Water Environment Research最新文献

The hybrid membrane aerated biofilm reactor (MABR) process combines the advantages of the counter-diffusional biofilm and bubbleless aeration of the MABR with the good bioflocculation and carbon processing capabilities of suspended growth processes. These features result in a process with reduced physical footprint, excellent biological nutrient removal capabilities, potentially reduced greenhouse gas (GHG) emissions, and significantly reduced energy requirements that can be easily retrofitted into existing suspended growth processes. Commercially introduced in the mid-2010s, the demonstrated advantages of the hybrid MABR process are resulting in rapid full-scale adoption. Meanwhile, researchers are advancing knowledge on the hybrid MABR process and revealing potential opportunities for improved performance. This paper summarizes recent findings and identifies areas that can be further developed to advance hybrid MABR process evaluation and development. PRACTITIONER POINTS: Rapid application of the hybrid MABR process is leading to significant new developments that can enhance performance. Sizing MABR for nearly complete nitrification allows significant downsizing of the bioreactor, coupled with excellent nitrogen removal and energy savings. Online exhaust gas % O₂ and bulk ammonia concentration can be used to create a soft sensor characterizing changes in biofilm thickness enabling biofilm control to optimize performance. Further advancements through improved aeration control, configurations to achieve partial nitritation and annammox, and achieving granulation offer further significant advances.

Microplastic pollution has become an emerging environmental issue in the past decades. Plasticizers are organic compounds applied during the manufacturing process and are of particular interests to researchers. Phthalate esters (PAEs) and organophosphate esters (OPEs) are two common types of plasticizers that have been found to be prevalent in water and the atmosphere. Investigating their air-water exchange process is crucial for understanding their sources and fate as pollutants. This study employs a systematic review and data synthesis to evaluate the air-water exchange and dry deposition flux of PAEs and OPEs on a global scale, aiming to identify the factors influencing their exchange process. Results showed that the air-water exchange and dry deposition flux vary among different types of plasticizers, and climatic conditions may also have impact on the air-water exchange flux. Future research is needed to explore more mechanisms related to the influencing factors. PRACTITIONER POINTS: The study presents a data synthesis of air-water exchange and dry deposition flux of plasticizers. Results indicate the sources and sinks of plasticizers on surface water, which helps to understand the consequence of plastic pollution. The air-water exchange and dry deposition flux of PAEs and OPEs vary due to different chemical properties and climatic conditions. Further research is needed to better understand the influencing factors of this process.

Bottled drinking water of numerous brands from different countries, including Bangladesh, Malaysia, Australia, India, Singapore, Norway, Japan, Vietnam, and Taiwan, were studied using three-dimensional fluorescence (excitation-emission matrix, EEM) spectroscopy and multivariate parallel factor analysis (PARAFAC) model. Fluorescent-dissolved organic matter (DOM) components such as microbial processed tyrosine-, fulvic acid (M)-, and tryptophan-like had maximum intensity/concentration at 70.8%, 16.7%, and 12.5% bottled drinking water samples, respectively. The total intensity of all fluorescing DOM components was minimum and maximum in one of the brands from Australia and Vietnam, respectively. Unlike in Japan, the concentrations of DOM components in bottled drinking water were comparable to or higher than groundwater, freshwater, and marine water in Bangladesh, Malaysia, India, and Taiwan. The concentration of Escherichia coli was quantified from its significant correlation equation with the microbial-processed tryptophan-like component. Apart from 60% and 20% of bottled water samples from Malaysia and Bangladesh, the remaining samples of studied countries were medium to very high-risk because of E. coli signatures. The adverse health impacts from previously identified over-acceptable-limit mineral concentrations in bottled drinking water are discussed. DOM components at such concentrations in bottled drinking water also strengthened doubts about the efficiency of conventional water treatment techniques and biofilm control. Economic indicators of the studied countries affirmed that willingness and proper management knowledge are necessary to ensure safe bottled drinking water besides budget and labor wages. PRACTITIONER POINTS: Higher protein-like components intensity than humic-like affirmed microbial abundance Risks for E. coli availability was medium to very high in maximum samples Adverse health impacts for overlimit Pb, Al, and PO₄ ^3- minerals in Bangladeshi brands Inefficiency of drinking water treatment techniques in DOM and biofilm control Importance of labor wage, willingness, and knowledge for drinking water treatment.

