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While the application of mesophilic anammox process is currently the state of the art, the feasibility of a thermophilic anammox bioprocess is still unclear. In this study, we investigate whether glycine betaine (GB) addition can enhance the thermotolerance of mesophilic anammox biomass in the upflow anaerobic sludge blanket (UASB) reactors fed with synthetic wastewater at a nitrogen loading of approximately 4 kg N m–3 d−1. The results showed that during a long-term operation at 45°C with GB (0, 0.1, 1, 2 mM) addition, anammox performance became worse with the final effluent concentrations of NO2–N of 145 ± 11.6 mg L−1 and nitrogen removal efficiency decreased from 92.3–6.9%. Specific anammox activity decreased from 392.1 ± 12.1–6.0 ± 0.8 mg N g−1 VSS d−1, which were not significantly higher than those in the control reactor. The content of heme c showed a stronger downward trend in T1 (with GB addition) than in the control reactor T0. The qPCR results showed that the relative abundance of Candidatus Kuenenia decreased in both the experimental (from 53.5–28.8%) and control reactors (from 54.1–35.1%). Overall, continuous addition of exogenous GB did not improve the thermotolerance of mesophilic anammox consortia at 45°C. [ABSTRACT FROM AUTHOR]

The response of anaerobic ammonium oxidation (anammox) process and granular sludge in the upflow anaerobic sludge blanket reactor was analyzed under long-term exposure to MnO 2 nanoparticles (NPs) (1–200 mg L−1). The addition of 200 mg L−1 MnO 2 NPs had a significantly positive effect on nitrogen removal and this system exhibited excellent performance, with a total nitrogen removal efficiency of 93.1%. Moreover, the specific anammox activity enhanced with increasing concentrations of MnO 2 NPs up to the maximum value of 657.3 ± 9.3 mg TN g−1 VSS d−1 under MnO 2 NPs concentration of 200 mg L−1. This value was approximately 1.6-fold higher than that of the reactor in the absence of MnO 2 NPs. The extracellular polymeric substances and settling velocity were both increased with MnO 2 NPs addition. Meanwhile, the high-throughput sequencing results revealed that MnO 2 NPs increased the relative abundance of dominant bacteria (Candidatus Kuenenia) from 17.3% at the absence of MnO 2 NPs to 23.9% at 200 mg L−1 MnO 2 NPs, which resulted in a higher efficiency of biological nitrogen removal on the anammox system. These results indicated that MnO 2 NPs enhanced nitrogen removal performance of anammox process. Image 108286 • Long-term effects of MnO 2 NPs on the anammox system were firstly evaluated. • MnO 2 NPs in a wide concentration range enhanced the anammox performance. • The SAA, EPS and V S had the similar variations to NRR. • " Ca. Kuenenia " dominated the community under the tested MnO 2 NPs levels. [ABSTRACT FROM AUTHOR]

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 Extracellular microbial products (EMP) in biological wastewater treatment systems vary with operational conditions and in turn indicate the metabolic status of functional bacteria. In this study, the response of EMP from autotrophic and mixotrophic anammox consortia (AAC and MAC) to the variation of total nitrogen loading rates (TNLR) were investigated as well as their correlations with the community evolution. The variation of TNLR showed a significantly negative correlation with the production of bound microbial products (BMP) but a significantly positive correlation with the production of soluble microbial products (SMP). The presence of organic matters with COD/TN ratio of 0.15 limited the abundance of anammox bacteria in MAC at the full-load phase and suppressed their proliferation at the restart phase. Due to the improved abundance of carbohydrate metabolism genes, MAC with lower abundance of anammox bacteria produced lower soluble polysaccharides than AMC at the full-load phase. Furthermore, four components (C1–4) were identified on the excitation–emission matrix fluorescence spectra of SMP using parallel factor analysis. C1 exhibited a relative higher proportion at the full-load phase, whereas C4 was generated only at the light-load phase or empty-load phase. At the restart phase, C2 and C3 appeared simultaneously and accounted for a high proportion. The information of four components also suggested the metabolic status of AC as revealed by the specific anammox activity, which therefore provided a novel complementary but direct approach for monitoring the operation status of anammox bioreactors. Graphical abstract Unlabelled Image Highlights • The response of EMP from anammox consortia to the TNLR variation was characterized. • The productions of BMP and SMP showed different correlation with TNLR variation. • Four fluorescent components of SMP varied with the operation status of bioreactors. • EEM-based SMP monitoring offers a novel tool to assess reactor performance. [ABSTRACT FROM AUTHOR]

