Environmental Science: Water Research & Technology最新文献

Currently, common fecal source identification methods in water environments are based on the detection of host-specific gene markers, such as 16S rRNA gene fractions of Bacteroidales and mitochondrial DNA. However, with this approach, identifying all animals contributing to fecal pollution in a catchment has been a challenge, considering numerous species and populations of animals in the area. In this study, we examined the effectiveness of a metabarcoding approach that comprehensively targets mammalian and avian mitochondrial DNA as an approach to identify animal species potentially contributing to pollution. Surface water samples (n = 108) were collected monthly at five sites in Toyama prefecture, Japan under wet and dry weather conditions for two years. The samples were subjected to the metabarcoding targeting mammalian and avian mitochondrial DNA. Further, human (HF183)-, pig (Pig-2-Bac)-, and ruminant (BacR)-specific gene markers were quantified. Human-like DNA (74 samples) and livestock-like DNA, namely, pig-(66 samples), cattle-(23 samples), and chicken-(52 samples) like DNA were frequently observed. Additionally, DNA associated with wild terrestrial animals, waterfowls, and urban birds commonly found in the study area were observed regardless of the weather conditions. Human- and livestock-like DNAs exhibited similar detection trends to their corresponding markers across sites, though the presence of mitochondrial DNA from non-fecal sources was also suggested. The metabarcoding assay was effective for simultaneously and comprehensively evaluating animal species' potential contributions to fecal pollution. Comparing the stability of animal markers and their DNA in the environment would help to further validate the effectiveness of the assay.

With the expanding use of antibacterial and disinfection products, chloroxylenol (para-chloro-meta-xylenol, PCMX) has been detected in various environments, especially in sewage treatment plants. However, the influence of PCMX has received limited attention, with only sporadic studies available. Over a period of 110 days, efforts were undertaken to restore the performance of PCMX-affected anaerobic sludge through the addition of nanoscale zero-valent iron (nZVI) and the reduction of PCMX concentration. nZVI addition promoted COD removal efficiency under a high PCMX concentration (50.0 mg L⁻¹, GH) and accelerated the anaerobic digestion process under a low PCMX concentration (0.5 mg L⁻¹, GL). The slow recovery in GH highlighted the difficulty in restoring the functionality of municipal anaerobic sludge under the prolonged influence of high PCMX concentrations. Microbial communities exhibited distinct succession patterns under different treatments. nZVI demonstrated efficacy in mitigating the decline in microbial richness induced by PCMX. Shannon and Pielou evenness and niche breadth increased as the PCMX concentration decreased, suggesting an enhanced restorative capacity of the microbial community when alleviating the stress imposed by PCMX. Bacteroidetes, Proteobacteria, Actinobacteria, Firmicutes, and Chloroflexi were predominant functional phyla in the anaerobic digestion process. Olsenella, Rectinema, Desulfovibrio, Azonexus, and Methanobacterium were key genera responding to nZVI and PCMX. PCMX markedly diminished community resistance and resilience, while nZVI mitigated the damage of PCMX on community stability. Altogether, this study contributes to a better understanding of the performance and microbial succession in anaerobic sludge through the addition of nZVI and variations in PCMX concentration.