Oil sands process-affected water (OSPW) is a by-product of bitumen extraction from oil sands surface mining in Alberta, Canada. A major group of organics in OSPW known as naphthenic acid fraction compounds (NAFCs) are of concern due to their persistence and toxicity. Constructed wetland treatment systems have emerged as potential biological treatment approaches for reducing NAFC concentrations within OSPW. In this study, greenhouse-scale mesocosms simulating a constructed wetland consisting of coarse sand tailings (CST) and OSPW were used to evaluate the ability of Scirpus microcarpus, Triglochin maritima, and unplanted controls to attenuate NAFCs under spring/fall and summer temperatures (10°C/5°C and 20°C/10°C day/night). Overall, in this mesocosm system, NAFC attenuation was similar regardless of different design parameters such as plant type, plant presence, and temperature. By the end of the study, NAFCs attenuation was 30% to 50% lower than the initial OSPW depending on plant species, plant presence, and temperature. The relative abundance of the acutely toxic O₂-NAFCs decreased over time, with an increase in the less toxic O₃, O₄, and SO₃ classes. Various hydrocarbon-degrading microbial families such as Comamonadaceae and Xanthobacteraceae were found to be dominant in OSPW, while cyanobacteria (Trichormus) were enriched in the CST. Principal component analysis indicated that only time led to distinct clusters for NAFC composition, while plant type, temperature, and time influenced the microbial communities. Shifts in microbial communities over time corresponded to shifts in NAFCs, possibly due to a decrease in toxicity with increased oxidation of NAFCs and/or an increase in available nutrients from a decrease in plant fitness in the planted mesocosms. PRACTITIONER POINTS: Constructed wetland mesocosms for NAFC attenuation from OSPW comparing three planted/unplanted conditions under two temperatures. Mesocosms had 30%-50% removal of total NAFCs, with a decrease in O₂-NAFCs and increase in O₃, O₄, and SO₃ classes. NAFC composition only shifted with time, while microbial communities were influenced by plant type, temperature, and time. Lack of difference in NAFC attenuation between treatments could indicate a high level of functional redundancy between the microbial communities.

Ionophores, a class of animal antibiotics, are widely used in intensive livestock farming to enhance feed efficiency and control coccidiosis. These compounds, known for their ability to transport cations across biological membranes, are crucial in maintaining cellular homeostasis. However, their extensive use raises environmental and human health concerns. This manuscript offers a comprehensive review of ionophores in livestock production, highlighting their environmental impact and potential to contribute to antimicrobial resistance (AMR). It emphasizes the fate and transport of ionophores in various environmental matrices, providing a holistic framework for assessing ecological risks. The study calls for improved management practices like enhanced waste management through anaerobic digestion, and composting is essential. Establishing Maximum Residue Limits (MRLs) and using LC-MS/MS for residue detection will help manage exposure. Educating livestock producers and researching alternatives like probiotics can decrease reliance on ionophores to mitigate the ecological footprint of ionophores, making it a timely and relevant piece of research. Ionophores can persist in the environment, potentially contributing to AMR in gram-positive bacteria. Furthermore, their presence in manure, runoff, and agricultural soils has been documented, leading to contamination of water bodies and sediments. Ionophores pose risks to terrestrial and aquatic ecosystems, with studies revealing hazardous effects even at low concentrations. This review highlights the need for improved management practices to mitigate the environmental impacts of ionophores, particularly regarding AMR development and ecosystem disruption. Careful monitoring and sustainable use of these antibiotics are essential to reduce their ecological footprint in livestock production. PRACTITIONER POINTS: Ionophores enhance feed efficiency, but pose environmental health risks. Their persistence may lead to antimicrobial resistance in gram-positive bacteria. Ionophore contamination threatens both terrestrial and aquatic ecosystems. Monitoring and management are crucial to mitigate ionophore-related risks.

Harmful algal blooms (HABs), driven by eutrophication, are a growing ecological threat, compromising water quality and ecosystem health through the release of toxic microcystins (MCs). These toxins pose significant risks to both aquatic life and human health. Among the emerging solutions, UV-C technology has gained attention for its efficiency in inhibiting algal growth and degrading MCs, offering a cost-effective and environmentally friendly approach with minimal secondary pollution. However, existing studies often overlook key aspects, including the variability in algae sensitivity to UV-C wavelengths, the stability of treatment across diverse aquatic conditions, and the toxicity of degradation byproducts. This review highlights the mechanisms underlying UV-C-based algae removal, explores its potential limitation, such as algal resistance, and compares its efficacy with other remediation methods. Notably, the lack of comprehensive research on wavelength-specific sensitivity and real-world application efficacy represents a significant knowledge gap. Further investigation into these areas is essential to optimize UV-C technology for mitigating HABs and improving water safety in eutrophic environments. PRACTITIONER POINTS: The choice of UV band should be adjusted to the algae species. The UV-C system, with limited studies and applications in natural water bodies, demonstrates instability. Combining UV-C with other technologies substantially enhances the efficiency of algal control. Future research should emphasize strategies to prevent the rapid release of microcystins (MCs) from this system due to cell lysis and extracellular release within a short time frame.

Water is a crucial raw material in economic production activities. Research indicates that water scarcity can lead to significant economic output losses (water scarcity risk, WSR), affecting not only the local area (referred to as local water scarcity risk, LWSR) but also causing economic losses to other regions through trade networks (referred to as virtual water scarcity risk, VWSR). With climate change exacerbating this challenge, understanding the water scarcity risk under changing climatic conditions is essential. However, few studies have addressed this issue comprehensively. To fill this gap, we developed a comprehensive model incorporating environmental flow requirements, water withdrawal, supply, economic output, and trade networks to assess LWSR and VWSR among China's provinces under climate change. Our analysis reveals a growth in China's WSR from $4.6 trillion in 2020 to $5 trillion in 2030. Specifically, both local water scarcity risk (LWSR) and virtual water scarcity risk (VWSR) amounted to $0.9 trillion and $3.7 trillion, respectively, in 2020, increasing to $1.0 trillion and $4.0 trillion by 2030. We also identified hot-spot provinces and sectors with high WSR and proposed relevant policy implications. Our findings contribute to China's climate change mitigation efforts, particularly in formulating strategies to address water scarcity risk. PRACTITIONER POINTS: Spatial heterogeneity-based environmental flow requirement is considered. The water scarcity risk of the Chinese agricultural sector in 2017 amounted to $1.1 trillion. LWSR and VWSR are 0.3 and 0.8 $trillion, respectively. Hotspot Chinese provinces and sectors are identified.

