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The increasing release of engineered nanoparticles (NPs) from consumer products has raised great concerns about their impacts on biological wastewater treatment. In this study, the widely-used ZnO NP was selected as a model NP to investigate its impact on high-rate denitrifying granular sludge in terms of sludge properties and community structure. A hormesis effect was observed during short-term exposure, in which the specific denitrification activity (SDA) was stimulated by 10% at 1 mg L−1 ZnO NPs, but inhibited by 23% at 5.0 mg L−1 ZnO NPs. When continuously exposed to 2.5 mg L−1 ZnO NPs, the nitrogen removal capacity of the denitrification reactor was nearly deprived within 15 days, and the relative abundance of the dominant denitrifying bacterium (Castellaniella) was decreased from 51.0 to 8.0%. Meanwhile, the dehydrogenase activity (DHA) and the content of extracellular polymeric substance (EPS) significantly decreased to 22.3 and 61.1%, respectively. Nevertheless, the presence of phosphate substantially weakened the adverse effects of ZnO NPs on the SDA, EPS, DHA and the relative abundance of functional genes even exposed to 6.25 mg L−1 ZnO NPs, which was associated with the fact that the level of Zn(II) released from ZnO NPs was significantly reduced in the presence of phosphate. Therefore, the toxicity of ZnO NPs may be mainly attributed to the release of toxic Zn(II) and could be attenuated in the presence of phosphate. Overall, this study provided further reference and meaningful insights into the impact of engineered NPs on biological wastewater treatment. Image 1 • A hormesis effect was observed during short-term exposure. • 2.5 mg L−1 ZnONPs reduced the nitrogen removal capacity by 72.5% within two weeks. • 310 mg P L−1 phosphate increased the metabolic activity and abundance of denitrifying bacteria. • Based on the PICRUSt, the abundance of genes related to zinc ion assimilation was decreased. [ABSTRACT FROM AUTHOR]

Abstract Both nickel and salinity are often detected in the environment. Especially electroplating wastewater contains some salt and nickel, which affects microbial activity in biological wastewater treatment process. In this study, the effects of sustaining addition of a high-concentration salinity and Ni(II) on the anaerobic ammonium oxidation (anammox) process were examined. The results indicated that the anammox system had an acclimation ability to <0.2 mg L−1 Ni(II) and 20 g L−1 NaCl. After a recovery phase of approximately 70 days, the nitrogen removal efficiency and rate reached at 77.1% and 1.18 kg N m−3 d−1, respectively. The three-dimensional excitation-emission matrix fluorescence and Fourier transform infrared spectra results showed that the introduction of NaCl and Ni(II) caused a substantial variation in the quantity and composition of the bound EPS in the surface of anammox granules. The present study is the first to document the long-term effect of co-existence of salinity and Ni(II) on the performance of the freshwater-derived anammox bacteria in the upflow anaerobic sludge blanket reactor and to provide a reference for the stable operation of anammox bioreactors for the treatment of sulfonamide-containing wastewater. Graphical abstract Unlabelled Image Highlights • Long-term exposure to NaCl and Ni(II) resulted in co-inhibition on the anammox UASB system. • The sludge characteristics changed after chronic exposure to NaCl and Ni(II). • 3D-EEM analyses showed a change in organic compositions in B-EPS. • FTIR analyses suggested a shift in functional groups in B-EPS. • The deleterious impact of NaCl and Ni(II) was reversible. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The suppression threshold of Zn(II) on reactor performance was 10 mg L−1 for long-term exposure. • Castellaniella mainly was devoted to denitrification under no or low Zn(II) stress conditions. • Klebsiella was the dominant denitrifying bacteria under high Zn(II) stress conditions. Abstract High-rate denitrification is a popular and efficient process for treatment of nitrate-rich wastewater. Knowing the effect of heavy metals on denitrification is essential for industrial development. In the present study, the long-term impacts of Zn(II) on denitrifying granular sludge were investigated. The suppression threshold of Zn(II) on denitrifying bacteria was 10 mg L−1 for long-term exposure. The nitrogen removal rate was decreased by long-term addition of 10 mg L−1 Zn(II). Castellaniella and Klebsiella were the two dominant genera under Zn(II) stress. The relative abundance of Klebsiella sharply decreased to 4.64% after the addition of 10 mg L−1 Zn(II), whereas Castellaniella was susceptible to 2 mg L−1 Zn(II), revealing that Castellaniella mainly was devoted to denitrification under no or low Zn(II) stress conditions, whereas Klebsiella was effective under high Zn(II) stress. [ABSTRACT FROM AUTHOR]

