ACS ES&T engineering最新文献

Colloidal activated carbon (CAC) is a promising technology for the in situ remediation of groundwater impacted by perfluoroalkyl and polyfluoroalkyl substances (PFAS). The long-term performance of an engineered CAC barrier will depend, in part, on the emplacement and remobilization of CAC particles within aquifer media. We here explored the influence of calcium ions (Ca²⁺) and Suwanee River natural organic matter (SRNOM) on CAC deposition and remobilization within saturated sand columns. Our results showed that the presence of Ca²⁺ (e.g., >5 mM) under high ionic strength conditions (100 mM) enhanced CAC deposition and subsequently reduced its remobilization upon the introduction of a low ionic strength solution (i.e., DI water). A combination of cation bridging and electrostatic screening, driven by Ca²⁺, contributed to the increased retention of CAC in the sand column. In contrast, when SRNOM was present at concentrations above 5 mg/L, CAC exhibited reduced deposition under high ionic strength conditions (100 mM), followed by markedly enhanced remobilization upon flushing with a low ionic strength solution. This behavior is primarily driven by increased electrosteric repulsion at the CAC–sand interface when the sand surfaces are coated by NOM. Atomic force microscopy (AFM) force measurements showed that under the same ionic strength, Ca²⁺ increased the work of adhesion between CAC and silica surfaces, whereas NOM decreased it. Our work underscores the critical influence of both the presence and concentration of Ca²⁺ and NOM on the deposition and remobilization behaviors of CAC, providing valuable insights into the engineering design and practical implementation of in situ CAC sorptive barriers for effective PFAS remediation.

The inhibition of nitrite-oxidizing bacteria (NOB) has long been regarded as a major challenge for achieving stable partial nitrification (PN) process. However, the persistence of NOB, even under inhibitory conditions, suggests its potential functional importance in PN systems. This study comparatively analyzed the response of PN systems from reactor performance to gene expression, under ammonium and nitrite shock loadings to elucidate the hidden role of NOB. Results demonstrated that PN systems exhibited greater resistance to nitrite shock, maintaining a 58.2% ammonium removal efficiency even at a nitrite concentration of 300 mg L^–1. But this resistance impaired when NOB activity was suppressed. Unlike elevated ammonium, high nitrite concentrations stimulated the expression of amo, hao, nirSK, norBC, and nosZ genes, enhanced ammonia monooxygenase and nitrite reductase activities, and improved the overall activity of ammonia-oxidizing bacteria (AOB). Isotopic analysis using ¹⁵N-labeled nitrite revealed the production of ³⁰N and ²⁹N, indicating that nitrite reduction mitigated nitrite toxicity to AOB. Notably, NO was identified as a potential signaling molecular mediating synergistic interactions between AOB and NOB, contributing to support system stability. Overall, this study provides unique insights into the functional role of NOB in improving the resilience and stability of PN systems under stress conditions.

High-valent metal oxidants (HVMOs) have attracted considerable attention in advanced oxidation processes (AOPs) due to their high selectivity for oxidizing organic pollutants. However, the pursuit of green and efficient activators, together with the clarification of external factors affecting HVMO performance, remains a major challenge in practical applications. In this review, we present a comprehensive overview of the chemical properties of HVMOs, with a particular emphasis on their oxidation characteristics, focusing on permanganate (MnO₄^–), ferrate (FeO₄^–), dichromate (Cr₂O₇^2–). We further analyze energy changes and redox potential variations during the oxidation process. Recent advances in the activation of HVMOs by metal-free carbon materials are summarized, and the potential effects of common coexisting substances in environmental matrices, such as H⁺, OH^–, inorganic anions, metal ions, and natural organic matter (NOM), are critically examined. Moreover, potential risks associated with residual HVMOs after organic pollutant oxidation are discussed, along with relevant separation and purification strategies. This review aims to deepen the understanding of HVMOs in environmental catalysis, explore their potential for resource recovery, and provide perspectives on future research directions and practical applications.

