Performance Of Aerobic Granular Sludge Research Articles

Dewatering performance of aerobic granular sludge under centrifugal with different sludge conditioning agent.

The aerobic granular sludge(AGS) technology draw scientific researchers attention, and more and more scientific research focuses on it, due to its superior advantages, such as good settling performance, high biological phase, high toxicity resistance and multiple biological effects. With the rapid development of AGS technology, a considerable amount of residual AGS will be produced, and dehydration is the biggest bottleneck of sludge reduction. This study investigated the dewatering process and method of residual AGS cultured by continuous flow experiment. Experiments were conducted using centrifugal dewatering technology with a dosing scheme to analyze the granular sludge dewatering process, and investigate the release process of EPS component in AGS dewatering. Our results implied the specific resistance of AGS has a very low value ((1.82 ± 0.03) × 109 m/kg) and it was not obvious for the conditioning effect of chemical conditioner on AGS dewatering. However, the moisture content can be reduced to 63.5% after dewatering with the presence of inorganic substances. The addition of drinking water treatment plant sludge (Alum sludge) can improve the efficiency of the dewatering of AGS. A possible dewatering process of AGS dewatering was proposed which was divided into two stages: First, a considerable amount of free water in the sludge was quickly removed under the action of gravity without pressure filtration. Second, the bound water release required cooperation between applying centrifugal or pressing force to grind granular cells and separate protein-like substances with the inorganic matter inside the granular sludge. The possible mechanism of AGS dewatering and hypothesis dewatering process are useful to optimize the AGS dewatering process.

Rapid Formation and Performance of Aerobic Granular Sludge Driven by a Sodium Alginate Nucleus under Different Organic Loading Rates and C/N Ratios

The use of aerobic granular sludge (AGS) for wastewater treatment has emerged as a promising biotechnology. A sodium alginate nucleus (SAN) incorporated into the AGS system can enhance aerobic granulation. Two important parameters influencing AGS formation and stability are the organic loading rate (OLR) and C/N ratio. In this study, AGS containing the SAN was cultivated under different OLR and C/N ratios. Through morphological analysis, physicochemical properties, and water quality analysis, the effects of the OLR and C/N ratio on the rapid formation and performance of AGS containing the SAN were investigated. The results showed that the most suitable OLR and C/N ratio in the SAN system were 1.4–2.4 kg/(m3∙d) and 10–15, respectively. A recovery experiment of sodium alginate (SA) showed that the group that formed AGS generally had a higher recovery efficiency compared with the group that did not form granular sludge. This work explored the suitable granulation conditions of AGS containing the SAN, and the results provide a theoretical basis for future practical applications. The recycling of SA as presented in this study may broaden the application prospects of SA.

Impact of stepwisely reducing settling time on the formation and performance of aerobic granular sludge

The impact of gradually reducing the settling time strategy on the formation, performance, and microbial succession of aerobic granular sludge (AGS) was investigated in a sequencing batch reactor (SBR). The results showed that the short settling time accelerated the granulation of AGS and the granulation was completed within 35 d. When the settling time was 10 min, the granular sludge had good settling performance and significant biological activity, and the average particle size and integrity coefficient increased to 1.017 mm and 93.3 %. The shortening of settling time stimulated bacteria to secrete more extracellular polymeric substances (EPS). Three-dimensional fluorescence spectrum analysis showed that aromatic proteins had high fluorescence intensity. According to the analysis of high-throughput sequencing, Rhodanobacter and Klebsiella were the dominant bacteria, and carbohydrate metabolism and amino acid metabolism were significantly enhanced, which may play an important role in maintaining the stability of AGS.

Effect of different feeding strategies on performance of aerobic granular sludge: From perspective of extracellular polymeric substances and microorganisms

Long-term structural stability of aerobic granular sludge (AGS) is a major challenge in AGS biotechnology. This work investigated variations in the sludge performance, structural stability, and intrinsic mechanisms of AGS under three feeding strategies (R1 direct aeration after fast feeding, R2 anaerobic stirring after fast feeding and R3 anaerobic plug-flow slow feeding). The AGS sequencing batch reactor used in this study was in stable operation with biomass of 6–10 gMLSS/L and a hydraulic retention time of 4 h. The results showed that the best sludge performance was demonstrated in R3, followed by R2 and R1. These differences were caused by extracellular polymeric substances (EPS) and microbial communities. The excellent sludge performance in R3 was attributed to the high hydrophobicity in the EPS as well as the gel properties due to the high hydrogen bonding content in the exopolysaccharide (PS). Similarly, the gel properties formed by the high hydrogen bonding content maintain the sludge stability in R1. Slow-growing dominant bacteria were enriched in the AGS of R2 and R3 with alternating anaerobic/aerobic operation modes, resulting in outstanding sludge performance. In contrast, high abundance of the filamentous bacteria Neomegalonema was enriched in the AGS of R1 without an anaerobic phase, resulting in relatively poor sludge stability. Variations in EPS characteristics and microbial community under the different feeding strategies were the main mechanisms responsible for the long-term operation of AGS. This study could provide a theoretical foundation and technical assistance for the sustainable operation of AGS reactors.

