Anaerobic Ammonium Oxidation Reactor Research Articles

Effects of inorganic carbon on the nitrous oxide emissions and microbial diversity of an anaerobic ammonia oxidation reactor

Inorganic carbon (IC) is important for anaerobic ammonium oxidation (anammox). In this study, the effects of the IC concentration on N2O emissions and microbial diversity in an anammox reactor were investigated. N2O emissions were positively correlated with IC concentrations, and IC concentrations in the range of 55–130 mg/L were optimal, considering the nitrogen removal rate and N2O emissions. High IC concentrations resulted in the formation of CaCO3 on the surface of anammox granules, which impacted the diffusion conditions of the substrate. Microbial community analysis indicated that high IC concentrations decreased the populations of specific bacteria, such as Achromobacter spanius strain YJART-7, Achromobacter xylosoxidans strain IHB B 6801, and Denitratisoma oestradiolicum clone 20b_15. D. oestradiolicum clone 20b_15 appeared to be the key contributor to N2O emissions. High N2O emissions may result from changes in organic carbon sources, which lead to denitrification by D. oestradiolicum clone 20b_15.

Quick Start-up Performance of Combined ANAMMOX Reactor Based on Different Inoculated Sludge Types

In order to determine the optimal sludge source of anaerobic ammonium oxidation (ANAMMOX) and the rapid formation of ANAMMOX granular sludge, two CAMBRs (combined ABR and MBR) were compared for ANAMMOX enrichment with different inoculated sludge types, the anaerobic granular sludge (R1) and flocculent denitrifying sludge (R2). The results showed that ANAMMOX was successfully initiated after 45 d (R1) and 60 d (R2) in both reactors, respectively. The enrichment processes are divided into three different phases, lag phase, activity elevation phase, and stationary phase but the removal rules of nitrogen in each phase were different. In the steady phase, the average removal rates of NH4+-N and NO2--N were higher than 95%. In addition, the red ANAMMOX granular sludge with the main diameter of 0.8-1.6 mm was formed in R1 while the flocculent sludge and irregular block with a low degree of granulation were mainly developed in R2. The phenomenon of red granular sludge floating in the two reactors was also observed. The quantitative relationship analysis between NH4+-N, NO2-N, and NO3--N showed the occurrence of nitrate-dependent ANAMMOX, which resulted in the oxidation of excess ammonia and the typical nitrite-dependent ANAMMOX occurred in R2.

Removal of Nitrogen from Alcohol Wastewater by PN-ANAMMOX

An integrated partial nitrification anaerobic ammonia oxidation reactor was used to explore the feasibility of nitrogen removal from recycled ethanol wastewater. The results show that the integrated partial nitrification-anaerobic ammonia oxidation (PN-ANAMMOX) reactor was started successfully after 40 d under the conditions of pH 7.8±0.5, temperature 30-35℃, and aerobic ORP value 120-150 mV. The total nitrogen removal rate of 0.125 kg·(m3·d)-1 increased to 0.75 kg·(m3·d)-1, Inoculation of mature nitrosated biofilms and anaerobic ammonium oxide granules can accelerate the start of the reactor. The effects of alcohol wastewater on the PN-ANAMMOX reactor were mainly caused by biodegradable TOC, The biodegradable TOC concentration of 100mg·L-1 in alcohol wastewater can reduce the removal rate of total nitrogen from 0.75 kg·(m3·d)-1 to 0.25 kg·(m3·d)-1,this inhibition can be restored. Different concentrations of alcohol wastewater were dosed into the PN-ANAMMOX reactor to acclimate the bacteria. The total nitrogen removal rate first decreased and then increased, as the influent concentration gradient increased, which was beneficial for improving the efficiency of nitrogen removal by extending the HRT and increasing the dissolved oxygen in the PN stage. Finally, the nitrogen removal rate stabilized at 0.65 kg·(m3·d)-1. These results show that PN-ANAMMOX can be used for the treatment of alcohol wastewater.

Performance and kinetics of ANAMMOX granular sludge with pH shock in a sequencing batch reactor.

