ACS ES&T water最新文献

Microplastics (MPs) pollution has become an urgent global environmental issue due to its widespread distribution and persistence in aquatic ecosystems. Although there is growing interest in remediation technologies, effective methods for microplastic (MP) removal remain limited. In this study, we report for the first time the application of bath-type ultrasonication for MP remediation, representing a novel and chemical-free approach in this field. Results demonstrated that ultrasonic treatment effectively removed MPs from water within 5 s, with removal efficiency positively correlated with particle concentration and strongly influenced by material density─achieving over 90% removal for high-density polyvinyl chloride (PVC), while only ∼13% for low-density polyethylene (PE). Interestingly, under the tested power level of 500 W, the removal efficiency was largely independent of treatment duration, and no significant difference was observed between 200 and 500 W. The removal mechanism was attributed to ultrasound-induced particle motion that facilitated agglomeration and subsequent sedimentation. This pioneering work fills a critical knowledge gap in the ultrasonic remediation of MPs pollution and introduces a new physical treatment method for addressing this pressing environmental challenge.

Antibiotic resistance is a growing threat to public health, and environmental factors, including metals in drinking water distribution systems, are increasingly recognized as contributors to the spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Zinc orthophosphate, a common corrosion inhibitor, and copper corrosion products (CuO and Cu₂O) are frequently present in drinking water systems. While each has been shown to increase ARB and ARGs individually, their combined effects remain unknown. The objective of this study was to evaluate the combined impact of copper corrosion products and the corrosion inhibitor zinc orthophosphate on antibiotic resistance. Two sets of lab-scale microcosms were used, in which CuO and Cu₂O were added with and without zinc orthophosphate, and impacts on ARB abundance, ARG abundance, and microbial community structure were assessed. Overall, the combined addition of copper corrosion products and corrosion inhibitor increased ARB and ARGs, coinciding with changes to the microbial community’s β-diversity. In most cases, the coaddition of the corrosion product with the corrosion inhibitor resulted in greater changes in antibiotic resistance abundance than the addition of the corrosion product alone. This research improves our understanding of how the coexistence of metal corrosion products and corrosion inhibitors in drinking water pipes can impact antibiotic resistance.

The coexposure of copper corrosion products and zinc orthophosphate, common in drinking water systems, increases antibiotic-resistant bacteria and antibiotic-resistant genes and alters microbial communities.

Most data on laboratory-scale experiments evaluating E. coli and enterococci disinfection are from experiments conducted using laboratory-cultured bacteria. However, environmental bacteria, such as those in wastewater, have potential to be more resistant to disinfection than their laboratory-cultured counterparts. Additionally, most Enterococcus disinfection studies have only evaluated E. faecalis despite the diversity of Enterococcus species in the environment. In this study, we evaluated inactivation kinetics of wastewater-sourced E. coli and enterococci, laboratory-cultured E. coli, and three species of laboratory-cultured Enterococcus with exposure to free chlorine, monochloramine, UVC, and simulated sunlight. All bacteria were purified and suspended in a chlorine-demand-free buffer with minimal light attenuation to allow comparison between populations without confounding matrix effects. Laboratory-cultured bacteria were more susceptible to the oxidants than the wastewater-sourced bacteria, highlighting that research using reference-strain bacteria in the laboratory may not reflect inactivation kinetics in the environment. When exposed to the light-based disinfectants, only laboratory-cultured E. coli and E. faecalis were more susceptible than the wastewater-sourced bacteria. Notably, different laboratory-cultured Enterococcus species had different inactivation rates, with E. faecalis being the most susceptible. These findings highlight the importance of incorporating indigenous environmental bacteria in laboratory studies and assessing a variety of Enterococcus species in disinfection research.

Environmental bacteria in wastewater can have slower disinfection kinetics than bacteria grown in the laboratory and should be included in laboratory-based experiments evaluating the mechanisms and kinetics of disinfection.

