Aerobic Granular Sludge Technology Research Articles

Digestibility of waste aerobic granular sludge from a full-scale municipal wastewater treatment system

Full-scale aerobic granular sludge technology under the trade name Nereda® has been implemented for municipal, as well as industrial wastewater treatment. Owing to the operational reactor procedures, two types of waste aerobic granular sludge can be clearly distinguished: 1) aerobic granular sludge selection discharge (AGS-SD) and 2) aerobic granular sludge mixture (AGS-RTC). This study systematically compared the anaerobic biodegradability of AGS-SD and AGS-RTC under mesophilic conditions. Results were further compared with the anaerobic conversion of waste activated sludge (WAS) as well as primary sludge (PS) from full-scale municipal wastewater treatment plants. Analysis showed similar chemical characteristics for AGS-SD and PS, which were both characterized by a high carbohydrate content (429 ± 21 and 464 ± 15 mg glucose/g VS sludge, respectively), mainly cellulosic fibres. Concurrently, AGS-RTC exhibited chemical properties close to WAS, both characterized by a relatively high protein content, which were individually 498 ± 14 and 389 ± 15 mg/g VS sludge. AGS-SD was characterized by a high biochemical methane potential (BMP) (296 ± 15 mL CH4/g VS substrate), which was similar to that of PS, and remarkably higher than that of AGS-RTC and WAS. Strikingly, the BMP of AGS-RTC (194 ± 10 mL CH4/g VS substrate) was significantly lower than that of WAS (232 ± 11 mL CH4/g VS substrate). Mechanically destroying the compact structure of AGS-RTC only accelerated the methane production rate but did not significantly affect the BMP value. Results indicated that compared to WAS, the proteins and carbohydrates in AGS-RTC were both more resistant to anaerobic bio-degradation, which might be related to the presence of refractory microbial metabolic products in AGS-RTC.

Performance and microbial community structure of aerobic granular bioreactors at different operational temperature

Three lab-scale sequential batch reactors were operated under aerobic granular sludge technology for 150 days. The reactors were inoculated with mild temperature-adapted activated sludge from Granada wastewater treatment plant (WWTP) in order to evaluate the microbial dynamics, the granulation process and the performance of the systems under low, mid and high temperature. The faster start-up was achieved at mid temperature at operational day 6, followed by warm temperature at day 10, with nitrogen and organic matter removal ratio higher than 90%. Conversely, the reactor under cold temperature produced granular biomass but the nitrogen and carbon removal ratios did not achieve good performance, close to 80%. The dynamics of Prokarya communities showed that Corynebacterium phylotype was present in all bioreactor despite temperature, although the microbial diversity at mid and warm temperature was higher than at cold temperature. The Eukarya communities in mature granules were represented by Pezizomycotina fungi and Oligohymenophorea ciliate.

Modeling cell aggregate morphology during aerobic granulation in activated sludge processes reveals the combined effect of substrate and shear

Past research on AGS (aerobic granular sludge technology) has mainly focused on macro-environment factors, such as settling time, feeding pattern, OLR (organic loading rate), SRT (sludge retention time), among others, and their effects on the granulation process. The biomass granulation process, however, is significantly affected by the micro-environment surrounding these biomass aggregates. In this research, an in silico computational approach was adopted to study the impact of the micro-environment on the biomass granulation process. A 2-D biofilm model based on the cellular automata algorithm and computational fluid dynamics was used to simulate the development of an individual biomass aggregate under specific hydrodynamic and substrate availability conditions. The simulation results indicated that shear and bulk substrate concentration combined to create the optimal conditions for aerobic granule formation. This process can be characterized by the RT (reversed Thiele) modulus value, which is the ratio of the maximum substrate transport over the maximum substrate reaction rate and an indicator of substrate availability. For AGS formation, the RT value should be greater than 0.1. Many common strategies, such as the application of batch reactors, selection for slow-growing microorganism, F/M (food/mass) ratio adjustment, feast and famine condition, and short settling time, for biomass granulation production can be explained by the RT value. The results suggest that rethinking unit process configurations in wastewater treatment facilities will be required to achieve reliable AGS formation.

