Aerobic Granular Sequencing Batch Reactor Research Articles

Pollutants removal and connections among sludge properties, metabolism potential and microbial characteristics in aerobic granular sequencing batch reactor for petrochemical wastewater treatment

Petrochemical wastewater contains inhibitory compounds such as aromatics that are toxic to microorganisms during biological treatment. The compact and layered structure and the high amount of extracellular polymeric substances (EPS) in aerobic granular sludge (AGS) can contribute to protecting microorganisms from the harsh environment. This study evaluated the changes in the granule properties, pollutants removal, microbial metabolic potential and molecular microbial characteristics of the AGS process for petrochemical wastewater treatment. Granules treating petrochemical wastewater had a higher SVI30/SVI5 value (0.94) than that treating synthetic wastewater. An increase in bioactivity and EPS secretion with higher bio-polymer composition, specifically the functional groups such as hydroxyl, alkoxy and amino in protein, was observed, which promoted biomass aggregation. The granules also had more than 2-fold higher specific oxygen utilization rate. The AGS-SBR process obtained an average COD removal of 93% during petrochemical wastewater treatment and an effluent bCOD of below 1 mg L−1. No obvious inhibition of nitrification and denitrification activity was observed in the processes attributed to the layered structure of AGS. The average effluent NH4+-N of 5.0 mg L−1 was obtained and TN removal efficiencies of over 80.0% was achieved. Molecular microbial analysis showed that abundant functional genera Stenotrophomonas and Pseudoxanthomonas contributed to the degradation of aromatics and other petroleum organic pollutants. They were enriched with the variation of group behavior while metabolisms of amino acids and carboxylic acids by the relevant functional genera (e.g., Cytophagia) were significantly inhibited. The enrichment of Flavobacterium and Thermomonas promoted nitrification and denitrification, respectively. This research revealed the rapid start-up, enhanced granule structural strength, high inhibition resistance and considerable performance of AGS-SBR for petrochemical wastewater treatment.

Coupling of endogenous/exogenous nitrification and denitrification in an aerobic granular sequencing batch reactor

ABSTRACT The performance of endogenous/exogenous nitrification and denitrification in an aerobic granular sequencing batch reactor was investigated for treating inorganic wastewater with ammonia nitrogen of 250 mg/L. The sequencing batch reactor with an effective volume of 120.5 L was started by seeding autotrophic nitrifying granular sludge (ANGS) and operated under oxic (110 min)/anoxic (120 min)/oxic (110 min) aeration mode. The total inorganic nitrogen (TIN) removal efficiency of ANGS was between 60% and 70% without external carbon sources in days 1–25. However, the operation mode was unsustainable as endogenous nitrification and denitrification would lead to an obvious decrease of sludge concentration. After sodium acetate (the contributed chemical oxygen demand in the reactor was 250–300 mg/L) was added at the beginning of the anaerobic/anoxic stage from day 26, aerobic granules were inadaptable in a few days, which resulted in particle disintegration and SVI increase. As microbes gradually acclimated to the new environment, the aerobic granular sludge became smoother and denser, the relative abundance of denitrifying bacteria increased to 66.07%, and the removal efficiency of TIN gradually increased to more than 90% from day 89. Contributions of endogenous/exogenous nitrification and denitrification to TIN removal were 54.09% and 46.01%, respectively. The coupling of endogenous/exogenous nitrification and denitrification could reduce the aeration consumption, save the external carbon source dosage and decrease the alkalinity consumption, which provided another option for treating wastewater from ionic rare earth mine.

Micronutrients and COD/N ratio as factors influencing granular size and SND in aerobic granular sequencing batch reactors operated at low organic loading

Simultaneous nitrification-denitrification (SND) depends on dissolved oxygen, granule size and COD/N ratio. Slow-growing nitrifying bacteria at low COD/N ratio lead to the formation of small-size granule. Anoxic denitrification is encouraged at higher granule size. In the present study, the effect of different COD/N ratios and addition of micronutrients (Fe, Zn, Mn, Cu, Co, Mo, B) on granule size and SND was studied in a laboratory-scale aerobic SBR at low organic loading (358.4–1075.2 mg COD.(L·day)−1). Synthetic cheese whey wastewater and ammonia was used. Small-size granules (0.28–0.7 mm) were developed at COD/TKN ratio of 8.6–13.7 with micronutrients and long famine phase (83–92% of the cycle). COD/TKN ratio of 13.7 achieved the best removal of inorganic nitrogen Ni (62%). At COD/TKN ratio of 8.6, without micronutrients, the low COD uptake rate caused shortening of the famine phase to 66%. Large-size granules (3.0 mm) with limitation of substrates diffusion showed low Ni removal and dominant slow-growing rhizobia (Bradyrhizobium) as detected by 16S rRNA gene amplicon sequencing. In small granules, without diffusion limitations and higher ammonia exposition, the energetically unfavorable heterotrophic nitrification occurred. Heterotrophic nitrifiers Lysobacter and Dyadobacter were found. Hydrogenophaga was a potential aerobic denitrifier. SND process was probably performed by AOB, heterotrophic nitrifiers, and anoxic and aerobic denitrifiers.

