Aerobic Granular Sludge Technology Research Articles

A systemic evaluation of aerobic granular sludge among granulation, operation, storage, and reactivation processes in an SBR

As a biological promising wastewater treatment technology, aerobic granular sludge (AGS) technology had been widely studied in sequencing batch reactors (SBRs) for the decades. Presently, the whole processes of its granulation, long-term operation, storage, and reactivation have not been thoroughly evaluated, and also the relationships among microbial diversity, granular size, and characteristics were still not that clear. Hence, they were systematically evaluated in an AGS-SBR in this work. The results demonstrated that Proteobacteria and Bacteroidetes were the dominant phyla, Flavobacterium, Acinetobacter, Azoarcus, and Chryseobacterium were the core genera with discrepant abundances in diverse stages or granular size. Microbial immigration was significant in various stages due to microbial diversity had a line relationship with COD/MLVSS ratio (R2 = 0.367). However, microbial diversity had no line relationship with granular size (R2 = 0.001), indicating the microbial diversity in different-sized AGS was similar, although granular size had a line relationship with settleability (R2 = 0.978). Overall, compared to sludge traits (e.g., sludge size, settleability), COD/MLVSS played a key role on microbial evolution. This study revealed the relationships between granule characteristics and microbial community, and contributed to the future AGS-related studies.

Evaluation of leachate impact on domestic sewage co-treatment in aerobic granular sludge systems

Aerobic granular sludge (AGS) technology has been consolidated for sewage treatment. However, studies about the co-treatment of landfill leachate in municipal wastewater treatment plants (MWWTPs) with AGS systems are still incipient. The engineering and microbiological aspects of leachate co-treatment with sewage in step-feeding (R1) and conventional (R2) AGS systems were evaluated. Initially, synthetic sewage with a gradual increase in the organic load for granule formation was used (Periods I and II). Subsequently, co-treatment with leachate pre-treated by coagulation-flocculation was carried out with 5% (Period III) and 10% (Period IV) concentrations. Finally, methanol supplementation was conducted as an attempt to improve nutrients removal performance (Period V). Based on the results obtained, the co-treatment in granular reactors was feasible. The best conditions were obtained in R1 during Period V with methanol supplementation. Step-feeding produced a more compact and resistant aerobic granular biomass, resulting in better operational stability. Moreover, this strategy favored denitrification, especially during methanol supplementation, minimizing one of the main problems reported regarding leachate co-treatment in AGS systems. As a result, higher total nitrogen (TN) removals were obtained. At the end of the last period, in R1, Chemical Oxygen Dissolved (COD), TN, and Dissolved Organic Carbon (DOC) removals were 93%, and phosphorus removal was 54%, reaching values higher or similar to other AGS investigations with sewage, leachate, or co-treatment. Therefore, the strategies investigated unprecedentedly contribute to consolidating the domestic sewage co-treatment with leachate in AGS systems and providing a good perspective for other industrial wastewaters.

Anaerobic digestibility of aerobic granular sludge from continuous flow reactors: the role of granule size distribution.

There is an increasing interest in integrating aerobic granular sludge (AGS) technology into wastewater industries. Several projects are being performed to cultivate the aerobic granules for continuous flow reactors (AGS-CFR), while there is a scarcity of those projects that investigate the bio-energy recovery from AGS-CFR. This research was designed to examine the digestibility of AGS-CFR. Beyond that, it aimed at defining the role of the granule size on their digestibility. For this purpose, a series of bio-methane potential (BMP) tests have been run at mesophilic conditions. The results showed that AGS-CFR has a lower methane potential (107.43 ± 4.30 NmL/g VS) compared to activated sludge. This may be the result of the high sludge age (30 days) of AGS-CFR. Additionally, the results revealed that the average size of granules is among the main factors that reduce their digestibility, but it does not inhibit it. It was noticed that granules of size >250 μm have a significantly lower methane yield than the smaller ones. Kinetically, it was noticed that the kinetic models with two hydrolysis rates fit well with the methane curve of AGS-CFR. Overall, this work showed that the average size of AGS-CFR characterizes its biodegradability, which in turn defines its methane yield.