Cellulose can be oxidised with periodate to obtain hairy cellulose, which, thanks to the aldehyde groups, facilitates chemical modification with different functional groups, such as carboxylates, which enhance interaction with various types of analytes. The dicarboxylated product is soluble in water, and in some cases, this is a disadvantage as it can complicate phase separation and quantification of the analyte of interest. Crosslinking with calcium produces an insoluble solid (DCCa) that can be used as a sorbent; therefore, in this work DCCa application in the removal and confinement of Pb(II) was evaluated. The removal process was carried out in a column, optimised with the assistance of a Box–Behnken design and found as optimal conditions: pH 4.3, 15 mg of sorbent and 80 minutes of contact time; with these conditions, it was possible to achieve more than 90% removal of the ion in solution. The process was analysed with a breakthrough curve, and the Yan model showed the best fit to the data; from this, a sorbent capacity of 615.21 mg_Pb g⁻¹ was estimated. Interference from other metallic ions was also evaluated, and there was no significant change in removal percentage. Thus, the sorbent removed more than 80% of Pb(II) from industrial synthetic wastewater. Finally, the sorbent capacity as a confining material for lead was evaluated with different lixiviation and sequential extraction techniques; these analyses showed that it is possible to contain more than 98% of the ion in mild conditions (0.11 mol L⁻¹ acetic acid and 0.5 mol L⁻¹ hydroxylamonium chloride), which makes it a competitive material for the removal and confinement of Pb(II).

Metal (hydro)oxide particles with efficient phosphate removal properties are widely used in the treatment of eutrophic waters (mainly phosphorus). However, the disadvantages of easy agglomeration and difficult separation limit their application. In this study, a polyurethane sponge (PU) was coated with sodium carboxymethyl cellulose (CMC-Na) to anchor FeO(OH) to prepare a novel functional composite (CFe@PU), which overcame the disadvantages of metal (hydro)oxide particles. The results revealed that the coating process of CMC-Na on the PU surface contributed to loading of FeO(OH) and enhanced the affinity for phosphate. The maximum adsorption capacity of CFe@PU was 21.22 mg phosphate-P per g, which was 1.74 times that of Fe@PU, and the effect of the coating process was significant (P = 0.01). The material displayed remarkable selectivity when exposed to a diverse array of anions and within the pH range of 4–8. The phosphorus removal efficiency by CFe@PU was >71.34% after three regeneration cycles. Investigating the adsorption mechanisms revealed that electrostatic attraction and inner-sphere ligand exchange were involved in the adsorption process. In a lake water experiment, the phosphorus in the CFe@PU treated group decreased from 0.2 mg L⁻¹ to 0.004 mg L⁻¹, limiting algae growth significantly. These results indicated that CFe@PU was a potential adsorbent in controlling eutrophication.

Water resources are scarce in arid and semi-arid regions. Urban rivers, vital water sources, are susceptible to the influences of climate change and human activities. However, there have been few studies analyzing the responses of water quality and health risks to these factors over long-term scales. This study focused on the Diannong River (Shizuishan section) in the upper reaches of the Yellow River from 2011 to 2020. The results reveal significant declines (P < 0.05) in water quality index (WQI), non-carcinogenic risk (HI), and carcinogenic risk (R) during the study period. Regression models based on corrected Akaike information criterion and partial least squares path models demonstrated that human activities contributed significantly to WQI, HI, and R (78.2–85.9%), exerting positive effects on water quality improvement and health risk reduction. Changes in population, land use, and GDP were identified as core reasons. Economic restructuring played a crucial role in ameliorating water pollution. It is noteworthy that continuous environmental protection funds over the decade did not yield significant beneficial effects. The contribution of climate change ranged from 14.1% to 21.8%. Extreme climate indices, especially the maximum length of wet spell, maximum length of dry spell, and growing season length, exerted negative effects on WQI, HI, and R. Temperature and evaporation only inhibited the decrease in WQI, but not HI and R. Under sustained pressure from urbanization and climate change, similar rivers in arid and semi-arid areas can enhance the security and availability of water resources by controlling GDP, urban and farmland area, and population.

