying photoelectron transfer mechanisms are discussed. Finally, we summarize and prospect these technologies, highlighting that solar-driven biological nitrogen removal technology is a promising area for future sustainable wastewater treatment. This review has important guiding significance for the design of low-carbon wastewater treatment systems.

● Nanoconfinement growth produces metastable ZrP with dual Lewis and Brønsted acidity.

Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through inner-sphere coordination, strong competition for hydroxyl ions still hinders efficient water defluoridation. In addition, the critical issue of polysilicate scaling that results from the ubiquitous silicates must be addressed. To tackle these issues, an alternative approach to enhancing adsorption reactivity by modifying nano-adsorbents with dual Lewis and Brønsted acidity is proposed. The feasibility of this approach is demonstrated by growing zirconium phosphate (ZrP) inside a gel-type anion exchanger, N201, to produce nanocomposite ZrP@N201, in which the confined ZrP contained an otherwise metastable amorphous phase with Lewis acidic Zr⁴⁺ sites and Brønsted acidic monohydrogen phosphate groups (–O₃POH). Compared with the Lewis acidic nano-zirconium oxide analog (HZO@N201), ZrP@N201 exhibited a greatly improved adsorption capacity (117.9 vs. 52.3 mg/g-Zr) and mass transfer rate (3.56 × 10⁻⁶ vs. 4.55 × 10⁻⁷ cm/s), while bulk ZrP produced a thermodynamically stable α-phase with Brønsted acidity that exhibited negligible adsorption capability toward fluoride. The enhanced defluoridation activity of ZrP@N201 is attributed to Brønsted acidity and the increased outer electron density of Zr⁴⁺ sites, as corroborated using XPS and solid-state NMR analysis. Moreover, Brønsted acidity strengthens the resistance of ZrP@N201 to silicate, allowing its full regeneration during cyclic defluoridation. Column tests demonstrated 3–10 times the amount of clean water from (waste) for ZrP@N201 as compared to both HZO@N201 and the widely used activated aluminum oxide. This study highlights the potential of developing nano-adsorbents with dual acidities for various environmental remediation applications.

● H-CWs synergistically eliminate NH₄⁺ and NO₃⁻ while reducing N₂O emissions.

Constructed wetlands (CWs) are widely applied for decentralized wastewater treatment. However, achieving efficient removal of ammonia (NH₄⁺–N) has proven challenging due to insufficient oxygen. In this study, natural hematite (Fe₂O₃) was employed as a CW substrate (H-CWs) for the first time to drive anaerobic ammonia oxidation coupled with iron(III) reduction (Feammox). Compared to gravel constructed wetlands (G-CWs), ammonia removal was enhanced by 38.14% to 54.03% and nitrous oxide (N₂O) emissions were reduced by 34.60% in H-CWs. The synergistic removal of ammonia and nitrate by H-CWs also resulted in the absence of ammoxidation by-products. Inhibitor and ¹⁵N isotope tracer incubations showed that Feammox accounting for approximately 40% of all ammonia removal in the H-CWs. The enrichment of iron phosphate (Fe₃Fe₄(PO₄)₆) promoted the accumulation of the Feammox intermediate compound FeOOH. Microbial nanowires were observed on the surface of H-CW substrates as well, suggesting that the observed biological ammoxidation was most likely related to extracellular electron transfer (EET). Microbial and metagenomics analysis revealed that H-CWs elevated the integrity and enhanced the abundance of functional microorganisms and genes associated with nitrogen metabolism. Overall, the efficient ammonia removal in the absence of O₂ together with a reduction in N₂O emissions as described in this study may provide useful guidance for hematite-mediated anaerobic ammonia removal in CWs.

● First to apply spatial autocorrelation analysis to rural domestic sewage discharge.

The traits of rural domestic sewage emission are unclear, negatively affecting rural domestic sewage treatment and sewage management. This study used data from the Second National Pollution Source Census Bulletin to establish a data set. The spatial distribution characteristics and main factors influencing rural sewage discharge in the Northern Region were studied using spatial autocorrelation analysis and structural equations. The findings demonstrated that (1) a significant Spearman correlation between drainage water volume (DWV), chemical oxygen demand (COD), ammonia nitrogen (NH₃-N), total nitrogen (TN), and total phosphorus (TP) and that the correlation coefficients between DWV and COD, NH₃–N, TN and TP were 0.87**, 1.0**, 0.99**, 0.99**, respectively; (2) rural sewage discharge showed spatial autocorrelation, and rural domestic sewage discharge in the districts and counties with an administration was significantly higher than in the surrounding areas; and (3) social development was the main driver rural domestic sewage changes (path coefficient was 0.407**), and the main factors influencing rural domestic sewage discharge were the urbanization rate, years of education, and population age structure. This study obtained the spatial variation law and clarified the main influencing factors of rural domestic sewage to provide data support and a theoretical basis for subsequent rural sewage collection and treatment. Use of the Inner Mongolia Autonomous Region in northern China as a typical case, provides a theoretical foundation for scientific decision-making on rural domestic sewage treatment at the national and regional levels and offers new perspectives for managing pollutants.

