Anaerobic Ammonium Oxidation Performance Research Articles

Analyzing the nitrogen removal performance and cold adaptation mechanism of immobilized cold-acclimation ANAMMOX granules at low temperatures.

To improve the treatment performance of anaerobic ammonium oxidation (ANAMMOX) processes at low temperatures, the immobilized cold-acclimation ANAMMOX granules (R3) were prepared and their low-temperature nitrogen removal ability as well as the cold adaptation mechanism were analyzed. The results indicated that the total inorganic nitrogen (TIN) removal efficiency of R3 was significantly higher than that of R2 (cold-acclimation granules without immobilization) and R1 (common granules), especially at 11 ± 2 and 7±2°C (68% and 54%). These were attributed to the remarkable biomass retention capacity of R3, high up to 4.3-4.9mg/gVSS even at 5-18°C. Besides, higher protein (PN) content of tightly bound extracellular polymeric substances (TB-EPS) also facilitated microbial aggregation in R3. Meanwhile, R3 granules retained higher ANAMMOX activity and heme c content at 5-25°C. The original dominant ANAMMOX genus (Candidatus Kuenenia) in R3 kept higher abundance (49%-57%) at 23 ±2 and 16 ±2°C, whereas Candidatus Brocadia became the dominant ANAMMOX genus (25%-32%) in R3 at 11 ±2 and 7±2°C. Notably, different ANAMMOX genera in R3 may adapt to cold environment by regulating the expression of cold-stress proteins (CspA, CspB, PpiD, and UspA). PRACTITIONER POINTS: Immobilized cold-acclimation ANAMMOX granules showed higher nitrogen removal efficiency at 23°C → 5°C. Immobilization method effectively retained biomass (Candidatus Kuenenia and Candidatus Brocadia). Immobilization facilitated TB-EPS release and biological aggregation in cold-acclimation granules. Expression of cold-stress proteins in immobilized cold-acclimation granules was more active.

Anaerobic Ammonium Oxidation Performance in Shrimp Pond Wastewater Treatment

Intensive shrimp culture waste contains high nitrogen, reducing water quality and environmental carrying capacity. Anaerobic ammonium oxidation (anammox) is a potential technology for nitrogen removal. This research aimed to analyze nitrogen removal performance in a filter bioreactor (FtBR). Ammonium and nitrite concentrations of 70-100 mg-N/L were added to sterilized seawater as artificial wastewater and flowed to the reactor with HRT 24-hour. After 120 days of the experiment, the maximum nitrogen removal performance with parameters ACE, NRE, NRR were 82.48%, 72.58%, 0.12 kg-N/m3·d, respectively. The nitrogen stoichiometric ratio NH4+-N:NO2--N:NO3--N was 1:1,40:0,12, which was close to the stoichiometry of anammox process. The anammox process can be a new method for intensive shrimp culture wastewater treatment.

Effect of hydraulic retention time on effluent pH in anammox bioreactors: Characteristics of effluent pH and pH as an indicator of reactor performance

In order to assess the performance of anaerobic ammonium oxidation (anammox) bioreactors, it is necessary to study the stoichiometry of the anammox reaction and pH. This study focused on the effect of the hydraulic retention time (HRT) on the effluent pH in anammox-upflow anaerobic sludge blanket (UASB) bioreactors. Anammox-UASB bioreactors with and without a recirculation system were used to investigate the effluent pH and bioreactor performance. It was concluded that under varying HRT conditions, the decrease in effluent pH did not indicate the deterioration of nitrogen removal, but did indicate that the nitrogen removal efficiency was reduced owing to a sudden increase in the nitrogen loading rate resulting from the decrease in HRT. Moreover, the results showed that the HRT directly affected the concentration of OH−, which affected the increase/decrease in effluent pH. This study demonstrated that effluent pH is a more powerful tool than previous techniques used to assess bioreactor performance. We suggest that the effluent pH could be used for preliminary assessment.