Summary: Conductive hearing loss, the second most common type of hearing loss, happens when there is a problem transmitting sound waves into inner ear, which will bring a lot of inconvenience to the patient in life and put the impaired person at a competitive disadvantage. Although conductive hearing loss could be relieved by hearing aids, the inconvenience of using these removable aids or the surgery trauma of the implanted ones should not be overlooked. Transversal maxillary deficiency and high palatal arches are often found in patients with conductive hearing loss. Some researchers have reported that there is close relationship between the maxillary contraction and hearing damage. Luckily, rapid maxillary expansion (RME) has been proved to be an effective treatment method for the transversal maxillary deficiency in clinical orthodontics for more than 40years. Thus, we hypothesized that RME treatment would be a potential therapeutic method for conductive hearing loss in growing children with maxillary constriction. [Copyright &y& Elsevier]

• Better resistance and resilience were observed in unacclimated anammox granular sludge. • Anammox system was significantly suppressed by the addition of high level Cu NPs and OTC. • Dominant bacteria and functional genes coincide with each other. • The presence of ARGs improved the resistance of anammox sludge to Cu NPs and OTC. Nanoparticles and antibiotics, the two most frequently detected emerging pollutants from different wastewater sources, are eventually discharged into wastewater treatment plants. In this study, the widely used materials CuNPs and oxytetracycline (OTC) were selected as target pollutants to investigate their joint effects on anaerobic ammonium oxidation (anammox). The results indicated that the environmental concentration slightly inhibited the performance of the reactors, while the performance rapidly deteriorated within a week under high-level combined shocks (5.0 mg L−1 CuNPs and 2.0 mg L−1 OTC). After the second shock (2.5 mg L−1 CuNPs and 2.0 mg L−1 OTC), the resistance of anammox bacteria was enhanced, with an elevated relative abundance of Candidatus Kuenenia and absolute abundance of hzs A, nir S, and hdh. Moreover, the extracellular polymeric substance (EPS) content and specific anammox activity (SAA) showed corresponding changes. Improved sludge resistance was observed with increasing CuNP and OTC doses, which accelerated the recovery of performance. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) bacteria are sensitive and susceptible to operating condition fluctuations that can lead to the instability of a bioreactor. Through multivariate spectral analysis, the dynamic changes of intracellular and extracellular metabolites of anammox sludge under the declined temperature stress were characterized. It was found that effluent fluorescence components were positively related to the bacterial activity, and the response of the protein-like substances to the temperature change was more sensitive than that of humic substances. Under the transient disturbance during temperature change from 35 to 15 °C, anammox system tended to considerably excrete extracellular polymeric substances to resist the low temperature inhibition. However, the long-term exposure of the sludge at 10 °C resulted in the considerably inhibition of sludge activity, granular disintegration and heterotrophic denitrification bacteria increase. The two-dimensional correlation analysis further revealed that the humic acid in extracellular polymeric substances was preferentially responded to the temperature change than protein. Anammox bacteria tended to increase the intracellular protein and electron transfer-related reactive substance excretion to counteract the low temperature inhibition. Herein, both the intra- and extra-cellular response characteristics of anammox sludge to temperature variation were successfully resolved via the combined spectra. This work provides a comprehensive understanding on the mechanism of anammox sludge to temperature variation and may be valuable for the development of bioreactor monitoring techniques. Unlabelled Image • The performance of anammox bioreactor was characterized by spectra combination. • 2-dimension correlation spectroscopy was used for extracellular substances analysis. • Effluent fluorescence components were positively related to the bacterial activity. • 15 °C was an inflection temperature for the extracellular substances excretion. [ABSTRACT FROM AUTHOR]

Abstract: Glycyrrhetinic acid (GA), the main active constituents of Glycyrrhiza glabra roots, is extensively used as food additives and herbal medicines. This study was carried out to evaluate the effects of different dietary levels of GA on growth, body composition and plasma biochemical index of channel catfish (average weight, 159.0±5.0g). Five diets were formulated to contain five levels of GA (0, 0.075, 0.15, 0.3 and 0.6g/kg). Fish were randomly distributed into 30 tanks and fed three times daily (08:30, 12:00 and 16:30h) for 8weeks. Dietary GA levels have little significant effect on weight gain (WG) and feed conversion ratio (FCR). Intraperitoneal fat ratio (IFR) (P <0.05) and viscera/body ratio (VBR) (P <0.01) decreased significantly as GA levels increased, and hepatosomatic index (HSI) tended to decrease as dietary GA levels increased (P <0.1). Lipid content of liver decreased significantly as GA concentrations increased (P <0.01), and lipid content of muscle tended to decrease as dietary GA concentrations increased (P <0.1). Plasma triglycerides (TG) and total cholesterol (CHO) were decreased as dietary GA concentrations increased (P <0.05); whereas, plasma cortisol and glucose (GLU) showed an opposite tendency (P <0.05). Results of this study indicate that 0.3g/kg GA had a positive influence in improving lipid deposition in channel catfish without negative effect on growth; the beneficial effect may be due to promoting lipolysis. [Copyright &y& Elsevier]