Abstract At least 11% of total nitrogen (TN) remains in the anammox effluent, making it difficult to meet increasingly stringent discharge standards. To overcome this bottleneck, an innovative process to achieve completely anaerobic ammonium removal over nitrite (CAARON) in one single up-flow anaerobic sludge blanket reactor was proposed in this study. The synchronous feeding of acetate at a C/N (nitrite) ratio of 0.6 significantly reduced the nitrogen removal capacity of anammox reactor by limiting the abundance and metabolism of anammox bacteria. In contrast, the asynchronous feeding of acetate optimized the partition of the reactor column into two specific compartments: the lower half favoring anammox and the upper half dominated by DEAMOX (DEnitrifying AMmonium Oxidation). A high TN removal efficiency of 96.2 ± 0.4% and a low effluent TN concentration of 9.3 ± 0.9 mg L−1 were obtained under a high TN loading rate of 9.0 kgN m−3 d−1. The dominant functional microbes in the CAARON process were identified as Candidatus Kuenenia and Thauera , which were responsible for the anammox and denitratation reactions, respectively. Overall, the results in this study provide valuable insight into the coupling of anammox with denitratation, which is a cost-efficient approach for treating ammonium-rich wastewaters. Graphical abstract Unlabelled Image Highlights • A novel CAARON process was achieved for complete ammonium removal over nitrite. • High total nitrogen removal efficiency of >95% was achieved in CAARON process. • High total nitrogen removal rate of 8.6 kgN m−3 d−1 was achieved in CAARON process. • The functional microbes responsible for the CAARON process were identified. [ABSTRACT FROM AUTHOR]

Abstract Given the increasing applications of NiO nanoparticles (NPs) in battery products, the potential effects of NiO NPs on anaerobic ammonium oxidation (anammox) systems were studied for the first time. The results showed that the anammox system performance obviously differed under the stresses of different NiO NPs concentrations. After the withdrawal of NiO NPs, the nitrogen removal performance of the anammox reactor returned to nearly that of the initial phase within 35 days. Compared with 0 mg L−1 NiO NPs, the specific anammox activity first increased and then decreased to the minimum value of 116.8 ± 13.8 mg TN g−1 VSS d−1 at 60 mg L−1 NiO NPs. The variations in the heme c contents and extracellular polymeric substance amounts were similar to the variations in the specific anammox activity throughout the whole experiment. Additionally, the relative abundance of the dominant bacteria (Candidatus kuenenia) increased from 20.44% at 60 mg L−1 NiO NPs to 23.14% at the end of the last phase. Thus, the potential effects of NiO NPs on anammox systems should be a cause for great concern. Graphical abstract Unlabelled Image Highlights • Long-term effects of NiO NPs on the anammox system were firstly investigated. • The anammox performance was enhanced below 10 mg L−1 NiO NPs and suppressed by 10–60 mg L−1 NiO NPs. • The stability of the reactor operation could be controlled by the (F/M)/SAA ratio. • "Ca. kuenenia " dominated the community in the presence of 1–60 mg L−1 NiO NPs. • The performance of the anammox reactor could recover after withdrawing the NiO NPs. [ABSTRACT FROM AUTHOR]

