Table 2 Performance of the methane-yielding microbial communities processing a lactate-rich artificial medium
M1A | M1B | |
|---|---|---|
A. Characteristics of the biogas | ||
Total biogas production | ||
L/working volume of the bioreactor/day | 28.6 ± 0.45 | 34.9 ± 4.0 |
Composition of biogas (%) | ||
Methane | 66.0 ± 0.02 | 71.8 ± 1.2 |
Carbon dioxide | 33.3 ± 0.02 | 28.1 ± 1.3 |
Hydrogen | 0.66 ± 0.01 | 0.02 ± 0.03 |
Hydrogen sulfide | 0.01 ± 0.01 | 0.01 ± 0.01 |
Methane production | ||
l-CH4/working volume of the bioreactor/day | 18.9 ± 0.3 | 25.10 ± 2.85 |
l-CH4/g COD | 2.53 ± 0.04 | 3.64 ± 0.41 |
B. Characteristics of the substrate and effluent after the methanogenic process | ||||
|---|---|---|---|---|
Substrate | Effluent | Substrate | Effluent | |
COD (g O2/L) | 15.5 ± 1.2 | 2.3 ± 0.4 | 12.5 ± 1.8 | 0.4 ± 0.1 |
Concentration of | See Table 1 | See Table 1 | ||
Acetic acid (mg/L) | 443 ± 236 | 68 ± 41 | ||
Butyric acid (mg/L) | 126 ± 43 | < 1.0a | ||
Lactic acid (mg/L) | 22.0 ± 36 | 4.3 ± 5.8 | ||
Propionic acid (mg/L) | 518 ± 145 | 38 ± 22 | ||
Sulfide (mg/L) | < 0.05a | 0.03 ± 0.03 | < 0.05a | 0.09 ± 0.04 |
pH | 5.69 ± 0.17 | 6.95 ± 0.15 | 4.91 ± 0.12 | 7.41 ± 0.05 |
Redox potential in the UASB bioreactor (mV)b | (− 277) to (− 290) | (− 273) to (− 307) | ||