Preparation of hydroxyapatite (HAP) from waste eggshells for enhancing the granulation and treatment performance of aerobic granular sludge: Enhancement effects and mechanism insights

Hydroxyapatite (HAP), an inorganic mineral that is generated in situ within the core of aerobic granular sludge (AGS), plays a pivotal role in both the granulation process and system stability. Due to the slow precipitation rate of HAP, waste eggshells were utilized as a readily available source for preparing HAP by using the conventional hydrothermal (C-HAP) and microwave hydrothermal (M-HAP) methods. Subsequently, the prepared HAP was employed to promote AGS formation. Results showed that the prepared HAP exhibits superior morphology, crystallinity, functional groups, and specific surface area compared to the commercial grade HAP, whereby M-HAP outperforms C-HAP for functional groups and specific surface area. The addition of 0.5 g/L HAP facilitated the granulation process (within 20 days), leading to the development of structurally compact AGS, which was attributed to the microbial attachment onto HAP particles. Moreover, the presence of HAP greatly improved the nutrient removal efficiency (80.8 % of TN and 82.4 % of PO43−-P), most likely due to the enrichment of denitrifying and phosphorus-accumulating microorganisms (e.g., Candidatus_Competibacter and Flavobacterium). Further analysis revealed that an increase in the relative abundance of denitrification-related genes (e.g., narG and nirK) was responsible for the intrinsic mechanism behind the enhanced nitrogen removal, while phosphorus removal occurred through biomineralization and abiotic precipitation pathways. Overall, the present study highlights the potential of utilizing waste eggshells to enhance AGS systems for wastewater treatment, thus realizing a circular economy approach.

Aerobic granular sludge development using diatomite for low-strength wastewater treatment

This paper presents an assessment of the start-up performance of aerobic granular sludge (AGS) for the treatment of low-strength (chemical oxygen demand, COD < 200mg/L) domestic wastewater by the application of a diatomite carrier. The feasibility was evaluated in terms of the start-up period and stability of the aerobic granules as well as COD and phosphate removal efficiencies. A single pilot-scale sequencing batch reactor (SBR) was used and operated separately for the control granulation and granulation with diatomite. Complete granulation (granulation rate ≥ 90%) was achieved within 20days for the case of diatomite with an average influent COD concentration of 184mg/L. In comparison, control granulation required 85days to accomplish the same feat with a higher average influent COD concentration (253mg/L). The presence of diatomite solidifies the core of the granules and enhances physical stability. AGS with diatomite recorded the strength and sludge volume index of 18 IC and 53mL/g suspended solids (SS) which is superior to control AGS without diatomite (19.3 IC, 81mL/g SS). Quick start-up and achievement of stable granules lead to an efficient COD (89%) and phosphate removal (74%) in 50days of bioreactor operation. Interestingly, this study revealed that diatomite has some special mechanism in enhancing the removal of both COD and phosphate. Also, diatomite has a significant influence on microbial diversity. The result of this research implies that the advanced development of granular sludge by using diatomite can provide promising low-strength wastewater treatment.

Processo de granulação aeróbia aplicado ao tratamento de lixiviado de aterro sanitário

ABSTRACT The performance of aerobic granular sludge (AGS) process was evaluated for real leachate treatment, assessing the system capacity to form granules, biomass characteristics, and other engineering and microbiological aspects. Two sequencing batch reactors were operated with a leachate concentration of 25% (R1) and 50% (R2), with an 8-h cycle. The time required for granulation was greater than 80 days in both reactors, and solids loss was significant. The sedimentation rate was also outside the typical values for AGS reactors, with a sludge volumetric index in 30 min (SVI30) greater than 70 mL/g. Although the granules produced in R2 were more compact (200 μm), they were more resistant. Proteobacteria and Rhodobacteraceae were the phyla and the most abundant family in R2. The phylum Planctomycetota and the family Pirellulaceae were the most abundant in R1. Settling time reduction, feeding phase increase, and increased dissolved oxygen (DO) levels were fundamental strategies to improve reactors’ performance and stability.