The increasing use of engineered Ag nanoparticles (NPs) in consumer products raises great concerns about their environmental impacts, but their potential impact on anaerobic ammonium oxidation (anammox) bacteria in wastewater treatment remains unclear. In this study, the response of anammox consortia inhabiting in granules to long-term exposure of AgNPs was investigated. The gradually increased stress of AgNPs (1, 10, 50 mg L −1 ) showed no adverse effects on the nitrogen removal performance and on the relative abundance of Ca. Kuenenia inhabiting in granules. Notably, in response to the escalating burden of AgNPs, anammox consortia tended to secrete more protein but less polysaccharide, and meanwhile increase the relative abundances of Ag + efflux protein SilA and regulatory protein SilR. Overall, these results suggested that the strong resistance of anammox granules to AgNPs might be mainly attributed to the defense role of extracellular polymeric substances and gene-based regulation of ion transport. [ABSTRACT FROM AUTHOR]

The increasing use of engineered nanoparticles (NPs) in consumer and industrial products raises concerns about their environmental impacts, but their potential influence on anaerobic ammonium oxidation (anammox) process in wastewater treatment remains unknown. In this study, the response of granule-based anammox reactor to different loads of ZnONPs was investigated. The introduction of 1–5 mg L − 1 ZnONPs did not affect reactor performance, but 90% of the nitrogen removal capacity was deprived by a shock of 10 mg L − 1 ZnONPs within 3 days. Anammox activity was significantly inhibited, but no significant stimulation of intracellular reactive oxygen species (ROS) production or extracellular lactate dehydrogenase (LDH) activity was observed. The inhibition was thus mainly due to the accumulation of toxic Zn(II) ions in anammox biomass. However, the resistance and resilience of this anammox reactor to ZnONPs were enhanced by intermittent perturbations in the mode of “shock-recovery”. The up-regulated abundance of Zn(II)-exporter ZntA might contribute to the enhanced resistance. In addition, these repeated transient disturbances improved the functional specificity of the anammox community despite the reduction of its diversity. Overall, these results may provide useful references for evaluating and controlling the risk of NPs to anammox process. [ABSTRACT FROM AUTHOR]

Abstract While the application of anammox-based process for mesophilic sidestream treatment is at present the state of the art and mainstream treatment at ambient temperature is also in development, the feasibility of thermophilic anammox process is still unclear. This study investigated the effects of salinity on the thermotolerance of mesophilic anammox sludge. In batch activity tests, 45 °C seems to be the critical temperature for the tolerance of mesophilic anammox consortia without acclimatization or amendments. The optimal anammox activity at 40, 42.5, and 45 °C can be achieved with the amendment of salt at 5–8, 8–10, and ~12 g NaCl L−1, respectively. However, this improvement effect was limited at 50 °C or when the shock duration was longer than 24 h even at 45 °C. In continuous-flow bioreactors, mesophilic anammox consortia could gradually adapt to 40–50 °C under a transition of 2.5 °C, and the performance was enhanced by an increase in salinity, which may be associated with the increase in extracellular polymeric substances. A nitrogen removal rate of 0.53 kgN m−3 d−1 was finally obtained at 50 °C. Overall, these interesting results facilitate further opportunities for thermophilic anammox process. Graphical abstract Unlabelled Image Highlights • The thermotolerance of mesophilic anammox consortia was first investigated. • Salt addition alleviated the shock of 40–50 °C to mesophilic anammox consortia. • Thermophilic reactor performance could be enhanced by increased salinity. • A nitrogen removal rate of 0.53 kgN m−3 d−1 was finally obtained at 50 °C. [ABSTRACT FROM AUTHOR]

In this work, a systematic research was on CdS crystalline structure by changing pH value of the solution and annealing treatments. CdS thin film deposited on ITO were prepared by chemical bath deposition using the reaction between CdAc 2 and H 2 NCSNH 2 at a certain bath temperature. In this reaction, NH 3 H 2 O was used to control pH value. Annealing treatments included coating CdCl 2 and annealing directly. Morphological, structural and optical properties were investigated using scanning electron microscopy (SEM), X-ray diffraction and UV–vis spectrophotometer. As the pH value increased to 10.5, CdS film formed the best crystalline. Diffraction patterns were seen to sharpen and crystallite sizes were found to increase by annealing. However, the film annealed with CdCl 2 had a blue shift compared with the direct annealing one, which is conducive to improve the efficiency of CdS/CdTe the solar cell. [ABSTRACT FROM AUTHOR]

