Table 2.
Summary of studies that applied micro-aeration for anaerobic removal of pollutants, including key parameters such as substrate, reactor configuration, air/oxygen dosage, and observed effects
| Substrate | Reactor type | Air/pure O2 | Pretreatment (Pt) Direct (D) |
Aerationa | Effect | Reference |
|---|---|---|---|---|---|---|
| Olive mill wastewater | Glass flask (batch) | Air | Pt—continuous (5 or 7 days) | 936 L L−1 d−1 |
Decrease of phenols (78–90%) Decrease total COD (65%) |
González-González and Cuadros (2015) |
| Synthetic BTEX-contaminated water | UASB | Air | D—intermittent (through feeding line) | 0.07, 0.10, and 0.30 L L−1 d−1 |
Removal of BTEX (> 83%) Without volatilization |
Siqueira et al. ((2018) |
| Petrochemical wastewater | Digestion reactor | Air | Pt—intermittent (ORP-based) | 0.04–0.06 mg L−1 |
Reduced H2S Removal of BTEX |
Wu et al. (2015) |
| Petrochemical wastewater | Full scale | Air | Pt—intermittent (ORP-based) | 0.08–0.10 mg L−1 |
Increased COD removal (55%) Increased removal of all micropollutants Increased acidogenesis |
Wu et al. (2018) |
| Anionic surfactants | AnMBR | Air | D—intermittent (ORP-based) | NM |
Removal of surfactant (80%) No foam No VFA accumulation |
Cheng et al. (2018) |
| 2-Butenal manufacture wastewater | EGSB | Air | D—continuous | 0.04–0.10 mg L−1 |
COD removal (24%) Increased acidification (21%) |
Song et al. (2019) |
| Textile wastewater (azo dye Direct Black 22) | UASB | Air | D—intermittent (DO monitored daily) | 0.04 ± 0.01 mg L−1 |
No difference in dye removal Increased aromatic amines removal Decreased toxicity |
Carvalho et al. (2020) |
| Synthetic pharmaceutical wastewater | UASB | Air | D—intermittent (through feeding line) | 0.08 L L−1 d−1 |
Increased removal of micropollutants (> 50%) Community not changed |
Buarque et al. (2019) |
| Domestic with pharmaceutical wastewater | Anaerobic baffled biofilm-membrane bioreactor (AnBB-MBR) | Air | D—intermittent (DO monitored) | 0.06–0.10 mg L−1 |
Enhanced adsorption and biodegradation of pharmaceuticals Ciprofloxacin (78%) Sulfamethoxazole (89%) Diclofenac (41%) |
Buakaew and Ratanatamskul (2024) |
| Fresh leachate | Sequential reactors (anoxic/micro-aerobic/oxic) | Air | D—intermittent (relay-controlled DO) | < 0.15 mg L−1 |
Increased acetogenesis Improved denitrification Antibiotics removal (50% efficiency) |
Wei et al. (2021) |
| Synthetic wastewater with 2,4-dinitrophenol | Membrane-based bubbleless micro-aeration hydrolysis acidification (MBL-MHA) | Air | D—continuous (through membrane) | 0.06–0.60 L L−1 d−1 | Degradation of 2,4-dinitrophenol achieving 2 to 3% higher degradation rates compared to bubble aeration method | Zhang et al. (2022) |
| WAS with siloxanes | Bach assays | O2 | D—intermittent (time-based) | 1% or 3% (v/v) | Enhanced methane production | Ortiz-Ardila et al. (2024) |
BTEX; benzene, toluene, ethylbenzene, and xylene, WAS; waste activated sludge; MBL-MHA; membrane-based bubbleless micro-aeration coupled with hydrolysis acidification, MABR; membrane-aerated biofilm reactor, UASB; upflow anaerobic sludge blanket, AnMBR; anaerobic membrane bioreactor, EGSB; expanded granular sludge bed, NM; not mentioned, COD; chemical oxygen demand, VFA; volatile fatty acids, DO; dissolved oxygen, OTR; oxygen transfer rate
aDepending on the information available, aeration is expressed either as the aeration rate (volume of O2 per unit of reactor working volume and time), or as the target dissolved oxygen (DO) concentration (mass of O2 per unit of reactor working volume) maintained throughout the experiment