A novel strategy for anammox consortia preservation: Transformation into anoxic sulfide oxidation consortia.

The preservation of anaerobic ammonia oxidation (anammox) consortia is crucial for the rapid start-up and the process stability of the anammox based bioreactor. This work proposed and evaluated the feasibility of an anammox consortia preservation strategy, in which the anammox sludge was transformed into intermediate anoxic sulfide oxidation (ASO) functional microorganisms. Initially, the ASO process was successfully started up by inoculating anammox sludge and the overall sulfide and nitrate removal rates stabilized at 57.5 ± 0.22 and 10.0 ± 0.18 kg m-3 day-1, respectively. Then, the bioreactor function was reversely transformed into anammox, whose nitrogen removal rate reached 1.68 kg m-3 day-1. Granule characteristics analysis revealed that both biomass and extracellular polymeric substance content returned to their original states after the reverse start-up. Although the population of Candidatus_Kuenenia was greatly declined during ASO process, its richness was successfully recovered after the reverse start-up of the anammox process. The inferred metagenomes analysis demonstrated that the shifts in functional microorganisms were related to variation in the main metabolic pathways. The specific activities of anammox and ASO both are regarded as key indicators for the successful start-up of bioreactor. This work revealed a novel technique for the preservation of anammox consortia and might be a potential strategy for overcoming the drawback of long start-up time.

Effect of divalent nickel on the anammox process in a UASB reactor.

The anaerobic ammonium oxidation (anammox) process has the advantages of a high nitrogen removal rate, low operational cost, and small footprint and has been successfully implemented to treat high-content ammonium wastewater. However, very little is known about the toxicity of the heavy metal element Ni(II) to the anammox process. In this study, the short- and long-term effects of Ni(II) on the anammox process in an upflow anaerobic sludge blanket (UASB) reactor were revealed. The results of the short-term batch test showed that the half maximal inhibitory concentration (IC50) of Ni(II) on anammox biomass was 14.6 mg L-1. A continuous-flow experiment was performed for 150 days of operation, and the results illustrated that after domestication, the achieved nitrogen removal efficiency was up to 93±0.03% at 10 mg L-1 Ni(II). The settling velocity, specific anammox activity and EPS content decreased as the Ni(II) concentration increased. Nevertheless, the content of heme c increased as the Ni(II) increased. These results indicate that short-term exposure to Ni(II) has an adverse impact on anammox process, but the anammox system could tolerate 10 mg L-1 Ni(II) stress after acclimation during continuous-flow operation for 150 days. High-throughput sequencing results indicated that the presence of Ni(II) had an impact on the microbial community composition in the anammox reactor, especially Candidatus Kuenenia. At Ni(II) concentrations of 0-10 mg L-1, the relative abundance of Candidatus Kuenenia decreased from 36.23% to 28.46%.

Co-inhibition of salinity and Ni(II) in the anammox-UASB reactor.

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.

Anammox granule as new inoculum for start-up of anaerobic sulfide oxidation (ASO) process and its reverse start-up.

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 ±â€¯0.11 kg S m-3 d-1 and 28.45 ±â€¯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.

Insight into the short- and long-term effects of quinoline on anammox granules: Inhibition and acclimatization.

The short- and long-term influence of quinoline on the properties of anaerobic ammonium oxidation (anammox) biogranules was evaluated. During batch tests, the bioactivity of anammox granules in the presence of different quinoline concentrations was monitored, and the IC50 of quinoline was calculated to be 13.1 mg L-1 using a non-competitive inhibition model. The response of anammox granules to pre-exposure to quinoline was dependent on metabolic status, and the presence of both quinoline and NO2--N had a rapid detrimental effect, resulting in a 64.5% decrease within 12 h. During continuous-flow experiments, the nitrogen removal rate (NRR) of the reactor decreased sharply within 3 days in the presence of 10 mg L-1 quinoline and then was restored to 2.6 kg N m-3 d-1. In the presence of quinoline-induced stress, the specific anammox activity and levels of extracellular polymeric substance and heme c were decreased, while settling velocity persistently increased. After cultivation and acclimation obtained by adding a medium level of quinoline to the influent, the anammox granule sludge was able to tolerate 10 mg L-1 quinoline in 178 days.