Potential of direct granulation and organic loading rate tolerance of aerobic granular sludge in ultra-hypersaline environment

Salt-tolerant aerobic granular sludge (SAGS) technology has shown potentials in the treatment of ultra-hypersaline high-strength organic wastewater. However, the long granulation period and salt-tolerance acclimation period are still bottlenecks that hinder SAGS applications. In this study, “one-step” development strategy was used to try to directly cultivate SAGS under 9% salinity, and the fastest cultivation process was obtained under such high salinity compared to the previous papers with the inoculum of municipal activated sludge without bioaugmentation. Briefly, the inoculated municipal activated sludge was almost discharged on Day 1–10, then fungal pellets appeared and it gradually transitioned to mature SAGS (particle size of ∼4156 μm and SVI30 of 57.8 mL/g) from Day 11 to Day 47 without fragmentation. Metagenomic revealed that fungus Fusarium played key roles in the transition process probably because it functioned as structural backbone. RRNPP and AHL-mediated systems might be the main QS regulation systems of bacteria. TOC and NH4+-N removal efficiencies maintained at ∼93.9% (after Day 11) and ∼68.5% (after Day 33), respectively. Subsequently, the influent organic loading rate (OLR) was stepwise increased from 1.8 to 11.7 kg COD/m3·d. It was found that SAGS could maintain intact structure and low SVI30 (< 55 mL/g) under 9% salinity and the OLR of 1.8–9.9 kg COD/m3·d with adjustment of air velocity. TOC and NH4+-N (TN) removal efficiencies could maintain at ∼95.4% (below OLR of 8.1 kg COD/m3·d) and ∼84.1% (below nitrogen loading rate of 0.40 kg N/m3·d) in ultra-hypersaline environment. Halomonas dominated the SAGS under 9% salinity and varied OLR. This study confirmed the feasibility of direct aerobic granulation in ultra-hypersaline environment and verified the upper OLR boundary of SAGS in ultra-hypersaline high-strength organic wastewater treatment.

Non-filamentous sludge bulking induced by exopolysaccharide variation in structure and properties during aerobic granulation

The forming mechanism of non-filamentous sludge bulking during aerobic granulation were investigated basing on three feeding strategies (R1 direct aeration after fast feeding, R2 anaerobic stirring after fast feeding and R3 anaerobic plug-flow slow feeding). Results showed that strong selection stress (shortening settling time) led to a sharp flocs washout and the subsequent increase of food to microorganisms (F/M) in R1 and R3 reactors, but not found in R2 due to the different strategies of feeding modes. With the increase of F/M, zeta potential and hydrophobicity of sludge surfaces significantly decreased and thus leading to an enhanced repulsive force and energy barriers for sludge aggregation. Particularly, when F/M exceeded 1.2 kgCOD/(kgMLSS·d), non-filamentous sludge bulking was ultimately triggered in R1 and R3. Further analysis showed that massive extracellular exopolysaccharide (PS) accumulated on the surfaces of non-filamentous bulking sludge due to the increased abundance of the microorganisms related to PS secretion during sludge bulking. In addition, significantly increased intracellular second messenger (c-di-GMP), a key substance regulating PS biosynthesis, was confirmed via its concentration determination as well as microbial function prediction analysis, which played a critical role in sludge bulking. Combing with the systematic detection from surface plasmon resonance system, rheometer and size-exclusion chromatography-multiangle laser light detection-refractive index system, higher molecular weight, compact conformation, higher viscosity and higher hydrophilicity was determined in sludge bulking PS relative to PS extracted from non-filamentous bulking sludge. Clearly, the changes of PS (content, structures and properties) driven by c-di-GMP are the dominant mechanism for the formation of non-filamentous sludge bulking during aerobic granulation. This work could provide theoretical support for successful start-up and application of aerobic granular sludge technology.

De novo granulation of sewage-borne microorganisms: A proof of concept on cultivating aerobic granular sludge without activated sludge and effective enhanced biological phosphorus removal