Water reclamation facilities contribute to the emission of greenhouse gases during the treatment of wet waste and following the release of the treated water effluent in receiving water bodies due to the high concentration of greenhouse gas precursors dissolved in the effluent. Here, an electrochemical cell was used to capture inorganic carbon dissolved in the treated liquid effluent discharged from four wastewater treatment plants. A pH gradient was induced in the effluent flowing in the electrochemical cell, facilitating the transformation of bicarbonate ions into carbon dioxide and solid metal carbonates that were removed from solution with overall efficiencies exceeding 57 ± 2% (96 ± 0.5% as gaseous CO₂ at the anode and 19 ± 4% as CaCO₃ at the cathode). Understanding how solution chemistry and electrochemical parameters dictated the performance of CO₂ capture allowed to optimize operational parameters and reactor architecture to minimize energy demand to 3.4 kWh/kg CO₂ with real treated effluents, a value that makes this approach competitive with current technologies for commercial CO₂ capture from the ocean or the atmosphere. Finally, performance stability was investigated by operating the cell for 55 h, quantifying carbon capture efficiency and energy demand over time. This study demonstrates for the first time that electrochemical CO₂ capture from treated water effluents provides an end-of-the-pipe decarbonization approach that, when implemented in conjunction with the use of renewable electricity, can accelerate the decarbonization of the water infrastructure and reduce the emission of greenhouse gases in the environment.

Recent advances in the electric vehicle technology and industry caused a substantial growth of the LIB market, which increased the demand for the key resources such as lithium, nickel, and cobalt. There have been significant efforts to recycle spent LIB electrodes in order to secure the supply chains of the resources and make LIB production and utilization cycles more sustainable. In this study, we developed processes for the selective recovery of lithium and nickel from the black mass produced from spent LIBs. By using HCl solution at the optimized conditions, leaching of lithium and nickel from the black mass could be performed with high selectivity over other metallic species. A flow-type integrated electrochemical system was prepared by using lithium nickel manganese oxide (LiNi_0.5Mn_1.5O₄) and titanium foil electrodes for lithium electrosorption and nickel electrodeposition, respectively. By cyclic operation of the electrochemical process, both lithium and nickel could be recovered effectively with reasonable energetics and stability, corroborating the capability of the integrated system.

The practical application of nanoscale catalysts in water treatment is hindered by challenges such as inefficient solid–liquid separation and aggregation-induced deactivation, while simultaneously the oxidation performance of peracetic acid (PAA) in complex wastewater matrices remains underexplored. Herein, we developed a fixed-bed continuous-flow reactor system utilizing millimeter-scale chitosan beads embedded with in situ synthesized cobalt–manganese spinel (CMO@CS). The beads exhibited enhanced catalytic activity (90.1% pollutant removal vs 66.1% for powdered CMO) and structural stability, effectively overcoming engineering bottlenecks of nanoparticle recovery and aggregation. The CMO@CS/PAA system achieved 85.6% removal of over 200 antibiotics, as confirmed by ultrahigh-resolution mass spectrometry (UHRMS), while simultaneously increasing the effluent C/N ratio through controlled carbon supplementation, thereby optimizing compatibility with downstream biological processes. UHRMS and three-dimensional fluorescence spectroscopy indicated that the system achieved a significant reduction in the dissolved organic matter molecular weight, effectively removing or converting macromolecules into small-molecule intermediates. Metagenomic analysis revealed a substantial 46% reduction in top 30 antibiotics resistance genes (ARGs) abundance, demonstrating the system’s capacity to mitigate ecological risks associated with horizontal gene transfer. This work establishes a scalable advanced oxidation process paradigm integrating pollutant elimination, microbial community regulation, and ARGs suppression, providing critical insights into the sustainable management of livestock wastewater.

Selective catalytic reduction of NO_x by ammonia under the exposure of alkaline and heavy metals in fly ash still remains a major challenge for NO_x elimination among air pollution control. Herein, self-protective NO_x reduction catalysts with remarkable alkaline and heavy metal resistance are originally designed by Ce and Cu dual active metal cations coexchanging attapulgite clays. It is revealed that the inherent Si–OH sites among attapulgite and partially exchanged Cu species effectively captured alkaline and heavy metal cation poisons through coordinate bonding or ion exchanging to protect the active components from being deactivated. Ultimately, highly efficient NO_x reduction for stationary source flue gas catalytic purification is realized via the ingenious design of dual metal exchanged clay catalysts that own self-protective capacity to resist alkaline and heavy metal poisoning. This strategy paves the way for the development of low-temperature and high-efficiency denitrification catalysts with alkaline and heavy metal resistance for stationary source flue gas purification.