Effect of Ni(Ⅱ) on Anaerobic Ammonium Oxidation and Changes in Kinetics

Anaerobic ammonium oxidation (ANAMMOX) is widely used for treatment of ammonium-rich wastewater because of its economic and environmental benefits. However, ANAMMOX bacteria are sensitive to environmental conditions, especially to heavy metals. The short-term and long-term effects of Ni(Ⅱ) on ANAMMOX were studied by batch and continuous flow experiments, respectively. Results showed that low concentrations of Ni(Ⅱ) had promoted nitrogen removal by ANAMMOX and high concentrations inhibited ANAMMOX performance during a short-term period. Compared with the specific anaerobic ammonium oxidation activity (SAA) without Ni(Ⅱ) addition, SAA with 1 mg·L-1 Ni(Ⅱ) addition increased by 11.14% and the SAA with 100 mg·L-1 Ni(Ⅱ) addition reduced by 49.55%. The IC50 of Ni(Ⅱ) for ANAMMOX was determined to be 83.86 mg·L-1. In contrast, long-term Ni(Ⅱ) addition significantly suppressed nitrogen removal of ANAMMOX, and the suppression threshold of Ni(Ⅱ) on ANAMMOX was 15 mg·L-1. The Monod model was applied to simulate the kinetics of ANAMMOX without Ni(Ⅱ) addition. The qmax0(TN/VSS) and KS0 values were 12.25 mg·(g·h)-1 and 405.36 mg·L-1, respectively. The modified Haldane model was suitable to describe the kinetics of ANAMMOX with 50 mg·L-1 Ni(Ⅱ) addition. The qmax(TN/VSS), KS, and Ki values were 6.78 mg·(g·h)-1, 313.2 mg·L-1, and 1.32, respectively. The inhibition of ANAMMOX by Ni(Ⅱ) is anticompetitive inhibition. In addition, the inhibition of Ni(Ⅱ) on ANAMMOX was mainly related to the content of intracellular Ni(Ⅱ). The IC50intracellular Ni(Ⅱ)(VSS) of intracellular Ni(Ⅱ) was 0.072 mg·g-1.

Long-term effects of Fe3O4 NPs on the granule-based anaerobic ammonium oxidation process: Performance, sludge characteristics and microbial community

The performance of anaerobic ammonium oxidation (anammox) granules were studied under long-term exposure to Fe3O4 NPs. The Fe3O4 NPs had no negative impacts on nitrogen removal performance with the addition of 2−200 mg L−1. The specific anammox activity (SAA) slightly decreased from 287.0 ± 13.2 to –253.0 ± 9.2 mg TN g-1VSS d-1 with the increase in Fe3O4 NPs level from 2 to 60 mg L-1, and then significantly enhanced to 381.8 ± 15.7 mg TN g-1VSS d-1 at 200 mg L-1 Fe3O4 NPs. And the change trends of the heme c content, extracellular polymeric substance amount and settling velocity were consistent with that of SAA. The Candidatus_Kuenenia was the dominant species during the entire experiment and its relative abundance was up to 33.4 % at the end the experiment. The results provide some useful information for comprehending the impact of Fe3O4 NPs on the performance of wastewater biological treatment systems.

What's the variation in anammox reactor performance after single and joint temperature based shocks?

A laboratory-scale up-flow anaerobic sludge blanket reactor was used to investigate the effects of temperature-based (single and combined with loading) shocks on the performance of anaerobic ammonium oxidation (anammox) reactor. The reactor was tolerant to 15 °C and 25 °C shocks; however, temperature shock of 55 °C led to severe accumulation of effluent NO2−-N (>100 mg L−1), which induced substrate inhibition. Although the shock experiments achieved a maximum effluent NO2−-N concentration of 205.4 mg L−1 after a hydraulic retention time-substrate concentration shock at 25 °C, the inhibition was still reversible. During the experiments, the content of extracellular polymeric substances (EPS) increased significantly after each shock to protect the anammox bacteria, and the value decreased correspondingly at the end of the recovery phase. The specific anammox activity showed the opposite tendency compared with that of the EPS. The performance of anammox reactor under a series of short-term temperature shocks was investigated, and the results can provide new ideas for future research.

