Simultaneous Anammox And Denitrification Research Articles

Removal behavior, inhibition kinetics, microbial community and metabolic pathways in simultaneous anammox and denitrification under indole exposure

Simultaneous anammox and denitrification (SAD) has been proven to be one promising process to remove nitrogen and organics from wastewater. However, how indole as one of nitrogen-containing heterocyclic compounds (NHCs) affecting SAD is still unclear. This study first explored the effect of short-term indole exposure (0–150 mg/L) on SAD. The degradation rate of indole was the highest at 100 mg/L indole, while the maximum nitrogen removal efficiency occurred at 10 mg/L indole. As the indole level increased, both anammox activity and the contribution of anammox to nitrogen removal had rapid decreases, whereas the denitrification was significantly enhanced. Moreover, 50% inhibitory concentration (IC50) and substrate inhibition constant (Ki) were 147.04 mg/L and 149.22 mg/L, respectively based on inhibition models. With increasing indole, the abundance of Candidatus Brocadia and Candidatus Kuenenia sharply decreased, while indole-degraders, denitrifiers and dissimilatory nitrate reduction to ammonium (DNRA) bacteria were found. High-throughput sequencing demonstrated that metabolic pathways involving nitrogen removal and indole biotransformation could be driven via a series of key functional genes. These findings offer novel insights into SAD process under the indole stress.

Microbial community dynamics and performance of simultaneous anammox and denitrification (SAD) process at varying substrate loadings during long-term operation

The simultaneous anammox and denitrification (SAD) process has attracted more and more attention due to its low energy consumption and high-efficiency, but its optimal operating conditions and the interspecies interactions between the main functional microorganisms anaerobic ammonia oxidation bacteria (AnAOB) and denitrifying bacteria (DNB) have not been fully elucidated. In this study, SAD was achieved by enriching DNB through the addition of sodium acetate to anammox granular sludge. Furthermore, the pollutant removal effect and the composition of the main functional microbial community under different organic loads were investigated by manipulating the influent C/N ratio. The results indicated that the reactor achieved the highest total nitrogen removal efficiency of 89.05% at a C/N ratio of 1 and the activity of AnAOB was inhibited on a higher C/N ratio, leading to the deterioration of effluent quality. Candidatus_Brocadia was the dominant genus of AnAOB, reaching a maximum relative abundance of 0.49% at a C/N ratio of 1. DNB was also significantly enriched after the addition of sodium acetate, and the synergistic effect of the two functional bacteria contributed the simultaneous nitrogen and carbon removal of the SAD process.

Distinct mechanisms underlying assembly processes and interactions of microbial communities in two single-stage bioreactors coupling anammox with denitrification

Coupling anammox with denitrification processes are promising technologies for total nitrogen removal from wastewater. However, the assembly processes and interactions of functional bacteria in the coupling systems are still poorly understood. Herein, two lab-scale up-flow bioreactors were separately operated to achieve the simultaneous anammox and denitrification (SAD) and the partial denitrification and anammox (PDA) systems under different substrate loading conditions. Although the two bioreactors seemed to have similar composition of functional bacteria, denitrifying bacteria Denitratisoma and Thauera exhibited higher abundances in the PDA bioreactor. In contrast, the genus Candidatus Jettenia was more abundant in the SAD bioreactor. The null model showed that stochastic processes dominantly governed the community assembly in both bioreactors across different substrate loadings. However, homogeneous selection appeared to be more important for shaping communities in the SAD system under high and moderate substrate-loading conditions. Particularly, drift was the most important process in driving the assembly of dominant denitrifying bacteria (e.g. genera Denitratisoma and Thauera), whereas anammox bacteria were primarily governed by the homogenous selection under high substrate-loading conditions. Moreover, anammox and denitrifying bacteria in the PDA bioreactor established simple and efficient networks, probably exerting impacts on the assembly processes of their co-occurring species. By contrast, the networks in the SAD bioreactor showed low modularity and interconnectivity. This study highlighted the specificity of community assembly processes and interactions in SAD and PDA systems, which would advance our understanding of the fundamental ecological laws underpinning the collaboration of anammox and denitrifying bacteria.

