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Published on: December 25, 2015
Start-up strategies to develop aerobic granular sludge and photogranules in sequential batch reactors
Marcos Sales1, Talita Marinho1, Idayana C Marinho1
1Federal University of Pernambuco, Department of Civil and Environmental Engineering, Laboratory of Environmental Sanitation. Av. Academico Helio Ramos, s/n. Cidade Universitária, CEP 50740-530 Recife, PE, Brazil.
This study compared conventional aerobic granular sludge (AGS) and algal aerobic granular sludge (AAGS) start-up strategies. Algal AGS showed better stability and size, while both methods achieved high nutrient removal efficiencies, especially with longer feeding times.
Area of Science:
- Environmental Engineering
- Wastewater Treatment
- Microbiology
Background:
- Aerobic granular sludge (AGS) is an effective wastewater treatment technology.
- Algal aerobic granular sludge (AAGS), or photogranules, offers potential for enhanced stability and performance.
- Optimizing start-up strategies is crucial for efficient granulation and wastewater treatment.
Purpose of the Study:
- To investigate and compare start-up strategies for conventional AGS and AAGS (photogranules).
- To evaluate the impact of feeding duration on granulation and biomass characteristics.
- To assess the removal efficiencies of chemical oxygen demand (COD) and ammonium nitrogen (NH4+-N) under different operational conditions.
Main Methods:
- Four sequencing batch reactors (SBRs) were used: two conventional SBRs (RC1, RC2) and two photo-SBRs (R1, R2).
- Reactors were operated in two phases with varying carbon-to-nitrogen (C:N) ratios (4:1 and 8:1).
- Feeding durations were set at 40 minutes for R1/RC1 and 60 minutes for R2/RC2.
Main Results:
- AAGS demonstrated superior stability and larger granule diameter compared to AGS.
- AGS exhibited a higher abundance of extracellular polymeric substances (EPS) producing bacteria.
- COD and NH4+-N removal efficiencies reached over 95% and 93% respectively in Phase II, with longer feeding times (60 min) yielding better nitrogen removal and more compact granules.
Conclusions:
- Both AGS and AAGS are viable for wastewater treatment, with AAGS offering improved granule characteristics.
- Optimizing feeding duration significantly impacts biomass composition, granule structure, and nitrogen removal efficiency.
- Adjusting operational parameters like C:N ratio and feeding time is key to achieving high removal efficiencies in SBR systems.