Discrepant effects of metal and metal oxide nanoparticles on anammox sludge properties: A comparison between Cu and CuO nanoparticles.

Metal and metal oxide nanoparticles (NPs) show differences in antimicrobial activity due to different chemical and physical properties. Using copper as a representative example, this study compared the NP effects on anaerobic ammonium oxidation (anammox) bacteria in wastewater treatment. Long-term exposure to 5 mgCu L-1 CuNPs reduced the physiological activity and abundance of anammox bacteria, thereby causing deterioration of reactor performance. However, anammox granules exhibited stronger resistance and resilience to perturbation by 1-160 mgCu L-1 CuONPs, and no adverse effects on performance were observed. Moreover, the level of Cu(II) released from NPs in the influent exhibited good correlations with variations of the community structure and sludge properties. Therefore, the effects of Cu-based NPs on anammox sludge properties are dependent on their forms and levels, and their discrepant effects are partially attributed to their ability to release ionic copper.

Evaluating the effects of metal oxide nanoparticles (TiO2, Al2O3, SiO2 and CeO2) on anammox process: Performance, microflora and sludge properties.

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 SiO2NPs, Al2O3NPs and CeO2NPs 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 SiO2 > CeO2 > Al2O3 > TiO2.

Transient disturbance of engineered ZnO nanoparticles enhances the resistance and resilience of anammox process in wastewater treatment.

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 1-5mgL-1 ZnONPs did not affect reactor performance, but 90% of the nitrogen removal capacity was deprived by a shock of 10mgL-1 ZnONPs within 3days. 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.

Enhanced effects of maghemite nanoparticles on the flocculent sludge wasted from a high-rate anammox reactor: Performance, microbial community and sludge characteristics.

Magnetic nanoparticles (NPs) have been widely applied in environmental remediation, biomass immobilization and wastewater treatment, but their potential impact on anaerobic ammonium oxidation (anammox) biomass remains unknown. In this study, the short-term and long-term impacts of maghemite NPs (MHNPs) on the flocculent sludge wasted from a high-rate anammox reactor were investigated. Batch assays showed that the presence of MHNPs up to 200 mg L-1 did not affect anammox activity, reactive oxygen species production, or cell membrane integrity. Moreover, long-term addition of 1-200 mg L-1 MHNPs had no adverse effects on reactor performance. Notably, the specific anammox activity, the abundance of hydrazine synthase structural genes and the content of extracellular polymeric substance were increased with elevated MHNP concentrations. Meanwhile, the community structure was shifted to higher abundance of Candidatus Kuenenia indicated by high-throughput sequencing. Therefore, MHNPs could be applied to enhance anammox flocculent sludge due to their favorable biocompatibility.

Mass transfer characteristics, rheological behavior and fractal dimension of anammox granules: The roles of upflow velocity and temperature.

In this study, the mass transfer, rheological behavior and fractal dimension of anaerobic ammonium oxidation (anammox) granules in upflow anaerobic sludge blanket reactors at various temperatures (8.5-34.5°C) and upflow velocities (0.06, 0.18mh-1) were investigated. The results demonstrated that a lower temperature increased the external mass transfer coefficient and apparent viscosity and impaired the performance of anammox granules. The external mass transfer coefficient was decreased, but efficient nitrogen removal of up to 96% was achieved under high upflow velocity, which also decreased the apparent viscosity. Furthermore, a fractal dimension of up to 2.93 achieved at low temperature was higher than the previously reported values for mesophilic anammox granules. A higher upflow velocity was associated with the lower fractal dimension. Because of the disturbance in granule flaking, the effectiveness factor was less suitable than the external mass transfer coefficient for characterization of mass transfer resistance.

Unraveling the impact of nanoscale zero-valent iron on the nitrogen removal performance and microbial community of anammox sludge.

Given the increasing use of nanoscale zero-valent iron (NZVI) particles for environmental remediation and wastewater treatment, their potential impact on anaerobic ammonium oxidation (anammox) bacteria was investigated in this study using anammox sludge. Batch assays showed that NZVI concentrations up to 200mgL-1 did not affect anammox activity, reactive oxygen species production, and cell membrane integrity. The nitrogen removal efficiency of the continuous-flow reactor fluctuated in the presence of 20 or 50mgL-1 NZVI, but it could return to normal over time, even at 200mgL-1 NZVI. 16S rDNA-based high-throughput sequencing indicated that although the presence of 10, 20, 50, and 200mgL-1 NZVI to some extent affected microbial composition, the anammox bacteria (Candidatus Kuenenia) never lost its dominance. The abundance of gene families that are related to the assimilation and utilization of iron was down-regulated in response to the stress of high-level NZVI.