As an efficient and cost-effective nitrogen removal process, anaerobic ammonium oxidation (ANAMMOX) could be well operated at suitable pH condition. However, pH shock occurred in different kinds of wastewater and affected ANANNOX process greatly. The present research aimed at studying the performance and kinetics of ANAMMOX granular sludge with pH shock. When influent pH was below 7.5, effluent [Formula: see text]-N and [Formula: see text]-N increased with decreasing pH. At Ph 6.0, effluent [Formula: see text]-N approached 100mg/L, and the ratios of [Formula: see text] approached 2.2 and 1.3, respectively. Both greatly deviated from theoretical values. When influent pH was above 7.5, effluent [Formula: see text]-N and [Formula: see text]-N increased with increasing pH. At pH 9.0, ammonium removal rate (ARR) and nitrite removal rate (NRR) decreased to 0.011±0.004 and 0.035±0.004kg/(m3·d), respectively. Besides, [Formula: see text]-N:[Formula: see text]-N deviated from theoretical value. Longer recovery time from pH 9.0 than from pH 6.0 indicated that alkaline surroundings inhibited anaerobic ammonium oxidizing bacteria (AAOB) greater. The sludge settling velocity was 2.15cm/s at pH 7.5. However, it decreased to 2.02cm/s when pH was 9.0. Acidic pH had little effect on sludge size, but disintegration of ANAMMOX granule was achieved with pH of 9.0. The Bell-shaped (A) model and the Ratkowsky model were more applicable to simulate the effect resulting from pH shock on ANAMMOX activity (R2>0.95), and both could describe ANAMMOX activity well with pH shock. They indicated that qmax was 0.37 kg [Formula: see text]-N/(kgMLSS·d) at the optimum pH value (7.47) in present study. The minimum pH during which ANAMMOX occurred was 5.68 while the maximum pH for ANAMMOX reaction was 9.26. Based on nitrogen removal performance with different pH, strongly acidic (pH≤6.5) or alkaline (pH≥8.5) inhibited ANAMMOX process. Besides, ANAMMOX appeared to be more susceptible to alkaline wastewater. Compared to extremely acidic condition (low pH), extremely alkaline condition (high pH) affected ANAMMOX granules much more.

Inhibition kinetics and granular sludge in an ANAMMOX reactor treating mature landfill leachate.

The present study reports the inhibition kinetics and granular sludge in an anaerobic ammonium oxidation (ANAMMOX) - up-flow anaerobic sludge blanket reactor fed with diluted mature landfill leachate. The activity of ANAMMOX bacteria was inhibited by addition of mature landfill leachate, but gradually adapted to the leachate. The system achieved efficient nitrogen removal during 65-75 d and the average removal efficiencies for NH4+-N, NO2--N and total nitrogen (TN) were 96%, 95% and 87%, respectively. ANAMMOX was the main pathway of nitrogen removal in the system, and heterotrophic denitrification occurred simultaneously. In addition, aerobic ammonia oxidation and aerobic nitrite oxidation were active in this system. Inhibition kinetic experiments showed that the NH4+-N and NO2--N inhibition concentration threshold of ANAMMOX were 489.03 mg/L and 192.36 mg/L, respectively. ANAMMOX was significantly inhibited by mature landfill leachate, and was completely inhibited when the leachate concentration was 1,450.69 mg/L (calculated in chemical oxygen demand). Thus, the inhibition concentration of substrate and landfill leachate should be considered when applying the ANAMMOX process to landfill leachate. The color of granular sludge ANAMMOX changed from brick-red into a reddish-brown. The particle size increased from small to large, with evident granulation of the ANAMMOX sludge.