The studies on purifying water and wastewaters contaminated with phenolic compounds have always been set up within recent years either full-scale or lab-scale experiments. In this research, treatment of the synthesized catechol (CC) solution was done by using magnetized granular activated pomegranate peel carbon (GAPPC) simultaneously with an electrocoagulation (EC) system for the first time. The experiments on both the EC-magnetic GAPPC and the magnetic GAPPC to find the optimum operating parameters like pH, contact time (CT), supportive electrolyte concentration, current densities (DC), adsorbent dosage, temperature to remove CC were conducted in batch-mode. The highest removal rate (88%) was achieved at pH = 6-8, CT = 30, supportive electrolyte = 0.25 g/L, DC = 0.5 A/m², magnetic GAPPC dosage = 0.25 g/L. Under this condition, the rate of anode dissociation was 2.9 mg/L as the produced coagulant, the used electrical energy was 3.5 kW h, and the produced sludge rate was not more than 220 mg/L. However, synergistic order to remove CC could be as EC-magnetic GAPPC > EC > > magnetic GAPPC. Chromatographic analysis suggested that benzoquinone could be regarded as EC degradation intermediate of CC and simple aliphatic acids as its semifinal oxidation products along with Fe-bonded complexes. Adsorption isotherm followed Freundlich model having higher R² representing multilayer adsorption. The adsorption kinetics investigation demonstrated that the pseudo-second-order model better fits the experimental data rather with higher R². The cost analysis revealed that treating aqueous CC solutions using EC-magnetic GAPPC does not cost more than $0.8. PRACTITIONER POINTS: Using simultaneously electrocoagulation and magnetic AC made by pomegranate peel is extremely cost-effective having high efficiency (88%) for removing CC. Benzoquinone is the intermediate of CC electrochemical degradation through EC-magnetic GAPPC treatment process, and formic and acetic acids, and Fe-bonded complexes as its semifinal and final products. Adsorption mechanism was multilayer following Freundlich isotherm model and kinetics adsorption was well-fitted with pseudo-second-order model. CC adsorption by magnetic GAPPC was a spontaneous and exothermal mechanism. The synergic order of EC-magnetite GAPPC was EC-magnetic GAPPC > EC > > magnetic GAPPC.

Persulfate-based advanced oxidation processes (PS-AOPs) catalyzed by carbon-based catalysts are promising for removing organic pollutants via radical/non-radical pathways. However, the activation efficiency of peroxymonosulfate (PMS) or peroxydisulfate (PDS) usage and the reaction mechanism remain insufficiently understood. In this study, the effects of PMS/PDS dosage on the degradation of bisphenol A (BPA, 10 mg/L) were evaluated using N-doped biochar (N-BC, 0.2 g/L) assisted PS-AOPs. The reaction pathways were comprehensively investigated through a combination of characterization techniques and molecular simulations. With low PS dosages (0.05 and 0.1 mM), the degradation rate constants ( $k_{\mathrm{obs}}$ ) were higher in N-BC/PDS (0.04 and 0.07 min^-1) compared to N-BC/PMS (0.02 and 0.04 min^-1), likely due to higher PDS utilization, which enhanced the contribution of the non-radical pathway. Interestingly, with higher PS dosages (0.5 and 1.5 mM), the $k_{\mathrm{obs}}$ values were 0.16 min^-1 and 0.18 min^-1 in N-BC/PMS, respectively, significantly exceeding those determined in N-BC/PDS (0.11 and 0.11 min^-1). This result stemmed from the greater adsorption capacity of N-BC for PMS compared to PDS, leading to increased formation of ¹O₂. The contribution of non-radical pathways for both PMS and PDS increased with higher PS dosage. The results highlighted that BPA degradation improved significantly with the increase in PMS dosage; meanwhile, BPA degradation was insensitive to PDS dosage. The optimal PMS dosage for BPA degradation was found to be 1.5 mM and 0.1 mM for PDS. This study offered valuable insights for optimizing PS-AOPs in environmental remediation, helping to guide the selection of appropriate oxidants and dosages for maximizing pollutant removal. PRACTITIONER POINTS: Effect of PMS/PDS dosage on BPA degradation by N-doped biochar was revealed. Contribution of dominated non-radical pathway increased as PMS/PDS dosage increased. The greater PDS utilization and non-radical pathway resulted in the higher $k_{\mathrm{obs}}$ at low dosage. N-BC adsorbed more PMS than PDS, leading to an increase in $k_{\mathrm{obs}}$ at high dosage.