Integrated leachate management approach incorporating nutrient recovery and removal

This manuscript presents an integrated management scheme for leachate which employed struvite precipitation to recover ammonia nitrogen and phosphorus, aerobic granular sludge process for carbon oxidation (in the form of BOD and sCOD) and single stage anaerobic ammonia oxidation (ANAMMOX) for nitrogen management. The influent fed to the integrated treatment scheme was a mixture of anaerobic digester centrate and real leachate in 4:1 ratio. Almost 77% recovery of phosphorus and 25% removal of NH4+-N were accomplished through struvite precipitation at an optimum pH of 9. High pH contributed to free ammonia loss during struvite precipitation experiments. In the aerobic granular sludge reactor overall, BOD5, COD and NH4+-N removal percentages were 74%, 45% and 35% and in the PN/A reactor, overall 35% removal of total inorganic nitrogen (TIN) was observed. More than 80% BOD removal was recorded in the granular reactor with soluble COD (sCOD) removal fluctuating between 28 and 57% depending on the operational phase. High-throughput amplicon sequencing of 16S rRNA gene targeting V4 region revealed a dominance of phylum Planctomycetes, in the PN/A reactor system. Presence of Rhodobacteraceae, Xanthomonadaceae, Flavobacteriaceae in the granular biomass confirmed the defined redox zones inside mature granules indicating simultaneous removal of nitrogen (N) and organics in aerobic granular sludge technology. Exposing the synthetically cultured aerobic granules directly to the mixture of leachate and centrate unveiled an alteration in physical characteristics of granules; however, reactor operational data and microbial community analysis ascertain the effectiveness of the treatment scheme treating two urban waste-streams.

The effect of quorum sensing on performance of salt-tolerance aerobic granular sludge: linking extracellular polymeric substances and microbial community.

Aerobic granular sludge (AGS) technology is generally negatively affected by the salinity in high saline organic wastewater. The effect of salinity on organic pollutants removal of AGS was studied in three parallel sequencing batch reactors. The results indicated that the performance of reactors operating at relative low salinity (1%) remained stable. However, at medium salinity (2%) and higher salinity (4%) conditions, the organic pollutants removal efficiencies deteriorated from 93.7 ± 3.0 to 71.6 ± 6.8 and 53.6 ± 5.4%, respectively. The addition of a mixture of acyl-homoserine lactone (AHL) mediated quorum sensing (QS) signaling molecules (0.1μmol/L of mixed C6-HSL, C8-HSL and 3OC8-HSL) only restored the performance of the 2% salinity reactor back to 86.3 ± 6.2% due to the changing of hydrophobic extracellular polymeric substance ratio from 64 ± 3 to 71 ± 4%. Addition of the AHL had no effect on the pollution removal efficiency at the 4% salinity conditions. Microbial community analysis showed that Dyella (32.3%) species were the dominant member of the community and its occurrence was positively correlated with organic pollutants removal efficiency at relative high salinity (2% and 4%), while Mangrovibacter showed the opposite trend. Higher abundances of hdtS and acylase genes, the synthesis and degradation genes of AHL, were found after adding AHLs to reactors at 2% salinity, which indicated that AHL mediated QS was the primary QS system in salt-tolerant AGS.

Using carbon substrate as a selection pressure to enhance the potential of aerobic granular sludge microbial communities for removing contaminants of emerging concern

The ability of aerobic granular sludge (AGS) technology to biotransform contaminants of emerging concern (CECs) is largely unknown. AGS supplemented with either acetate, 2-propanol, glycerol, or a 1:1:1 mixture of all three, were cultivated to investigate the link between carbon supplements and biotransformation of six CECs. Carbon substrate had a significant effect on the microbial community composition, as assessed by 16S rRNA gene sequence analyses. Substrate degradation requiring a larger number of catabolic reactions (i.e., glycerol and the mix) was associated with greater microbial richness. The biotransformation of CECs was 45.9% greater in communities supplemented with glycerol (60.3 ± 30.2 µg L−1 VSS−1) compared to acetate (20.9 ± 29.7 µg L−1 VSS−1). Database surveys of metabolic reactions indicate that microbial communities supplemented with glycerol have the greatest capacity for the degradation of aromatic compounds, while those supplemented with acetate community have the lowest.