Long start-up periods for granulating activated sludge and concerns on granular stability are the bottlenecks reported during implementation of novel aerobic granular sludge (AGS) technology in municipal wastewater treatment plants. Here, de novo granulation of sewage-borne microorganisms without using activated sludge (AS) inoculum was investigated in bench-scale sequencing batch reactors (SBR). Data showed that formation of AGS from sewage-borne microorganisms was rapid and first granules appeared within one week. Granulation was indicated by appearance of biomass particles (size >0.12 mm), high biomass levels (∼8 g/L) and superior settling properties (SVI30 min: 30 mL/g). Granulation process involved distinct stages like formation of aggregates, retention of aggregates, and growth of millimetre sized granules. Simultaneous COD, nitrogen and phosphorous removal was established within 10 days of start-up in the SBR without using AS inoculum. However, phosphorus removal became stable after 50 days of start-up. Total nitrogen (TN) and total phosphorus (TP) removals of 92% and 70%, respectively, were achieved from real domestic wastewater. Furthermore, addition of granular activated carbon (GAC) had improved both granulation and biological nutrient removals. Interestingly, phosphorus removal became quite stable within 10 days of start-up in the SBR operated with GAC particles. TN and TP removals were found to be higher at >98% and >94%, respectively, in GAC-augmented SBR. Removal of ammonia and phosphorus were mediated by nitritation-denitritation and enhanced biological phosphorus removal (EBPR) pathways, respectively. The bacterial diversity of AGS was lower than that of sewage. Quantitative PCR indicated enrichment of ammonia oxidizing bacteria, denitrifying bacteria and polyphosphate accumulating organisms during granulation. De novo granulation of sewage-borne microorganisms is a promising approach for rapidly cultivating AGS and establishing biological nutrient removal in sewage treatment plants.

Review on Digestibility of Aerobic Granular Sludge

Full-scale wastewater treatment plants utilizing aerobic granular sludge technology are being built in many countries worldwide. As with all biological wastewater treatment plants, the produced waste biomass must be stabilized to protect the population, wildlife, and the environment. Digestion is usually used to break down the complex organics in the waste sludge; however, the digestibility of aerobic granular sludge still needs to be fully understood compared to the conventional activated sludge. This paper reviews the studies published on the digestibility of waste aerobic granular sludge to date. Studies comparing aerobic granular sludge and activated sludge in terms of composition, properties, and digestibility are highlighted. The impact of biological composition and physical properties on the digestibility of sludge is reviewed in terms of biomethane production and biodegradability. The effect of pre-treatment is also covered. Areas for future research are presented.

The applications of aerobic granular sludge for leachate treatment: A review

The vast majority of the world’s daily municipal solid waste (MSW) is dumped in landfills without being treated first. Leachate generated from these landfills is defined as dark-coloured, highly contaminated wastewater that has become a problem for the environment, posing a threat to soil, surface water, and groundwater quality and having a detrimental influence on human health. Thus, leachate treatment is strongly recommended prior to final discharge. The application of aerobic granular sludge (AGS) technology for wastewater treatment has increased in recent years, especially for industrial wastewater such as leachate. Due to its significant advantages over conventional activated sludge technology, such as denser structure, improved settleability, faster effluent separation, higher biomass content, and improved shock loading resistance, AGS is a viable option for leachate treatment. This article provides detailed discussions of the leachate characteristics along with the available treatment systems, focusing on the AGS system. The efficacy of AGS technology in the treatment of landfill leachate was elucidated by highlighting its benefits, governing factors affecting its performance, and limitations. Based on the latest literature, this paper attempts to identify the research gaps and obstacles in using AGS technology for landfill leachate treatment.

Coupling high-rate activated sludge process with aerobic granular sludge process for sustainable municipal wastewater treatment

Achieving a neutral/positive energy balance without compromising discharge standards is one of the main goals of wastewater treatment plants (WWTPs) in terms of sustainability. Aerobic granular sludge (AGS) technology promises high treatment performance with low energy and footprint requirement. In this study, high-rate activated sludge (HRAS) process was coupled to AGS process as an energy-efficient pre-treatment option in order to increase energy recovery from municipal wastewater and decrease the particulate matter load of AGS process. Three different feeding strategies were applied throughout the study. AGS system was fed with raw municipal wastewater, with the effluent of HRAS process, and with the mixture of the effluent of HRAS process and raw municipal wastewater at Stage 1, Stage 2 and Stage 3, respectively. Total suspended solids (TSS), chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and total phosphorus (TP) concentrations in the effluent were less than 10 mg/L, 60 mg/L, 0.4 mg/L, and 1.3 mg/L respectively at all stages. Fluctuations were observed in the denitrification performance due to changes in the influent COD/total nitrogen (TN) ratio. This study showed that coupling HRAS process with AGS process by feeding the AGS process with the mixture of HRAS process effluent and raw municipal wastewater could be an appropriate option for both increasing the energy recovery potential of WWTPs and enabling high effluent quality.

