Pulsed aeration enhances aerobic granular biomass properties

• Published in: Biochemical engineering journal Vol. 149; p. 107244
• Main Authors: Carrera, P., Mosquera-Corral, A., Méndez, R., Campos, J.L., Val del Rio, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2019
• Subjects: Aerobic granular sludge; Low-strength wastewater; Phosphate accumulating organisms; Pulsed aeration; Aerobic granular sludge; Pulsed aeration; Phosphate accumulating organisms; Low-strength wastewater
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2019.107244

[Display omitted] •Pulsed aeration as new strategy which shortens the time of the granulation process.•Pulsed aeration favours a faster development of PAOs and GAOs than continuous one.•Minimum superficial gas velocities are different in pulsed and continuous aeration.•Removal efficiencies of C, N and P do not depend on the aeration regime.•To form aerobic granules with low-strength wastewater (190 mg COD/L) is possible. The reduced footprint of Aerobic Granular Sludge (AGS) systems constitutes a good alternative to conventional treatments, despite their associated drawbacks (long start-up periods and high aeration requirements for granules formation and integrity). This study presents a pulsed aeration regime as a strategy to overcome these problems. Two AGS sequencing batch reactors (SBRs) were operated treating low-strength wastewater (190 mg COD/L) with pulses of 1 s ON/2 s OFF (R1) and continuous aeration (R2). Initially, different superficial gas velocities (SGV) of 3.6 cm/s (R1) and 1.2 cm/s (R2) were imposed for the same airflow (448 L/cycle). The granulation process was completed in 38 days for R1 whereas it took 48 days for R2. Denser and smaller granules were formed with pulsed regime and phosphate accumulating organisms were developed faster. The removal efficiencies were practically the same in both SBRs, being of 85% for COD, 95% for phosphorus and 30% for nitrogen. After granules formation the airflow in both reactors was reduced. For a SGV of 1.2 cm/s both systems behaved similarly. The minimum SGV required to maintain a uniform mixture of the biomass inside the reactor was 1.2 (R1) and 0.5 cm/s (R2), meaning less air consumption in the pulsed system (149 L/cycle) compared to the continuous one (179 L/min). Therefore, pulsed aeration successfully reduced granulation periods and aeration requirements in AGS systems.