Nitrogen removal performance and sludge characteristics of wastewater from industrial recirculating aquaculture systems via anammox coupled with denitrification

Wastewater from industrial recirculating aquaculture systems is highly susceptible to eutrophication and may harm aquatic organisms. To address this problem, a simultaneous anammox and denitrification (SAD) process was applied to treat industrial recirculating aquaculture systems wastewater, and static research test and continuous flow test lasting 132 days were conducted herein. Based on the results, the optimal working parameters of the SAD coupling process are as follows: temperature = 30 °C, pH = 8, dissolved oxygen = 0–0.3 mg/L, and solid–liquid ratio = 1:1. At 132 d of operation, the NH4+-N, NO2−-N, and total nitrogen (TN) removal rates were 93.13 %, 93.54 %, and 89.42 %, respectively. The average particle size of the anammox granular sludge increased from 1 mm to 1 cm; the extracellular polymeric substances content increased from 39.09 mg/g VSS to 137.31 mg/g VSS; and the PN/PS value increased from 1.97 to 5.73, which enhanced the aggregation performance of granular sludge. A very strong correlation was observed between heme concentration and nitrogen removal load, and the coefficient of determination of linear regression was close to 0.99. The 16S rRNA gene sequencing showed that the Planctomycetes became the dominant phylum, with the abundance increasing from 18.62 % to 41.21 %. Moreover, the abundance of Candidatus Kuenenia increased from 1.22 % to 15.52 %, and the abundance of denitrifying bacteria also increased. It indicated that the synergistic effect of AnAOB and denitrifying bacteria in nitrogen removal was excellent. Finally, the SAD coupling process was successfully used to treat actual aquaculture wastewater with a TN removal rate of 86.51 %.

Insights into a novel nitrogen removal process based on simultaneous anammox and denitrification (SAD) following nitritation with in-situ NOB elimination

Simultaneous anammox and denitrification (SAD) is an efficient approach to treat wastewater having a low C/N ratio; however, few studies have investigated a combination of SAD and partial nitritation (PN). In this study, a lab-scale up-flow blanket filter (UBF) and zeolite sequence batch reactor (ZSBR) were continuously operated to implement SAD and PN advantages, respectively. The UBF achieved a high total nitrogen (TN) removal efficiency of over 70% during the start-up stage (days 1–50), and reached a TN removal efficiency of 96% in the following 90 days (days 51–140) at COD/NH4+-N ratio of 2.5. The absolute abundance of anammox bateria increased to the highest value of 1.58 × 107 copies/µL DNA; Comamonadaceae was predominant in the UBF at the optimal ratio. Meanwhile, ZSBR was initiated on day 115 as fast nitritation process to satisfy the influent requirement for the UBF. The combined process was started on day 140 and then lasted for 30 days, during the combined process, between the two reactors, the UBF was the main contributor for TN (66.5% ± 4.5%) and COD (71.8% ± 4.9%) removal. These results demonstrated that strong SAD occurred in the UBF when following a ZSBR with in-situ NOB elimination. This research presents insights into a novel biological nitrogen removal process for low C/N ratio wastewater treatment.

Varied interspecies interactions between anammox and denitrifying bacteria enhanced nitrogen removal in a single-stage simultaneous anammox and denitrification system

The simultaneous anammox and denitrification (SAD) system has received growing interest for the enhanced nitrogen removal, while the ecological traits of microbial community including spatial distribution characteristics, assembly processes and interspecies interactions have not been fully unraveled. The present study applied metagenomics and ecological analysis methods to gain the ecological traits of microbial communities in the SAD system across different organic substrate loadings. Results showed that organic matter significantly affected the bioreactor performance, and the optimal total nitrogen removal efficiency reached 93.4 ± 0.7% under the COD concentrations of 180 ± 18.2 mg/L. Functional organisms including Candidatus Brocadia (3.9%), Denitratisoma (1.6%), Dokdonella (4.4%) and Thauera (4.6%) obviously enriched under the optimal organic loading conditions. Moreover, microbial communities were significantly governed by deterministic process under high organic concentrations, and the denitrifying organisms displayed important ecological roles in the communities. Although anammox bacteria obviously enriched at the middle of bioreactor, it possessed the highest expression activities at both bottom and middle sites. Denitrifying bacteria that enriched at the bottom sites strongly achieved nitrate reduction and provided nitrite for anammox bacteria, while these organisms trended to compete nitrite with anammox bacteria at the middle site. These findings highlight the importance of microbial ecology in the SAD systems, which may expand our understanding of the synergistic patterns between anammox and denitrifying bacteria.