• 5 mg L−1 SDBS promoted the release of extracellular microbial products from sludge. • SDBS-induced sludge disaggregation caused the wash-out of anammox population. • SDBS-induced cell damage caused the metabolic inhibition on anammox activity. • The potential risk of LAS to anammox process should be of concern. The increase of emerging contaminants, such as surfactants, is one of the major challenges to biological wastewater treatment. However, the potential impact of linear alkylbenzene sulphonates (LAS), a major class of anionic surfactants, on anammox process is unclear. The long-term effects of sodium dodecyl benzene sulfonate (SDBS, as a model LAS) on reactor performance, microbial community and sludge properties were investigated in this study. The presence of 5 mg L−1 SDBS promoted the release of extracellular microbial products from anammox granules and the wash-out of anammox population via effluent. Despite sludge disaggregation, the reactor performance was robust to the exposure of 5 mg L−1 SDBS due to functional redundancy. With the further increase of SDBS to 10 mg L−1, the metabolic activity of anammox biomass and the transcription and post-translation of hydrazine dehydrogenase were significantly decreased. The potential mechanism might be associated with the damage on cell membrane that induced the leakage of intracellular matrix. These results highlight the need to consider the potential risk of LAS to operation of anammox process in biological wastewater treatment plant. [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 The feasibility of implementing anaerobic ammonium oxidation (anammox) granules to start up high-loading anaerobic sulfide oxidation (ASO) in an upflow anaerobic sludge bed (UASB) reactor was investigated. An innovation method of the reverse start-up of anammox was also validated. Firstly, the reactor was operated to treat sulfide-rich wastewaters into which nitrite was introduced as an electron acceptor. An high-rate performance with sulfide and nitrate removal rates of 105.5 ± 0.11 kg S m−3 d−1 and 28.45 ± 3.40 kg N m−3 d−1, respectively, was accomplished. Sulfurovum were enriched with the increase of the substrate load and then conquered Candidatus Kuenenia to be the predominant bacteria. Excitation-emission matrix (EEM) spectroscopy showed that the intensities of fluorescence decreased and protein-like substrates were the main components associated with the process of start-up. FT-IR analysis found that the main functional groups indicator were O-H groups. Secondly, the reverse start-up of anammox (achieving 90% TN removal) was achieved immediately when the substrate changed. 16S rRNA analysis indicated the successfully enrichment of anammox bacteria (Candidatus Kuenenia). These results suggest that anammox granules can act as inoculum of high-loading ASO process and the reverse start-up provides a new perspective for the fast initiation of anammox process. Graphical abstract Image 1 Highlights • High-loading ASO process was started up by inoculation of anammox sludge. • Microbial community dynamics over different operational periods were revealed. • The reverse start-up of anammox process was quickly achieved. • EEM and FT-IR spectroscopy were employed to characterize changes in EPS. [ABSTRACT FROM AUTHOR]

The long-term impacts of MnO 2 on performance, sludge characteristics and microbial community of biogranule-based anaerobic ammonium oxidation (anammox) process were evaluated in an up-flow anaerobic sludge blanket reactor. It was found that the total nitrogen removal efficiency of reactor was fluctuated between 90%–93% at 1–200 mg L −1 MnO 2 . Notably, the specific anammox activity was increased to maximum value of 657.3 ± 10.6 mg TN g −1 VSS d −1 at 50 mg L −1 MnO 2 and then slightly decreased, but still higher than that achieved at 0–15 mg L −1 MnO 2 , which had similar variation trends to the content of heme c and extracellular polymeric substances in anammox granules. High throughput sequencing indicated that MnO 2 could improve the microbial richness and diversity of anammox granules and Candidatus Kuenenia was always the dominant species, and its abundance continued to increase to 21.3% at the end of operational experiment. Therefore, MnO 2 could be applied to enhance the anammox process and the optimal influent MnO 2 concentration was lower than 50 mg L −1 in view of the reactor performance and cost issues. [ABSTRACT FROM AUTHOR]

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]