Enhancing biological nitrogen and phosphorus removal performance in aerobic granular sludge sequencing batch reactors by activated carbon particles

Long start-up periods for aerobic granular sludge (AGS) formation and establishment of P removal pathways are challenges for widespread implementation of AGS process. External additives such as activated carbon (AC) attracted interest for accelerating AGS formation. However, the roles of AC in granulation and biological nutrient removal (BNR) are not understood. Here, the role of AC was investigated in decreasing start-up periods in AGS formation and BNR under different carbon substrate conditions (i.e., acetate (HAc), propionate (HPr) and HAc-HPr) in sequencing batch reactors (SBRs). AC addition increased aggregation index and settleability of activated sludge (AS) inoculum which minimized AS washout from SBRs. AC addition hastened AGS formation and establishment of BNR pathways by facilitating AS retention and biofilm formation. Feeding HAc or HAc-HPr supported better granulation (MLSS: 6–7 g l−1, SVI: 30–40 ml g−1) than HPr (MLSS: 4 g l−1, SVI: 70). The start-up periods for efficient total nitrogen (TN) removals were decreased to 22 and 16 d from 38 to 25 d, respectively, in AC augmented SBRs fed with either HAc or HAc-HPr. TN removals were higher at ≥95% in HAc or HAc-HPr fed SBRs. Total phosphorus (TP) removals were also higher in AC-augmented SBRs at 80% and ≥90% in HAc and HAc-HPr fed SBRs, respectively. In contrast, TN and TP removals were lower at 70% and 35%, respectively, in HPr fed SBR. Ammonium was primarily removed via nitritation-denitritation pathway. Phosphorus removal was at 1.7 to 2-fold higher in AC augmented SBRs and driven by enhanced biological phosphorus removal (EBPR) pathway. MiSeq sequencing and qPCR revealed higher enrichment of polyphosphate accumulating organisms (PAOs), denitrifying PAOs, and ammonia oxidizers in AC-augmented SBRs fed with HAc or HAc-HPr. This study demonstrates that AC addition can be considered for enrichment of PAOs and establishment of EBPR in aerobic granular SBRs.

Stability and nutrients removal performance of a Phanerochaete chrysosporium-based aerobic granular sludge process by step-feeding and multi A/O conditions

A Phanerochaete chrysosporium-based aerobic granular sludge (PC-AGS) was developed by inoculating fungal mycelial pellets into a lab-scale aerobic granular sequencing batch reactor (AGSBR). A strategy using step-anaerobic feeding coupled with multi A/O conditions was adopted. The results showed that the removal efficiencies for total phosphorus (TP) and total inorganic nitrogen (TIN) were 94.56 ± 2.92% and 75.20 ± 7.74%, respectively, under relatively low aeration time. Compared with original AGS, the content of extracellular proteins for PC-AGS obviously increased from 18.61 to 41.44 mg/g MLSS by the end of phase I. Moreover, the mature granules had a larger size and better stability during the 100 days operation. Furthermore, the analysis of microbial diversity detected many key functional groups in PC-AGS granules that were beneficial to nutrients removal. This work demonstrated that the addition of fungal pellets not only enhanced the removal performance, but also improved the stability of the AGS system.

