Comparison of VFA production in the relevant literature.
| Substrate | Inoculum | Operational conditions | VFAs | References |
|---|---|---|---|---|
| Food waste | Dewatered sludge | pH 9.0, 35 °C | 25.93 g COD/L | 23 |
| Kitchen waste | Waste-activated sludge | pH 8.0, 37 °C | 692.4 mg COD/g VS | 24 |
| Food waste | Anaerobic digested sludge | pH 6.0, 35 °C | 24.5–25.5 g L−1 | 18 |
| Waste activated sludge | — | pH 11.0, 25 °C | 219.7 mg COD/g VS | 25 |
| Food waste | Sludge | 37 °C, microwave | 23.02 g L−1 | 26 |
| Food waste | Excess sludge | 40 °C | 867.42 mg COD/g VS | 27 |
| Food waste | Sludge | pH 7.0, 35 °C | 26.17 g L−1 (443 mg COD/g VS) | This study |