•Anammox biofilm removed nitrogen efficiently from low-strength wastewater.•High influent ammonium resulted in a dense biofilm by regulating protein in EPS.•Candidatus Kuenenia dominated in Anammox ...biofilm with low-strength wastewater.•Signal substances for QS were detected in Anammox biofilm reactors.•More QS processes occurred in Anammox biofilm with high influent ammonium.
Anammox-based nitrogen removal can advance sustainable wastewater treatment, especially for the main-stream wastewater treatment. Two lab-scale Anammox biofilm reactors fed with influent ammonium concentrations of 110 mg/L (Anammox-H) and 50 mg/L (Anammox-L) were operated, and nitrogen removal and mechanisms of quorum sensing (QS)/quorum quenching (QQ) were examined. The achieved nitrogen removal rates were 0.65 g N/L·d in Anammox-H and 0.25 g N/L·d in Anammox-L. Candidatus Kuenenia was dominant in both reactors. Higher contents of tight extracellular polymeric substance and hydrophobic amino acid confirmed that dense Anammox biofilm developed in Anammox-H. N-hexanoyl-l-homoserine lactone and N-octanoyl-l-homoserine lactone were detected in Anammox-H and Anammox-L. High concentrations of acyl-homoserine lactones (AHLs) in water and biomass phases of Anammox-H were consistent with that more active QS processes existed in Anammox-H. Functional genes including hao, pmoA-amoC, nirK and narGZHY were detected and harbored by Candidatus Kuenenia stuttgartiensis, Nitrosomonas europaea and Lautropia sp. SCN 69-89. These organisms not only involved in nitrogen metabolism, but also in pyruvate, fatty acid and S-Adenosy-l-methionine synthesis (important for AHLs). Influent ammonium concentrations affected the balance between QQ and QS activities, resulting in different Anammox activity and biofilm morphology. This study advanced the Anammox application for low-strength wastewater, especially from the aspect of QQ and QS balance.
Agricultural nonpoint pollution has been recognized as the main source of aquatic contaminants worldwide, such as inorganic nitrogen (ION) and heavy metals (HMs). It is an important challenge to ...simultaneously and efficiently immobilize soil ION and HMs in farmland. Herein, we present a polyporous Mg/Fe-layered double hydroxide and biochar composite (Mg/Fe-LDH@biochar) with the efficient coadsorption capacity of ION and HMs for the mitigation of agricultural nonpoint pollution toward aquatic systems. The Mg/Fe-LDH@biochar showed strong adsorption toward ION (i.e., NH4 +–N and NO3 ––N) and HMs (i.e., Cu, Zn, Ni, Pb, and Cd), with maximum capacity of 98.53 mg of NH4 +–N/g, 27.09 mg of NO3 ––N/g, 295.80 of mg Cu/g, 141.70 mg of Zn/g, 75.59 mg of Ni/g, 1264.10 mg of Pb/g, and 126.30 mg of Cd/g, respectively. More attractively, by deionized water extraction, the adsorbed ION on the composite was more easily rereleased, with a desorption percentage of about 42.33 ± 6.87% NO3 ––N and 1.42 ± 0.78% NH4 +–N, than that of HMs (<1.0%). This difference is primarily related with the strength of bonding forces of ION and HMs when adsorbed on Mg/Fe-LDH@biochar, in the sequence of NO3 ––N (van der Waals force and electrostatic attraction) < NH4 +–N (hydrogen bonding) < HMs (ionic/coordinate bonding). Finally, to examine the performance of Mg/Fe-LDH@biochar for practical applications in farmland, column leaching experiments were successfully conducted by stimulated rainfall events. The addition of Mg/Fe-LDH@biochar into soils could greatly reduce the leaching of ION and HMs simultaneously, with reduction ratios of >60, >40, and >90% for NH4 +–N, NO3 ––N, and HMs, respectively, at 3.0% addition. Moreover, there was no leaching risk of Fe ions into the water body from Mg/Fe-LDH@biochar-amended soils.
Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) causes the infectious disease COVID-19 (coronavirus disease 2019), which was first reported in Wuhan, China, in December 2019. Despite ...extensive efforts to control the disease, COVID-19 has now spread to more than 100 countries and caused a global pandemic. SARS-CoV-2 is thought to have originated in bats; however, the intermediate animal sources of the virus are unknown. In this study, we investigated the susceptibility of ferrets and animals in close contact with humans to SARS-CoV-2. We found that SARS-CoV-2 replicates poorly in dogs, pigs, chickens, and ducks, but ferrets and cats are permissive to infection. Additionally, cats are susceptible to airborne transmission. Our study provides insights into the animal models for SARS-CoV-2 and animal management for COVID-19 control.