● Wood powder reconstitution strategy was developed to prepare hydrogel membrane.

To avoid resource wastage and secondary environmental pollution, recycling and reusing waste wood powder is still a great challenge. Moreover, the poor viscosity and irregular pore size of wood powder limit its practical application. This study employed a green and convenient wood powder reconstitution strategy to achieve highly adhesive bonding and pore size control between wood powder particles, thus preparing a high-strength and super hydrophilic wood powder membrane. The wood powder fibers were partially dissolved and regenerated to create a reconstituted wood powder hydrogel membrane, using waste wood powder as the raw material. The wood powder reconstitution strategy offers advantages such as environmental friendliness, simplicity, cost-effectiveness, and strong universality. Furthermore, the materials exhibit excellent self-cleaning properties and superhydrophilicity. Driven by gravity, the membrane can purify oily wastewater and dyes. Additionally, the reconstitution strategy offers a new pathway for recycling wood powder.

● Electrostatic virus sampler was designed and evaluated in a pandemic scenario and real indoor field environment.

The World Health Organization has raised concerns about the possibility of airborne transmission in enclosed and poorly ventilated areas. Therefore, rapid monitoring of airborne viruses is necessary in multi-use facilities with dense population. Accordingly, an electrostatic air sampler (250 L/min) was developed in this work to obtain indoor viral aerosol samples for analysis via the Polymerase Chain Reaction (PCR). Aerosol tests with H1N1 and HCoV-229E were performed to evaluate the sample collection efficiency. PCR analysis, along with another aerosol test, was conducted to evaluate the recovery of the virus particles collected by the sampler. In laboratory tests, our electrostatic sampler obtained viral samples that were detectable by PCR under the simulated viral pandemic scenario (3000 RNA copies per cubic meter of air) within 40 min. The resulting cycle threshold (C_t) values were 35.07 and 37.1 for H1N1 and HCoV-229E, respectively. After the performance evaluation in the laboratory, field tests were conducted in a university classroom from October 28 to December 2, 2022. Influenza A and HCoV-229E were detected in two air samples, and the corresponding C_t values were 35.3 and 36.8. These PCR results are similar to those obtained from laboratory tests, considering the simulated viral pandemic scenario.

● Recent progress of bismuth tungstate (Bi₂WO₆) as photocatalyst was summarized.

Photocatalysis has emerged a promising strategy to remedy the current energy and environmental crisis due to its ability to directly convert clean solar energy into chemical energy. Bismuth tungstate (Bi₂WO₆) has been shown to be an excellent visible light response, a well-defined perovskite crystal structure, and an abundance of oxygen atoms (providing efficient channels for photogenerated carrier transfer) due to their suitable band gap, effective electron migration and separation, making them ideal photocatalysts. It has been extensively applied as photocatalyst in aspects including pollutant removal, carbon dioxide reduction, solar hydrogen production, ammonia synthesis by nitrogen photocatalytic reduction, and cancer therapy. In this review, the fabrication and application of Bi₂WO₆ in photocatalysis were comprehensively discussed. The photocatalytic properties of Bi₂WO₆-based materials were significantly enhanced by carbon modification, the construction of heterojunctions, and the atom doping to improve the photogenerated carrier migration rate, the number of surface active sites, and the photoexcitation ability of the composites. In addition, the potential development directions and the existing challenges to improve the photocatalytic performance of Bi₂WO₆-based materials were discussed.

● WSC improves physicochemical properties of soil for plant growth.

Water-soluble chitosan (WSC) has been studied for its ability to mobilize soil Pb and promote the phytoremediation by Hylotelephium spectabile in Pb-contaminated fields. We aimed to clarify the internal mechanism by which WSC impacts phytoremediation by examining plant growth and Pb accumulation performance of H. spectabile as well as the Pb form, functional groups, and mineral phases of Pb-contaminated soil. WSC effectively decreased soil pH and activated Pb migration in rhizosphere soils, with a considerable increase in water-soluble and acid-extractable Pb by 29%–102% and 9%–65%, respectively, and a clear decreasing trend in reducible and oxidizable Pb. Fourier-transform infrared spectroscopy revealed a significant increase in amino and hydroxyl groups in the soil generated by WSC. The coordination of Pb with amino and hydroxyl groups may play an important role in the formation of Pb complexes and activation of Pb in soil. In field trials, the application of WSC significantly increased Pb accumulation in H. spectabile by 125.44%, reaching 92 g/hm². Moreover, the organic matter and nitrogen in the soils were increased by WSC, which improved the growth conditions of H. spectabile. No obvious growth inhibition was observed in either the pot or field trials. Therefore, WSC is a promising chelating agent for mobilizing Pb in soil. Additionally, WSC can be potentially used to boost H. spectabil-mediated phytoremediation of Pb-contaminated farmland.