The compensation of micro-carriers on hydraulic shear force during aerobic sludge granulation

Hydraulic shear force (HSF) is of great importance in granulation and treatment performance of aerobic granular sludge (AGS) process. High HSF has been shown to be conductive to granulation, which could be obtained by high superficial gas velocity (SGV). Micro-carriers could influence the flow regime in reactors. Thus, AGS system with micro-carriers addition could obtain higher HSF. In this paper, impact of SGV on granulation under micro-carriers enhancement was comparatively evaluated by keeping SGV at 0.6 cm/s (R1) and 1.2 cm/s (R2), respectively. Results showed that sludge granulation and nutrient removal performance was greatly enhanced by micro-carriers under low SGV. However, microorganisms were suppressed inside micro-carriers under high SGV, although the extracellular polymeric substances (EPS) contents in R2 were higher. The gas holdup in R2 was 1.32 times higher than traditional AGS system, resulting in excessive collision and velocity field difference. Overall, addition of micro-carriers could compensate the HSF under low SGV, which is of great significant in reducing the energy consumption of AGS system.

Tolerance and recovery of aerobic granular sludge: Impact of perfluorooctanoic acid

The widespread use of perfluorooctanoic acid (PFOA) has rendered its frequent detection in wastewater. The tolerance and recovery of aerobic granular sludge (AGS) to PFOA were investigated in short-term (Phase Ⅰ) and long-term (Phase Ⅱ, operation strategy adjustment: shortening aeration time and prolonging anaerobic and anoxic time). Results showed that in Phase Ⅰ, the performance of R2 reactor (0.05 mg/L PFOA) was slightly negatively affected, while 0.5 and 2.0 mg/L PFOA in R3 and R4 reactors significantly damaged the key enzyme activities of AGS, leading to deterioration of nutrients removal. TN and TP removal efficiencies decreased correspondingly from 79.32% to 78.41% on day 0 to 74.66% and 74.14% in R2 and 68.57% and 67.80% in R3 and 56.94% and 57.47% in R4 on day 7, respectively. In Phase Ⅱ, the key enzyme activities of AGS were obviously renewed dependent on operation strategy adjustment and AGS self-regulation. The performance of AGS in R2 (continuously dosing 0.05 mg/L PFOA) and R4 (stopping dosing PFOA) recovered quite good, while the long-term adverse effects of 0.5 mg/L PFOA on AGS in R3 were still more difficult to be alleviated. In end of Phase Ⅱ (69–97days), the average TN and TP removal efficiencies correspondingly reached 83.31% and 82.09% in R1 (control), 80.67% and 79.62% in R2, 76.38% and 74.27% in R3, and 79.01% and 78.25% in R4, respectively. Further analysis revealed that the effect of PFOA on proteins in extracellular polymeric substances (EPS) was greater than that on polysaccharides. Specifically, short-term dosage of PFOA mainly affected loosely bound EPS, while long-term dosage of PFOA affected tightly bound EPS. Although AGS is severely inhibited by short exposure to 2.0 mg/L PFOA (in R4), after the operation strategy adjustment, EPS content decreased, nutrient and oxygen transport channels of AGS were re-established, which contributed to the recovery of AGS.

Physical Characteristics and Removal Performance of Aerobic Granular Sludge in Biological Treatment of Domestic Wastewater

This study aims to demonstrate the formation of aerobic granular sludge (AGS) for domestic wastewater treatment applications in hot climate and low humidity conditions (e.g. Saudi Arabia) as well as to characterize and examine the bioreactor performance in removing organic matter and nutrients. Based on the study, aerobic granular sludge (seeded with domestic activated sludge from Al-Madina Wastewater Treatment Plant and fed with synthetic wastewater with an organic loading rate (OLR) of 1.6 kg COD m−3d−1) was successfully cultivated with average size ranging from 1 to 2 mm in a laboratory scale sequencing batch reactor (SBR) system operated at 30 days with a complete cycle time of 3 h and at the working temperature of 30 ± 1°C. Results also showed that the aerobic granular sludge formed had excellent settling ability (settling velocity, 38.98 mh−1 and MLSS, 7.8 gL−1) and great removal performance of COD and nutrient (i.e. more than 90%).