Petrochemical slop wastewater treatment by means of aerobic granular sludge: effect of granulation process on bio-adsorption and hydrocarbons removal

The aim of this work is to study the mechanism for hydrocarbons removal from slop wastewater by means of aerobic granular sludge technology (AGS). Two sequencing batch reactors (SBRs), R1 and R2, worked for 150 days according to two different strategies: (i) slop treatment with mature salt-adapted granules (R1); (ii) cultivation of AGS with slop wastewater for its treatment (R2). Results revealed that, despite the similar physical properties of AGS at the end of experimental period (4.4–4.8 gTSS·L−1 and 2.2–2.5 gVSS·L−1, and mean dimensions of 1.15 mm and 1 mm, for R1 and R2 respectively), in R2 granules highlighted better total petroleum hydrocarbons (TPHs) removal efficiencies than R1 (83% vs 36%), when real slop was fed to the reactors. The direct cultivation of AGS with slop (R2) prompted a higher extracellular polymeric substances (EPSs) production that enhanced the bio-adsorption of TPH, thus favouring the adaptation of bacteria to hydrocarbons.

Performance and microbial community structure of an aerobic granular sludge system at different phenolic acid concentrations.

The present work aims to use aerobic granular sludge technology for the treatment of wastewater containing high organic matter loads and a mixture of phenolic compounds normally present in olive washing water. The physicochemical performance of five bioreactors treating different concentrations of mixture of phenolic acid was monitored to observe the response of the systems. The bioreactors that operated at 50, 100 and 300 mg L-1 did not show relevant changes in terms of performance and granules properties, showing high ratio of phenolic compound removal ratio. However, the bioreactors operated with high phenolic compound concentrations showed low rates of organic matter, nitrogen and phenolic acid removal. In the same way, high concentrations of phenolic compounds determined the disintegration of the granular biomass. Next-generation sequencing studies showed a stable community structure in the bioreactors operating with 50, 100 and 300 mg L-1 of phenolic acids, with the genera Lampropedia and Arenimonas, family Xanthobacteraceae and Fungi Pezizomycotina as the dominant phylotypes. Conversely, the reactors operated at 500 and 600 mg L-1 of phenolic substances promoted the proliferation of Oligohymenophorea ciliates. Thus, this study suggests that aerobic granular sludge technology could be useful for the treatment of wastewaters such as olive washing water.

WASTEWATER CHARACTERIZATION AND SEQUENCING BATCH REACTOR OPERATION FOR AEROBIC GRANULAR SLUDGE CULTIVATION

Studying the possibility of forming aerobic granules on real domestic sewage was a logical step in the scaling-up process and development of Aerobic Granular Sludge (AGS) technology. It was noted that influent wastewater composition and Sequencing Batch Reactor (SBR) operation cycle time are important factors that can influence the formation of AGS. Therefore, this study aims to determine the suitability of influent wastewater from Bunus Wastewater Treatment Plant (WWTP) for AGS cultivation and then propose a proper SBR operation cycle time. In this study, wastewater characterization was done for the influent of wastewater treatment plant located in Bunus, Kuala Lumpur. The result was then analysed and compared with previous research to determine the suitability of AGS cultivation. The information on SBR from previous studies were also gathered to propose SBR operation cycle time that suit the Bunus WWTP influent. The findings indicate that the wastewater can be characterized as low strength domestic wastewater with low organic and nutrients content. The values of related parameters in this study have shown that influent wastewater of Bunus WWTP is suitable for cultivating AGS. For the proposed SBR operation, the cycle time is 3h, which consist of 60 min (fill), 110 min (aerate), 5 min (settle), and 5 min (discharge), respectively.

WASTEWATER CHARACTERIZATION AND SEQUENCING BATCH REACTOR OPERATION FOR AEROBIC GRANULAR SLUDGE CULTIVATION

Studying the possibility of forming aerobic granules on real domestic sewage was a logical step in the scaling-up process and development of Aerobic Granular Sludge (AGS) technology. It was noted that influent wastewater composition and Sequencing Batch Reactor (SBR) operation cycle time are important factors that can influence the formation of AGS. Therefore, this study aims to determine the suitability of influent wastewater from Bunus Wastewater Treatment Plant (WWTP) for AGS cultivation and then propose a proper SBR operation cycle time. In this study, wastewater characterization was done for the influent of wastewater treatment plant located in Bunus, Kuala Lumpur. The result was then analysed and compared with previous research to determine the suitability of AGS cultivation. The information on SBR from previous studies were also gathered to propose SBR operation cycle time that suit the Bunus WWTP influent. The findings indicate that the wastewater can be characterized as low strength domestic wastewater with low organic and nutrients content. The values of related parameters in this study have shown that influent wastewater of Bunus WWTP is suitable for cultivating AGS. For the proposed SBR operation, the cycle time is 3h, which consist of 60 min (fill), 110 min (aerate), 5 min (settle), and 5 min (discharge), respectively.

