ACS ES&T water最新文献

Selenium (Se) is an essential micronutrient but toxic at high concentrations, posing challenges for water treatment. This study investigated the removal of selenate (SeO₄ ^2-) and selenite (SeO₃ ^2-) using the strong-base anion-exchange resin IRA-900, particularly in the presence of competing sulfate (SO₄ ^2-). The performance of the commercially available resin IRA-900 was systematically investigated. The batch equilibrium behavior was studied in both single- and binary-component systems, and the kinetic behavior was investigated in single-component systems. Results confirmed a selectivity order of SeO₄ ^2- > SO₄ ^2- > SeO₃ ^2-, indicating preferential SeO₄ ^2- removal over competing SO₄ ^2- but lower affinity for SeO₃ ^2-. The maximum total exchange capacity was determined to be 2.04 mequiv/g. Furthermore, SeO₃ ^2- uptake was found to be pH-dependent, whereas SeO₄ ^2- uptake remained stable across a broad pH range. From a modeling perspective, the Law of Mass Action model effectively described equilibrium data, and a transport-reaction modeling framework captured removal kinetics of oxyanions including film and intraparticle diffusion. Finally, X-ray photoelectron spectroscopy confirmed ion exchange between chloride and Se oxyanions as the primary removal mechanism. These findings provide fundamental insights into the removal of Se oxyanions from aqueous solutions by ion exchange.

Sequencing batch reactors (SBRs) performing partial nitritation (PN) for treating high-strength ammonium wastewater are known to exhibit elevated levels of nitrous oxide (N₂O) emissions. This study investigated N₂O production and hydroxylamine accumulation in a PN-SBR operated using three distinct strategies. The N₂O emission factor (EF) and net production rate (N2OR) were determined under stable conditions for (i) single feeding with continuous aeration and one microaerobic stage before settling (strategy I), yielding EF = 4.4% and N2OR = 14 mg N g^-1 VSS d^-1; (ii) single feeding with multiple microaerobic stages distributed throughout the cycle (strategy II), yielding EF = 13.5% and N2OR = 85 mg N g^-1 VSS d^-1; and (iii) step feeding with one single microaerobic stage before settling (strategy III), yielding EF = 10% and N2OR = 45 mg N g^-1 VSS d^-1. The distribution of microaerobic stages throughout the cycle (strategy II) promoted the highest hydroxylamine accumulation (0.18 mg N L^-1) during the aerated stage, whereas strategy I showed the lowest accumulation (0.01 mg N L^-1). A strong positive correlation (R ² ≥ 0.9) was observed among the specific ammonium oxidation rate (AOR), specific N2OR, and bulk liquid hydroxylamine concentration during the aerated stages.

Climate change-related increases in organic carbon in surface waters may present challenges in meeting regulatory requirements with regard to drinking water quality. Treatment adaptation that alters natural organic matter (NOM), metal oxides, and water chemistry can have a downstream influence on lead release. We compared the effect of the coagulant and filter type on water quality and lead release in a galvanic lead solder-copper system. Aluminum sulfate (alum), polyaluminum chloride (PACl), anthracite/sand, and granular activated carbon (GAC) were tested in a pilot-scale system. Lead release was evaluated in a bench-scale dump and fill experiment with treated water dosed with 0-2 ppm zinc-orthophosphate. GAC contactors reduced organic carbon in both systems and had a strong protective effect on lead release, likely due to less NOM complexation and improved orthophosphate performance. At equivalent Al doses, organic carbon removal was comparable between PACl and alum, but PACl showed slower GAC exhaustion rates, improving the removal efficiency. PACl was linked with increased galvanic corrosion due to higher CSMR. Zinc-orthophosphate mitigated galvanic corrosion of lead solder. Treatment facilities can decrease lead release by removing NOM, but alternative coagulants that may be considered for enhanced NOM removal can increase the chloride concentration and have detrimental effects as well.