Step-feeding in aerobic/anoxic cycles enhanced the performance of aerobic granular sludge (AGS) systems treating effluents with low C:N ratios

Aerobic granular sludge (AGS) systems treating effluents with a C:N:P ratio similar to real old landfill leachate were evaluated on simultaneous C, N and P removals, and to reduce the main problems encountered, such as nitrite accumulation, biomass loss, and granule disintegration. Therefore, six sequential batch reactors (SBR) were operated with different anaerobic (A), anoxic (An), and aerobic (O) configurations: A/O (R1 and R2), O/An with conventional feeding and well-defined anoxic phase (R3), O/An with step-feeding and well-defined anoxic phase (R4), and O/An (R5 and R6). The O/An with step-feeding reactor (R4) had the highest biomass retention/settleability (SVI30 < 50 mL/g), the best nitrification rates (99%), and chemical oxygen demand (COD) (97%), total nitrogen (91%) and total phosphorous (55%) removals. Furthermore, there was no nitrite accumulation, and granules’ disintegration was insignificant. The most abundant phylum in the reactors O/An was Planctomycetota, composed mainly of organisms from the Pirellulaceae and Legionellaceae families. In these reactors, the abundance of phosphorus-accumulating organisms (PAOs) and denitrifying bacteria were similar, while the abundance of glycogen-accumulating organisms was much higher than PAOs. Therefore, the type of cycle directly influences performance, granule characteristics, and system stability, being important for future investigations applying the AGS technology to leachate treatment.

Assessing the effect of SiO2 and TiO2 nanoparticles on granule stability and microbial community shift in aerobic granular sludge process

The widely used SiO2 and TiO2 nanoparticles (NPs) can accumulate in industrial wastewaters, thereby posing challenge to biological wastewater treatment processes. In this work, the performance of aerobic granular sludge (AGS) reactors fed with wastewater containing 50 mg L−1 SiO2 and TiO2 NPs were investigated. The results showed that the granules could resist the NPs in wastewater (no disintegration of granules was observed). SiO2 NPs had a negative effect on the settleability of granules, with the SVI30 increased by 64.5% and protein secretion decreased by 29.9%. To the contrary, the settleability of granules was improved in the presence of TiO2 NPs due to the increase of the protein secretion. Possibly because of the compact and layered structure of granules, in the presence of both types of NPs, no obvious reduction of the overall removal efficiency of organics was found, and nanoparticle-resistant strains were enriched. The overall nitrification and denitrification efficiencies were hardly affected by SiO2 NPs while significantly inhibited by TiO2 NPs. Some functional genera, such as Hyphomicrobium and Acidovorax, showed growth inhibition with TiO2 NPs, which might be responsible for the reduction of nitrification and denitrification efficiencies.

Effect of magnetic field intensity on aerobic granulation and partial nitrification-denitrification performance

Magnetic field, acknowledged as a sustainable approach, is a promising method to improve the formation, stability and treatment performance of aerobic granular sludge (AGS). In this study, partial nitrification-denitrification was achieved in three AGS sequencing batch reactors (SBRs), and the effect of magnetic field intensity on AGS formation and partial nitrification-denitrification performance were investigated. 50 mT magnetic field could accelerate complete granulation time from 45 d (0 mT) to 30 d (50 mT) by promoting the settling ability of AGS and stimulating the secretion of extracellular polymeric substances (EPS). With 50 mT magnetic field, partial nitrification-denitrification in AGS was enhanced, and the removal efficiency of chemical oxygen demand (COD), NH4+-N and TN increased by 7.6%, 26.2% and 41.5% comparing with the control (0 mT). Magnetic field balanced the dominant genera Thauera, Flavobacterium, Chryseobacterium and Meganema, which further enhanced the aerobic granulation and partial nitrification-denitrification in AGS. Thus, the application of magnetic field is reliable for accelerating aerobic granulation and enhancing partial nitrification-denitrification process.

Enhanced simultaneous partial nitrification and denitrification performance of aerobic granular sludge via tapered aeration in sequencing batch reactor for treating low strength and low COD/TN ratio municipal wastewater