Landfill leachate is a major source of refractory dissolved organic nitrogen (rDON), which can exacerbate eutrophication and harmful algal blooms in downstream aquatic ecosystems. This study evaluates the effectiveness of two advanced physicochemical treatments─Fenton oxidation and granular activated carbon (GAC) adsorption─for rDON removal from biologically treated landfill leachate blended with sewage, and their impacts on the estuarine algal (phytoplankton) community with in situ algal bioassays. Fenton oxidation achieved 52%–60% rDON removal by converting rDON into ammonium nitrogen (NH₄⁺-N), enhancing its biodegradability and suitability for subsequent biological treatments. In contrast, GAC adsorption achieved higher removal efficiencies (86%–92%) by physically adsorbing nitrogenous species, including rDON and NH₄⁺-N, without altering their chemical structure. We deployed in situ algal bioassays to analyze the impacts of advanced wastewater treatment processes on the algal growth dynamics. Bioassays revealed distinct effects on algal growth: Fenton treatment temporarily increased algal biomass due to elevated NH₄⁺-N levels, while GAC treatment mitigated nutrient availability, inhibiting algal proliferation. While GAC was more effective overall, its regeneration requirements and associated costs pose applicability challenges. Fenton treatment is best suited as a pretreatment step to enhance rDON biodegradability.

This study evaluated two advanced treatment technologies for refractory dissolved organic nitrogen and analyzed their impacts on algal (phytoplankton) growth dynamics with the application of an in situ algal bioassay.

Thallium (Tl) is a toxic element typically enriched in sulfide minerals and ferromanganese oxides, and its immobilization depends largely on the stability of thallium sulfide (Tl₂S) under various environmental conditions. This study examines Tl(I) immobilization using ferromanganese sulfides, focusing on the effects of Fe/Mn/S molar ratios, oxygenation levels, and stirring intensity on Tl₂S stability. Under anaerobic conditions, Tl(I) immobilization efficiency reached 96.1 ± 0.3% in 14 days and increased to 99.4 ± 0.2% over 6 months. Under microaerobic and aerobic conditions, efficiencies decreased to 85.7 ± 0.4 and 83.4 ± 0.8%, respectively. Oxygen facilitated the formation of Fe/Mn (oxyhydr)oxides, a sink for Tl(I), primarily present as ≡FeOTl and ≡MnOTl. Continuous stirring enhanced the removal of Tl(I) under anaerobic conditions, whereas static conditions favored Tl(I) immobilization in aerobic environments. Under aerobic conditions, sulfides were oxidized into elemental sulfur (77.2%) and sulfate (11.7%), leading to Tl(I) dissolution and an impact on its immobilization dynamics. Pb²⁺, Hg²⁺, Cu²⁺, Ni²⁺, and Zn²⁺ further promoted Tl(I) dissolution through competitive adsorption and a reduction in solution pH. Key strategies for Tl(I) immobilization include maintaining low dissolved oxygen and redox potential levels, enhancing surface hydroxyl complexation, and promoting sulfide-induced precipitation and electrostatic adsorption. This study provides insights into Tl(I) immobilization dynamics within complex Fe–Mn–S systems subjected to redox cycling and varied environmental conditions.

Electrodialysis (ED) is a promising technology for the recovery of ammonia from wastewater. However, separating ammonia directly from complex wastewater mixtures using ED is challenging due to membrane scaling, low selectivity, and high energy consumption. Here, we evaluate the potential of electrodialysis for ammonia recovery from simulated and real wastewater mixtures. The specific energy consumption (SEC) of electrodialysis exceeded 31 kWh/kg-N for simulated wastewater but decreased 4-fold to 7 kWh/kg-N after hardness removal. Concentration factors (CFs), the final concentration relative to the initial concentration, of NH₄⁺ for real wastewater after ultrafiltration and for synthetic wastewater without hardness were 7.5 and 10, comparable to the CF of 9 for single-salt solutions (nonmixtures). We find that the concentrated product after ED with real and simulated synthetic wastewater includes K⁺ and Na⁺, as cation exchange membranes exhibit K⁺/NH₄⁺ and Na⁺/NH₄⁺ selectivities near one. Thus, if the concentrated product is directly used as an aqueous fertilizer, the resulting product will be 30/30/30 for Na⁺, K⁺, and NH₄⁺. Finally, staged electrodialysis achieved a CF of ∼50 (2.42 N wt %) with SECs of 15.2–18.1 kWh/kg-N for synthetic wastewater without hardness, demonstrating promise for recovering ammonia from wastewater with a high concentration and low energy demand.

Recovering ammonia from wastewater with electrodialysis requires pretreatment of hardness to reduce energy consumption.