Properly operated and maintained drinking water distribution system (DWDS) storage tanks are crucial for allocating safe drinking water, but varying operational processes and infrequent maintenance can result in water quality degradation, including disinfectant residual loss, sediment accumulation, bacterial growth, and potential contamination. This study assessed how the physical, chemical, and hydraulic characteristics of representative chlorinated DWDS tanks relate to bacterial communities in water and sediment; investigated water quality variation by depth within tanks; and explored the infrastructure and management characteristics influencing bacterial community composition in tanks. Bulk water and sediment samples were collected from seven tanks in a chlorinated DWDS system, and 16S rRNA gene amplicon sequencing was used to characterize the bacterial community. Bulk water and sediment communities were distinct, dominated by Alphaproteobacteria and Gammaproteobacteria, respectively. Spatial variations as a function of distance from the treatment plant, tank-specific characteristics, and sediment accumulation were found to shape bacterial communities within tanks. Total coliforms and Escherichia coli were undetectable in all water samples, but genetic signatures indicated the presence of multiple genera associated with opportunistic pathogens (OPs). This study aims to establish a deeper understanding of the bacterial community within DWDS tanks and the impact that tank conditions and characteristics have on DWDS water quality.

UV light-based advanced oxidation processes have shown considerable promise for mitigation of trace organic contaminants (TrOCs). Recent work has garnered interest in ambient NO₃ ^- as a photooxidant within UV treatment processes. This work provides a systematic investigation on the efficacy of NO₃ ^- as a photooxidant for removal of aqueous 17β-estradiol (17β-E2) and its metabolites, estrone (E1) and estriol (E3). Results demonstrate that even low (1 mg L^-1) concentrations of NO₃ ^- enhance degradation of 17β-E2 by >48% during medium-pressure UV (MP UV) treatment in comparison to control conditions, and NO₃ ^- concentrations ≥5 mg L^-1 resulted in >90% removal of 17β-E2 at fluences ≥1000 mJ cm^-2. Three photoproducts consistent with known nitrogenous byproducts of 17β-E2 were also observed throughout treatment and found to persist even under high (2000 mJ cm^-2) fluence conditions. In a municipal wastewater matrix, estrogen removal was improved under high (25 mg L^-1) NO₃ ^- conditions as compared to ambient (∼3 mg L^-1) levels. This work demonstrates the utility of NO₃ ^- as an in situ photooxidant for removal of TrOCs such as steroid estrogens in real waters and provides an impact to stakeholders interested in leveraging these processes in complex matrices such as municipal wastewater.

Removal of carcinogenic arsenic (As) from groundwater is essential for providing safe drinking water. Arsenate (As-(V)) is more effectively removed in groundwater filters than arsenite (As-(III)), making the oxidation of As-(III) to As-(V) a key step in the treatment process. This study distinguishes between surface-catalytic and biological As-(III) oxidation on natural manganese oxide (MnO _x ) coated filter sand, since it is unknown which pathway dominates in filters. The MnO _x coated sand was collected from a full-scale groundwater filter and consisted of a mixture of different abiotically and biologically formed Mn oxides, such as Birnessite and Todorokite. A lab-scale filter setup was operated with As-(III)-containing water. Within 3 weeks, a shift from surface-catalytic to biological As-(III) oxidation was observed. Initially, surface-catalytic As-(III) oxidation (k _CHEM = 0.318 min^-1) was coupled to Mn-(II) release at a ratio of 0.96, approximating the stoichiometric ratio of 1. This coupling disappeared over time, indicating the biological nature of the reaction, as confirmed by microbial inhibition. An increase in relative abundance of the known As-oxidizing families Comamonadaceae, with Polaromonas as the dominant genus, and Microscillaceae were found post experiments. Except for these changes, the microbial community on the sand grains stayed relatively similar prior to and post experiments. No significant changes in the physical-chemical properties of the MnO _x coating were found post experiments. A first-order biological As-(III) oxidation rate constant k _BIO of 4.64 min^-1 was found, yielding a half-life of 9 s. This represents a 14-fold acceleration compared with surface-catalytic oxidation, revealing that kinetic limitations rather than surface passivation can be attributed to the loss of surface-catalytic oxidation. Our study demonstrates that biological oxidation of As-(III) can outpace the acknowledged oxidizing power of MnO _x , offering a potential new pathway for the development of effective As removal systems.

Monitoring surface water temperature (SWT) in transitional environments remains challenging due to the interplay of natural and anthropogenic processes, which introduce greater complexity than in open-ocean systems. This study evaluates four SWT products for their ability to capture temperature dynamics in the Venice Lagoon, a well-monitored coastal system. The assessment included (1) output from the hydrodynamic model SHYFEM (System of Hydrodynamic Finite Element Module), (2) a satellite-based Level 4 product from the European Space Agency Climate Change Initiative (ESA CCI), (3) the Landsat 8 Level 2 standard thermal product, and (4) Landsat 8 Level 1 data processed using the Thermal Atmospheric Correction Tool (TACT). Validation against in situ observations indicated that SHYFEM and TACT showed lower bias (-0.48 °C and -0.30 °C, respectively) and RMSE (∼1.2 °C) than the other products. SHYFEM effectively reproduced intra-annual SWT trends with comprehensive temporal coverage, while TACT captured fine-scale spatial features, including thermal anomalies from industrial discharges. Building on this, an integrated product combining SHYFEM and TACT was developed, providing a more accurate and coherent representation of spatiotemporal SWT dynamics. This transferable framework advances understanding of thermal variability in transitional waters and has potential to support ecosystem management and climate adaptation strategies.