Long-term stability of aerobic granular sludge for the treatment of very low-strength real domestic wastewater

Aim of the present study was to assess the feasibility of cultivating aerobic granular sludge for the treatment of real very low-strength (COD <120 mg L−1) municipal wastewater by the application of a strict metabolic selective pressure. The feasibility was evaluated in terms of long-term physical stability of the granular biomass as well as COD and phosphate removal efficiencies. A laboratory-scale sequencing batch reactor was inoculated with conventional activated sludge and operated for 175 d. Complete granulation of conventional activated sludge (SVI5/SVI30 = 1) was achieved within 45 d at an average influent COD concentration of 290 ± 44 mg L−1 obtained by the addition of an external source of acetate. At day 51, acetate dosage was stopped and the reactor was then operated for other four months with only real wastewater as carbon source, resulting in an influent COD concentration as low as 115 ± 23 mg L−1. Besides the decrease of the influent COD concentration and of the organic load, the long term stability of the granular sludge was not affected and granular size continuously increased until it reached a maturation phase with an average diameter of 1.5 mm, with more than 30% of the aggregates being larger than 2 mm and marginal presence of floccular biomass (about 5%). The applied metabolic selective pressure based on the complete biodegradable COD uptake under anaerobic conditions (85 ± 7% biodegradable COD removal efficiency obtained) was shown to be able to stimulate the formation of stable and large granules, indicating the other commonly applied selective pressure based on settling velocity (commonly > 8 m h−1 versus 1.9 m h−1 applied in this study), as not strictly required. The identification of the key factors to preserve biomass long-term stability and functionality, poses the basis to allow the application of aerobic granular sludge technology in the context of combined sewers systems and facilitate the retrofitting of existing wastewater treatment plants excluding the need for a plug-flow distribution system for the influent wastewater.

Extensive studies on the treatment of pulp mill wastewater using aerobic granular sludge (AGS) technology

Aerobic granular sludge (AGS) offers the potential to degrade tannin/lignin found in pulp and paper wastewater (PPW). In this study, aerobic granules were cultivated in a sequencing batch reactor (SBR) with tannin/lignin present in the range of 50–200 mg/L. The mature granules were transferred to a real PPW wastewater system containing tannin/lignin concentration up to 500 mg/L. Biodegradation and biosorption were observed to be the two pathways for the removal tannin/lignin. Biosorption was a primary form of removal at lower concentrations, achieving 74% removal at 50 mg/L. The biosorption ability reduced to 58% removal at 200 mg/L. This reveals that biodegradation prevails at these higher concentrations. The Haldane kinetic parameters were: Vmax = 0.93 (g tannin/lignin/g VSS·day), Ks = 1910 mg/L, and Ki = 27 mg/L. Various adsorption kinetic models and isotherms were fitted to the system. The Langmuir isotherm coefficients were: (x/m) max = 21.5 (mg tannin/lignin/g SS), b = 0.00386 L/mg. The Freundlich isotherm had coefficients of n = 1.172, K = 0.1174. The study also delves into applying the technology towards real wastewater, achieving a COD removal of 79% and a tannin/lignin removal of 56%. Furthermore, experimental runs in warmer and more humid temperature conditions revealed higher removal efficiencies, achieving about 80% tannin/lignin degradation at a concentration of 130 mg/L. Results from this study will help ascertain an appropriate design protocol for full-scale industrial applications.

Degradation of industrial tannin and lignin from pulp mill effluent by aerobic granular sludge technology

Tannin and lignin from pulp and paper wastewater (PPW) are two compounds that have been proven to cause a variety of toxic effects in several aquatic species. Aerobic granular sludge (AGS) technology has emerged with strong potential to provide the desired treatment. This work presents the first attempt at the microbial degradation of these compounds using AGS technology, with promising results. Granules were cultivated within 9 days of operation of the sequencing batch reactor (SBR), with SVI30 of 51.6 mL/g, achieving steady-state within the first three weeks of operation. On average, COD removal efficiency was 90%. Granules cultivated from the SBR were transferred into a batch system with real pulp mill effluent. Tannin/lignin removal efficiency was 97% at an initial concentration of 50 mg/L, and slowly decreased to about 60% when the influent concentration increased to 100 mg/L. The most prominent species responsible for the degradation of these toxic substances were Pseudomonas, Corynebacteriaceae and Flavobacterium. These key findings demonstrate the capability of AGS to provide adequate treatment for PPW.

