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Table 1 Biogas production and sludge characteristics

From: Metagenome from a Spirulina digesting biogas reactor: analysis via binning of contigs and classification of short reads

Units Period I Period II Period III Period IV Period V
  Days 116 74 100 21 29
OLR g Spirulina (LR day)−1 1.0 2.0 3.0 4.0 5.0
Daily biogas production mL biogas day−1 470 ± 69 986 ± 176 1487 ± 252 2096 ± 118 2210 ± 325
Daily methane production mL CH4 day−1 327 ± 49 648 ± 117 972 ± 190 1397 ± 79 1399 ± 260
CH4 % 69 ± 5 69 ± 2 70 ± 13 68 ± 1 62 ± 4
CO2 % 30 ± 5 30 ± 2 25 ± 10 31 ± 1 37 ± 4
N2;O2 % 1 ± 1 1 ± 1 5 ± 16 1 ± 1 1 ± 1
H2S % <1.0 <1.0 <1.0 <1.0 <1.0
Specific biogas and methane productions
SBP-VS added mLbiogas (day g VS)−1 354 ± 52 369 ± 66 372 ± 63 393 ± 22 334 ± 47
SBP-g Spirulina added mLbiogas (day g Spirulina)−1 313 ± 46 329 ± 58 330 ± 55 349 ± 19 297 ± 42
SMP-VS added mLmethane (day g VS)−1 246 ± 37 243 ± 44 243 ± 47 262 ± 14 211 ± 39
SMP-g Spirulina added mLmethane (day g Spirulina)−1 218 ± 33 216 ± 39 216 ± 42 233 ± 13 188 ± 34
Sludge characteristics
pH   7.5 ± 0.3 7.9 ± 0.1 8.5 ± 0.1 8.6 ± 0.1 8.6 ± 0.1
Alkalinity g CaCO3 L−1 8.6 ± 0.7 11.4 ± 0.8 16.5 ± 3.1 20.8 ± 1.2 25.4 ± 2.4
Total Solids g Kg−1 17.6 ± 1.3 21.7 ± 1.2 26.6 ± 2.6 29.3 ± 1.4 38.2 ± 5.0
Volatile Solids g Kg−1 10.2 ± 1.0 13.7 ± 1.2 18.9 ± 2.5 21.1 ± 1.2 29.1 ± 4.6
CODT g O2 L−1 17.2 ± 1.0 24.1 ± 3.5 33.2 ± 2.5 36.6 ± 3.8 54.8 ± 8.34
CODs g O2 L−1 3.9 ± 1.0 5.5 ± 0.5 8.6 ± 2.9 7.2 ± 0.1 19.3 ± 6.5
BOD5 g O2 L−1 2.0 ± 0.6 3.3 ± 1.1 4.4 ± 0.1 4.9 ± 0.1 12.9 ± 0.1
Total Nitrogen g L-1 3.2 ± 0.3 4.5 ± 0.6 5.8 ± 0.3 6.7 ± 0.6 8.0 ± 0.8
NH4 +-N g L-1 2.2 ± 0.2 2.9 ± 0.2 2.8 ± 0.2 3.0 ± 0.2 3.7 ± 0.4
NH3-N g L-1 0.1 ± 0.1 0.3 ± 0.1 1.1 ± 0.2 1.4 ± 0.2 1.6 ± 0.3
Acetic acid mg L-1 376 ± 301 646 ± 168 1647 ± 858 1836 ± 919 3117 ± 1526
Propionic acid mg L-1 35 ± 10 173 ± 66 629 ± 614 713 ± 623 1582 ± 521
  1. n.d non detected
  2. Biogas and methane production, biogas characteristics, specific biogas and methane productions and sludge characteristics from the anaerobic digestion of Spirulina obtained with the five organic loading rate tested. Shown are the mean values of each period with their respective standard deviation