Surface water-based utilities increasingly face challenges in drinking water production during prolonged droughts and heavy rainfall events. We assessed the impact of climate and hydrological variability on trihalomethane (THM) levels in two drinking water treatment plants in Barcelona: one river-based (Llobregat plant) and one reservoir-based (Ter plant). We examined data from 15 years (2010-2024) using generalized additive models (GAMs) to evaluate the change (β) in chloroform, bromodichloromethane, dibromochloromethane, bromoform, and total THMs (THM4), by extreme (≤percentile 10, ≥percentile 90) hydrometeorological predictors, including temperature, river flow, or reservoir level relative to normal conditions (P10-P90), and the Standardized Precipitation Evapotranspiration Index (SPEI 1). In the Llobregat plant, THMs were unaffected under low river flow events (≤P10), while THM4 decreased by -1.41 (confidence interval (CI) 95%: -2.77, -0.05) during high river flow events (≥P90), mainly driven by bromoform (β: -2.64, CI 95%: -3.61, -1.67). In the Ter plant, THM4 increased by 1.64 (CI 95%:0.09, 3.19) and 4.08 (CI 95%:0.83, 7.33), respectively, under high (≥P90) and low (≤P10) reservoir levels. Overall, moderate effects of extreme weather events on THM levels were observed, attributed to climate-resilient water management strategies. Further research is needed in other settings with diverse water sources and management.

Despite advances in the removal of pharmaceutical residues from aqueous effluents, carbamazepine (CBZ) remains challenging due to its persistence. The low removal efficiency of conventional wastewater treatments reinforces the need to develop innovative approaches, such as hybrid systems. This study combined photo-Fenton reactions with the enzyme laccase (Lac) to effectively remove CBZ from aqueous solutions in batch and continuous-flow regimes. Lac was immobilized on functionalized magnetite nanoparticles (MNPs) to improve stability and operational efficiency. Investigation of the effects of pH, temperature, UVC radiation, and H₂O₂ dose on Lac activity revealed promising results. Immobilized Lac retained 77.7% of its initial activity after 60 min of UVC exposure. In contrast, the free enzyme lost its activity within 30 min of exposure. In batch mode, the Lac-MNPs/UVC/H₂O₂ system with 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as the inducer degraded 91.9% of CBZ in 15 min of reaction at neutral pH. For continuous operation mode, optimization based on a Central Composite Rotatable Design achieved 91.1% CBZ removal at 10 min space-time, 20:1 H₂O₂:CBZ molar ratio, and 30 μmol L^-1 ABTS. The high removal efficiency in both batch and continuous modes indicates the potential application of the developed hybrid laccase-photo-Fenton treatment for effective CBZ degradation.

To advance a nitrogen circular economy, wastewater treatment plants (WWTPs) must use technologies that recover waste nitrogen and transform it into valuable products. One emerging option is partition-release-recover (PRR) technology. It transforms waste nitrogen into cyanophycin-accumulating organism microbial protein (CAO MP), which can be used as a protein source in animal feed. In this study, we perform a life cycle assessment and techno-economic analysis of a prospective WWTP configuration that incorporates this technology and assess whether it merits further development. Conventional activated sludge and anaerobic/anoxic/oxic WWTP systems are comparator baseline systems. We compare CAO MP to five different protein sources (soybean meal, alfalfa feed, fishmeal, cottonseed feed, and dried distiller grain solubles). The PRR approach has a median GWP that is 1-32% lower than the comparator WWTP systems. The median levelized cost of wastewater treatment using the PRR technology is 34-58% lower than the A²O configuration. Finally, CAO MP shows substantially lower global warming potential and water consumption compared to traditional protein sources. We conclude that the PRR pathway to transform waste nitrogen into CAO MP is a promising pathway toward more sustainable nitrogen recovery technology and protein production, warranting further research and development.