The development of low-cost and practicable technologies for the treatment of wastewater will be essential to ensure the adequate disposal of the residues generated by carwash businesses. The present study developed a novel wastewater treatment system, based on the Depth Filtration with a Moderate Application Rate (DFMR), which is a low-cost alternative for the treatment of carwash wastewater with simple operational and servicing technology. The proposed system was composed of sequential depth filtration units, containing gravel, zeolite, and activated charcoal as the filtration media. A parallel system, composed of additional gravel and zeolite filters, was also installed, to provide an operational safety valve. At an application rate of 45.7 m³.m^–2.day^–1, the system obtained 90.8% efficiency for the reduction of turbidity, and 72.4% for the removal of COD and 54.9% for surfactants, achieved exclusively by the application of a depth filtration process. These results highlight the potential of the proposed system as a low-cost and practicable alternative for the adequate treatment of wastewater produced by small- and medium-sized carwash businesses.

The proposed depth filtration technology offers an innovative, efficient, and affordable solution for the treatment of carwash wastewater.

Groundwater contamination from industrial effluents, agricultural runoff, and landfill leachate threatens water quality and public health. Aligning with United Nations Sustainable Development Goal 6 (UN SDG 6) on clean water and sanitation, this study evaluates groundwater quality in and around the Brahmapuram landfill (Kochi, Kerala, India) with respect to Indian and World Health Organization (WHO) standards. Comprehensive physicochemical analysis, water quality index (WQI) assessment, correlation matrix, and statistical evaluations were conducted to analyze key water quality parameters. WQI analysis indicated that 40% of the samples exhibited poor to very poor quality, rendering them unsuitable for direct consumption without treatment. Spatial distribution maps for pH, temperature, color, total alkalinity, total hardness (TH), chloride, sulfate, dissolved oxygen, biochemical oxygen demand (BOD), and turbidity were developed using QGIS, contamination hotspots were identified. A strong correlation between TH and sulfate (r = 0.83) suggested common contamination sources. Significant variations in chloride and hardness levels were also observed. The findings highlight the urgent need for leachate control, sustainable water management, and stricter landfill regulations, particularly following incidents such as the Brahmapuram landfill fire outbreak. Beyond its regional significance, this study provides a replicable framework for assessing landfill-induced groundwater pollution and supports evidence-based governance.

Despite the significant demand, accurate determination of the permanganate index in high-chloride bodies of water remains extremely limited. This study introduces an iodine-thiosulfate method that effectively eliminates the interference of chloride ions in the permanganate index determination. In this method, organic and inorganic substances in a water sample are oxidized with KMnO₄ in an alkaline medium to mitigate chloride ion interference. To further minimize this interference during back-titration, the remaining KMnO₄ is reduced using KI under adjusted acidic conditions. The released iodine is then titrated with standardized Na₂S₂O₃ until the starch–iodine complex’s blue–black color disappears. The iodine-thiosulfate method demonstrated a method detection limit of 0.4 mg L^–1 (n = 7) and a corresponding interlaboratory quantification limit of 1.6 mg L^–1 in water samples with chloride concentrations of 5000 mg L^–1. The method’s precision and accuracy ranged from 1.4% to 6.7% and −1.0% to 5.0%, respectively. The relative error in permanganate index determination remained below 20% even at chloride concentrations up to 60 g L^–1, whereas the conventional oxalate-permanganate method exceeded a 20% relative error once the chloride concentration reached 10 g L^–1 or higher. The sufficiently low detection limit along with excellent repeatability (intralaboratory precision), reproducibility (interlaboratory precision), and accuracy confirms its practical feasibility for routine analysis.

Environmental waters contain diverse microbial and macrobial DNA, necessitating methods capable of efficiently concentrating various organisms, cells, and free DNA. This study compared hollow fiber ultrafiltration (HFUF) and syringe microfiltration (MF) for recovering microbial and macrobial cells and DNA from surface water and stormwater runoff. Performance was assessed by quantifying a spiked virus (phiX174), naturally occurring E. coli, bacterial 16S rRNA genes, and crAssphage, along with metabarcoding of mitochondrial DNA and full-length 16S rRNA genes. The syringe MF method showed higher recovery and quantitative accuracy for bacterial and viral targets but suffered from membrane clogging, reducing DNA extraction efficiency. HFUF had higher sensitivity for low-abundance targets, particularly E. coli, due to its greater concentration factor. However, it was more prone to PCR inhibition, especially for long-fragment targets. Metabarcoding demonstrated that both methods captured microbial and macrobial community composition, although HFUF detected more fish DNA and a slightly greater number of bacterial genera. Overall, syringe MF is more suitable for accurate quantification, while HFUF is better for detecting low-abundance and small targets. The choice of method should be based on study objectives, target organisms, and trade-offs among recovery efficiency, DNA extraction, and PCR performance.