ACS ES&T water最新文献

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.

ZrO-Chelex diffusion gradient in thin film (DGT) probes and high-resolution peepers were used in this study for the synergy between phosphorus (P) and iron (Fe) at the water-sediment boundary (WSB) of the reservoir. A negative oxidation–reduction potential (ORP) across all sampling areas (SA) was observed, indicating hypoxic bottom waters. Positive flux values of Fe (41.75–63.50 mg/m²/day) and P (0.04–0.39 mg/m²/day) indicate their release from sediments into the overlying water column. A strong positive Pearson correlation existed between labile Fe and P across all sampling areas (p < 0.05), highlighting their coupled mobilization through reductive dissolution of iron oxyhydroxides (FeOOH). Spatial variations in the labile Fe:P slope revealed notable variations in P corelease efficiency, signifying how sediment iron dynamics impact P mobility. Strong correlation between dissolved organic carbon (DOC) and both labile Fe and P (0.7 ≤ r ≤ 0.9 for Fe-DOC and 0.6 ≤ r ≤ 0.9 for P-DOC, p < 0.05) indicated that organic carbon was a key driver of Fe and P mobilization. Ca²⁺ concentrations influenced P mobility by facilitating competing immobilization pathways, revealed by its negative correlation with P flux (r = −0.6). These findings provide a comprehensive framework for predicting nutrient fluxes and guiding water quality strategies in similar monsoonal ecosystems prone to black water formation.

Excess CO₂ emissions cause global warming, a catastrophic effect that leads to ocean acidification, agricultural losses, droughts, disrupted rainfall, and emerging diseases. This ultimately impacts biodiversity, human health, and environmental sustainability. Hence, it is essential to reduce CO₂ emissions to keep the planet cooler. Several countries set a carbon-neutral target of 50% by 2030 and net zero by 2070. To achieve carbon neutrality, several research communities and policymakers have developed innovative and economic solutions for carbon capture and sequestration. Biological carbon sequestration offers a more eco-friendly and sustainable approach to carbon capture than conventional methods. Microalgae act as potent biocatalysts, capturing CO₂ through photosynthesis and producing biomass. The produced biomass serves as a resource for producing carbon-neutral bioproducts. This Review focuses on advances in microalgae-mediated carbon capture, sequestration, various microalgae cultivation strategies, and underlying mechanisms. At the end of the paper, various CRISPR-Cas-based gene-editing strategies aimed at enhancing photosynthesis are discussed, with a focus on key enzymes involved in efficient carbon capture and sequestration. Additionally, we highlight how the biomass generated through carbon fixation can be utilized for diverse bioproducts and conclude by addressing the future research priorities needed to optimize microalgae-based carbon sequestration for economically and environmentally sustainable bioprocesses.

The growing demand for lithium-based materials stems predominantly from the rapid proliferation of renewable energy technologies. Given the growing demand for lithium, extracting the metal from salt lake brines has gained significant research attention. While positively charged nanofiltration (NF) membranes exhibit promising Mg²⁺/Li⁺ separation efficacy, the interfacial polymerization technique remains constrained by the inherent permeability-selectivity trade-off. This study optimized the microstructure and surface properties of the polyamide (PA) separation layer by regulating the additional amount of 3-aminobenzenesulfonamide (ABSA) based on the principle of hydrophilic steric dynamic equilibrium. The best-performing membrane, with 0.05 ABSA added, was the polyethylenimine (PEI)/trimesoyl chloride (TMC) NF membrane sample (PEI/ABSA-0.05-TMC), which retained 93.7% of Mg²⁺ and 28.4% of Li⁺. Compared to the PEI-TMC NF membrane without ABSA addition, water flux was increased from 12.5 L·m^–2·h^–1·bar^–1 to 17.7 L·m^–2·h^–1·bar^–1, MWCO was adjusted from 584 to 487 Da, and the corresponding separating factor of S_Li,Mg increased from 8.51 to 13.3. Throughout prolonged experimental trials, the PEI/ABSA-0.05-TMC NF membrane demonstrated sustained separation stability. This work establishes a robust framework for optimizing NF membranes, providing a strategic pathway toward Mg²⁺/Li⁺ separation technologies.

Groundwater pollution by natural arsenic can be induced by the reduction of subsurface iron oxides that host arsenic. Characterization of the chemical species of arsenic and iron in groundwater is critical to diagnosing the cause of arsenic mobilization and assessing the potential for downgradient attenuation. A streamlined plan is reported to preserve and analyze aqueous Fe(II), Fe(III), As(III), and As(V). In succinic acid, both Fe(II) and As(III) are stable for 9 days, allowing adequate time for the analyses. The revised Fe speciation is based on the o-phenanthroline (o-phen) method, with limits of quantitation (LOQ) of 0.2 and 0.07 μM for Fe(II) and Fe(III), respectively. This method can tolerate 100× of Ca²⁺, 100× of Mg²⁺, 100× of Mn²⁺, and 500× of F^–. The revised As speciation is based on the analysis of As(V) with mixed mode LC-ESI-MS. The LOQ for As(V) is 0.13 μM. A generic protocol has been developed to prepare synthetic groundwater with the desired compositions of 11 major ions. These methods have been applied to characterize the oxidation and sequestration of Fe(II) and As(III) in synthetic groundwater when exposed to air over 16 h.