Comparing the performance of aerobic granular sludge versus conventional activated sludge for microbial log removal and effluent quality: Implications for water reuse

The application of aerobic granular sludge (AGS) technology has increased in popularity, largely due to the smaller physical footprint, enhanced biological nutrient removal performance and ability to perform with a more stable operation when compared to conventional activated sludge (CAS) systems. To date, the ability of AGS to remove microbial pathogens such as; Escherichia coli, Giardia, and Cryptosporidium has not been reported. This study compared the log10 removal performance of commonly used pathogen surrogates (sulfite-reducing clostridia spores, f-RNA bacteriophage, E. coli and total coliforms) by AGS and CAS during the start-up phase, through to maturation. Results showed that AGS performed as well as CAS for the log10 removal performance of all microbial surrogates, except for spores which were removed more effectively by AGS most likely due to greater adherence of spores to the AGS biomass compared to CAS mixed liquor. Results suggest that AGS is capable of meeting or exceeding CAS-equivalent health-based targets for pathogen removal in the context of water recycling as well as not adversely affecting the secondary effluent water quality (suspended solids, turbidity and particle size) in terms of ultraviolet light transmissivity (254 nm). These findings confirmed for the first time that the adoption of AGS operation would not adversely impact downstream tertiary disinfection processes from altered water quality, nor would it require further pathogen treatment interventions in addition to what is already required for CAS systems.

A comparison of aerobic granular sludge with conventional and compact biological treatment technologies

ABSTRACTThe aerobic granular sludge (AGS) technology is growing towards becoming a mature option for new municipal wastewater treatment plants and capacity extensions. A process based on AGS was compared to conventional activated sludge processes (with and without enhanced biological phosphorus removal), an integrated fixed-film activated sludge (IFAS) process and a membrane bioreactor (MBR) by estimating the land area demand (footprint), electricity demand and chemicals’ consumption. The process alternatives compared included pre-settling, sludge digestion and necessary post-treatment to achieve effluent concentrations of 8 mg/L nitrogen and 0.2 mg/L phosphorus at 7°C. The alternative based on AGS was estimated to have a 40–50% smaller footprint and 23% less electricity requirement than conventional activated sludge. In relation to the other compact treatment options IFAS and MBR, the AGS process had an estimated electricity usage that was 35–70% lower. This suggests a favourable potential for processes based on AGS although more available experience of AGS operation and performance at full scale is desired.

Powdered keramsite as unconventional method of AGS technology support in GSBR reactor with minimum-optimum OLR

Aerobic Granular Sludge (AGS) technology becomes a very competitive method to activated sludge system. Its main advantages include: high energy efficiency and low investment costs. Despite this fact, intensive research on biogranulation optimization are still carried out, both at laboratory and technical scale. In order to intensify the AGS technology, new methods of biogranulation and ways of improving the stability of aerobic granules are sought. So far, several studies have been conducted in this area, with using among others: chemical coagulants, dosage fragments of granules and powdered materials. The aim of this study was to evaluate the impact of powdered keramsite on the feasibility of rapid aerobic granulation in a GSBR reactor with a minimum-optimum organic loading rate (OLR). The research presents an effective way of cultivating stable aerobic granules in a Granular Sequencing Batch Reactor (GSBR) under specific technological parameters.

Aerobic granular biomass technology: advancements in design, applications and further developments

AbstractAerobic granular sludge is seen as the future standard for industrial and municipal wastewater treatment. Through a Dutch research and development program, a full-scale aerobic granular biomass technology has been developed – the Nereda® technology – which has been implemented to treat municipal and industrial wastewater. The Nereda® system is considered to be the first aerobic granular sludge technology applied at full-scale and more than 40 municipal and industrial plants are now in operation or under construction worldwide. Further plants are in the planning and design phase, including plants with capacities exceeding 1 million PE. Data from operational plants confirm the system's advantages with regard to treatment performance, energy-efficiency and cost-effectiveness. In addition, a new possibility for extracting alginate-like exopolysaccharides (ALE) from aerobic granular sludge has emerged which could provide sustainable reuse opportunities. The case is therefore made for a shift away from the ‘activated sludge approach’ towards an ‘aerobic granular approach’, which would assist in addressing the challenges facing the wastewater treatment industry in Asia and beyond.