The aerobic granular sludge simultaneous partial nitrification, denitrification and phosphorus removal (AGS-SPNDPR) process was carried out via tapered aeration in sequencing batch reactor (SBR) for treating low strength and low COD/TN ratio municipal wastewater. The results showed that aerobic granular sludge was successfully cultivated with good sedimentation performance when treating the municipal wastewater. Meanwhile, the median granule size increased to 270 (R1) and 257 (R2) μm on day 80. The excellent removal performance of COD (92%) and NH4+-N (95%) were achieved under different aeration modes, while the higher TN removal efficiency (76%) was achieved by tapered aeration. The accumulation of NO2−-N in R2 indicated that the tapered aeration was beneficial to achieve simultaneously partial nitrification and denitrification. Meanwhile, the high-efficiency phosphorus (95%) removal was realized via additional carbon source, and SPNDPR process was formed under tapered aeration. The bacterial community analysis indicated denitrifying glycogen-accumulating organisms (DGAOs) Candidatus_Competibacter and ammonia-oxidizing bacteria (AOB) Nitrosomonas were more effectively enriched via tapered aeration, while phosphorus-accumulating organisms (PAOs) Candidatus_Accumulibacter were effectively enriched under additional organic carbon. AOB, denitrifying bacteria and PAOs were simultaneously enriched by tapered aeration and additional carbon source, which was beneficial to nutrients removal. This study might be conducive to the application of AGS-SPNDPR system for treating low strength and low COD/TN ratio municipal wastewater under tapered aeration.

Response of aerobic sludge to AHL-mediated QS: Granulation, simultaneous nitrogen and phosphorus removal performance

The effects of different species and concentrations’ signal molecules on aerobic activated sludge system were investigated through batch experiments. Results showed that the fastest NH4+-N oxidization rate and the most extracellular polymeric substances (EPS) secretion were obtained by adding 5 nmol/L N-hexanoyl-l-homoserine lactone (C6-HSL) into the aerobic activated sludge. Further study investigated the correlation among N-acyl-homoserine lactones-mediated quorum sensing (AHLs-mediated QS), nutrient removal performances and microbial communities with the long-term addition of 5 nmol/L C6-HSL. It was found that C6-HSL-manipulation could enhance the stability and optimize the decontamination performance of aerobic granular sludge (AGS) system. Microbial compositions considerably shifted with long-term C6-HSL-manipulation. Exogenous C6-HSL-manipulation inhibited quorum quenching-related (QQ-related) activities and enhanced QS-related activities during the stable period. The proposed C6-HSL-manipulation might be a potential technology to inhibit the growth of harmful bacteria in AGS, which could provide a theoretical foundation for the realization of more stable biological wastewater treatments.

Microplastics affect the ammonia oxidation performance of aerobic granular sludge and enrich the intracellular and extracellular antibiotic resistance genes

Microplastics (MPs) and antibiotic resistance genes (ARGs), as emerging pollutants, are frequently detected in wastewater treatment plants, and their threats to the environment have received extensive attentions. However, the effects of MPs on the nitrification of aerobic granular sludge (AGS) and the spread patterns of intracellular and extracellular ARGs (iARGs and eARGs) in AGS were still unknown. In this study, the responses of AGS to the exposure of 1, 10 and 100 mg/L of typical MPs (polyvinyl chloride (PVC), polyamide (PA), polystyrene (PS) and polyethylene (PE)) and tetracycline were focused on in 3 L nitrifying sequencing batch reactors. 10 mg/L MPs decreased the nitrification function, but nitrification could recover. Furthermore, MPs inhibited ammonia-oxidizing bacteria and enriched nitrite-oxidizing bacteria, leading partial nitrification to losing stability. PVC, PA and PS stimulated the secretion of extracellular polymeric substances and reactive oxygen species. PE had less negative effect on AGS than PVC, PA and PS. The abundances of iARGs and eARGs (tetW, tetE and intI1) increased significantly and the intracellular and extracellular microbial communities obviously shifted in AGS system under MPs stress. Potential pathogenic bacteria might be the common hosts of iARGs and eARGs in AGS system and were enriched in AGS and MPs biofilms.

The performance of aerobic granular sludge for simulated swine wastewater treatment and the removal mechanism of tetracycline

In this study, aerobic granular sludge (AGS) cultivated in a sequencing batch reactor (SBR) was employed to investigate its ability on the decontamination of tetracycline (TC) from swine wastewater (SWW). The removal mechanism of TC by AGS was studied. Results showed that the AGS process could effectively remove chemical oxygen demand (COD), ammonium nitrogen (NH+ 4-N), total phosphorus (TP), and TC during operation. The removal of TC by AGS was mainly due to adsorption and biodegradation, and the contribution rate of biodegradation increased after AGS adaptation to TC. Twenty-two by-products were detected during biodegradation of TC, and accordingly the degradation pathway of TC was speculated. Compared to the control reactor, the microbe diversity in different levels of classification was richer in the TC fed reactor according to the LefSe analysis. The results revealed that enzymes that participated in the metabolic pathway of microbial biodegradation of polycyclic aromatic compounds were enriched and may have played a key role in the biodegradation of TC.