Heterotrophic nitrification-aerobic denitrification performance in a granular sequencing batch reactor supported by next generation sequencing

Several nitrogen transformation processes occur in wastewater treatment; among them, heterotrophic nitrification-aerobic denitrification (HNAD) has not been adequately quantified. In the present study, a comprehensive analysis of the simultaneous ammonia and organic carbon removal was carried out in an aerobic granular sequencing batch reactor (SBR) operated under feast/famine regime. For this, biological processes, microbial community composition and metabolic pathways were evaluated. Mass balances allowed estimating the ammonia assimilation and simultaneous nitrification and denitrification (SND). Better SND process (55%) was achieved in starvation period involving that denitrification driven by intracellular carbon reserves is more efficiently coupled to the ammonia oxidation with regard to external carbon-driven denitrification. Proton balances and titration monitored the organic carbon and nitrogen removal. High abundance of HNAD bacteria, Diaphorobacter sp. and Flavobacterium sp., and Zoogloea sp. aerobic denitrifier was detected by next generation sequencing (NGS) technology. Bioinformatics analysis predicted enzymes involved in nitrogen transformation pathways present in Phylogenetic investigation PYCRUSt database. Heterotrophic nitrification took place involving detoxification against ammonia. Non-limiting nitrate and high oxygen concentrations were favorable for aerobic denitrifiers. HNAD was the main process responsible for the biological nitrogen removal according to NGS and operational conditions given by high dissolved oxygen and low COD:NO3−-N ratio.

Micronutrients and Cod/N Ratio as Factors Influencing Granular Size, Autotrophic and Heterotrophic Nitrification and Denitrification in Aerobic Granular Sequencing Batch Reactors

Micronutrients and Cod/N Ratio as Factors Influencing Granular Size, Autotrophic and Heterotrophic Nitrification and Denitrification in Aerobic Granular Sequencing Batch Reactors

Performance and operational strategy of simultaneous nitrification, denitrification, and phosphorus removal system under the condition of low organic loading rate in wet weather

A pilot-scale aerobic granular sequencing batch reactor (SBR) with domestic wastewater was operated to evaluate the effects of the low organic loading rate (OLR) due to wet weather flow conditions on simultaneous nitrification, denitrification, and phosphorus removal (SNDPR). As the OLR decreased from 0.85 to 0.43 kg COD m−3 d−1, the total nitrogen (TN) and total phosphorus (TP) removal efficiencies decreased from 84.0% and 94.1% to 51.3% and 73.8%, respectively, the sludge volume index (SVI) increased from 42.3 to 85.5 mL g−1, and the average granular size decreased from 1022 to 742 μm; however, no sludge disintegration and biomass loss were observed. The poor nutrient removal efficiencies and settling ability were due to the shrinking anoxic zone and substrate scarcity inside the granules, wherein the activity decay of ammonia-oxidizing bacteria and overgrowth of filamentous bacteria played an important role. Alternating the aeration intensity was effective in enhancing nitrogen removal and sludge settling by improving the anoxic activity in granules and inhibiting the proliferation of filamentous bacteria. Returning 20% of sludge from the end of one anaerobic stage to the beginning of the next anaerobic stage (midway sludge return) was beneficial for phosphorus removal as it improved phosphorus storage by phosphorus-accumulating bacteria. A smaller granular size with stronger stability and better nutrient removal performance was the new steady state of the SNDPR system under wet-weather flow conditions.

Enhanced nitrogen removal in an aerobic granular sequencing batch reactor under low DO concentration: Role of extracellular polymeric substances and microbial community structure

In this study, the role of extracellular polymeric substances (EPSs) in nitrogen removal and the microbial community structure of aerobic granular sludge (AGS) were analyzed under different dissolved oxygen (DO) conditions (6–7, 4–5, and 2–3 mg·L−1). The EPSs transported and retained nitrogen in the denitrification process, and the total inorganic nitrogen (TIN) in the EPSs decreased from 6.09 to 5.54 mg·g−1 MLSS when the DO concentration decreased from 6–7 to 2–3 mg·L−1. The microbial community showed different core denitrifying bacterial populations involved in nitrogen removal in the AGS system under different DO conditions, with more species when they were higher relative abundances of denitrifying bacteria participating in the nitrogen removal process in AGS under low DO conditions, including Hydrogenophilaceae, Thauera, Enterobacter, Xanthomonadaceae_unclassified, Comalmonadaceae_unclassified, Nitrosomonas and Paracoccus. This study provides a more comprehensive understanding of the DO effect on the TIN removal mechanism by AGS.

