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Table 2 Physico-chemical parameters of sludges measured after 23 days of anaerobic digestion

From: Biomethane potential of industrial paper wastes and investigation of the methanogenic communities involved

Name TS (% FW w/v) VS (% FW w/v) pH TAN (mg L−1) Acetate (mM) Propionate (mM) CH4 (Nml gVS−1)
WR37 7.74 (0.13) a 5.44 (0.08) a 7.81 (0.02) a 1533 (44.1) ab 0.13 (0.13) nd 116 (7.51) a
WR37au 7.34 (0.07) ac 5.27 (0.05) a 8.16 (0.02) b 1867 (136) b nd nd 165 (2.08) ab
WR37us 6.35 (0.07) b 4.53 (0.05) b 8.04 (0.01) b 1250 (50.0) a 0.04 (0.04) nd 195 (4.42) ab
WR37al 6.10 (0.08) bd 4.17 (0.07) d 8.11 (0.01) b 1350 (132) a 0.57 (0.46) 0.25 (0.25) 139 (12.4) ab
WR37mo 6.95 (0.14) c 4.86 (0.06) c 7.82 (0.04) a 1367 (183) ab nd nd 137 (36.2) ac
WR37en 6.09 (0.18) bd 4.20 (0.08) d 7.79 (0.06) a 1433 (44.1) ab 0.10 (0.05) nd 203 (23.3) bc
WR37us+en 5.63 (0.04) d 3.99 (0.03) d 7.64 (0.01) c 1417 (60.1) ab nd nd 222 (5.04) b
PR37 7.87 (0.02) a 4.74 (0.03) a 7.82 (0.02) a 1800 (50.0) a 0.12 (0.07) nd 323 (4.96) a
PR37au 7.61 (0.26) a 4.67 (0.21) a 8.15 (0.02) b 1683 (174) ab nd nd 331 (8.53) a
PR37us 7.25 (0.25) a 4.62 (0.13) a 8.00 (0.01) c 1650 (104) ab 0.03 (0.03) nd 400 (7.30) b
PR37al 6.06 (0.16) bc 3.57 (0.13) b 8.06 (0.02) c 1567 (267) ab 0.49 (0.24) 1.17 (0.62) 202 (17.8) c
PR37mo 7.17 (0.07) a 4.23 (0.05) ac 7.79 (0.01) a 1567 (44.1) ab 0.07 (0.04) nd 324 (5.73) a
PR37en 6.38 (0.05) b 3.81 (0.02) bc 7.66 (0.01) d 1500 (50.0) ab 0.03 (0.03) nd 351 (2.79) a
PR37us+en 5.54 (0.03) c 3.41 (0.03) b 7.59 (0.02) e 1067 (16.7) b nd nd 408 (8.37) b
WR55 3.81 (0.30) 2.48 (0.22) 8.30 (0.03) 1550 (76.4) nd 1.65 (1.30) 171 (6.01)
PR55 2.91 (0.02) 1.77 (0.05) 8.31 (0.04) 1567 (44.1) 1.11 (0.35) 6.75 (0.66) 368 (7.89)
  1. n = 3; standard error is given in brackets. Different letters (a–e) indicate significant differences between pretreatments (p < 0.05) for each waste material according to the Tukey HSD test
  2. TS total solids, VS volatile solids, FW fresh weigh, nd not detected, WR wood residues, PR pulp residues, 37 AD at 37 °C, 55 AD at 55 °C, au autoclave pretreatment, us ultrasound pretreatment, al alkaline pretreatment, mo pretreatment with commercial microorganism mixture, en enzyme pretreatment