Environmental Science: Water Research & Technology最新文献

Ammonia recovery from various waste streams offers a promising pathway to move towards a more sustainable fertilizer production while minimizing the heavy reliance on fossil fuels. Several electrochemical methods have demonstrated promise over existing biological and physicochemical approaches due to the ability to separate and convert ammonium to ammonia via electrochemically mediated processes. However, the performance is generally standardized only to energy consumption that may overlook the effectiveness of ammonia recovery, thereby leading to an incomplete assessment. In this mini-review, we created a new plot to compare energy consumption and productivity as key performance metrics. The productivity was calculated using the molar flux of ammonium N separated from wastewater, which was then normalized by the mass of membranes as the key active component as well as to grasp the key operating condition and system parameter. By analyzing a comprehensive set of the literature data on the energy–productivity plot, we aimed to provide valuable insights into the current status and future directions of electrochemically mediated ammonia recovery from wastewater.

As part of our continuous research focused on enhancing sensing technologies, this article presents a series of ground-breaking fluorochromes that feature a biphenyl scaffold. Novel fluorochrome sensors are developed with various heterocyclic aldehydes via Claisen–Schmidt condensation. This condensation is performed using KOH and pyrrolidine as catalysts to provide two different methods with competitive studies. The obtained results show that KOH is a rapid catalyst (2–3 h; 71–80%), while pyrrolidine is an effective catalyst (5–6 h, 85–95%). The structures of the prepared fluorochromes are characterized using various spectral techniques and single crystal XRD. The photophysical properties of these fluorochromes are investigated using UV-vis and Fluorescence spectrophotometry in different solvent systems. Density functional theory (DFT) calculations are carried out and have a good correlation with experimental results. The obtained results for absorption, photoluminescence, and their theoretical correlation suggest that the prepared fluorochromes can be optimized for applications in optoelectronics, sensing, and bioimaging. Fluorochrome 3g, which exhibits the highest Stokes shift (129 nm) and photoluminescence (QY 0.87), is used to demonstrate the detection of hydrazine in actual water, soil, and air samples. The fluorochromes are inherently colored compounds and exhibit good photoluminescence, which is significantly quenched when hydrazine is added in very small quantities. The disappearance of the color and quenching of the photoluminescence signal are attributed to the formation of hydrodiazole via cyclization with hydrazine. A strong linear relationship for detecting hydrazine is observed over the concentration range of 1–5 μM in methanol. The limit of detection (LOD) for hydrazine is observed to be 1.1 μM with 5 μM 3g. Moreover, the color change of the fluorochrome solution from yellow to colorless can be observed by the naked eye, indicating that these fluorochromes can also be used as a colorimetric sensors for detecting hydrazine at very low concentration. Fluorochrome 3g was evaluated for its real-time detection ability over a pH range of 4–10, showing excellent efficiency in selectively detecting hydrazine among interfering analytes, and in soil and water samples. A probable mechanism for the detection of hydrazine is also established via spectral study. Additionally, this study describes a straightforward cost-effective probe-coated paper sheet for the detection of hydrazine in the environment and gives further hope for its commercial applications.

Complex and frequent anthropogenic activities have released tons of numerous exogenous pollutants into aquatic ecosystems, notably heavy metals (HMs) and microplastics (MPs) in urban channelized rivers. A stereomicroscope, Raman spectroscopy and ICP-MS were employed to systematically investigate the occurrence characteristics, environmental behaviors, and combined pollution effects of microplastics and HMs in urban channelized rivers. The average abundance of microplastics in the urban channelized rivers was (10.1 ± 0.7) items per L, predominantly in fibrous form (54.79%) and with particle sizes <0.5 mm (61.96%), mainly composed of polypropylene (37%) and polyethylene (24%). Compared to Chinese Environmental Quality Standards for Surface Water (GB 3838-2002), the exceedance rates of HMs Mn and As in the river water relative to the standard limits were 22.22% and 61.11%, respectively. The average concentrations of HMs in river water were as follows: W-Mn (580.43 μg L⁻¹) > W-As (184.22 μg L⁻¹) > W-Cr (168.88 μg L⁻¹) > W-Cu (157.76 μg L⁻¹) > W-Ni (153.76 μg L⁻¹) > W-V (78.03 μg L⁻¹) > W-Pb (28.54 μg L⁻¹) > W-Co (15.90 μg L⁻¹) > W-Cd (9.42 μg L⁻¹). The average concentrations of HMs adsorbed by microplastics in the river followed the order: MP-V (42.37 μg g⁻¹) > MP-As (22.33 μg g⁻¹) > MP-Cr (18.97 μg g⁻¹) > MP-Mn (18.82 μg g⁻¹) > MP-Pb (13.88 μg g⁻¹) > MP-Cu (3.41 μg g⁻¹) > MP-Ni (3.23 μg g⁻¹) > MP-Co (1.85 μg g⁻¹) > MP-Cd (1.60 μg g⁻¹). The concentration of microplastics adsorbing HMs in river water at the discharge outlets of wastewater treatment plants was significantly higher than at non-discharge sampling sites. The concentration of HMs adsorbed on microplastics is associated with the color, shape, and size of the microplastics. MP-Cr shows a significant negative correlation with W-Cr, while MP-As demonstrates a significant positive correlation with W-As (p < 0.05). Approximately 72.22% of MP-Cd, 16.67% of MP-Pb, and 5.56% of MP-As were identified as posing moderate ecological risks, while the remaining six HMs were classified as low ecological risk. This study recommends enhancing source control, optimizing wastewater treatment processes, and promoting basin-wide joint prevention and control to provide a scientific basis for managing microplastic–heavy metal composite pollution in urban channelized rivers.

