ACS ES&T water最新文献

Elevated conductivity (i.e., specific conductance or SC) causes osmotic stress in freshwater aquatic organisms and may increase the toxicity of some contaminants. Indices of benthic macroinvertebrate integrity have declined in urban areas across the Chesapeake Bay watershed (CBW), and more information is needed about whether these declines may be due to elevated conductivity. A predictive SC model for the CBW was developed using monitoring data from the National Water Quality Portal. Predictor variables representing SC sources were compiled for nontidal reaches across the CBW. Random forests modeling was conducted to predict SC at four time periods (1999-2001, 2004-2006, 2009-2011, and 2014-2016), which were then compared to a national data set of background SC to quantify departures from background SC. Carbonate geology, impervious cover, forest cover, and snow depth were the most important variables for predicting SC. Observations and modeled results showed snow depth amplified the effect of impervious cover on SC. Elevated SC was predicted in two-thirds of reaches in the CBW, and these elevated conditions persisted over time in many areas. These results can be used in stressor identification assessments to prioritize future monitoring and to determine where management activities could be implemented to reduce salinization.

We investigate the effects of seasonal variations in water composition and temperature on the performance of two full-scale drinking water treatment plants in Scotland, equipped with tubular cellulose acetate nanofiltration membranes. Multiple environmental and water quality parameters, recorded over a 4.5-year period, were correlated against membrane permeance, cleaning frequency, and useful life. Membrane autopsies enabled the characterization of the foulant composition. Temporal variations in temperature at plant X led to significant biofouling (manifested by permeance losses of 30-50%, and bacteria detected on the membrane surface) during the summer months, when water temperatures exceeded 20 °C and microbiological activity was highest. Plant Y, in contrast, displayed smaller seasonal variations and was operationally stable without significant fouling. A pronounced increase in manganese and iron (up to 200 and 600 μg/L, respectively) in the lake water at plant X in summer was accompanied by elevated content (∼60 mg/m²) of those metals on the membrane surface, which was consistent with lake thermal stratification and metal input from the sediment into the water column. Our work shows that membrane plants in regions supplied by standing surface water bodies, such as plant X, are more vulnerable to biofouling, especially during warmer months.

UV-advanced reduction processes (UV-ARP), characterized by the strongly reducing aqueous electron (e_aq ^-), have been shown to degrade perfluoroalkyl and polyfluoroalkyl substances (PFAS). Due to the high cost of PFAS destruction technologies, concentrated waste streams derived from physical treatment processes, such as ion exchange or membrane concentrates, are promising targets for implementation of these technologies. However, there are limited studies on the application of UV-ARP for PFAS destruction in concentrated waste streams. This study evaluates the effectiveness of the UV/sulfite ARP in reverse osmosis concentrate (ROC) containing high concentrations of dissolved organic carbon (DOC), nitrate, and carbonate species, spiked with mg/L concentrations of perfluorooctanesulfonic acid, perfluorobutanesulfonic acid, perfluorooctanoic acid, and perfluorobutanoic acid. We demonstrate that hardness removal and preoxidation of ROC with UV/persulfate enables >90% PFAS defluorination within 24 h of subsequent UV/sulfite treatment, a 3-fold enhancement in defluorination % compared to UV/sulfite treatment without preoxidation. This enhancement is shown to result from abatement of the light shielding and e_aq ^- scavenging capacity of DOC during UV/persulfate oxidation. Collectively, these results demonstrate that appropriate pretreatment steps increase the effectiveness of PFAS destruction using UV-ARP, supporting the application of UV-ARP for PFAS destruction in ROC and other concentrated waste streams.

Surfactants are amphiphilic molecules that adsorb to interfaces and affect the interfacial tension. Surfactants in seawater can impact gas-exchange, surface properties, and the composition and fate of sea spray aerosol. The accurate quantification of surfactants and their classes is crucial to constraining the effect of surfactants in seawater and their role in air-sea exchanges. Here, we evaluate and optimize a solid phase extraction (SPE) method paired with colorimetry and UV-vis spectroscopy to quantify the concentrations of anionic, cationic, and nonionic surfactants in seawater. We compare tandem SPE with two-step SPE and different elution volumes and evaluate the impact of different interferents. Improved extraction efficiencies were obtained with an 8 mL acetonitrile elution and with separate ENVI-18 and ENVI-Carb extractions, instead of tandem. With complex surfactant mixtures, the presence of anionic surfactants interfered with the quantification of cationic surfactants and caused underestimations of up to 83%. Using a two-step extraction and analyzing each seawater SPE extract separately during colorimetric quantification help avoid the effects of interferents and ensure more representative quantification of surfactants. With this method, average seawater surfactant concentrations ranged from 0.04 to 0.06 μM. At the highest concentrations, the class composition comprised 23% anionic, 21% cationic, and 56% nonionic surfactants.

Per- and polyfluoroalkyl substances (PFAS) make up a large class of anthropogenic micropollutants prevalent in wastewater. Oxidative processes commonly used in wastewater potable reuse treatment may affect transformation of PFAS precursors, leading to elevated concentrations of perfluorinated alkyl acids (PFAAs) that are significant health concerns. This work conducted a pilot-scale investigation to assess the influence of ozonation (O₃) and ozone/hydrogen peroxide (O₃/H₂O₂) advanced oxidation process (AOP), respectively, on the fate of PFAS in a wastewater effluent subjected to reuse. The study evaluated 40 target PFAS and associated precursors [based on the total oxidizable precursor (TOP) assay] under various treatment conditions, including different ozone doses (1.0-4.0 mg·L^-1), H₂O₂ doses (0-0.20 mg·L^-1), and contact time (0-20 min). Results indicated that short-chain (C3-C7) PFAAs dominated in concentrations, while overall PFAA concentrations were elevated by both oxidative treatment processes, particularly after high-dose ozonation treatment. TOP assays revealed that there were considerable amounts of PFAA precursors in the reuse wastewater, and their concentrations were decreased after the oxidative treatment with an increase of some of the PFAAs. This pilot study demonstrated that ozone and ozone-based AOP treatments can have a moderate influence on the transformation of PFAS and increase in PFAA levels under practical conditions.