Effect of flow regime on mass transfer diffusion and stability of aerobic granular sludge (AGS) in view of interfacial thermodynamic

Aerobic granular sludge (AGS) technology has been widely studied as “The Next Generation Wastewater Treatment technology”. The effect of hydraulic conditions on the structural stability of AGS has been widely studied. However, the function of flow regime on the AGS stability, especially dissolved oxygen (DO) mass transfer, is still unknown. In this study, we used the Reynolds number (Re) to quantify the flow regime and selected different stages of AGS as experimental subjects. Results showed that the relatively suitable Re (Re = 150) could create lower DO mass transfer limitation (Lc = 27.4 μm) and increase protein (PN) contents and the abundance of hydrophobic functional groups in AGS. At this condition (Re = 150), the interfacial Gibbs free energy of sludge-water (ΔGLSa) was at a lower state (−129.75 ± 2.15 mJ·m−2), which favored the stability of AGS. Principal component analysis (PCA) and correlation analysis indicated that the response of ΔGLSa was affected by Lc, PN, and hydrophobic groups. In addition, results obtained for unstable AGS further verified that suitable Re regulates the structural stability of AGS. This study deepens the understanding of Re as an important hydraulic parameter for structural stability of AGS, which is also of great significance for energy saving of sequential batch reactors (SBRs) with agitation in practical engineering.

A Review on Development of Aerobic Granular Sludge Membrane Bioreactor for the Industrial Effluent Treatment

The technology of aerobic granular sludge and Membrane Bioreactor (MBR) were combined to develop an Aerobic Granular Sludge Membrane Bioreactor (AGMBR). Biomass content is high, higher the retention time of biomass, and the capacity of phosphorus and nitrogen removal has been shown by aerobic granular sludge; now a day it is a promising option for wastewater treatment. Reclaiming wastewater one of the favourite choices is Membrane technology in removing organic and inorganic impurities they have recognised as moderately operative with biological entities removal from wastewater. Consequently, the wastewater treatment membrane bioreactor and aerobic granular sludge technology are dynamic and new trending cost-efficient technologies. This article aims to review all the potential applications and principles in AGMBR technology.

Valorization of full-scale waste aerobic granular sludge for biogas production and the characteristics of the digestate.

Despite the dynamic development of aerobic granular sludge (AGS) technology in wastewater treatment, there is limited data on how the different properties of AGS and activated sludge (AS) translate into differences in waste sludge management. Waste sludge generated in both AGS and AS technology is the biggest waste stream generated in wastewater treatment plants (WWTPs). This study aimed to assess biogas production from waste AGS from a full-scale system. Additionally, the properties of the digestate were investigated in terms of its management in line with the assumptions of a circular economy. Both aspects are important because the characteristics of AGS differ from those of AS. Its dense, extracellular-polymer-rich granule structure makes the susceptibility of AGS to anaerobic stabilization lower than that of AS. Given the advantages of AGS for sustainable wastewater treatment and its increasing popularity, waste AGS management will pose a serious challenge for WWTP operators. Therefore, AGS from a full-scale municipal WWTP was valorized for biogas production by increasing the accessibility of the organics in the sludge by homogenization or ultrasound pretreatment. Ultrasound pretreatment released about an order of magnitude more organics from the biomass than homogenization and significantly improved the production of methane-rich biogas (455L/kg VS, about 66% of CH4). The digestion time of pretreated AGS was reduced by 25% in comparison with that of untreated AGS making anaerobic digestion of AGS a feasible solution for sludge management. The AGS digestate was rich in Ca (77.0g/kg TS), Mg (10.9g/kg TS), N (35.1g/kg TS) and P (32.4g/kg TS), whereas its heavy metal levels and biochemical methane potential were low. AGS digestate is not only environmentally safe, but it can serve as a rich source of organics and elements essential for soil fertility and stability.

Evaluation of an aerobic granular sludge reactor with biological filtration (AGS-BF reactor) in municipal wastewater treatment: A new configuration

Aerobic Granular Sludge (AGS) technology is considered promising, but many aspects are being studied and developed to increase system reliability. In this regard, the research assessed the performance of a conventional AGS (R1) sequencing batch reactor (SBR) system compared to a new AGS design through the inclusion of a biological filter (BF) compartment in the upper zone (R2), treating municipal wastewater. BF insertion in R2 improved total nitrogen removal (> 85 %) and effluent clarification. Effluent total suspended solids (TSS) average values of 44.1 and 17.1 mg/L were found for R1 and R2, respectively. Sludge production was evaluated, and the yield coefficient (Y) and sludge concentration were different in the two reactors. The new system (R2) can be an interesting alternative to improve some aspects of conventional AGS reactors, such as denitrification and nitrite accumulation, effluent TSS concentration, and system reliability increase during periods of instability and granules breakage.