• The presence of 1 mg L−1 Cu NPs was supposed to be safe in granule-based denitrification systems. • The system lost 51.9% of nitrogen removal capacity under the stress of 5 mg L−1 Cu NPs. • The presence of 5 mg L−1 Cu NPs reduced the gene abundance of nap A, nar G and nos Z. • The introduction of Cu NPs shifted the community composition of denitrifying bacteria. The widespread use of copper nanoparticles (CuNPs) has attracted increasing concern because of their potential effects on biological wastewater treatment. However, their effect on granule-based denitrification systems is unclear. Hence, the effects of CuNPs on denitrifying granules were investigated during long-term operation. The results showed that 51.9% of nitrogen removal capacity was lost after exposure to 5 mg L−1 CuNPs, with the amount of Cu(II) gradually increasing with elevating CuNP levels. Moreover, the relative abundance of denitrifying bacteria (Castellaniella) and denitrifying functional genes (nir K, nap A, nar G and nos Z) obviously decreased. Meanwhile, the specific denitrification activity, the content of extracellular polymeric substances and dehydrogenase activity decreased by 44.0%, 15.2% and 99.9%, respectively, compared to their values in the initial sludge. Considering the downtrend in the abundance of copper resistance genes, it was deduced that the toxicity of CuNPs was mainly or at least partially due to the release of Cu(II). [ABSTRACT FROM AUTHOR]

• High-intense light would inhibit anammox sludge activity decline. • Light induced · OH and · O 2 − were able to destruct ladderane lipids structure. • Se-CQDs would greatly mitigate the photoinhibition and maintain a stable performance. • The potential mitigation mechanism by Se-CQDs was clarified. External stimulus such as light irradiation is able to deteriorate intracellular redox homeostasis and induce photooxidative damage to non-photogenic bacteria. Exploiting effective strategies to help bacteria resisting infaust stress is meaningful for achieving a stable operation of biological treatment system. In this work, selenium-doped carbon quantum dots (Se-CQDs) were blended into anaerobic ammonia oxidation (anammox) bacteria and an inorganic nanoparticle-microbe hybrid was successfully fabricated to evaluate its nitrogen removal performance under solar-simulated irradiation. It was found that the specific anammox activity decreased by 29.7 ± 5.2% and reactive oxygen species (ROS) content increased by 134.8 ± 4.1% under 50,000 lux light. Sludge activity could be completely recovered under the optimum dosage of 0.42 mL·(g volatile suspended solid) -1 Se-CQDs. Hydroxyl radical (·OH) and superoxide anion radical (·O 2 −) were identified as the leading ROS inducing lipid peroxidation and antioxidase function detriment. Also, the structure of ladderane lipids located on anammoxosome was destroyed by ROS and functional genes abundances declined accordingly. Although cell surface coated Se-CQDs could absorb ultraviolet light and partially mitigated the photoinhibition, the direct scavenging of ROS by intracellular Se-CQDs primarily contributed to the cellular redox homeostasis, antioxidase activity recovery and sludge activity improvement. The findings of this work provide in-depth understanding the metabolic response mechanism of anammox consortia to light irradiation and might be valuable for a more stable and sustainable nitrogen removal technology, i.e., algal-bacterial symbiotic system, development. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The coercive effect of coagulants on EBPR system was investigated. • EPS secretion was increased as a response to metal salt stress in the short term. • Coagulants can cause damage to cells through mediating the formation of ROS. • Metal salts put PAOs at a disadvantage position in competition with GAOs. Enhanced biological phosphorus removal (EBPR) process is susceptible to the changed operation condition, which results in an unstable treatment performance. In this work, long-term effect of coagulants addition, aluminum salt for the reactor R 1 and iron salt for the reactor R 2 , on EBPR systems was comprehensively evaluated. Results showed that during the initial 30 days' coagulant addition, effluent chemical oxygen demand and phosphorus can be reduced below 25 and 0.5 mg·L-1, respectively. Further supply of metal salts would stimulate microbial extracellular polymeric substance excretion and induce reactive oxygen species accumulation, which destroyed the cell membrane integrity and deteriorated the phosphorus removal performance. Moreover, coagulants would decrease the relative abundance of Candidatus Accumulibacter while increase the relative abundance of Candidatus Competibacter, leading phosphors accumulating organisms in a disadvantage position. The results of this work might be valuable for the operation of chemical assisted biological phosphorus removal bioreactor. [ABSTRACT FROM AUTHOR]