Microalgae, particularly Chlorella vulgaris (CV), have gained increasing attention for their role in bioremediation and carbon sequestration due to their high photosynthetic efficiency, rapid biomass production, and ability to mitigate environmental contaminants. This study investigates the potential of an engineered nanoenabled microalgal system to enhance the simultaneous degradation of 2-nitroaniline (2-NA), a persistent nitroaromatic pollutant, and carbon sequestration under the influence of titanium dioxide nanoparticles (TiO₂ NPs). The experimental approach assessed the effects of TiO₂ NPs on CV growth kinetics, photosynthetic pigment synthesis, and CO₂ fixation rates while analyzing the degradation efficiency of 2-NA. Results revealed that 20 mg L^–1 TiO₂ NPs optimized algal growth and photosynthetic activity, leading to a 37.4% increase in biomass productivity and enhanced CO₂ sequestration rates compared to control. Extensive characterization including Raman and Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) confirmed TiO₂ NP interactions with algal cellular components, demonstrating maintained structural integrity and biocompatibility. However, coexposure to 2-NA induced oxidative stress, evidenced by significant upregulation of catalase (CAT) and superoxide dismutase (SOD) activities, indicating a defensive response. The TiO₂-integrated CV system demonstrated a 59.8% degradation efficiency of 2-NA at 10 mg L^–1, surpassing biological degradation alone (39%). These findings underscore the dual benefits of integrating nanotechnology with microalgal systems for environmental remediation, offering a circular bioeconomy approach that couples wastewater treatment with carbon capture.

Assessing the risks associated with antibiotic resistance genes (ARGs) in the environment remains challenging due to limited understanding of their distribution and transmission across various media, including wastewater, air, and biosolids. This study addresses this gap by systematically collecting samples from diverse environmental sources and investigating the dynamics of ARG transmission in wastewater treatment plants (WWTPs). A low-cost 3D-printed air sampler was developed using off-the-shelf components and evaluated alongside a commercial active air sampler under identical conditions. The custom sampler was equipped with interchangeable filters, including glass fiber and PVDF membranes, and showed comparable or better performance in terms of ARG detection. While only single 24-h sampling events were conducted per sampler, differences in ARG yield, microbial diversity, and assembly metrics were observed. Using metagenomic sequencing, air samples from locations near effluent discharge points and within biosolids processing areas, alongside wastewater samples, were analyzed. Genomic predictions and homology analyses revealed that ARGs are widely distributed across environmental media, with significant overlap between air and water samples. ARG abundance was higher in the biosolids processing area than at the effluent discharge point. This study introduces a cost-effective monitoring tool for airborne ARGs and provides novel insights into their environmental distribution and potential transmission in WWTPs, informing future risk assessment strategies.

H₂S reforming with CH₄ (H₂SMR) provides a viable approach for the elimination of hazardous H₂S and the direct utilization of sour natural gas, efficiently producing CO_x-free H₂ while simultaneously yielding high-value-added sulfur chemicals. Herein, MoS₂ catalysts enriched with edge sites and sulfur vacancy defects were fabricated via a cost-effective one-step solvothermal synthesis method and examined for the H₂SMR reaction. MoS₂ synthesized using ethylene glycol (EG) solvent (MoS₂-EG) presented oxygen doping and featured fewer layers and a larger interlayer spacing, thus possessing abundant active edge sites and sulfur vacancy defects. Consequently, MoS₂-EG demonstrated exceptional hydrogen production efficiency and stability, achieving a hydrogen yield of 8.5 mmol/(g min) at 900 °C and a H₂S/CH₄ molar ratio of 3. The abundant defects and edge sites in MoS₂-EG contributed to the facile H₂S activation to preferentially form reactive sulfur species for C–H bond activation, which is responsible for the superior H₂SMR activity. This study significantly advances the development of high-efficiency, scalable catalysts for H₂SMR, presenting a transformative approach to utilizing sour natural gas as a resource while addressing environmental challenges.