To alleviate escalating antibiotic pollution in the environment, there is a pressing need for sustainable antibiotic remediation techniques. Considering this, the present study focuses on entrapping β-lactamase from Bacillus tropicus EMB20 within an agarose matrix, subsequently employing it for the bioremediation of doripenem (a carbapenem antibiotic) and other β-lactam antibiotics. The agarose discs containing entrapped lactamase efficiently hydrolysed 50 mg L⁻¹ of doripenem within 30 min of batch mode treatment. The toxicity of the antibiotic hydrolysed products was assessed using MTT assay and confocal microscopy, revealing their non-toxic nature to the antibiotic-sensitive cells of E. coli BL21 (DE3). These discs were successfully recovered and reused for up to 5 cycles with an efficiency rate of 72%. Furthermore, the discs demonstrated effectiveness in hydrolysing a mixture of antibiotics, including doripenem, meropenem, and amoxicillin, removing 100%, 96.4%, and 71.5% of each antibiotic after 30 min of treatment. This enzymatic treatment process was upscaled using a continuous mode fixed-bed column bioreactor (FBCR) packed with layers of lactamase-entrapped agarose discs and sand gravels. Remarkably, a mixture of doripenem, amoxicillin, and meropenem (each at 50 mg L⁻¹) was completely removed after a retention time of 20 min in the FBCR. This setup proved to be reusable for up to 5 cycles. Overall, the study emphasises the potential of utilising these β-lactamase-entrapped agarose discs as an effective remediation tool to control antibiotic pollution from the environment.

To facilitate broader implementation of potable reuse, it is important to fully account for pathogen log₁₀ reduction values (LRVs), including unit processes that are historically uncredited or under-credited. Despite its potential for pathogen removal, coagulation coupled with flocculation (C/F) has historically been omitted or overlooked when pursuing credits for potable reuse. However, with greater implementation of carbon-based advanced treatment (CBAT), which utilizes a combination of ozone, biofiltration, and granular activated carbon treatment as an alternative to membrane treatment (i.e., reverse osmosis), C/F may emerge as a valuable unit process for achieving improvements in water quality, operational performance, and public health protection in potable reuse systems. This study evaluated the ability of C/F with ferric chloride to improve both bulk and microbial water quality of secondary wastewater effluent and improve downstream ozone performance. This study also evaluated potential surrogates for microbial removal during C/F treatment. C/F removed 17–54% of DOC with ferric doses ranging from 10–50 mg Fe per L, with 30 mg Fe per L sufficient for meeting TOC removal requirements from the Stage 1 D/DBPR for all evaluated secondary effluents. Coagulant doses of 30 mg Fe per L obtained LRVs ranging from 2–3 for MS2 and B. subtilis spores. MS2 and B. subtilis spore removal exhibited strong (r ≥ 0.8) and significant (p < 0.05) Pearson's correlation with the removal of intact cell counts and total cell counts via flow cytometry (FCM), DOC, total adenosine triphosphate (ATP), and intracellular ATP. C/F immediately preceding ozone treatment improved inactivation of B. subtilis spores, lowered applied ozone doses, and increased ozone exposure (Ct) for similar specific ozone doses as compared to secondary effluent without C/F pre-treatment. Overall, C/F with ferric chloride was determined to be a valuable treatment step for removal of dissolved organic matter, MS2 bacteriophage, B. subtilis spores, and improvement of downstream ozone treatment. Furthermore, FCM, ATP, and DOC were determined to be strong potential candidates as surrogates for microorganism removal during C/F treatment, although further testing with pathogens is still necessary to justify LRV crediting.