Impact of hydraulic retention time on swine wastewater treatment by aerobic granular sludge sequencing batch reactor.

In this study, the effect of hydraulic retention time (HRT) on the performance of aerobic granular sludge (AGS) treating swine wastewater (SW) in sequencing batch reactor (SBR) was investigated. The HRT was set at 4.8, 6, 8, 12, and 16 h and performed in five parallel aerobic granular sludge sequence batch reactors (AGSBRs), respectively. The results showed that sedimentation performance and biomass concentration were improved by decreasing the HRT from 16 to 8 h. However, when further decreasing HRT from 8 to 4.8 h, the AGS performance became worse. The AGS process with HRT of 8 h exhibited high pollutant removal efficiency, and an abundant microbial community and a stable microbial community structure were observed. High-throughput 16S rRNA analysis revealed that there were significant differences between the microorganisms in AGS samples with HRT of 8 h at the phylum level and that the dominant microbes changed as the process proceeded. At the genus level, the species and relative abundance of microorganisms gradually evolved for AGS stability in all cases.

Isolation of oxytetracycline-degrading bacteria and its application in improving the removal performance of aerobic granular sludge

Aerobic granular sludge (AGS) is a type of biofilm with good sedimentation and density, high biomass, high organic load tolerance and toxicity resistance. Oxytetracycline (OTC) is an antibiotic widely used in livestock and aquaculture, and its low absorption and high residue bring many risks and harms to the ecological environment. In this study, an OTC-degrading strain TJ3 was isolated from AGS and identified as Pandoraea sp. The biodegradation characteristics of OTC by strain TJ3 under different environmental conditions were also investigated. The results showed that the optimal initial pH value and temperature for the culture strain were 6.0 and 30 °C, respectively. At an inoculation dose of 6% (v/v), the removal rate of OTC by strain TJ3 was remarkable (59.4%). Furthermore, when the sodium acetate was present as an additional substrate, the biomass and the OTC removal rate of strain TJ3 were improved. The biodegradability of strain TJ3 to OTC was proved by LC-QTOF/MS, and two possible biotransformation products, i.e. m/z 416 and 219, were identified. In the bioaugmentation experiments of AGS by strain TJ3, the average OTC removal rate was 92.89% after the stable operation of bioreactor. The chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and total phosphorus (TP) were efficiently removed. The microbial community structure had significantly changed at the genus level, and the relative abundance of Zoogloea, Pandoraea, Cloacibacterium and Desulfovibrio increased evidently. These results implied that the OTC removal performance and the structural stability of AGS were improved. In this study, Pandoraea sp. TJ3 was applied to removal OTC for the first time, and results showed that Pandoraea sp. TJ3 may be a new auxiliary bacterial resource for the biodegradation of OTC and a potential candidate in the treatment of antibiotic wastewater.

Enhancing robustness of aerobic granule sludge under low C/N ratios with addition of kitchen wastewater

Aerobic granular sludge (AGS) is one of the most promising biotechnologies for wastewater treatment. However, the instability of AGS at low carbon to nitrogen (C/N) ratios limited its application. In this study, kitchen wastewater addition in the influent was found to improve the morphology, characteristics, and treatment performance of AGS at low C/N ratios of 10, 5 and 2, which strongly reduced the negative impact of low C/N ratios on the biomass concentration, settleability, EPS secretion, stability and performance of AGS. At C/N ratio of 2, sludge disintegration was observed in RA with synthetic wastewater as influent, while the sludge in RB was able to keep a compact microbial structure with particle size of 1.0–1.5 mm. When C/N ratio decreased from 20 to 2 (phase 1 to 4), the MLSS, SVI and EPS secretion in RB were negatively affected at the beginning of each phase, but recovered to 4800 mg L−1, 60 mL g−1, and 86 mg/g SS at the end of phase 4 (C/N ratio of 2), which were 1.3, 0.6 and 1.3 times of those in RA, respectively. Meanwhile, the removal efficiencies of COD, TN, TP and NH4+-N in RB were 90%, 73%, 53%, and 99% at the end of phase 4, which were 1.1, 1.2, 2.2 and 2.4 times of those in RA, respectively. Thus, high-performance AGS with enhanced robustness and high abundance of HN-AD functional bacteria Paracoccus was obtained. These findings provided a promising and cost-effective method to improve the long-term stability and performance of AGS dealing with wastewater of low C/N ratio.