Globally, fluvial heavy metal (HM) pollution has recently become an increasingly severe problem. However, few studies have investigated the variational characteristics of fluvial HMs after rain over ...long periods (≥1 year). The Dakan River in Xili Reservoir watershed (China) was selected as a case study to investigate pollution levels, influencing factors, and sources of HMs under different rainfall conditions during 2015 and 2016. Fluvial HMs showed evident spatiotemporal variations attributable to the coupled effects of pollution generation and rainfall diffusion. Fluvial HM concentrations were significantly associated with rainfall characteristics (e.g., rainfall intensity, rainfall amount, and antecedent dry period) and river flow, which influenced the generation and the transmission of fluvial HMs in various ways. Moreover, this interrelationship depended considerably on the HM type and particle size distribution. Mn, Pb, Cr, and Ni were major contributors to high values of the comprehensive pollution index; therefore, they should be afforded special attention. Additionally, quantitative source apportionment of fluvial HMs was conducted by combining principal component analysis with multiple linear regression and chemical mass balance models to obtain comprehensive source profiles. Finally, an environment-friendly control strategy coupling “source elimination” and “transport barriers” was proposed for aquatic environment protection.
Display omitted
•Fluvial heavy metal contents vary spatially and seasonally.•Rainfalls affect fluvial heavy metal concentrations.•Mn, Pb, Cr, and Ni as major contributors of high CPI values need special attention.•Combined PCA–MLR and CMB models allow quantifying fluvial heavy metal sources.•A coupling strategy of “source elimination” and “transport barrier” was proposed.
African swine fever virus (ASFV) has been circulating in China for more than two years, and it is not clear whether the biological properties of the virus have changed. Here, we report on our ...surveillance of ASFVs in seven provinces of China, from June to December, 2020. A total of 22 viruses were isolated and characterized as genotype II ASFVs, with mutations, deletions, insertions, or short-fragment replacement occurring in all isolates compared with Pig/HLJ/2018 (HLJ/18), the earliest isolate in China. Eleven isolates had four different types of natural mutations or deletion in the EP402R gene and displayed a non-hemadsorbing (non-HAD) phenotype. Four isolates were tested for virulence in pigs; two were found to be as highly lethal as HLJ/18. However, two non-HAD isolates showed lower virulence but were highly transmissible; infection with 10
TCID
dose was partially lethal and caused acute or sub-acute disease, whereas 10
TCID
dose caused non-lethal, sub-acute or chronic disease, and persistent infection. The emergence of lower virulent natural mutants brings greater difficulty to the early diagnosis of ASF and creates new challenges for ASFV control.
The accuracy and reliability of urban stormwater quality modelling outcomes are important for stormwater management decision making. The commonly adopted approach where only a limited number of ...factors are used to predict urban stormwater quality may not adequately represent the complexity of the quality response to a rainfall event or site-to-site differences to support efficient treatment design. This paper discusses an investigation into the influence of rainfall and catchment characteristics on urban stormwater quality in order to investigate the potential areas for errors in current stormwater quality modelling practices. It was found that the influence of rainfall characteristics on pollutant wash-off is step-wise based on specific thresholds. This means that a modelling approach where the wash-off process is predicted as a continuous function of rainfall intensity and duration is not appropriate. Additionally, other than conventional catchment characteristics, namely, land use and impervious surface fraction, other catchment characteristics such as impervious area layout, urban form and site specific characteristics have an important influence on both, pollutant build-up and wash-off processes. Finally, the use of solids as a surrogate to estimate other pollutant species was found to be inappropriate. Individually considering build-up and wash-off processes for each pollutant species should be the preferred option.
► Pollutant wash-off changes step wise based on rainfall characteristics thresholds. ► Sole use of land use inadequate to predict stormwater quality modelling accurately ► Solids as surrogate for other pollutant species in modelling can lead to error
Here, single-atom Cu dispersed on N-doped graphene (Cu-SA/NGO) with relatively high Cu loading of 5.8 wt% was prepared for boosting the degradation of contaminants. This is the highest value yet ...reported for dispersion of single metal atoms on graphene. Atomically dispersed CuN
4
moieties were confirmed by high-angle annular dark field-scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy. The prepared Cu-SA/NGO shows remarkable activity and stability in the degradation of various organic contaminants at neutral pH. This excellent performance is mainly ascribed to the large number of active sites obtained from high single-atom-Cu loading. Density functional theory calculations confirmed that CuN
4
moieties serve as the active sites, with low energy barriers for hydroxyl radical (&z.rad;OH) generation. These supported single-atom catalysts (SACs) catalyze the heterogeneous Fenton reaction
via
proton-mediated H
2
O
2
-homolytic pathway. This work offers a new method for fabricating various SACs with high loading levels for catalytic oxidation reactions.
A single-atom Cu dispersed on N-doped graphene with ultrahigh Cu loading of 5.8 wt% was prepared for boosting the degradation of contaminants.
•A moderate concentration of iron ions (0.06mg/L) promoted the production of EPS.•EPS accelerated corrosion at the initial stage, but inhibited corrosion at the later stage.•Functional groups in the ...EPS acted as electron shuttles to bind iron ions.•The corrosion inhibition of EPS was correlated to phosphorus and corrosion products.