Urban areas generate high volumes of stormwater runoff that frequently contains complex mixtures of hydrophilic trace organic contaminants (TOrCs) and dissolved nutrients. Green stormwater infrastructure is becoming increasingly adopted as a nature-based solution for improving water quality but is typically inefficient for removing dissolved-phase contaminants. We recently developed and characterized novel bioactive composite alginate bead media (BioSorp Beads) containing encapsulated PAC and iron-based water treatment residuals [FeWTR] as sorbents and white rot fungi as model biodegrading organisms to effectively capture and biodegrade stormwater-relevant TOrCs. We created multiple abiotic (no fungi) and biotic beads (containing Trametes versicolor or Pleurotus ostreatus fungi) to investigate sorption removal of a suite of representative dissolved-phase stormwater relevant pollutants (a neonicotinoid/metabolite, phosphate, three PFAS, and one tire-wear compound [acetanilide]). We also measured coupled sorption and biodegradation of acetanilide as a proof-of-concept demonstration of encapsulated biodegrading organisms. Alginate encapsulation increased desnitro-imidacloprid sorption onto PAC, likely due to the interactions between compound altered insecticidal functional groups and alginate. The sorption capacity of imidacloprid and desnitro-imidacloprid was up to 29.1 mg g⁻¹ and 16.8 mg g⁻¹, respectively, and impacted by PAC presence and the partial charge distributions of the compounds. The encapsulated FeWTR and Fe³⁺-alginate beads drove phosphate sorption (42.1 mg phosphate per g beads). Long-chain PFAS removal in the beads (13.1 mg PFOA per g) was greater than short-chain PFAS removal capacity (5.2 mg PFBA per g, 5.1 mg PFBS per g). Encapsulated fungi were not inhibited by exposure to azide that typically kill fungi in laboratory experiments, indicating the potential for encapsulation to protect organisms from harsh conditions. Furthermore, biodegradation of acetanilide by encapsulated fungi beyond sorption controls demonstrated that coupled sorption and biodegradation with the beads occurred. BioSorp Beads successfully capture and biodegrade representative hydrophilic stormwater TOrCs and thus hold potential as a green stormwater infrastructure geomedium and bioaugmentation tool.

This study develops quantifiable metrics to describe the resilience of Water Resource Recovery Facilities (WRRFs) under extreme stress events, including those posed by long-term challenges such as climate change and population growth. Resilience is the ability of the WRRFs to withstand adverse events while maintaining compliance or an operational level of service. Existing studies lack standardised resilience measurement methods. In this paper, we propose a resilience metric based on signal temporal logic (STL) to describe acceptable functionality of the WRRFs (e.g. meeting regulatory limits). By using Monte Carlo simulations and scenario optimisation on a model of a WRRF, we determine the maximum stress the WRRF can handle while meeting STL constraints for biochemical oxygen demand (BOD) and chemical oxygen demand (COD) compliance limits. The results are applied to a simple digital model of a facility with 22 components. Importantly, this method can be applied to data that water companies routinely and regularly monitor, and could be incorporated into SCADA systems. In our case studies, we determine threshold stressor values of extreme rainfall that result in a loss of resilience. Our results offer insights into the design of more resilient treatment processes to reduce environmental impacts.

The present study aims to investigate the characteristics of dissolved organic matter (DOM) in the Huai River in the winter dry season using UV-visible absorption spectroscopy (UV-vis), three-dimensional fluorescence excitation–emission matrix spectroscopy-parallel factor analysis (EEM-PARAFAC), and liquid chromatography-organic carbon detection (LC-OCD). The PARAFAC model results revealed three DOM chemical components, namely: UV-type humic substances (C1), humic acid-like substances (C2), and protein-like substances (C3). However, humic substance components (C1 + C2) were the major fluorescent DOM components, accounting for 61.88 ± 6.45%. In this study, the reduced external inputs in the winter dry season resulted in a significantly higher fluorescence intensity of the C3 component than that of C2 (P < 0.01). On the other hand, the LC-OCD results indicated significant differences (P < 0.01) between different water body types of the Huai River due to the strong influences of human activities and sewage discharge. The polysaccharide, humic substance, low molecular acid, and nitrogenous compound concentrations in the river water exhibited decreasing trends from upstream to downstream of the river. In contrast, the concentrations of amino acid derivatives exhibited a significant increasing trend from upstream to downstream of the river. The concentrations of nitrogenous compounds were accumulated in the confluence zone of the river tributaries and mainstream. The DOM concentrations in the river water were influenced by multiple factors. However, the decrease in the concentrations of proteins and polysaccharides enhanced the autochthonous process in the river water body, gradually increasing the concentrations of humic substances.