Performance and microbial characteristics of biomass in a full-scale aerobic granular sludge wastewater treatment plant

By modification of the operational conditions of batch reactors, a municipal wastewater treatment plant was upgraded from activated sludge to aerobic granular sludge (AGS) technology. After upgrading, the volume of the biological reactors was reduced by 30%, but the quality of the effluent substantially improved. The concentration of biomass in the reactors increased twofold; the average biomass yield was 0.6 g MLVSS/g COD, and excess granular sludge was efficiently stabilized in aerobic conditions. Canonical correspondence analysis based on the results of next-generation sequencing showed that the time of adaptation significantly influenced the microbial composition of the granules. In mature granules, the abundance of ammonium-oxidizing bacteria was very low, while the abundance of the nitrite-oxidizing bacteria Nitrospira sp. was 0.5 ± 0.1%. The core genera were Tetrasphaera, Sphingopyxis, Dechloromonas, Flavobacterium, and Ohtaekwangia. Bacteria belonging to these genera produce extracellular polymeric substances, which stabilize granule structure and accumulate phosphorus. The results of this study will be useful for designers of AGS wastewater treatment plants, and molecular data given here provide insight into the ecology of mature aerobic granules from a full-scale facility.

Effect of COD/N ratio on N2O production during nitrogen removal by aerobic granular sludge.

N2O-production was investigated during nitrogen removal using aerobic granular sludge (AGS) technology. A pilot sequencing batch reactor (SBR) with AGS achieved an effluent in accordance with national discharge limits, although presented a nitrite accumulation rate of 95.79% with no simultaneous nitrification-denitrification. N2O production was 2.06 mg L-1 during the anoxic phase, with N2O emission during air pulses and the aeration phase of 1.6% of the nitrogen loading rate. Batch tests with AGS from the pilot reactor verified that at the greatest COD/N ratio (1.55), the N2O production (1.08 mgN2O-N L-1) and consumption (up to 0.05 mgN2O-N L-1), resulted in the lowest remaining dissolved N2O (0.03 mgN2O-N L-1), stripping the minimum N2O gas (0.018 mgN2O-N L-1). Conversely, the carbon supply shortage, under low C/N ratios, increased N2O emission (0.040 mgN2O-N L-1), due to incomplete denitrification. High abundance of ammonia-oxidizing and low abundance of nitrite-oxidizing bacteria were found, corroborating the fact of partial nitrification. A denitrifying heterotrophic community, represented mainly by Pseudoxanthomonas, was predominant in the AGS. Overall, the AGS showed stable partial nitrification ability representing capital and operating cost savings. The SBR operation flexibility could be advantageous for controlling N2O emissions, and extending the anoxic phase would benefit complete denitrification in cases of low C/N influents.

Rapid formation of aniline-degrading aerobic granular sludge and investigation of its microbial community succession

Aniline is one of common by-products in several industries such as petroleum and chemical and its discharge attracts increasing concern in recent years. Aerobic granular sludge (AGS) technology is regarded as one of the most promising biological processes. However, there are some drawbacks such as long start-up especially when the system is fed with toxic pollutants (e.g., aromatic compounds). In this study, rapid formation of AGS for aniline biodegradation was investigated. The aerobic granules were successfully developed in a sequencing batch airlift reactor (SBAR) fed with aniline-containing wastewater within 15 days. The sludge volume index decreased from 58.47 to 30.31 mL g−1 after AGS was formed. It was also found that extracellular polymeric substances (EPS) especially protein was increased significantly during aerobic granulation. Besides, the average removal efficiencies of aniline and COD from day 3–15 (the period since early observation of pinpoint particles in the mixed liquor) were 99.93% and 90.59%, respectively. NH4+-N was also remarkably reduced in the SBAR. Through pyrosequencing analysis, Proteobacteria was the most abundant phylum during granulation. There were several genera responsible for aniline biodegradation and EPS secretion such as Pseudomonas was found to be predominant in the system. The rapid formation of AGS and high removal efficiency of aniline and COD in the present system might provide an alternative for treating industrial effluents with presence of aniline.