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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., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The increasing use of engineered metal oxide nanoparticles (MONPs) in consumer products raises great concerns about their environmental impacts, but their potential impacts on anaerobic ammonium oxidation (anammox) process in wastewater treatment remain unclear. In this study, the presence of MONPs (1, 50, 200 mg L -1 ) exhibited no visible effects on the nitrogen removal performance of anammox reactors, but high levels (200 mg L -1 ) of SiO 2 NPs, Al 2 O 3 NPs and CeO 2 NPs had a distinct effect on shaping the anammox community. Long-term exposure of MONPs caused different responses in the relative abundance of Ca. Kuenenia, the level of functional gene HzsA and the activities of three key enzymes involved in anammox metabolism, but no significant inhibition effects on specific anammox activity were detected. Overall, the effects of MONPs on anammox community structure and sludge properties depended on their types and levels and followed the order SiO 2  > CeO 2  > Al 2 O 3  > TiO 2 ., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

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 1-200mgL -1 MnO 2 . Notably, the specific anammox activity was increased to maximum value of 657.3±10.6mgTNg -1 VSSd -1 at 50mgL -1 MnO 2 and then slightly decreased, but still higher than that achieved at 0-15mgL -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 50mgL -1 in view of the reactor performance and cost issues., (Copyright © 2018 Elsevier B.V. All rights reserved.)