The large time-delay in the coagulation process at drinking water treatment plants complicates accurate coagulant dosage determination. In this study, we proposed a Gated Recurrent Unit model enhanced with a local attention mechanism (GRU_LA) to precisely predict the required coagulant dosage and effluent turbidity. These models were integrated into a feed-forward-feedback composite control strategy, forming a data-driven control for coagulant dosing in drinking water treatment plants. Additionally, a hybrid rule-based expert system was also proposed as a knowledge-driven control component and combined with data-driven control to achieve a coagulant dosing system. Experimental results demonstrated that GRU_LA more effectively predicted the turbidity of effluent from the coagulant dosage, achieving a Mean Absolute Percentage Error (MAPE) of 1.61% for coagulant dosage and 0.86% for effluent turbidity, with a coefficient of determination (R²) of 0.90 and 0.94, respectively. After implementing the coagulant dosing control system in a drinking water treatment plant, the coefficient of variation of effluent turbidity throughout 2023 decreased by 5.58% compared to that of the monthly average in 2021, and the average annual coagulant usage was reduced by 7.83 mg L⁻¹, marking a 27.96% decrease and significantly lowering the cost of coagulants.

1,4-Dioxane (dioxane) is a persistent contaminant of concern due to its high mobility and stability in aquatic environments, posing significant environmental and public health risks. Azoarcus sp. DD4, a novel propanotrophic bacterium, has demonstrated an enhanced ability to cometabolize and degrade dioxane using propane or 1-propanol as the carbon source. In this study, we evaluated DD4's efficiency in dioxane degradation in groundwater samples from a landfill site at site-specific concentrations (41.7 ± 0.5 μg L⁻¹ in MW-A and 12.3 ± 0.2 μg L⁻¹ in MW-B). Bioaugmentation with DD4 reduced dioxane concentrations below the detection limit (0.13 μg L⁻¹) in both propane and 1-propanol treatments. Dioxane degradation rates were 2.23 and 0.72 μg L⁻¹ per day in propane-amended treatments for MW-A and MW-B, respectively, and 1.94 and 0.57 μg L⁻¹ per day in 1-propanol-amended treatments. While propane showed slightly higher degradation rates, the differences were not statistically significant. Parallel treatments mimicking natural attenuation and biostimulation with propane or 1-propanol showed minimal dioxane removal compared to abiotic losses. Although total biomass remained constant before and after DD4 bioaugmentation, DD4 proliferation was evident during incubation with both propane and 1-propanol. Microbial community analysis revealed that Azoarcus was abundant in bioaugmented samples, accounting for 5.6% to 45.4% of the overall biomass, highlighting substantial shifts in response to the auxiliary substrate used. These findings were supported by tmoA biomarker analysis specific to DD4 via qPCR. Overall, our results demonstrated the feasibility of 1-propanol as an auxiliary substrate alternative for propane for supporting dioxane cometabolic biodegradation by DD4 in complex landfill environments with trace levels of dioxane.

An estimated 20–25% percent of households in the US rely on on-site sanitation via septic tanks to manage their wastewater. Septage management strategies such as land application, treatment at wastewater treatment plants, and treatment at independent septage treatment plants are common regulated and protective processes for managing septage. There can, however, be potentially negative environmental impacts such as groundwater contamination if septic systems are failing or improperly designed. In this perspective, we reimagine septage management at each step of the septage value chain, identify barriers to change, and propose solutions to overcome these existing barriers. Reimagined septage management can take both high-level and context-specific approaches, including upgrading or retrofitting older septic takes to be impermeable and promoting proper tank pumping intervals, short transport distances, resource recovery, and safe reuse. These solutions could improve economic, environmental, and social sustainability over the status quo. Barriers such as lack of comprehensive data, aspects of decentralized regulation and management, public perception, and impacts of climate change can be overcome via policy best practices, increased stakeholder engagement, improved data collection, integration of machine learning, and climate change adaptation.