Susceptibility, resistance and resilience of anammox biomass to nanoscale copper stress.

The increasing use of engineered nanoparticles (NPs) poses an emerging challenge to biological wastewater treatment. The long-term impact of CuNPs on anaerobic ammonium oxidation (anammox) process was firstly investigated in this study. The nitrogen removal capacity of anammox reactor was nearly deprived within 30days under the stress of 5.0mgL-1 CuNPs and the relative abundance of anammox bacteria (Ca. Kuenenia) was decreased from 29.59% to 17.53%. Meanwhile, copper resistance genes associated with the Cus, Cop and Pco systems were enriched to eliminate excess intracellular copper. After the withdrawal of CuNPs from the influent, the nitrogen removal capacity of anammox biomass recovered completely within 70days. Overall, anammox biomass showed susceptibility, resistance and resilience to the stress of CuNPs. Therefore, the potential impacts of ENPs on anammox-based processes should be of great concern.

Individual and combined inhibition of phenol and thiocyanate on microbial activity of partial nitritation.

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 IC50 of phenol and SCN- on PN sludge were 5.6 and 351 mg L-1, respectively. The PN sludge was insensitive to phenol and SCN- at levels lower than 1.77 and 43.3 mg L-1, 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-1, 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.

Combined impacts of nanoparticles on anammox granules and the roles of EDTA and S2- in attenuation.

Previous studies investigating the risk of engineered nanoparticles (NPs) to biological wastewater treatment have primarily tested NPs individually; however, limited data are available on the impact of NPs on the anaerobic ammonium oxidation (anammox) process. In this study, the toxicity of CuNPs on anammox granules was investigated individually and in combination with CuONPs or ZnONPs. Exposure to CuNPs at 5mgg-1 suspended solids (SS) decreased the anammox activity to 47.1±8.5%, increased the lactate dehydrogenase level to 110.5±3.4% and increased the extracellular N2H4 concentration by 16-fold but did not cause oxidative stress. The presence of CuONPs or ZnONPs at 5mgg-1 SS did not significantly aggravate or alleviate the toxicity of the CuNPs; however, the introduction of EDTA or S2- could attenuate the adverse effects of the CuNPs, CuONPs and ZnONPs on the anammox granules. EDTA captured Cu ions, whereas S2- shielded and deactivated Cu ions and passivated CuNPs. Therefore, our results indicated that the toxicity of NPs was dependent on the amount of active metal reaching the anammox cells. Overall, the results of this study have filled knowledge gaps and provided insights into the combined toxicity of NPs on anammox biomass.

Short-term impacts of Cu, CuO, ZnO and Ag nanoparticles (NPs) on anammox sludge: CuNPs make a difference.

The increasing application of engineered nanoparticles (NPs) has posed an emerging challenge to wastewater treatment processes. The short-term impacts of CuNPs, CuONPs, ZnONPs and AgNPs on anaerobic ammonium oxidation (anammox) process were investigated firstly in this study. CuONPs, ZnONPs and AgNPs up to 50mgg-1 suspended solid (SS) did not affect anammox activity, reactive oxygen species (ROS) production or cell membrane integrity. However, 1.25mgg-1SS CuNPs significantly inhibited the anammox activity and the loads that caused 50% inhibition were 4.64±1.24 and 3.27±0.79mgg-1SS for anammox granules and flocs, respectively. 5mgg-1SS CuNPs caused serious accumulation of the toxic intermediate N2H4. Furthermore, CuNPs interacted with extracellular polymeric substances by specifically bonding to tyrosine or tryptophan-containing groups, C-O-C in polysaccharides and -OH in polymeric compounds. Therefore, this study calls for more attention to the risks of NPs to the anammox-based processes.

Inhibition of the partial nitritation by roxithromycin and Cu(II).