Performance of the Removal of Nitrogen During Anaerobic Ammonia Oxidation Using Different Operational Strategies

The effects of low substrate ratio, cooling methods, and pH on nitrogen removal performance were studied in a laboratory-scale anaerobic ammonium oxidation reactor (ASBR) while treating simulated domestic waste water. The results illustrated that the average removal efficiencies of NH4+-N and NO2--N increased from 54.4% and 65.3% to 95.8% and 92.5%, respectively, at a temperature of 30℃ and an influent concentration of NO2--N of (30±0.2)mg·L-1. The substrate ratio (NO2--N/NH4+-N) increased from 0.9 to 1.4.However, the removal efficiency of NH4+-N was affected negligibly, and the average removal efficiency of NO2--N decreased to 54.6% when the substrate ratio was increased to 1.6, suggesting that the nitrogen removal performance of anaerobic ammonium oxidation was best when the substrate ratio was close to the theoretical value of 1.32.The average removal efficiencies of NH4+-N and NO2--N decreased from 97.5% and 98.5% to 35.2% and 40.1%, respectively, when the temperature of the reactor dropped from 30℃ to 15℃ at one time. The average removal efficiencies of NH4+-N and NO2--N dropped from 97.7% and 98.6% to 52.7% and 62.4%, respectively, when the ladder cooling method(30℃→25℃→20℃→15℃) was used. The average removal efficiencies of NH4+-N and NO2--N increased initially and then decreased when the pH was increased gradually from 7.7 to 8.5.The highest nitrogen removal efficiency was achieved when the pH was controlled at 8.3 with a substrate ratio of NO2--N/NH4+-N equal to 1.4.

Fast Start-up of ANAMMOX and the Spatial Distribution of EPS in ANAMMOX Granules

An anaerobic sequencing batch reactor(ASBR) inoculated with activated sludge was employed to investigate the start-up of anaerobic ammonium oxidation(ANAMMOX) process and the spatial distribution of extracellular polymeric substances(EPS) in ANAMMOX granules. The results showed that the removal rates of NH4+-N and NO2--N reached more than 99%. The removal rate of total nitrogen(TN) was 89.87%±0.43% and the TN removal load in the ASBR was 1.7 kg·(m3·d)-1. The ratios of nitrite consumption and nitrate production to ammonium consumption were 1.32±0.08 and 0.24±0.03, respectively. Besides, the pH and the effluent nitrate concentration in bulk liquid were considered as two simple indicators for rapid diagnosis of ANAMMOX performance. The proteins(PN) was the main component of EPS in ANAMMOX granular sludge. The PN and polysaccharides(PS) in ANAMMOX granules were (59.61±5.64) mg·g-1 and (12.21±2.04) mg·g-1, respectively, with the ratio of PN/PS reaching approximately 4.88±1.39. β-D-glucofuranose and dead cells were distributed in the outermost layer of granules, while living cells, PN, lipids, α-glucosamine and α-mannose were distributed throughout the granules and mainly concentrated on the outside of granules. PN and lipids constituted the framework of ANAMMOX granules and ANAMMOX bacteria were embedded among the PN and lipids matrix.

The short- and long-term effects of Mn2+ on biogranule-based anaerobic ammonium oxidation (anammox)

The short- and long-term effects of Mn2+ on the performance of anaerobic ammonium oxidation (anammox) granules were investigated in the present study. Anammox activity was determined at various Mn2+ concentrations in batch assays, and the 50% inhibition concentration value was determined to be 7.33mgL−1. However, no obvious deterioration of reactor performance was observed during the 150-day continuous-flow operation, and the nitrogen removal efficiency of the test reactor (R1) fluctuated between 91% and 92% as the Mn2+ concentration was increased from 1 to 200mgL−1. Additionally, the specific anammox activity, heme c content and the amounts of extracellular polymeric substances in the anammox biomass increased and then subsequently decreased. The results demonstrated that short-term exposure to Mn2+ has a negative effect on anammox biomass, but the biomass could tolerate Mn2+ stress after acclimation to a high concentration of 200mgL−1 at the end of the continuous-flow experiment.