Although free amino acids (FAAs) are known as an important precursor of nitrogenous disinfection byproducts (N-DBPs), their levels and composition in source water as well as their contributions to drinking water N-DBPs are not clear. This review provides a summary of occurrence and compositions of FAAs in different water sources as well as their molar yields and contributions to N-DBPs formation. Moreover, the impacts of advanced oxidation processes (AOPs) on N-DBPs formation are also summarized. The average concentrations of FAAs in rivers, lakes, and reservoirs were 439, 402, and 370 nM (about 56.2, 51.5, and 47.4 μg/L), in which cysteine, ornithine, alanine, glutamic acid, and serine were dominant among individual FAAs, with an average level of 25.6, 8.6, 6.2, 6.0, and 5.3 μg/L, respectively. During the chlorination process, the molar yields of FAA for dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dichloroacetamide (DCAM), and trichloronitromethane (TCNM) were not detectable (ND)-7.1, ND-3.55, ND-0.93, and ND-1.99 μmol/mmol, respectively, contributing 7.0%, 11.9%, 0.3%, and 10.3%, on average, to drinking water N-DBPs. During chloramination, the molar yields of FAA fall within ND-5.55, ND-3.55, 0.4-176, and ND-1.52 μmol/mmol, constituting on average 5.3%, 18.4%, 0.8%, and 3.0% of DBPs’ formation in drinking water. The information provided may help enrich the knowledge of FAAs and gain insights toward the importance of FAAs in forming N-DBPs.

Coagulation is widely used in water treatment, generating large volumes of water treatment residual (WTR), most of which is aluminum salt-based water treatment residual (Al-WTR). This waste is environmentally and financially costly to manage. Al-WTR, however, can be upcycled into value-added products such as ceramsite, a porous material that can be used for adsorption or other beneficial purposes. Here, we review the fabrication processes for transforming Al-WTR into ceramsite, the strategies for enhancing its performance, and its potential environmental applications. Ceramsite has exhibited potential as an adsorbent in removing pollutants such as phosphorus and heavy metals as well as being a biofilm-supporting medium. Moreover, ceramsite has shown the effective removal of emerging pollutants from water matrices. Therefore, ceramsite represents a promising strategy for valorizing Al-WTR. Further investigations are required to improve the ceramsite performance and assess its applicability in environmental engineering. Furthermore, we also discuss the current challenges and barriers associated with the application of the Al-WTR-derived ceramsite and possible mitigation strategies. This Review aims to stimulate further research and development in sustainable WTR management, thereby contributing to the development of a circular economy in the water treatment sector.

Managing contamination by urban storm runoff is challenging because of numerous contaminant sources, the first flush phenomenon, and the fast drainage of stormwater by storm sewers. This paper presents the results of laboratory batch, column, and flow-through tests involving a novel in situ chemical oxidation scheme that combines oxidation and slow-release systems to reduce organic pollutants in urban storm runoff. In batch tests, the persulfate/iron system yielded the best overall removal efficiencies for benzene, toluene, ethylbenzene, xylene, and naphthalene, although the removal rates rapidly decreased after 2 to 3 min due to oxidation of ferrous iron in the solution. Slow-release persulfate (SRP), slow-release hydrogen peroxide (SRH), and slow-release Fe²⁺ (SRI) were created by dispersing salts in paraffin wax matrices in a cylindrical mold. Results of column tests indicated that the slow-release forms could release oxidants and Fe²⁺ in a controlled and continuing manner, and the release rates are constrained by the solubility of the dispersed salts and the mixing ratios of the salts and matrices. In the flow-through remedial tests, 89% of naphthalene, ethylbenzene, and xylene, 83% of toluene, and 73% of benzene were removed within 20 min when SRP and SRI were used together. These results suggested that the slow-release oxidants could be installed in multiple storm sewer inlets to rapidly reduce any oxidizable pollutants in storm runoff.

Climate change poses challenges to infrastructure resilience in Southeast Asia’s flood-prone regions. This study identifies and evaluates strategies for enhancing infrastructure resilience through wastewater treatment plants (WWTPs) in Singapore, Malaysia, Thailand, and Indonesia. Using a mixed-method approach, we analyzed the case studies and conducted quantitative assessments of flood mitigation efforts. Data were collected (2021–2024) through site visits, interviews with key stakeholders, and analysis of historical flood and infrastructure performance data. Data analysis involved statistical methods for assessing their effectiveness and comparative analyses across them. Singapore reduced flood-prone areas by 30% using integrated WWTP technologies with drainage systems, while Malaysia developed resilient infrastructure networks with WWTPs designed to withstand extreme weather, preventing 85% of contamination cases. Thailand combined green and blue infrastructure with WWTPs, decreasing flood vulnerability by 25%. Indonesia invested in decentralized WWTPs in urban areas, increasing infrastructure resilience by 40%. Nature-based solutions, such as ecological restoration, reduce flooding impacts by 20%. The implications for policymakers and practitioners include the need to integrate advanced technologies and nature-based solutions to bolster infrastructure resilience and mitigate flooding risks. This study offers insights into developing effective climate change adaptation strategies in flood-vulnerable regions, emphasizing the critical role of WWTPs in enhancing infrastructure resilience.