Ammonia and phosphorus removal from mixture of treated and raw cattle manure wastewater in a low‐O2 granular sequencing batch reactor

AbstractBACKGROUNDIn this study, the feasibility of an aerobic granular sequencing batch reactor (AGSBR) for elimination of nutrients at low dissolved oxygen (DO) level was investigated. It was fed by a mixture of treated and raw cattle manure wastewater. The behaviour of the AGSBR was assessed at different chemical oxygen demand (COD)/NH4+‐N ratios, feeding strategies (dump‐fill and slow‐rate feeding) and hydraulic retention times (24, 32 and 48 h). For a duration of 140 days, the capability of the AGSBR for reducing COD, ammonia and total phosphorus (TP) contents was studied. At DO concentrations of 0.3–1.0 mg L−1, the effect of different COD/NH4+ ratios (100:3–100:10) was evaluated.RESULTSA COD/NH4+‐N ratio of 100:10 resulted in higher nitrification rate (0.0714 gN gMLVSS−1 day−1) compared to a ratio of >100:3 (0.0175 gN gMLVSS−1 day−1). The active granular sludge in dump‐filling mode revealed better settling properties compared to the slow feeding rate. Microscopic observation of aerobic granules showed that the core of granules was dominantly occupied by filamentous microorganisms. Finally, at optimum conditions, removal efficiencies of NH4+‐N, TP and COD were 99.9, 99 and 79%, respectively.CONCLUSIONSApplying the AGSBR at low DO is promising as a cost‐effective technique for the secondary treatment of livestock wastewaters. © 2019 Society of Chemical Industry

Hydrodynamic shear force shaped the microbial community and function in the aerobic granular sequencing batch reactors for low carbon to nitrogen (C/N) municipal wastewater treatment

The lab-scale aerobic granules process was applied for low carbon to nitrogen (C/N < 4) wastewater treatment under different hydrodynamic shear forces. Results revealed that aerobic granules exhibited strong adaptability and stability. The aerobic granules might adopt an extracellular polymeric substances (EPS) regulating mechanism to address the changes in operational conditions, especially through growing secretion of fluorescence protein. The hydrodynamic shear force determinedly shaped and regulated the diversity and structure of dominant microbial community, briefly, reduced aeration intensity with increased time led to higher microbial richness, lower diversity and evenness, and shifts of predominant microorganisms. Phylogenetic classification of the key functional groups including bacteria related to carbon and nutrients removal, EPS production and quorum sensing (QS) presented much more differences among the reactors subject to different conditions. Therefore, the present work adds insight into the comprehensive understanding of the effect of aeration induced hydrodynamic shear force on aerobic granules.

Natural sunlight induced rapid formation of water-born algal-bacterial granules in an aerobic bacterial granular photo-sequencing batch reactor

Wastewater treatment by means of algal-bacterial granules has become a hot topic worldwide recently. Rapid granulation of algal-bacterial granules was achieved in an aerobic bacterial granular sequencing batch reactor (SBR) under natural sunlight exposure. Occurrence of abundant filamentous bacteria bridging the water-born algae, and overproduction of extracellular polymeric substances (EPS) (especially polysaccharides (PS), tryptophan & protein-like, and humic acid-like substances) were observed on the first 3 days, while the algae grew into the inner side of the granules and mature granules were obtained on day 7. The growth of the water-born algae slightly decreased the settleability, mean sizes of the granules, but stimulated the bioactivity significantly. Whereas, the biomass retention decreased before day 3, and got stable soon with the maturation period with symbiotic growth of algal-bacterial biomass. Illumina results revealed that the introduction of algae reduced the richness and diversity of bacterial community. Besides, few changes in structure and some compositions shifts in bacterial communities were found, while the predominant algae shifted from Diatomea to green algae Chlorophyceae. The possible mechanism for natural sunlight induced granulation of algal-bacterial granules was thus proposed based on the interactions between algae and bacteria.

Roles of bacterial and epistylis populations in aerobic granular SBRs treating domestic and synthetic wastewaters

Aerobic granular sludge (AGS) has been recently studied and developed as a way to circumvent the poor settling and biomass retention capacity of conventional activated sludge. While it is known that AGS allows the simultaneous presence of oxic and anoxic zones on the surface or within granules, respectively, the actual composition dynamics of those granules in relation to their underlying wastewater influent have receive little attention. The main goal of this study is thus to assess the relationship between wastewater composition, microbial community structure and epistylis abundance. Two SBRs (sequencing batch reactors) comprising the same inoculum and fed with either domestic or synthetic wastewater were used in this regard. The more complex composition of domestic wastewater promoted a higher bacterial richness than their synthetic counterparts. Indeed, the vast majority of the bacterial community in the SBR fed with synthetic wastewater was dominated by the genus Thauera. The SBR fed with domestic wastewater also showed a more thorough granulation and greater treatment efficiency. Surprisingly, the abundance of epistylis was positively correlated with remaining suspended solids, hinting that ciliates might be responsible for SS (suspended solids) removal and would be a desirable trait to include in wastewater treatment plants. In sum, our study gives insight into the differing population dynamics shaped by domestic and synthetic wastewaters inoculated with the same initial consortium, along with their overall pollutant removal efficiency.