Effect of Substrate Ratio on Nitrogen Removal Performance of ANAMMOX in ABR

In order to solve the problem of low nitrogen removal caused by incomplete removal of anaerobic ammonium oxidation (ANAMMOX) substrate, The nitrogen removal performance of the ANAMMOX was investigated by controlling different influent substrate ratios in an anaerobic baffled reactor (ABR). The result showed the optimal influent NO2--N/NH4+-N was 1.34 with which the NH4+-N and NO2--N removal efficiencies were about 99.99% and the total nitrogen removal efficiency reached a peak of 87%. When the influent NO2--N/NH4+-N gradually reduced from 1 to 0.49 and increased from 1.34 to 1.62, the absolute removal of NH4+-N and NO2--N was stable in the reactor and no significant inhibition was observed in the system. Under the condition of different substrate ratios, the removal of NH4+-N and NO2--N was basically consumed in the first compartment of ABR, the change of substrate ratio did not have an obvious impact on the nitrogen removal performance of each compartment in the ABR, thus, the ABR ANAMMOX system had good stability to the change of substrate concentration.

Nitrogen removal performance of anaerobic ammonia oxidation (ANAMMOX) in presence of organic matter.

A sequencing batch reactor (SBR) was used to test the nitrogen removal performance of anaerobic ammonium oxidation (ANAMMOX) in presence of organic matter. Mesophilic operation (30±0.5°C) was performed with influent pH 7.5. The results showed, independent of organic matter species, ANAMMOX reaction was promoted when COD was lower than 80mg/L. However, specific ANAMMOX activity decreased with increasing organic matter content. Ammonium removal efficiency decreased to 80% when COD of sodium succinate, sodium potassium tartrate, peptone and lactose were 192.5, 210, 225 and 325mg/L, respectively. The stoichiometry ratio resulting from different OM differed largely and R1 could be as an indicator for OM inhibition. When COD concentration was 240mg/L, the loss of SAA resulting from lactose, peptone, sodium potassium tartrate and sodium succinate were 28, 36, 50 and 55%, respectively. Sodium succinate had the highest inhibitory effect on SAA. When ANAMMOX process was used to treat wastewater containing OM, the modified Logistic model could be employed to predict the NREmax.

Nitrogen Removal Performance of ANAMMOX with Different Organic Carbon Sources

Anaerobic ammonium oxidation (ANAMMOX) has been regarded as an efficient process to treat high-strength wastewater without organic carbon source. To investigate the nitrogen removal performance of ANAMMOX in the presence of organic carbon source can broaden its application in organic wastewater treatment. In this work, an anaerobic sequencing batch reactor (ASBR) was used to study the effect of organic carbon source on ANAMMOX process. The experimental results indicated that the activity of anaerobic ammonia oxidizing bacteria (AAOB) decreased by 84.2% when 200 mg·L-1 COD of glucose was added. When sodium acetate was added, the activity of AAOB was affected little. Besides, it even promoted the activity with COD less than 120 mg·L-1. The effect of sucrose on ANAMMOX process was similar to that of sodium acetate and the maximum specific ANAMMOX activity (SAA) increased by 25.0% with 80 mg·L-1 COD. When citric acid was added, the maximum SAA peaked with 80 mg·L-1 COD. The order of ANAMMOX promotion resulted from organic carbon source was sucrose, sodium acetate, citric acid and glucose. With addition of organic carbon source, nitrate could also be removed through the synergy of ANAMMOX and denitrification, and the total nitrogen removal efficiency increased.

Effect of increase in salinity on ANAMMOX–UASB reactor stability

ABSTRACTThe effect of salinity on the anaerobic ammonium oxidation (ANAMMOX) process in a UASB reactor was investigated by analysing ammonium, nitrite, nitrate and TN concentrations, and TN removal efficiency. Extracellular polymeric substances (EPSs) and specific ANAMMOX activity (SAA) were evaluated. Results showed the effluent deteriorated after salinity was increased from 8 to 13 g/L and from 13 to 18 g/L, and TN removal efficiency decreased from 80% to 30% and 80% to 50%, respectively. However, ANAMMOX performance recovered and TN removal efficiency increased to 80% after 40 days when the influent concentrations of and were 200 mg/L and salinity levels were at 13 and 18 g/L, respectively. The amount of EPSs decreased from 58.9 to 37.1 mg/g volatile suspended solids (VSS) when the reactor was shocked by salinity of 13 g/L, and then increased to 57.2 mg/g VSS when the reactor recovered and ran stably at 13 g/L. The amount of EPSs decreased from 57.2 to 49.1 mg/g VSS when the reactor was shocked by salinity of 18 g/L, and then increased to 60.7 mg/g VSS when the reactor recovered and ran stably at 18 g/L. The amount of EPS and the amounts of polysaccharide, protein and humus showed no evident difference when the reactor recovered from different levels of salinity shocks. Batch tests showed salinity shock load from 8 to 38 g/L inhibited the SAA. However, when the reactor recovered from salinity shocks, SAA was higher compared to that when the reactor was subjected to the same level of salinity shock.