Responses of simultaneous anammox and denitrification (SAD) process to nitrogen loading variation: Start-up, performance, sludge morphology and microbial community dynamics

The effects of loading variation on the efficiency, EPS, sludge morphology and microbial population of simultaneous anammox and denitrification (SAD) were thoroughly investigated with the low-abundance SAD sludge. Results indicated that the first stage lasted the longest (33d), and the average removal rate of TN can be maintained above 95%. The specific anammox activity (SAA), specific denitrification activity and PN/PS continued to increase, but the excessive loading caused the effluent to deteriorate rapidly, and SAA and PN/PS also decreased slightly, but it could be recovered quickly. The contribution rate of anammox and denitrification to N removal reached 87.6% and 12.4% eventually, respectively. The abundance of AnAOB was 10.68%–18.01%, 9.01%–15.54%, 5.74%–12.88% in the upper, middle and lower layers, respectively. Candidatus Kuenenia was always the dominant AnAOB, especially after high loading inhibition. The abundance of denitrifying bacteria (mainly Bacillus, Comamonas and Denitratisoma) gradually became the highest.

Effects of salinity on the simultaneous anammox and denitrification process: performance, sludge morphology and shifts in microbial communities.

In this study, the long-term effects of different salinities on the performance, sludge morphology and shifts in microbial communities were studied in a simultaneous anammox and denitrification (SAD) process at a C/N ratio of 0.5. Stable nitrogen removal efficiencies of 86.96 and 84.58% and nitrogen removal rates of 0.95 and 0.93 kg (m3 d)−1 could be achieved under low (25 mmol l−1) and moderate (50 mmol l−1) salinity, respectively. However, the performance collapsed when the system was exposed to high salinity (100 mmol l−1). The content of extracellular polymeric substances increased as salinity increased, which resulted in larger sizes of granular sludge under low and moderate salinities. Nevertheless, high salinity shock disintegrated granular sludge, thereby decreasing the average granule size. The Illumina-Miseq sequencing results revealed that Candidatus Jettenia was the sole salinity-tolerant AnAOB genus during the entire operation, whereas the main denitrification bacterial genera shifted from Denitrisoma under low salinity to Denitrisoma, Thauera and Ignavibacterium under high salinity. The results of this study provide a comprehensive and practical evaluation of the SAD process for organic nitrogen-rich saline wastewater treatment.

The effects of undulating seasonal temperature on the performance and microbial community characteristics of simultaneous anammox and denitrification (SAD) process

The effects of undulating seasonal temperature change (USTC) (10.1 °C–31.8 °C) on the N and carbon removal efficiency of simultaneous anammox and denitrification (SAD) were investigated, and the recovery performance of SAD was simulated. Results showed that 15 °C was the critical temperature of SAD for N and carbon removal under USTC from summer to winter. The removal efficiency of NH4+-N was improved in the final stage after temperature rise, but still lower than that in summer after long-term low temperature inhibition. The contribution of anammox to N removal was more than denitrification. The abundance of anammox bacteria (AnAOB) in SAD reactor was 8.8%–11.7% from summer to autumn. Candidatus Kuenenia replaced Candidatus Brocadia as the main AnAOB gradually. Finally, AnAOB abundance increased from 4.2% to 6.6% after recovery, and the abundance of denitrifying bacteria (DB) became the highest, which mainly includes Thauera and Hydrogenophaga.

Enhancement of pollutants removal from saline wastewater through simultaneous anammox and denitrification (SAD) process with glycine betaine addition

Enhanced pollutants removal from saline wastewater was investigated in simultaneous anammox and denitrification (SAD) process with glycine betaine (GB) addition. Long-term operation indicated the optimal GB dose was around 0.4 mM, which enhanced both anammox and denitrifying activity by 30% and 45%, respectively. The total nitrogen and organic removal rates were 0.38 ± 0.2 kgN/m3/d and 0.34 ± 0.3 kgCOD/m3/d, respectively, which increased by 34.5% and 20.5%. Independent of GB dose, denitrifying activity was promoted, but anammox activity was drastically deteriorated after excessive GB addition. The optimal GB dose predicated by both Gaussian and Modified-Boltzmann models were 0.42–0.45 mM. Besides, the bacterial activity recovery after excessive GB addition could be analyzed by the Modified-Boltzmann model. With 1.5 mM GB, granular floatation occurred since numerous gas bubbles were inside the granules. In general, exogenous GB addition can mitigate salinity inhibition and promote pollutants removal from saline wastewater.