Simultaneous nitrification, denitrification and phosphorus removal in an aerobic granular sludge sequencing batch reactor with high dissolved oxygen: Effects of carbon to nitrogen ratios

Simultaneous nitrification, denitrification and phosphorus removal (SNDPR) using aerobic granules is a promising approach in water treatment. The present work investigated the effects of influent carbon to nitrogen (N) ratios (20, 10, and 4) on the SNDPR performance in aerobic granular sequencing batch reactors (AGSBR) under high aeration rate. Results revealed that granules remained long-term stability when the DO concentration was 7–8 mg/L. With the decline of COD/N ratios, the denitrification efficiency was reduced due to the accumulation of nitrate, although the removal of COD and TP remained stable with good efficiency. Rising concentration of ammonia N led to the increase of PN/PS ratio of EPS as well as the protein types according to the results of 3D-EEM fluorescence spectroscopy. MiSeq pyrosequencing technology indicated that the decreasing ratio of COD/N under high DO concentration contributed to accumulation of GAOs and DNPAOs rather than PAOs.

Simultaneous nitrification, denitrification and phosphorus removal in aerobic granular sequencing batch reactors with high aeration intensity: Impact of aeration time

A new operating approach by reducing the aeration time while keeping high intensity was evaluated for enhanced nutrients removal and maintenance of granular stability. Three aerobic granular sequencing batch reactors (SBR) performing simultaneous nitrification, denitrification and phosphorus removal (SNDPR) were run at different aeration time (120, 90, and 60 min). Aerobic granules could remain their integrity and stability over long-term operation under high aeration intensity and different time, and shorter aeration time favored the retention of biomass, better settleability, and more production of extracellular polymeric substances (EPS). Besides, efficient and stable reactor performance for carbon and phosphorus were achieved, especially, enhanced nitrogen removal was obtained due to reduction of aeration time. Further exploration revealed that the aeration time shaped the bacterial community in terms of diversity, composition, as well as the distribution of functional groups involving carbon, nitrogen and phosphorus removal.

Pollutants degradation performance and microbial community structure of aerobic granular sludge systems using inoculums adapted at mild and low temperature

Three aerobic granular sequencing batch reactors were inoculated using different inocula from Finland, Spain and a mix of both in order to investigate the effect over the degradation performance and the microbial community structure. The Finnish inoculum achieved a faster granulation and a higher depollution performance within the first two month of operation. However, after 90 days of operation, similar physico-chemical values were observed. On the other hand, the Real-time PCR showed that Archaea diminished from inoculum to granular biomass, while Bacteria and Fungi numbers remained stable. All granular biomass massive parallel sequencing studies were similar regardless of the inocula from which they formed, as confirmed by singular value decomposition principal coordinates analysis, expected effect size of OTUs, and β-diversity analyses. Thermoproteaceae, Meganema and a Trischosporonaceae members were the dominant phylotypes for the three domains studied. The analysis of oligotype distribution demonstrated that a fungal oligotype was ubiquitous. The dominant OTUs of Bacteria were correlated with bioreactors performance. The results obtained determined that the microbial community structure of aerobic granular sludge was similar regardless of their inocula, showing that the granulation of biomass is related to several phylotypes. This will be of future importance for the implementation of aerobic granular sludge to full-scale systems.

Sequencing Batch Reactor and Bacterial Community in Aerobic Granular Sludge for Wastewater Treatment of Noodle-Manufacturing Sector

The sequencing batch reactor (SBR) has been increasingly applied in the control of high organic wastewater. In this study, SBR with aerobic granular sludge was used for wastewater treatment in a noodle-manufacturing village in Vietnam. The results showed that after two months of operation, the chemical oxygen demand, total nitrogen and total phosphorous removal efficiency of aerobic granular SBR reached 92%, 83% and 75%, respectively. Bacterial diversity and bacterial community in wastewater treatment were examined using Illumina Miseq sequencing to amplify the V3-V4 regions of the 16S rRNA gene. A high diversity of bacteria was observed in the activated sludge, with more than 400 bacterial genera and 700 species. The predominant genus was Lactococcus (21.35%) mainly containing Lactococcus chungangensis species. Predicted functional analysis showed a high representation of genes involved in membrane transport (12.217%), amino acid metabolism (10.067%), and carbohydrate metabolism (9.597%). Genes responsible for starch and sucrose metabolism accounted for 0.57% of the total reads and the composition of starch hydrolytic enzymes including α-amylase, starch phosphorylase, glucoamylase, pullulanase, α-galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, and 1,4-α-glucan branching enzyme. The presence of these enzymes in the SBR system may improve the removal of starch pollutants in wastewater.