● Signatures and genesis of the hydrochemistry of water resources was determined.

Water resources have crucial implications for the steady development of the urban social economy. This study investigated the hydrochemical signatures and genesis of water resources in the urban area of Lhasa City (UALC). To this end, several analyses, such as ion ratio analysis and correlation analysis, were performed by comprehensively applying mathematical statistics and integrated hydrochemical methods. The results show relatively low concentrations of major ions in the groundwater and surface water (GSW) of the UALC. The primary anions and cations are HCO₃^– and Ca²⁺, reflecting the HCO₃-Ca water type. Nevertheless, groundwater exhibits higher concentrations of key chemical components compared to surface water. GSW are weakly alkaline, with pH values of 7.78 and 7.61, respectively, and they have low salinity with average concentrations of total dissolved solids being 190.74 and 112.17 mg/L, respectively. Anthropogenic inputs have minimal influence on the hydrochemical features of GSW, whereas rock weathering is the dominant controlling factor. Furthermore, cation exchange is a significant hydrogeochemical process influencing their hydrochemical features. According to the isotope analysis (²H and ¹⁸O), the primary source of recharge for GSW is atmospheric precipitation, with some input from melted ice and snow. Moreover, GSW samples from the UALC show relatively similar ²H and ¹⁸O isotopic compositions, indicating the existence of a discernible hydraulic connection linking the two water sources. The research findings can serve as a valuable scientific reference and foundation for the sustainable development, effective utilization, and proper safeguarding of regional water resources in high-altitude areas.

● Surface water, sediment, and different fish species were analysed in this study.

Fish are important food sources for humans, and the availability of appropriate amount of trace elements (TEs) plays a crucial role in fish growth. Currently, due to large volumes of sewage discharge, high levels of certain elements are present in aquatic environments, and these elements accumulate in fish and potentially affect human health. In this study, the distribution and bioaccumulation capacity of trace elements in six dominant fish species from Chaohu Lake (China) were analyzed. The results showed that the bioaccumulation capacity of fish for Zn was greater than other TEs. And the source of the TEs in the fish were explored along with the concentration of the TEs in the aquatic environment, which indicated that TEs in fish were mainly obtained through ingestion and indirectly affected by the industrial activities in the basin. Additionally, stable carbon and nitrogen isotopes were used to classify the trophic levels and explore the biological magnification of TEs of the fish. It was found that Sb and Sr showed biomagnification with the increase of trophic level of fish. Based on the above analyses, the environmental biogeochemical cycle model of TEs in the lake was distinguished and established, which can offer valuable insights for sustainable fishery management in the downstream Yangtze River Delta ecosystem.

● The connections between protein structure and environmental research are proposed.

The deep-learning protein structure prediction method AlphaFold2 has garnered enormous attention beyond the realm of structural biology, for its groundbreaking contribution to solving the “protein folding problem”. In this perspective, we explore the connection between protein structure studies and environmental research, delving into the potential for addressing specific environmental challenges. Proteins are promising for environmental applications because of the functional diversity endowed by their structural complexity. However, structural studies on proteins with environmental significance remain scarce. Here, we present the opportunity to study proteins by advancing experimental determination and deep-learning prediction methods. Specifically, the latest progress in environmental research via cryogenic electron microscopy is highlighted. It allows us to determine the structure of protein complexes in their native state within cells at molecular resolution, revealing environmentally-associated structural dynamics. With the remarkable advancements in computational power and experimental resolution, the study of protein structure and dynamics has reached unprecedented depth and accuracy. These advancements will undoubtedly accelerate the establishment of comprehensive environmental protein structural and functional databases. Tremendous opportunities for protein engineering exist to enable innovative solutions for environmental applications, such as the degradation of persistent contaminants, and the recovery of valuable metals as well as rare earth elements.

● Neutrons reveal the structure and dynamics of materials nondestructively.

The use of neutron methods in environmental and biological sciences is rapidly emerging and accelerating with the development of new instruments at neutron user facilities. This article, based on a workshop held at Oak Ridge National Laboratory (ORNL), offers insights into the application of neutron techniques in environmental and biological sciences. We highlight recent advances and identify key challenges and potential future research areas. These include soil and rhizosphere processes, root water dynamics, plant-microbe interactions, structure and dynamics of biological systems, applications in synthetic biology and enzyme engineering, next-generation bioproducts, biomaterials and bioenergy, nanoscale structure, and fluid dynamics of porous materials in geochemistry. We provide an outlook on emerging opportunities with an emphasis on new capabilities that will be enabled at the Spallation Neutron Source Second Target Station currently under design at ORNL. The mission of scientific neutron user facilities worldwide is to enable science using state-of-the-art neutron capabilities. We aim to encourage researchers in the environmental and biological research community to explore the unique capability afforded by neutrons at these facilities.