Simultaneous anammox and denitrification process shifted from the anammox process in response to C/N ratios: Performance, sludge granulation, and microbial community

An up-flow anaerobic sludge blanket (UASB) reactor was operated to investigate the performance, sludge granulation, and microbial community dynamics of the simultaneous anammox and denitrification (SAD) process at different C/N ratios by inducing a shift from the anammox process. The nitrogen removal efficiency (NRE) increased with an increase in the C/N ratio at lower C/N ratios (≤ 0.5). The NRE and nitrogen removal rate (NRR) were 90.81% and 1.75 kgN m-3d-1, respectively, at a C/N ratio of 0.5. The contribution of the anammox process to nitrogen removal (Eanammox) decreased sharply to 51% from 81% as a result of the decreased activity of the anaerobic ammonia-oxidizing bacteria (AnAOB) at a C/N ratio of 0.9. The EPS production and the ratio of the protein fraction of EPS (EPSp) to the carbohydrate fraction of EPS (EPSc) increased with the increase in the C/N ratio (0.0-0.9), which induced sludge aggregation and resulted in larger particle size. The enrichment of denitrifying bacteria (DNB) on the surface of the AnAOB due to EPS bridging further enhanced sludge granulation. The Illumina sequencing results showed that the dominant genus of AnAOB (Candidatus Jettenia) initially increased with an increase in the C/N ratio at lower levels and then decreased sharply at a C/N ratio of 0.9. The relative abundance of Candidatus Jettenia was promoted by decreasing the C/N ratio, which supported the recovery of the AnAOB activity. Denitratisoma, Bacillus, Acinetobacter, and Pseudomonas were responsible for denitrification throughout the entire operational period.

Advanced nitrogen removal from municipal wastewater via two-stage partial nitrification-simultaneous anammox and denitrification (PN-SAD) process

A modified two-stage anammox process was constructed and achieved advanced nitrogen removal from municipal wastewater. The first stage was Partial Nitrification (PN), in which nitrite accumulation rate was over 95% by controlling dissolved oxygen concentration (<1 mg/L) and aeration time (90–120 min). The second stage was simultaneous anammox and denitrification (SAD), in which the reactor was fed with the effluent of the first stage and a part of raw wastewater. The effluent total inorganic nitrogen (NH4+-N, NO2−-N and NO3−-N) was only 1.6 ± 0.8 mg N/L and the nitrogen removal efficiency reached 97.1%. The proportion of anammox in nitrogen removal was up to 73–82% and Candidatus Brocadia was the main anammox genus accounted for 8.0–2.2%. And partial denitrification occurred with the appearance of Thauera (0–1.0%). The PN-SAD process is an energy-saving treatment for municipal wastewater with a total hydraulic retention time of 6 h.

Start-up of Simultaneous ANAMMOX and Denitrification Process and Changes in Microbial Community Characteristics

To understand the relationship between nitrogen and carbon removal performance and the microbial community during start-up of simultaneous ANAMMOX and denitrification (SAD), nitrogen and carbon removal performance and microbial community change were studied by gradually increasing the influent COD concentration. The results showed that with the increase of the influent COD concentration, NH4+-N and NO2--N effluent remained stable, and the average removal rate was more than 98%. The removal rate of TN increased gradually, and the rate was 95.6% in the third stage, which was 6.8% higher than that of ANAMMOX in theory. ΔNO3--N/ΔNH4+-N decreased significantly from 0.15-0.17 to 0.03-0.07. The contribution rate of ANAMMOX to nitrogen removal decreased gradually, denitrification for nitrogen removal increased gradually, and the COD removal rate increased. Sludge activity analysis showed that the denitrification activity of sludge increased significantly and the ANAMMOX activity decreased slightly after the start-up of SAD. High throughput sequencing results showed that the dominant phyla of microorganisms in the reactor were Chloroflexi, Planctomycetes, Firmicutes, Armatimonadetes, and Proteobacteria. The characteristics of the microbial community in the reactor were closely related to the performance of SAD in nitrogen and carbon removal. The main functional microorganisms related to nitrogen and carbon removal were ANAMMOX bacteria, anaerobic digestive bacteria, and denitrifying bacteria. The abundance of ANAMMOX bacteria decreased after the start-up of SAD, and the anaerobic digestive bacteria and heterotrophic denitrifying bacteria increased significantly.