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 IC50 of ROX and Cu(II) on PN sludge were 346 and 74.3mgL(-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 500mgL(-1). When the concentration of Cu(II) increased from 0 to 160mgL(-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 CO bonds, and the intensity of the absorption peak at 2100cm(-1) changed under Cu(II) exposure.

Insight into the short- and long-term effects of inorganic phosphate on anammox granule property.

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.

Long-term effects of heavy metals and antibiotics on granule-based anammox process: granule property and performance evolution.

The feasibility of the anaerobic ammonium oxidation (anammox) process to treat synthetic swine wastewater containing antibiotics and heavy metals was studied in this work. Nitrogen removal performance and granule characteristics were tracked by continuous-flow monitoring to evaluate the long-term joint effects of Cu and Zn and of Cu and oxytetracycline (OTC). Cu and Zn with a joint loading rate (JLR) of 0.04 kg m(-3) day(-1) did not affect the performance, while a JLR of 0.12 kg m(-3) day(-1) caused a rapid collapse in performance. Cu and OTC addition with a JLR of 0.04 kg m(-3) day(-1) for approximately 2 weeks induced significant nitrite accumulation. Granule characteristic analysis elucidated the disparate inhibition mechanisms of heavy metals and antibiotics: the internalization of heavy metals caused metabolic disorders, whereas OTC functioned as a growth retarder. However, anammox reactors could adapt to a JLR of 0.04 kg m(-3) day(-1) via self-regulation during the acclimatization to subinhibitory concentrations, which had a stable nitrogen removal rate (>8.5 kg m(-3) day(-1)) and removal rate efficiency (>75 %) for reactors with Cu-OTC addition. Therefore, this study supports the great potential of using anammox granules to treat swine wastewater.

Cucurbitacin B induces cell cycle arrest, apoptosis and autophagy associated with G actin reduction and persistent activation of cofilin in Jurkat cells.

AIM: The present study aimed to explore the antitumor effect and action mechanism of cucurbitacin B (CuB) on human T-cell leukemia Jurkat cells. METHODS: Cell proliferation was measured by the MTS assay. Cell cycle distribution, mitochondrial membrane potential and annexin V staining were analyzed using flow cytometry. Western blotting was used to determine the levels of apoptosis- and autophagy-related proteins. RESULTS: CuB inhibited the proliferation of Jurkat cells in a dose-dependent manner and induced G 2 /M phase arrest as well as formation of tetraploid cells. Accompanied with these effects, the actin dynamics was disrupted, and cofilin, a key regulator of actin dynamics, was persistently activated (dephosphorylated). Although CuB induced around 10% cells undergoing apoptosis, most of the cells were alive after CuB treatment for 24 h. Induction of autophagy was also evident by accumulation of LC3-II. CuB-induced autophagy seemed to be a prosurvival response, since suppression of CuB-induced autophagy significantly increased the activation of caspase-3. CONCLUSION: Our results demonstrated that CuB exhibited antitumor activity in Jurkat cells through induction of cell cycle arrest and apoptosis which was at least partly due to the disruption of actin dynamics.

[Effect of proteins extracted from mycelia of Omphalia lapidescens on inhibiting H, liver cancer in mice and regulating immune function].

OBJECTIVE: To explore the effect of proteins extraceed from mycelia of Omphalia lapidescens on inhibiting H22 liver cancer in vivo. METHODS: 50 hepatoma 22 tumor bearing mice models were divided into five groups randomly:control group( CG), cyclophosphamide group, and 3 groups of incremental Hepatoma 22 dosages (5, 3, 1 mg/kg). All groups were i.v. with drugs once a day. After 8 consecutive days, the concentrations of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in serum were detected by enzyme-linked immunoabsorbent assay (ELISA). The weight changes of tumor, thymus, liver, heart, spleen, lung and kidney were observed. RESULTS: It showed the tumors' weight were significant heavier in CG than in EGs. The tumor-inhibition rate (IR) was 36.4% in high dosage group,which was lower than 43.2% in cyclophosphamide group. The spleen mass of proteins groups increased significantly. The concentration of IFN-gamma in serum of proteins groups increased as CG, but IL-4 in inverse direction. The observations of thymus, liver, heart, lung and kidney in EGs were the same as CG. CONCLUSION: The proteins extracted from mycelium of Omphalia lapidescens can inhibit the growth of tumour and enhance the immune function of H22 tumor-bearing mice.