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This study evaluated the individual and interactive effect of phenol and thiocyanate (SCN) on partial nitritation (PN) activity using batch test and response surface methodology. The IC of phenol and SCN on PN sludge were 5.6 and 351 mg L, respectively. The PN sludge was insensitive to phenol and SCN at levels lower than 1.77 and 43.3 mg L, respectively. A regression model equation was developed and validated to predict the relative specific respiration rate (RSRR) of PN sludge exposed to different phenol and SCN concentrations. In the range of independent variables, the most severe inhibition was observed with a valley value (17%) for RSRR, when the phenol and SCN concentrations were 4.08 and 198 mg L, respectively. An isobole plot was used to judge the combined toxicity of phenol and SCN, and the joint inhibitory effect was variable depending on the composition and concentration of the toxic components. Furthermore, the toxic compounds showed independent effects, which is the most common type of combined toxicity. [ABSTRACT FROM AUTHOR]

To facilitate the application of partial nitritation (PN) – anaerobic ammonium oxidation process in nitrogen removal from livestock wastewater, the inhibition of roxithromycin (ROX) and Cu(II) on the PN sludge was examined using a respirometric method. The results showed that the IC 50 of ROX and Cu(II) on PN sludge were 346 and 74.3 mg L −1 , respectively. The relative specific respiration rate (SRR) of ammonia-oxidizing bacteria (AOB) decreased from 87.4% to 17.7% with the ROX concentration increased from 0 to 500 mg L −1 . When the concentration of Cu(II) increased from 0 to 160 mg L −1 , the SRRs of AOB and nitrite-oxidizing bacteria decreased by 85.5% and 11.2%, respectively. According to the isobole plots analysis, combined suppression by ROX and Cu(II) was synergistic. Fourier transform infrared spectroscopy analyses showed that ROX exposure altered the positions of C O bonds, and the intensity of the absorption peak at 2100 cm −1 changed under Cu(II) exposure. [ABSTRACT FROM AUTHOR]

The combined anammox (anaerobic ammonium oxidation) and autotrophic desulfurization–denitrification (AADD) process represents a promising innovative technology for biological nitrogen and sulfur removal. In this study, an up-flow anaerobic sludge blanket reactor, which was started with anammox and methanogenic granules, was operated for 245 days to evaluate the co-treatment of wastewater containing nitrogen and sulfur. The reactor demonstrated good performance in terms of nitrogen and sulfide removal and exhibited excellent behavior for removal of NH 4 + -N, NO 2 − -N and S 2− -S exceeding 252, 333 and 330 mg L −1 , respectively. The highest nitrogen removal rate and sulfide removal rate attained were 4.00 kgN m −3 d −1 and 2.39 kgS m −3 d −1 , respectively, which were also the highest reported values for a coupling-system. The influent NH 4 + -N:S 2− -S and NO 2 − -N:S 2− -S ratios set at 1.74 and 2.20–2.27 are suitable for maintaining system stability. The specific activities of anammox and autotrophic desulfurization–denitrification (SAA and SADD), extracellular polymeric substance (EPS), heme c (an important cofactor of some anammox bacterial enzymes) and the diversity of anammox and autotrophic desulfurization–denitrification (ADD) bacteria were investigated during the operation. The SAA and SADD are regarded as key factors for high efficiency. The granules contained many EPS (128.4–204.5 mg g −1 VSS) and minor heme c content (1.17 μmol g −1 VSS). The dominant bacteria belonged to members of Brocadiaceae and Hydrogenophilaceae , a majority of which were anammox bacteria and ADD bacteria, respectively. These observations suggest a new removal process for ammonia, nitrite and sulfide utilizing an uncommon mechanism involving simultaneous anammox and ADD. [ABSTRACT FROM AUTHOR]

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 Hzs A 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 . [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]

The short- and long-term effects of inorganic phosphate on property of anaerobic ammonium oxidation (anammox) granule were investigated in this study. Acute exposure to high-level phosphate (⩾50 mM) induced the cytoplasm leakage. During a 195-day continuous-flow operation, the gradually increasing phosphate (up to 500 mgP L −1 ) slightly affected the specific anammox activity, hardly impacted the heme c content, remarkably decreased the extracellular polymeric substances production and significantly stimulated the dehydrogenase activity of anammox granules. Microbial community analysis showed no shift in the dominant anammox strain and higher population but lower relative abundance of anaerobic ammonium-oxidizing bacteria compared to the control granules. Interestingly, novel anammox granules with a hydroxyapatite core were cultivated, which possessed excellent settleability, huge granule diameter and superior mechanical strength. This study supported the application of granule-based anammox process as a pre-processing treatment in phosphate-containing and ammonia-rich wastewaters. [ABSTRACT FROM AUTHOR]