Abstract: Siniperca chuatsi, Siniperca kneri, and Siniperca scherzeri are three of the most economically important sinipercid species. The ultrastructure and morphology of the mature spermatozoa of them are examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The sperm consists of an acrosome-less head, a short midpiece and a long flagellum. Ultrastructurally, it has a homogeneously electron-dense nucleus in a granular pattern with nuclear lucent and a nuclear fossa excluding the centriolar complex. One to four mitochondria with lamellar cristae encircle the basal body of the flagellum in the midpiece. The cytoplasm surrounding the centrioles and the cylindric cytoplasmic channel contains glycogen granules and vesicles. Comprising the conventional 9+2 axoneme, vesicles and lateral fins, the sperm flagellum is inserted laterally on the nucleus, therefore the spermatozoon is asymmetrical. All of the spermatozoa of the three species are of the primitive or ect-aquasperm form and conform to the teleostean type II spermatozoa instead of the previously supposed type I. Variations in the shape of the heads, angles between the two centrioles, location of the cytoplasmic vesicles, mitochondrial number and structural characteristics of the lateral fins are notable among the three species. S. chuatsi is a sister-group of the other two species and is the most differentiated. The present study provides fresh insights to the comparative spermatology of Siniperca fishes and will be useful to the existing knowledge of the sinipercid fishes in systematic characters, biodiversity conservation and reproduction. [Copyright &y& Elsevier]

The arsenic in livestock wastewater would induce adverse impact on the biological treatment technology such as anaerobic ammonium oxidation (anammox) process. Extracellular polymeric substances (EPS) play an important role in resisting such toxicity. Unfortunately, the role of EPS in protecting anammox from As(III) and the mechanisms underlying the protection still remains unclear. This work comprehensively evaluated the acute toxicity of arsenic on anammox sludge and investigated the binding property and interaction mechanism. The results revealed that the half maximal inhibitory concentration (IC 50) of As(III) on anammox sludge was estimated to be 408 mg L−1, which decreased to 41.97 mg L−1 when EPS was exfoliated. Complexation and hydrophobic interactions were the leading forces in preventing arsenic invasion. Protein was the main component that complexes with As(III), and O–H, –NH, –C O were binding sites. The response sequence of organic component in EPS to As(III) was ordered as hydrocarbons-proteins-polysaccharides-aliphatic amines. [Display omitted] • The IC 50 of As(III) was estimated as 408 mg L−1 in anammox process. • EPS was able to construct buffer zones to prevent As(III) invasion. • Protein is the main component within EPS to complex with As(III). • Response sequence of functional groups to As(III) was clarified via spectra analysis. [ABSTRACT FROM AUTHOR]

Persulfate based advanced oxidation process is a promising technology for refractory contaminants removal. Cobalt is considered as the most efficient metal in catalyzing peroxymonosulfate decomposition. Although different cobalt based nanomaterials have been developed, easy aggregation and metal ion leaching during catalytic reaction would result in its deficiency. To address the above issue, in this work, carbon supported Co/CoO core-shell nanocomposite was in-situ fabricated by using polyphenol-metal coordinate as precursor. Results indicated that cobalt nanoparticle with size of 10 nm was successfully prepared and well dispersed within the carbon matrix. By using as-prepared material as catalyst, 50 mg/L orange II was completely removed under the condition of 0.2 g/L peroxymonosulfate, 0.05 g/L catalyst, pH = 4.0–10.0. Both sulfate and hydroxyl radicals were formed during peroxymonosulfate decomposition, while sulfate radical dominated the pollutant removal. Mechanism study revealed that the cobalt was the key site for catalyzing peroxymonosulfate decomposition. This work might provide valuable information in designing and fabricating metal anchored carbon composite catalyst for efficiently and cost-effectively activate peroxymonosulfate. Image 1 • Co/CoO core-shell nanostructure was well dispersed within the carbon matrix. • Co/CoO@C nanocomposite remains stable within pH ranges of 4.0-10.0, rather than the current 4.0-7.0. • Sulfate radical was the dominant reactive species for orange II removal. • Peroxymonosulfate catalytic decomposition mechanism was explored and clarified. [ABSTRACT FROM AUTHOR]