Anaerobic ammonium oxidation (anammox) under realistic seasonal temperature variations: Characteristics of biogranules and process performance

In this study, the effects of realistic seasonal temperatures on the nitrogen removal performance of anaerobic ammonium oxidation (anammox) and the properties of the anammox granules were comparatively investigated for 330days. The results demonstrated that the nitrogen removal efficiency (NRE), nitrogen loading rate (NLR) and nitrogen removal rate (NRR) were decreased dramatically, as the temperature decreased from 31.2 to 2.5°C. However, the nitrogen removal performance recovered andante as the temperature increased gradually. After low temperature exposure, the settleability tended to worsen, and granules appeared to be more irregular with a smaller average granule diameter, and the extracellular polymeric substances (EPS) content increased slightly, while the specific anammox activity (SAA) decreased obviously. This realistic seasonal temperatures based research was an illation of the actual operation, and could be potentially implemented to maintain stability for the application of anammox technology.

The influences of temperature, salt and calcium concentration on the performance of anaerobic ammonium oxidation (anammox) process

Efficient biological nitrogen removal from high salinity wastewater has been focused recently. The present study comparatively investigated the effects of temperature, salinity and calcium concentration on the performance of anaerobic ammonium oxidation (anammox) processes using anammox granular sludge to treat synthetic wastewater. Four upflow anaerobic sludge blanket reactors were operated in parallel at ambient temperatures evolving from 25 to 9°C (reactor R1) and thermostatic room temperatures of 35±2°C (reactors R2, R3 and R4). The results demonstrated that low ambient temperature and high sodium levels impair the nitrogen removal performance of anammox granular sludge. The anaerobic ammonium-oxidizing bacteria gradually adapted to a salt concentration of 15gL−1 at low ambient temperature, and a nitrogen removal rate of 1.34±0.12kgNm−3d−1 was achieved. A nitrogen removal rate of 1.90±0.01kgNm−3d−1 in R4 was achieved at a salt concentration of 15gL−1. Moreover, 152mgL−1 calcium relieved the high salinity inhibition of anaerobic ammonium-oxidizing bacteria. Furthermore, the fractal dimension and permeability of anammox granules were also investigated with settling experiment, which indicated that the anammox granules were porous and permeable.

Effect of zero-valent iron on the start-up performance of anaerobic ammonium oxidation (anammox) process.

The long start-up time of anaerobic ammonium oxidation (anammox) process hinders the widespread application of anammox technology in practical wastewater treatment when anammox seed sludge is not available. Meanwhile, the production of nitrate cannot meet the increasingly more strict discharge standards. To combine the chemical nitrate reduction to ammonium with biological nitrogen removal, two anammox upflow anaerobic sludge blanket reactors packed with different types of zero-valent iron (ZVI), microscale ZVI (mZVI) and nanoscale ZVI (nZVI), were developed to accelerate the start-up of anammox process. The results revealed that anammox start-up time shortened from 126 to 105 and 84 days with the addition of mZVI and nZVI. The nitrogen removal performance was also improved remarkably by adding ZVI, especially in the start-up stage. The value of dissolved oxygen showed that ZVI could be regarded as a useful deoxidant to create anaerobic condition for the proliferation of anammox bacteria. ZVI was favorable for the secretion of EPS, which would represent the activity of anammox bacteria. The result of real-time quantitative PCR (qPCR) further confirmed that the proliferation of anammox bacteria was enhanced by ZVI.