Performance of partial denitrification (PD)-ANAMMOX process in simultaneously treating nitrate and low C/N domestic wastewater at low temperature

The simultaneous treatment of nitrate (NO3−-N∼50mgL−1) and domestic wastewater (ammonia (NH4+-N)∼60.6mgL−1, COD∼166.3mgL−1) via a novel partial denitrification (PD)-ANaerobic AMMonium OXidation (ANAMMOX) process was investigated at low temperature (12.9∼15.1°C). Results showed that desirable performance was achieved with average NO3−-N, NH4+-N and COD removal efficiencies of 89.5%, 97.6% and 78.7%, respectively. However, deteriorated sludge settleability in PD reactor was observed during operation, which bulked with serious sludge wash-out, leading to excess NO3−-N remaining in PD effluent. Fortunately, a satisfactory nitrogen removal was still achieved due to the occurrence of partial denitrification in ANAMMOX reactor. This was demonstrated by high-throughput sequencing, which revealed that the high nitrite (NO2−-N) production denitrifying bacteria of Thauera was detected (6.1%). ANAMMOX (above 70%) maintained the dominant pathway for nitrogen removal, and Candidatus Jettenia was identified as the major ANAMMOX species accounted for 2.7%.

Modeling, simulation and adaptive process control of biotechnological processes in decentralized anaerobic treatment of domestic wastewater

AbstractControl in anaerobic wastewater treatment plants is difficult to achieve but necessary due to a high sensitivity to disturbances and process complexity. With the help of different mathematical tools, control strategies can be developed. Particularly, a well‐defined mathematical model can be highly effective for design, assessment and optimization of treatment plants. However, applications directly in the control system of a treatment plant are hard to achieve due to model complexity and usually require specialized software and the engagement of experts in the subject. The objective of the present study was the development of less empirical methods for assessment and control of a decentralized anaerobic plant for the treatment of domestic wastewater. A lab‐scale plant, which consisted of a two‐stage anaerobic digestion process followed by an anaerobic ammonium oxidation (ANAMMOX) reactor for nitrogen removal, was used as object of study. Ordinary differential equation models were implemented to simulate the processes that took place in the treatment plant. With the help of the implemented models, control tools were developed. These tools include a standalone application for monitoring of the two‐stage anaerobic digestion process and an ammonium estimator for the ANAMMOX reactor by means of artificial neural networks (ANNs). The procedures followed aimed to reduce the amount of experimental work required so they can be easily transferred from laboratory to full‐scale conditions. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Correlation between microbial community and granule conductivity in anaerobic bioreactors for brewery wastewater treatment

Prior investigation of an upflow anaerobic sludge blanket (UASB) reactor treating brewery wastes suggested that direct interspecies electron transfer (DIET) significantly contributed to interspecies electron transfer to methanogens. To investigate DIET in granules further, the electrical conductivity and bacterial community composition of granules in fourteen samples from four different UASB reactors treating brewery wastes were investigated. All of the UASB granules were electrically conductive whereas control granules from ANAMMOX (ANaerobic AMMonium OXidation) reactors and microbial granules from an aerobic bioreactor designed for phosphate removal were not. There was a moderate correlation (r=0.67) between the abundance of Geobacter species in the UASB granules and granule conductivity, suggesting that Geobacter contributed to granule conductivity. These results, coupled with previous studies, which have demonstrated that Geobacter species can donate electrons to methanogens that are typically predominant in anaerobic digesters, suggest that DIET may be a widespread phenomenon in UASB reactors treating brewery wastes.

Performance and hydrodynamic features of a staged up-flow ANAMMOX sludge bed (SUASB) reactor

• The staged ANAMMOX reactor (SUASB) was investigated systematically. • The application of the kinetic model was validated. • The robust performance of the SUASB was demonstrated. • A maximum NRR of 6.04 kg N m −3 d −1 and NLR of 6.88 kg N m −3 d −1 were achieved. • The hydrodynamic type of the SUASB reactor was investigated. The performance and hydrodynamic features of a staged up-flow ANAMMOX (anaerobic ammonium oxidation) sludge bed (SUASB) reactor was evaluated. When the reactor was at steady-state conditions, the nitrogen loading rate (NLR) and nitrogen removal rate (NRR) were 5.63 and 4.82 kg N m −3 d −1 , respectively. The reactor could withstand a 1.5-fold substrate or hydraulic shock. The modified Stover–Kincannon model was used for the kinetic analysis, and the saturation value ( K B ) and maximum total substrate utilization rate ( U max ) were 14.5 and 14.8 kg N m −3 d −1 , respectively. Moreover, the C ( t )– Θ curve showed the existence of dead zones in the SUASB at the hydraulic retention times (HRTs) of 3 and 12 h, and the flow pattern performance of the SUASB fell between those of a continuous stirred tank reactor (CSTR) and a plug flow reactor (PFR).