New insights into the biocorrosion process may be gained through understanding of the interaction between extracellular polymeric substances (EPS) and iron. Herein, the effect of iron ions on the formation of biofilms and production of EPS was investigated. Additionally, the impact of EPS on the corrosion of cast iron coupons was explored. The results showed that a moderate concentration of iron ions (0.06mg/L) promoted both biofilm formation and EPS production. The presence of EPS accelerated corrosion during the initial stage, while inhibited corrosion at the later stage. The functional groups of EPS acted as electron shuttles to enable the binding of iron ions. Binding of iron ions with EPS led to anodic dissolution and promoted corrosion, while corrosion was later inhibited through oxygen reduction and availability of phosphorus from EPS. The presence of EPS also led to changes in crystalline phases of corrosion products.
The discovery of materials as soil conditioners for the improvement of soil nitrogen-use efficiency provides a promising strategy for simultaneously addressing production and pollution problems in ...agriculture. Herein, adsorption–desorption performance and mechanisms of ammonium (NH4 +–N) by a poly(acrylic acid)-grafted chitosan and biochar composite (PAA/CTS/BC) were studied to evaluate its potential in soil amendment. Furthermore, mathematical models were further applied to explore the effects of PAA/CTS/BC on controlling soil NH4 +–N loss. Results suggest that PAA/CTS/BC showed a high capacity of NH4 +–N adsorption, with a maximum value of 149.25 mg·g–1 at 25 °C, considerably higher than most of the reported BC-based adsorbents. Fast adsorption of NH4 +–N was completed with an efficiency of >90% within 20 min, primarily attributed to the dominant electrostatic interactions with carboxyl groups. Adsorbed NH4 +–N was capable of being easily re-released with the variation of the liquid-phase concentration because of the weak binding of NH4 +–N with the material. These results demonstrate that the PAA/CTS/BC can be considered as a nitrogen slow-release medium to dynamically maintain a plant-available NH4 +–N concentration in the soil. Finally, the mathematical simulation of NH4 +–N flow in the PAA/CTS/BC-amended soil revealed that soil NH4 +–N loss was effectively reduced by 24.18–31.77% at a 1.57–2.02% material dosage during a 10-week rice cultivation.
To understand the role bacterial communities play in corrosion scale development, the morphological and physicochemical characteristics of corrosion scales in raw and disinfected reclaimed water were ...systematically investigated. Corrosion tubercles were found in raw reclaimed water while thin corrosion layers formed in disinfected reclaimed water. The corrosion tubercles, composed mainly of α-FeOOH, γ-FeOOH, and CaCO3, consisted of an top surface; a shell containing more magnetite than other layers; a core in association with stalks produced by bacteria; and a corroded layer. The thin corrosion layers also had layered structures. These had a smooth top, a dense middle, and a corroded layer. They mostly consisted of the same main components as the tubercles in raw reclaimed water, but with different proportions. The profiles of the dissolved oxygen (DO) concentration, redox potential, and pH in the tubercles were different to those in the corrosion layers, which demonstrated that these parameters changed with a shift in the microbial processes in the tubercles. The bacterial communities in the tubercles were found to be dominated by Proteobacteria (56.7%), Bacteroidetes (10.0%), and Nitrospira (6.9%). The abundance of sequences affiliated to iron-reducing bacteria (IRB, mainly Geothrix) and iron-oxidizing bacteria (mainly Aquabacterium) was relatively high. The layered characteristics of the corrosion layers was due to the blocking of DO transfer by the development of the scales themselves. Bacterial communities could at least promote the layering process and formation of corrosion tubercles. Possible mechanisms might include: (1) bacterial communities mediated the pH and redox potential in the tubercles (which helped to form shell-like and core layers), (2) the metabolism of IRB and magnetic bacteria (Magnetospirillum) might contribute to the presence of Fe3O4 in the shell-like layer, while IRB contributed to green rust in the core layer, and (3) the diversity of the bacterial community resulted in the complex composition of the core layer, and gas producing bacteria (sulfate-reducing bacteria and methanogenic bacteria) played a role in the formation of the porous core layer.
Bacterial communities could promote the layering process and formation of corrosion tubercles. Possible mechanisms might include: (1) bacterial communities mediated the pH and redox potential in the tubercles. (2) the metabolism of IRB and magnetic bacteria might contribute to the presence of Fe3O4 in the shell-like layer, while IRB contributed to green rust in the core layer, and (3) gas producing bacteria (sulfate-reducing bacteria and methanogenic bacteria) played a role in the formation of the porous core layer. Display omitted
•The distinctive features of tubercles with bacteria were shell-like with core layers.•Bacteria could at least promote formation of corrosion tubercles.•The pH and redox potential mediated by bacteria help to form shell-like layers.•The metabolism of IRB and magnetic bacteria contributed to Fe3O4 and green rust.•The bacterial diversity related to the complexity and porosity of core layers.
PDF