Keystone taxa regulate microbial assemblage patterns and functional traits of different microbial aggregates in simultaneous anammox and denitrification (SAD) systems

Understanding the impacts of the ecological patterns and niche-based selection on microbial community assembly and nitrogen-cycling network is crucial for achieving energy-neutral wastewater treatment. However, little is known about the niche differentiation and microbial nitrogen-cycling traits of keystone taxa in flocs and granules in anammox-based systems. Herein, the aspects of community assemblage patterns, metabolic functions and nitrogen transformation pathways were explored. The findings discovered that the treatment performance and bacterial community assembly were regulated by core taxa and flocs and granules communities harbored core taxa based on their functional traits. Both niche differentiation and environmental filtering have profound influences on functional bacteria. Furthermore, a combined analysis showed that nitrogen removal in flocs and granules was regulated by different nitrogen transformation pathways. These results suggest that core taxa are the key drivers for the microbial nitrogen-cycling network and improve the understanding of cross-feeding and metabolic pathways between anammox and nitrogen-cycling-related microorganisms.

Roles and correlations of functional bacteria and genes in the start-up of simultaneous anammox and denitrification system for enhanced nitrogen removal

Simultaneous anammox and denitrification (SAD) is a newly developed wastewater treatment process efficient in nitrogen removal, but its underlying microbiological mechanisms during start-up remains unknown. This study investigated the changing patterns of functional bacteria and genes, as well as their correlation during the start-up (260 d) of the SAD systems in two lab-scale up-flow anaerobic sludge blanket bioreactors separately inoculated with anaerobic granular sludge (R1) and aerobic floccular sludge (R2). Results showed that high total nitrogen removal was achieved in the SAD systems of both R1 (88.25%) and R2 (89.42%). High-throughput sequencing of 16S rRNA gene amplicons revealed that Armatimonadetes phylum had a high abundance (44.34%) in R2, while was not detectable in R1 during the anammox stage. However, the SAD bioreactors retained inherent microbial community and the inoculation with different sludge showed less notable effects on their microbial composition. In the SAD systems, Candidatus Brocadia had high abundance in R1 (2.93%) and R2 (4.64%) and played important role in anammox. Network analysis indicated that Denitratisoma and Dokdonella were positively correlated with nitrite reductase genes nirS and nirK (p < 0.05), while Thermomonas and Pseudomonas showing a positive correlation with nitrate reductase gene narG (p < 0.05) were mainly responsible for the nitrate reduction in the SAD systems. Moreover, the overwhelming dominance of narG v.s. napA revealed the crucial roles of respiratory nitrate reduction in the bioreactors. The results extend our knowledge regarding the microbial ecology of the SAD system, which might be practically helpful for application of the process in wastewater treatment.

Enhanced Nitrogen and Carbon Removal Performance of Simultaneous ANAMMOX and Denitrification (SAD) with Trehalose Addition Treating Saline Wastewater

Enhanced nitrogen and carbon removal performance of simultaneous ANAMMOX and denitrification (SAD) process with trehalose addition treating saline wastewater was investigated in a sequencing batch reactor (SBR). The optimal nitrogen removal was achieved at 0.25 mmol·L-1 trehalose, during which NH4+-N, NO2--N, NO3--N, and COD could be completely removed. Compared to no addition of trehalose, ammonium removal efficiency (ARE), nitrite removal efficiency (NRE) and total nitrogen removal efficiency (TNRE) increased by 50%, 43% and 46%. Ammonium removal rate (ARR) and nitrite removal rate (NRR) increased by 81.25% and 75%, respectively. With increasing concentration of trehalose to 0.5 mmol·L-1, ARE was only 58.82% and the effluent concentration of NH4+-N was 33.25 mg·L-1. Compared to the Haldane model and the Aiba model, the Luong model was the most suitable to simulate the nitrogen removal performance of SAD with trehalose addition treating saline wastewater. The NRRmax, KS, Sm, and n fitted from Luong model were 0.954 kg·(m3·d)-1, 0 mg·L-1, 184.785 mg·L-1, and 0.718, respectively. Compared to the modified Logistic model and the modified Boltzman model, the modified Gompertz model was the most suitable to describe the degradation of a substrate in a single cycle.