Long-term performance and microbial ecology of a two-stage PN–ANAMMOX process treating mature landfill leachate

Long-term performance of a two-stage partial nitritation (PN)-anaerobic ammonium oxidation (ANAMMOX) process treating mature landfill leachate was investigated. Stable partial nitritation performance was achieved in a sequencing batch reactor (SBR) using endpoint pH control, providing an effluent with a ratio of NO2(-)-N/NH4(+)-N at 1.23 ± 0.23. High rate nitrogen removal over 4 kg N/m(3)/d was observed in the ANAMMOX reactor in the first three months. However, during long-term operation, the ANAMMOX reactor can only stably operate under nitrogen load of 1 kg N/m(3)/d, with 85 ± 1% of nitrogen removal. The ammonium oxidizing bacteria (AOB) in the PN-SBR were mainly affiliated to Nitrosomonas sp. IWT514, Nitrosomonas eutropha and Nitrosomonas eutropha, the anaerobic ammonium oxidizing bacteria (AnAOB) in the ANAMMOX reactor were mainly affiliated to Kuenenia stuttgartiensis.

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

Startup of Seawater Anaerobic Ammonia Oxidation Reactor

Muds and water samples collected from the Bohai Sea were selected to build seawater anaerobic ammonia oxidation reactor. The reaction volume was 18 L. The startup of reactor was divided into two stages. The first stage lasted five months and hydraulic retention time was 18L/7 d. The second stage lasted a month and hydraulic retention time was 18L/14 d. Ammonia and nitrite of influent and effluent were monitored. During the first stage, the removal rate of ammonia nitrogen was around 50% and the nitrite nitrogen increased by 50%. During the second stage, the removal rate of ammonia nitrogen reached more than 75% and the removal rate of nitrite nitrogen reached more than 90%. The removal ratio of ammonia nitrogen and nitrate nitrogen was about 1:1.17. These results suggested reactor start-up successful. Microbial community in reactor was monitored by polymerase chain reaction. Once the reactor started, specific bands of anaerobic ammonia oxidation microorganisms were found.

Transient and long-term effects of bicarbonate on the ANAMMOX process

In this study, the effects of both transient and long-term inorganic carbon (IC) addition on the anaerobic ammonium oxidation (ANAMMOX) process under pseudo-steady-state and substrate inhibitions were analyzed using reactor performance and measures of sludge activity. Compared with the nitrogen removal rate (NRR) of 3.42 kg N m(-3) day(-1) in the control bioreactor (ICDR) without IC, the peak NRR reached 21.0 kg N m(-3) day(-1) in the reactor (ICAR) with sufficient IC added. It was revealed that the long-term addition of bicarbonate significantly enhanced the performance of the ANAMMOX reactor. The optimum HCO3 (-)/TN ratio was considered to be 1.20, which is lower than that in normal conditions. The IC concentration affected biomass activity, and the transient addition or removal of IC to differing sludge media caused a significant loss of activity. Sufficient addition of IC alleviated the inhibition of excess substrates, while the inhibition was aggravated by the IC limitation. The half-maximal (50 %) inhibitory concentrations of substrate for the sludge were 295 mg L(-1) NO2 (-)-N and 361 mg L(-1) NH4 (+)-N with 120 mg L(-1) of fixed HCO3 (-) and 346 mg L(-1) NO2 (-)-N and 456 mg L(-1) NH4 (+)-N with unlimited IC, respectively. Changing the HCO3 (-)/TN (in milligrams per milligram) ratio resulted in the variation of ANAMMOX stoichiometric ratios. Sludge characterization parameters in the ICDR, including biomass, extracellular polymeric substances, heme C, and so on, were lower than those in ICAR. Filamentous bacteria and spherical bacteria were also observed in the reactor with limited IC.