Optimization of process performance in a granule-based anaerobic ammonium oxidation (anammox) upflow anaerobic sludge blanket (UASB) reactor

In this study, the individual and interactive effects of influent substrate concentration (TNinf), hydraulic retention time (HRT) and upflow velocity (Vup) on the performance of anaerobic ammonium oxidation (anammox) in a granule-based upflow anaerobic sludge blanket (UASB) reactor were investigated by employing response surface methodology (RSM) with a central composite design. The purpose of this work was to identify the optimal combination of TNinf, HRT and Vup with respect to the nitrogen removal efficiency (NRE) and nitrogen removal rate (NRR). The reduced cubic models developed for the responses indicated that the optimal conditions corresponded to a TNinf content of 644–728mgNL−1, an HRT of 0.90–1.25h, and a Vup of 0.60–1.79mh−1. The results of confirmation trials were similar to the predictions of the developed models. These results provide useful information for improving the nitrogen removal performance of the anammox process in a UASB reactor.

Bio-augmentation for mitigating the impact of transient oxytetracycline shock on anaerobic ammonium oxidation (ANAMMOX) performance.

The feasibility of applying bio-augmentation tactics to remit the influence of transient oxytetracycline (OTC) shock on the anaerobic ammonium oxidation (ANAMMOX) process was evaluated. The bio-augmentation was applied together with shock test, with OTC shock concentration of 518 mg L(-1) and 1-h duration. 0.655-2.62 g volatile suspended solid (VSS) sludges were varied to optimize bio-augmentation dosage (BAD), and appropriate bio-augmentation time (BAT) was determined. The validity of the bio-augmentation was indicated by recovery performance and sludge characteristics. The restoring time of 38 h for bio-augmented reactor was shorter than that of non-bio-augmented reactor (45 h), and heme c content was increased respectively from 0.195 ± 0.001, 0.267 ± 0.047, 0.301 ± 0.049, to 0.340 ± 0.053 μmol g(-1) VSS with the BAD of 0.655, 1.31, 1.97, 2.62 g-VSS. The results suggest that bio-augmentation enhances the recovery of ANAMMOX performance following OTC shock and BAT and BAD are key operational factors.

ANAMMOX performance, granulation, and microbial response under COD disturbance

BACKGROUND ANAMMOX (ANaerobic AMMonium OXidation), a promising process for biological nitrogen removal, is usually affected by organic matter. In order to fully understand the effect of chemical oxygen demand (COD) on the ANAMMOX process, reactor performance, granular characteristics and microbial response were evaluated systematically under glucose stimulation. RESULTS High removal efficiencies of ammonium and total nitrogen (> 90%) were achieved with 100 mg L-1 COD concentration. ANAMMOX contribution was reduced to only 69% as COD concentration was increased to 300 mg L-1. The granulation, EPS contents, TB-EPS/LB-EPS and protein/carbohydrate were increased at a specific COD, with higher COD disrupting the biofacies structure. The results also showed that EPS distribution and microbial structure were affected by the organic disturbance. CONCLUSION An appropriate COD concentration enhanced the total nitrogen removal during ANAMMOX process, by enabling a stable synergism between ANAMMOX bacteria and heterotrophic denitrificans. Furthermore, a proper COD stimulation promoted sludge granulation by influencing EPS composition and distribution. However, excessive COD disturbance disrupted the highly efficient biofacies structure and microbial balance, which then decreased the ANAMMOX competitiveness. © 2013 Society of Chemical Industry

The robustness of ANAMMOX process under the transient oxytetracycline (OTC) shock

The effect of transient oxytetracycline (OTC) shock on the stability of anaerobic ammonium oxidation (ANAMMOX) process was evaluated in the present study. The shock test was implemented with 155-1731mgL(-1) OTC, lasting for 1 to 3-fold hydraulic retention times, under the nitrogen loading rate (NLR) of 6.72 and 13.4kgm(-3)d(-1). The response of the process was divided into shock and recovery stage and the performance under the stress was indicated by stability index and granule characteristic. In the shock period, nitrogen removal rate (NRR) was ranged from 12.1 to 12.1-4.04kgm(-3)d(-1). The specific ANAMMOX activity (SAA) and heme c content, were respectively reduced by 1.4% and 17.6-29.4%. Foremost, the OTC shock was restorable and the recovery lasted for 4-353h. The robustness of ANAMMOX process was dependent on OTC level, duration of shock and NLR applied.