Impact of cycle type on aerobic granular sludge formation, stability, removal mechanisms and system performance

• Published in: Journal of environmental management 2020-02, Vol.256, p.109970-109970, Article 109970
• Main Authors: Rollemberg, Silvio Luiz de Sousa, Ferreira, Tasso Jorge Tavares, Firmino, Paulo Igor Milen, dos Santos, André Bezerra
• Format: Article
• Language: English
• Subjects: Aerobic granules; Aerobiosis; Biomass; Bioreactors; Denitrification; Nitrogen; Nutrients removal; Phase time distribution; Sewage; Waste Disposal, Fluid
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2019.109970

This paper aimed to assess the impact of the cycle type on aerobic granular sludge (AGS) formation, stability and system performance. Six AGS reactors were operated either on A/O cycles (anaerobic followed by oxic phase) or A/O/A cycles (anaerobic, followed by oxic and anoxic phases), changing only the phase time distribution. Reactors with high percentage of aerobic phase (65% of the total cycle time) generated granules with better settleability and resistance, however denitrification was impaired. On the other hand, reactors with long anaerobic or anoxic phases presented excellent nutrients removals, but the granules were fluffy and unstable. The best results in terms of performance and stability were achieved in an A/O/A reactor with short anoxic phase (10% of the total cycle) and medium aerobic phase (55% of the total cycle). Therefore, in AGS reactors, it is indispensable to optimize the cycle, aiming at fast biomass formation, long-term granule stability and high-rate pollutants removal. •The cycle configuration influenced the AGS formation, stability and performance.•A minimum aeration time (55% of the cycle) is necessary to obtain stable granules.•Long anaerobic or anoxic phases compromised the structure of the granules.•A short anoxic phase favored both nutrients removal and granule stability.