Enhancement of ANAMMOX activity by low-intensity ultrasound irradiation at ambient temperature

This paper aims to investigate the enhancement effect of low intensity intermittent ultrasound irradiation on the efficiency of anaerobic ammonium oxidation (ANAMMOX) process at ambient temperature. With intermittently irradiated (ultrasound intensity of 0.19 w/cm(2), exposure time of 0.2 min), the reactor (RU) had a nitrogen removal rate (NRR) of 5.49 kgTN/m(3)/d at 14.8°C, while the NRR was 1.53 kgTN/m(3)/d in the control reactor (RC). At the end of operation, the contents of polysaccharide, protein, TTC-dehydrogenase and VSS were 6.82 mg/mgVSS, 26.79 mg/mgVSS, 0.58 mgTF/L/H and 10.11 gVSS/L in RU, higher than the levels in the RC. These results demonstrated that it is possible to achieve stable and highly efficient operation in an ANAMMOX reactor at low ambient temperature by implementation of ultrasonication.

Anaerobic ammonia oxidation (ANAMMOX) for side‐stream treatment of anaerobic digester filtrate process performance and microbiology

A laboratory scale semi-batch fed anaerobic ammonia oxidation (ANAMMOX) reactor was operated in the lab under two different feeding operations. In the first scenario, termed as phase I, the reactor was seeded and operated with NO(2) -N added externally with the filtrate to the reactor in the ratio needed for the successful ANAMMOX. A second reactor was also initiated shortly after the start-up of the ANAMMOX to accomplish partial nitrification (nitritation reactor) to generate NO(2) -N. In phase II, the operation of the ANAMMOX reactor was switched to the mode in which case the partially nitrified effluent from the nitritation reactor was fed to the ANAMMOX reactor. In both phases, real filtrate from a local wastewater treatment plant was used as the feed. The ANAMMOX reactor sustained a loading rate (average 0.33 ± 0.03 with a max of 0.4 g N (L day)(-1) ) which is comparable with many other fed-batch reactors in the literature. Consistent total N removal (average of 82 ± 4%) could be sustained in the ANAMMOX reactor during both phases. The nitritation reactor also consistently enabled a NO(2) -N to NH(3) -N ratio of 1.2:1 which was needed for the successful operation of the ANAMMOX reactor in phase II. Sequence analysis and FISH showed that Kuenenia stuttgartiensis dominated the enriched ANAMMOX community along with several unidentified, but seemingly enriched, potential ANAMMOX strains. Microbial ecology analysis for nitritation reactor showed the dominance of Nitrosomonas europaea. In summary, this manuscript provides important information on the start-up and operation of anammox reactor with detailed investigation on microbial ecology in this reactor.

Performance of an ANAMMOX reactor treating wastewater generated by antibiotic and starch production processes

A pilot-scale anaerobic ammonia oxidation (ANAMMOX) reactor was used to treat mixed wastewater resulting from a chlortetracycline and starch production process. The results, collected over the course of 272 days, show that the ratio of influent ammonium to nitrite, pH, and temperature can all affect the efficiency of nitrogen removal. The ratio of influent ammonium to nitrite was maintained at about 1:1 at a concentration below 200 mg·L−1 for both influent ammonium and nitrite. The total nitrogen (TN) loading rate was 0.15–0.30 kgN·m−3·d−1, pH remained at 7.8–8.5, and temperature was recorded at 33±1°C. The rate of removal of ammonia, nitrite, and TN were over 90%, 90%, and 80%, and the effluent ammonium, nitrite and TN concentrations were below 50, 30, and 100 mg·L−1.