Biological nitrate removal from a drinking water supply with an aerobic granular sludge technology: An environmental and economic assessment

Nitrate pollution of groundwater, mainly from agricultural applications, is a widespread water quality problem in many countries. The aim of this study was to identify and compare the main environmental impacts and costs associated with removing nitrate from groundwater under a conventional treatment technology and a technology based on a biological treatment process (denitrification using aerobic granular sludge). The analysis focused on the first real-world experience of an industrial-scale implementation of said technology, applied to the drinking water supply in a small town in Spain. The methods selected for the environmental and economic evaluations were life cycle assessment and cost-effectiveness analysis, respectively. The drinking water treatment technologies under study were a conventional reverse osmosis plant and a plant using a biological treatment called ecogranularwater. The analysis of these two drinking water production processes was divided into two phases: structure and water treatment. This study demonstrates that the biological technology produces drinking water in a more environmentally-friendly, cost-effective way, and with lower energy costs. The greatest environmental impacts from the reverse osmosis technology occurred in the water treatment phase due to the high levels of energy consumption (up to 1.68 kWh m−3 higher than with the ecogranularwater technology). In the structure phase, the biological technology contributed more than reverse osmosis in all impact categories, with values ranging from 91% in freshwater ecotoxicity to 98% in stratospheric ozone depletion. The cost of producing 1 m3 of water was estimated as 43% lower with the ecogranularwater technology compared to reverse osmosis. In order to further lessen the environmental impact of the biological technology, efforts should be focused on reducing and optimizing energy use and making improvements to the design of the structure. This biological technology proved a good alternative for small and medium-sized municipalities with problems of nitrate-polluted water. The decision to apply technological innovations in drinking water treatments to remove nitrates can be supported by environmental and economic studies.

Comparison and Optimization of Continuous Flow Reactors for Aerobic Granule Sludge Cultivation from the Perspective of Hydrodynamic Behavior.

Improving treatment efficiency and reducing investment and operating costs make aerobic granular sludge technology (AGS) a promising technology for treating aquaculture wastewater. The development of continuous flow reactors (CFRs) has become a new direction in the research of AGS. This study clarifies the granulation effect, hydrodynamic behavior and particle separation of three different CFRs (R1 to R3). The established CFD model was able to explain the hydrodynamic behavior in all three CFRs; in particular, R3 performed the best from the perspective of hydrodynamic behavior due to its abundant turbulence. In addition, the optimal baffle distance and baffle angle of R3 were simulated to be 40 mm and 60°, respectively, due to them providing the best turbulent flow and particle separation effect. However, an overlarge baffle angle could weaken the turbulent pattern in the reactor. The retention time distribution further confirmed the reasonability of these optimal parameters with the highest effective volume ratio of 0.82. In short, this study gives an instruction for exploring the rapid formation mechanism of AGS in a CFR to promote its engineering application.

Landfill leachate biological treatment: perspective for the aerobic granular sludge technology.

Landfill leachates are high-strength complex mixtures containing dissolved organic matter, ammonia, heavy metals, and sulfur species, among others. The problem of leachate treatment has subsisted for some time, but an efficient and cost-effective universal solution capable of ensuring environmental resources protection has not been found. Aerobic granular sludge (AGS) has been considered a promising technology for biological wastewater treatment in recent years. Granules' layered structure, with an aerobic outer layer and an anaerobic/anoxic core, enables the presence of diverse microbial populations without the need for support media, allowing simultaneous removal of different pollutants in a single unit. Besides, its strong and compact arrangement provides higher tolerance to toxic pollutants and the ability to withstand large load fluctuations. Furthermore, its good that settling properties allow high biomass retention and better sludge separation. Nevertheless, AGS-related research has focused on carbon-nitrogen-phosphorus removal, mainly from sanitary sewage. This review aims to summarize and analyze the main findings and problems reported in the literature regarding AGS application to landfill leachate treatment and identify the knowledge gaps for future applications.