Simultaneous nitrification, denitrification and phosphorus removal in an aerobic granular sequencing batch reactor with mixed carbon sources: reactor performance, extracellular polymeric substances and microbial successions

Development of simultaneous nitrification, denitrification and phosphorus removal (SNDPR) is a promising approach for domestic wastewater treatment. Mixed carbon sources by sodium acetate and glucose at various ratios (3:1, 1:1, and 1:3) were investigated to evaluate the effects on the sequencing batch reactors (SBR) based on aerobic granules. Results revealed that the mixed carbon did not change the settleability of aerobic granules, while glucose was more favorable for biomass retention induced by heterotrophs. Both carbon and ammonia nitrogen removal remained unaffected, while increased residual nitrate and phosphorus were detected with higher glucose ratios. Growing percentages of glucose led to more production of extracellular polymeric substances (EPS), especially polysaccharides (PS). Shifts of compositions of EPS were observed by the three-dimensional exaction and emission matrix (3D-EEM) fluorescence spectroscopy. MiSeq pyrosequencing technology demonstrated that the increasing ratios of glucose reduced the diversity of microbial community, though the dominant microbes remained unchanged. Phylogenetic classification of key groups involved in carbon, nitrogen and phosphorus removal suggested that mixed carbon source decidedly shaped the bacterial community.

Effects of Inoculum Type and Aeration Flowrate on the Performance of Aerobic Granular SBRs

Aerobic granular sequencing batch reactors (SBRs) are usually inoculated with activated sludge which implies sometimes long start-up periods and high solids concentrations in the effluent due to the initial wash-out of the inoculum. In this work, the use of aerobic mature granules as inoculum in order to improve the start-up period was tested, but no clear differences were observed compared to a reactor inoculated with activated sludge. The effect of the aeration rate on both physical properties of granules and reactor performance was also studied in a stable aerobic granular SBR. The increase of the aeration flow rate caused the decrease of the average diameter of the granules. This fact enhanced the COD and ammonia consumption rates due to the increase of the DO level and the aerobic fraction of the biomass. However, it provoked a loss of the nitrogen removal efficiency due to the worsening of the denitrification capacity as a consequence of a higher aerobic fraction.

Enhanced nitrogen removal in an aerobic granular sequencing batch reactor performing simultaneous nitrification, endogenous denitrification and phosphorus removal with low superficial gas velocity

An aerobic granular simultaneous nitrification, endogenous denitrification and phosphorus removal (SNDPR) system was configured for simultaneous carbon and nutrients removal fed with low-strength synthetic wastewater (0.3kgCOD/(m3·d)). The SNDPR system was operated on an anaerobic/oxic/anoxic (AOA) mode with a gradually dropping superficial gas velocity (SGV) from 0.17, 0.11 to 0.04cm/s. Long term operation over 120days revealed decreasing SGV resulted in poorer settleability and microbial activity as well as larger particle sizes, which were in great linear correlations with the sharp decrease of protein/polysaccharides (PN/PS). Excellent removal of chemical oxygen demand (COD) and phosphorus were achieved during the whole process, while enhanced nitrogen removal was observed by dropping the SGV. Both simultaneous nitrification and denitrification rate (SND) and nitrite accumulation rate (NUR) increased significantly, as with the removal efficiency for nitrogen. Illumina MiSeq pyrosequencing displayed glycogen-accumulating organisms (GAOs) Candidatus_Competibacter predominated the SDNPR system, while the PAOs Candidatus_Accumulibacter grew notably with decreased SGV. Lower SGVs favored the enrichment of ammonia-oxidizing bacteria (AOB) while suppressed the accumulation of nitrite-oxidizing bacteria (NOB). This study might contribute to the application of SNDPR system for simultaneous carbon, nitrogen and phosphorus removal.