Anaerobic ammonium oxidation improvement via a novel capsule bioreactor

This study developed a capsule bioreactor made from polyvinyl alcohol (PVA) to entrap anaerobic ammonium oxidation (ANAMMOX) bacteria for the removal of nitrogen from synthetic wastewater. Experimental results demonstrate that the ANAMMOX bacteria were entrapped inside the capsule and not washed out from the bioreactor. This method also avoids damaging the ANAMMOX bacteria during immobilization. The proposed bioreactor also has a shorter start-up period. The diffusion rate of ammonium and nitrite from the bulk solution through the capsule determined the rate of the ANAMMOX reaction. The optimal ratio of was approximately 1 for the bioreactor. In addition, the capsule protected the ANAMMOX bacteria from nitrite inhibition. The bioreactor achieved a high stable nitrogen removal rate (5.8 Kg-N m−3 day−1) at high nitrite levels (up to 600 mg-N L−1 in the influent). Therefore, the proposed capsule bioreactor has considerable potential for actual nitrogen removal applications.

The ANAMMOX reactor under transient-state conditions: Process stability with fluctuations of the nitrogen concentration, inflow rate, pH and sodium chloride addition

The process stability of an anaerobic ammonium oxidation (ANAMMOX) was investigated in an upflow anaerobic sludge blanket reactor subjected to overloads of 2.0- to 3.0-fold increases in substrate concentrations, inflow rates lasting 12 or 24h, extreme pH levels of 4 and 10 for 12h and a 12-h 30gl−1 NaCl addition. During the overloads, the nitrogen removal rate improved, and the shock period was an important factor affecting the reactor performance. In the high pH condition, the reactor performance significantly degenerated; while in the low pH condition, it did not happen. The NaCl addition caused the most serious deterioration in the reactor, which took 108h to recover and was accompanied by a stoichiometric ratio divergence. There are well correlations between the total nitrogen and the electrical conductivity which is considered to be a convenient signal for controlling and monitoring the ANAMMOX process under transient-state conditions.

Assessment of Inocula and N-Removal Performance of Anaerobic Ammonium Oxidation (ANAMMOX) for the Treatment of Aged Landfill Leachates

Three kinds of seeding sludge, i.e. conventional activated sludge, anaerobic granular sludge and the nitrifying activated sludge from the nitritation reactor treating aged leachates were evaluated in batch mode to screen the optimized inoculum for the rapid start-up of ANAMMOX reactor. The feasibility of the ANAMMOX process for the treatment of aged leachates was also investigated in a modified upflow anaerobic sludge blanket (UASB, 0.05m3). The batch experiments revealed that the nitrifying activated sludge from the nitritation reactor could respectively achieve the NRR (nitrogen removal rate) of 0.0365 kg N/(m3.d) and the ARR (ammonium removal rate) of 0.013 kg N/(m3.d) on day 12, which were greatly higher than those of the other two tested sludge samples. The mixture of the aforementioned nitrifying activated sludge and anaerobic granular sludge was established as an effective inoculum for the prompt start-up of ANAMMOX reactor. The maximum total nitrogen removal rate of 0.826 kg N/(m3.d) could be obtained for the treatment of “old” leachates under NLR (nitrogen loading rate) of 1.028 kg N/(m3.d). It is concluded that the N-removal performance of ANAMMOX process is still to be improved for actual engineering application to aged landfill leachates.

Fast start-up of ANAMMOX reactor: Operational strategy and some characteristics as indicators of reactor performance

Fast start-up of anaerobic ammonium oxidation (ANAMMOX) reactor was investigated by inoculating the mixed sludge from a partial nitritation reactor and a low loaded ANAMMOX reactor. At room temperatures (24–30 °C) and without taking deoxygenated measures for preparing the influent, nitrogen removal rate (NRR) up to 2.0 kg/m 3/d on day 35 and 6.2 kg/m 3/d on day 91 was achieved, indicating successful rapid start-up of ANAMMOX reactor. Dissolved oxygen (DO) concentration of 0.30 mg/L inside the reactor did not impair the ANAMMOX performance, suggesting that there is no need to take deoxygenated measures for preparing the ANAMMOX influent. The pH, conductivity, effluent nitrate nitrogen concentration and sludge color were simple indicators of ANAMMOX performance.