Carbon and nitrogen removal through “Candidatus Brocadia sinica”-dominated simultaneous anammox and denitrification (SAD) process treating saline wastewater

“Candidatus Brocadia sinica”-dominated simultaneous anammox and denitrification (SAD) process was used to treat nitrogen-rich saline wastewater. The reactor was operated at 30 ± 0.5 °C with influent pH of 7.5 ± 0.1. ‘Ca. B. sinica’ could adapt to high saline surroundings after 42 cycles’ operation. With 100% seawater, nitrogen removal rate and organic removal rate were 0.71 kg/(m3·d) and 0.27 kg/(m3·d), respectively. Both were closed to those without seawater. Independent of salinity, percentage of nitrogen removal by anammox was higher than that by denitrification during the whole treatment period. ‘Ca. B. sinica’ had good tolerance to salinity. However, maximum removal rate of NH4+-N declined with growing salinity. Modified Boltzmann model was proper to analyze the effect resulting from salinity on the maximum removal rate of NH4+-N. Granular sludge characterized by anammox granule embedded in denitrifying granule might play an important role in salt tolerance of anammox bacteria.

Enhanced carbon and nitrogen removal performance of simultaneous anammox and denitrification (SAD) with mannitol addition treating saline wastewater

AbstractBACKGROUNDSimultaneous anammox and denitrification (SAD) can remove carbon and nitrogen. However, its performance is suppressed under saline surroundings. In this work, mannitol was used to enhance a SAD process treating saline wastewater.RESULTSThe optimum carbon and nitrogen removal was achieved at 0.2 mmol L−1 mannitol, during which ammonium removal efficiency (ARE), nitrite removal efficiency (NRE) and chemical oxygen demand (COD) removal efficiency were 96.95%, 93.70% and 90.05%, respectively. The maximum ammonium removal rate (ARR), nitrite removal rate (NRR) and the specific anammox activity (SAA) were increased by 25.49%, 55.84% and 33.83% with optimum addition (0.2 mmol L−1 mannitol) respectively. The diameter of sludge was enlarged with the addition of mannitol (≤0.2 mmol L−1). The Tseng‐Wayman model was more suitable to simulate the whole SAD process. The modified logistic model, the modified Boltzman model and the modified Gompertz model were all appropriate to describe nitrogen removal in a typical cycle with the addition of mannitol.CONCLUSIONMannitol was effective in enhancing a SAD process treating saline wastewater, and maximum nitrogen removal was achieved at mannitol = 0.2 mmol L−1. The Tseng‐Wayman model satisfactorily predicted the whole SAD process treating saline wastewater with mannitol addition. © 2018 Society of Chemical Industry

Divergent assemblage patterns of abundant and rare microbial sub-communities in response to inorganic carbon stresses in a simultaneous anammox and denitrification (SAD) system

Inorganic carbon has profound influence on anammox system and distinct microbial communities play pivotal roles in nitrogen removal, yet little is known about the ecological patterns of abundant and rare sub-communities in response to inorganic carbon stresses in simultaneous anammox and denitrification systems. Here the aspects of community ecology of abundant and rare taxa under abiotic constraints were explored. Results showed that different IC/NH4+-N ratios have significant influences on NH4+-N and TN removal. Co-occurrence networks revealed that abundant and rare taxa present contrasting assemblage patterns and ecological strategies. Spearman’s correlation indicated that environmental filtering had discrepancy influences on these two bacterial sub-communities. Moreover, rare taxa were the key regulators for NH4+-N accumulation and NO2−-N consumption. qPCR results indicated that nitrogen removal was mediated by multiple nitrogen transformation pathways. These findings collectively suggest that abundant and rare sub-communities have discrepant ecological patterns and provide insights into their structure-functional relationships.

Bacterial community evolutions driven by organic matter and powder activated carbon in simultaneous anammox and denitrification (SAD) process

A distinct shift of bacterial community driven by organic matter (OM) and powder activated carbon (PAC) was discovered in the simultaneous anammox and denitrification (SAD) process which was operated in an anti-fouling submerged anaerobic membrane bio-reactor. Based on anammox performance, optimal OM dose (50 mg/L) was advised to start up SAD process successfully. The results of qPCR and high throughput sequencing analysis indicated that OM played a key role in microbial community evolutions, impelling denitrifiers to challenge anammox’s dominance. The addition of PAC not only mitigated the membrane fouling, but also stimulated the enrichment of denitrifiers, accounting for the predominant phylum changing from Planctomycetes to Proteobacteria in SAD process. Functional genes forecasts based on KEGG database and COG database showed that the expressions of full denitrification functional genes were highly promoted in RC, which demonstrated the enhanced full denitrification pathway driven by OM and PAC under low COD/N value (0.11).