Emerging contaminants in aquatic environments have increased threats to human health in the last decade. Pharmaceuticals and personal care products (PPCPs) have received significant attention owing to their persistence, diverse sources, and concealed risks. Factors such as abundance, transformation, and treatment technology all affect the final fate of PPCPs. Herein, we investigate the sources of PPCPs in aquatic environments, analyze their distribution across various water bodies, and elucidate their photodegradation mechanisms under complex environmental factors. Our study provides crucial insights that facilitate the prediction of the occurrence and ultimate fate of PPCPs in aquatic systems.

Corrosive iron pipes in drinking water distribution systems favor biofilm growth. A high protein-to-polysaccharide ratio could reduce the adhesion of biofilm on the pipe wall; however, the effects of the protein-to-polysaccharide ratio on disinfection by-product (DBP) formation are unclear. To investigate this issue, this study used bovine serum albumin (BSA) and sodium alginate (SA) to simulate proteins and polysaccharides in extracellular polymeric substances (EPSs), respectively, and systematically examined the effects of different protein-to-polysaccharide ratios on the generation of DBPs during chlorination disinfection. BSA promoted the formation of regulated DBPs, including trihalomethanes (THMs) and haloacetic acids (HAAs), as well as emerging DBPs such as haloacetonitriles (HANs), but SA did not obviously affect DBP formation. BSA also increased turbidity, enhanced particle dispersion, and led to the formation of a greater number of smaller iron particles. In contrast, SA promoted particle aggregation and sedimentation, resulting in reduced turbidity. Particle characterization further demonstrated that BSA exhibited stronger binding with iron particles than SA. Notably, from a toxicological perspective, BSA led to higher levels of cytotoxicity and genotoxicity due to the increased formation of DBPs. Thus, this study identified a new risk that a high protein-to-polysaccharide ratio increases the formation of DBPs promoted by the iron particle interface, besides the risk of microorganism release from pipe wall into bulk water.

Membrane fouling hinders ultrafiltration applications of polyvinylidene fluoride (PVDF). Besides membrane modification, water regulation is another promising strategy. However, limited information is available on regulating water quality from actual field water with specific organic compositions, especially when using a modified membrane. We explored the influence of pH values, ionic strength (Na⁺), and water hardness (Ca²⁺) on filtration performance, including the removal of dissolved organic matter and anti-fouling ability. Alkaline conditions hindered hydrophilic removal of organic matter and led to severe fouling in the nascent membrane. In contrast, the modified membrane demonstrated effective hydrophilic organic removal and improved fouling mitigation under the same conditions. The nascent membrane exhibited reduced organic removal and experienced severe fouling as ionic strength increased, particularly at 3 and 100 mM; the negative influence of increased ionic strength (3 mM) can be partially counteracted for the modified membrane. An increase in water hardness promoted organic removal at 1–10 mM, while aggregated macromolecules induced by Ca²⁺ ions caused severe fouling in the nascent membrane; such fouling was alleviated by the modified membrane, with the highest residual flux at 3 mM. According to the fluorescence results, pH values barely affected organic properties in the feed water, but organic properties mattered a lot for Na⁺ and Ca²⁺ ions. This study provides a comprehensive basis for improving filtration performance by regulating water chemistry conditions with a modified membrane as an efficient, low-energy method.

Municipal wastewater treatment plants (WWTPs) serve as major recipients of microplastics (MPs) before these contaminants are discharged into local waterbodies. However, detailed investigations into MP pollution from wastewater in Australia remain limited. Therefore, understanding the occurrence and fate of MPs in WWTPs is crucial for developing effective control strategies. To address this gap, a year-long study was conducted to investigate the occurrence of MPs, seasonal trends, their removal efficiency, and the potential ecological risks posed by MPs from three water reclamation plants (WRPs) in Victoria, Australia. Nile red staining, Fourier transform infrared spectroscopy and scanning electron microscopy were used to detect and validate MPs in all wastewater samples. Results revealed that synthetic fibers were the dominant shape, accounting for 52–57% of all MPs. The influent predominantly contained MPs >500 μm, while effluent MPs were mostly sized between 300–100 μm. Five major polymers were identified: polyester, polyethylene terephthalate, polypropylene, polyethylene, and polystyrene. The MPs load in wastewater ranged from 25–37 MPs per L in the influent to 0–2 MPs per L in the effluent, demonstrating removal efficiencies ranging from 92% to 100% across the primary, secondary, and tertiary treatment processes. Notably, over 60% of MPs were removed during the primary treatment phase alone. Despite this high removal efficiency, between 3.63 × 10⁶ and 1.7 × 10⁸ MPs per day were released through WRP effluent, posing a low to medium ecological risk to the surrounding environment. Overall, this study underscores the effectiveness of current wastewater treatment processes in removing MPs and highlights the importance of long-term monitoring and sampling for managing MP pollution.