Laboratory-scale study of a biodegradable microplastic polylactic acid stabilizing aerobic granular sludge system

The effects of microplastics on aerobic granular sludge technology are an emerging issue, although the impact of degradable microplastics (DMPs) on the aerobic granular system is still unexplored. In this study, degradable microplastic polylactic acid (DMP-PLA) was added at three concentrations (5, 15, 40 mg/L), which strengthened the granular stability and consequently stabilized pollutant removal compared to the control (without DMP-PLA). The experiment showed that adding DMP-PLA made cells secrete more extracellular polymeric substances [64.8 mg/g MLVSS (mixed liquor suspended solids)], particularly retaining β-D-glucopyranose polysaccharides in experimental group. In addition, abundant hydrogen bonds were also maintained. The reactor under the stress of DMP-PLA exhibited high pollutant removal efficiency (COD>88%, TP>91%, TIN>86%), indicating high performance of the microbes. Microbial analysis at the genus level indicated that Defuviicoccus and Candidatus_Competibacter were dominant after DMP-PLA addition, which identified denitrifying glycogen-accumulating organisms as beneficial for nitrogenous compound removal. Redundancy analysis showed that the abundance of Candidatus_Competibacter was positively related to the addition of DMP-PLA. This study demonstrated that DMP-PLA was feasibly employed in the aerobic granular water treatment process, and presents a new method to optimize the stability and extracellular secretion of the microbial community.

Technical Note 6 - Applicability aerobic granular sludge technology in the Brazilian context

Aerobic granular sludge (AGS) is currently considered one of the most promising technologies for biological wastewater treatment. This fact is mainly due to the combined removal of organic matter and nutrients in the same reactor, eliminating secondary settlers, making it one of the most compact technology on the market. However, there are several reports of problems, including: (i) instability of the granular biomass; (ii) long start-up periods due to slow granule formation, especially when using sewage with a low concentration of organic matter; (iii) accumulation of nitrite in the final effluent; (iv) high demand for automation; and (v) operational process not yet fully established. Thus, despite considerable advances in sewage treatment with AGS systems and the increase in the number of full-scale sewage treatment plants (STPs) in several countries around the world, an integrated assessment of its application in Brazil is necessary. This technical note aims to present the state-of-the-art of AGS system, as well as to bring up a more in-depth discussion, in the Brazilian context, on the need or not to adopt it, and in what situations it should be implemented to replace other sewage treatment technologies with greater mastery of national engineering and usual lower investment and operating costs.

Biopolymers in Aerobic Granular Sludge—Their Role in Wastewater Treatment and Possibilities of Re-Use in Line with Circular Economy

Aerobic granular sludge (AGS) technology for wastewater treatment ensures better quality effluent and higher process sustainability than wastewater treatment systems based on activated sludge. One of the reasons for the better operational results of AGS systems is the high content of extracellular polymers (EPS) in the granule structures. EPS produced during granulation have a very complex composition with a predo minance of polysaccharides and proteins, and one of the main components, alginate, may have a wide variety of practical applications. This review summarizes up-to-date information on the composition of EPS in AGS, the manner in which their production and composition are affected by the operational parameters of wastewater treatment, and the effects of EPS in biomass on wastewater treatment and sludge management. Additionally, the possibility of polymer recovery from AGS is presented together with information regarding potential applications based on the newest findings. Re-use of AGS-derived polymers will increase the sustainability of wastewater treatment processes by making them more economical and reducing the amount of sludge that requires management.

Post-treatment of swine wastewater using aerobic granular sludge: Granulation, microbiota development, and performance

We studied the applicability of aerobic granular sludge (AGS) technology in association with upflow anaerobic sludge blanket (UASB) reactors for swine wastewater (SWW) treatment. Granule formation, long-term operational evaluation, and the system performance for simultaneous C, N, and P removals were assessed. Finally, the AGS microbial changes were evaluated by metagenomic analysis. Aerobic granulation occurred after 54 days of operation, and 81% of the granules had a diameter above 1.0 mm after 96 days of the experiment. The granules formed were spherical, had cohesive structure and good sedimentation capacity, although they were classified as non-resistant. After the sludge granulation (steady-state), high COD, BOD and ammonia removals were found, although the removals of TN and TP were considered moderate. Nonetheless, overall, a good operational stability was achieved. The metagenomic analysis revealed that the microbial groups suffered great influence from the substrate characteristics, but they are commonly found in AGS systems.