Skip to main content

Table 2 The early warning indicators of R1

From: Early warning indicators for mesophilic anaerobic digestion of corn stalk: a combined experimental and simulation approach

Reactor Parameters Units Date of abrupt change (day) Date of process failure (day) Warning time (day) Experimental results Simulated results
Abrupt changea Abrupt vs. steady-state value Abrupt change Abrupt vs. steady-state value
R1 CH4/CO2 112 (153) 112 (159) 0 (6) 1.28 (1.43) − 23.81 to − 18.48%
(− 16.38 to − 11.73%)
1.07 (1.03) − 2.49%
(− 11.95 to − 1.60%)
Acetate g/L 109 (147) 112 (159) 3 (11) 0.39 (0.59) + 105.26 to 129.41% (+ 145.83%) 0.44 (0.56) + 27.52 to 94.71%
(+ 48.06 to 234.57%)
Propionate g/L 109 (153) 112 (159) 3 (6) 0.3 (0.5) + 130.77 to 172.73% (+ 177.78 to 257.14%) 0.09 (0.12) + 18.46 to 101.87%
(+ 101.76 to 274.62%)
VFA g/L 109 (147) 112 (159) 3 (12) 0.80 (0.95) + 50.9 to 105.13% (+ 75.93 to 150%) 0.63 (0.76) + 19.49 to 22.20%
(+ 56.02%)
IA g CaCO3/L 105 (157) 112 (159) 7 (2) 0.79 (0.74) + 61.48%
(+ 20.68 to 30.65%)
0.28 (0.87) + 18.54 to 19.68%
(+ 63.22 to 180.86%)
BAb g CaCO3/L 107 (158) 112 (159) 5 (1) 1.21 (1.04) − 20.43 to − 11.10%
(− 23.22 to − 22.85%)
1.07 (0.70) − 32.84%
(− 27.40 to − 50.32%)
VFA/BA 109 (147) 112 (159) 3 (12) 0.77 (0.68) + 113.89 to 196.15% (+ 183.33%) 0.59 (0.70) − 23.06 to − 69.02% (+ 199.76%)
BA/TA 105 (158) 112 (159) 7 (1) 0.67 (0.56) − 19.28 to − 14.11%
(− 30.86 to − 25.34%)
0.80 (0.43) − 14.38%
(− 51.77 to − 33.80%)
IA/BA 105 (157) 112 (159) 7 (2) 0.53 (0.54) + 10.42 to 70.97% (+ 23.26%) 0.26 (1.06) + 20.06 to 26.02%
(+ 86.01%)
pH 112 (159) 6.24 (6.38) <6.4
CH4 yieldc L CH4/g VS 113 (161) 0.02 (0.12) 0.20 (0.04) + 47.01 to 68.95%
(− 32.33 to − 13.55%)
  1. aValues in the units indicated in the “Parameters” column
  2. bBA in simulated results expressed as the absolute change in the sum of dissolved HCO3 and CO32− over half a day, in %
  3. cThe values in brackets refer to the corresponding values of sudden overload. – means decrease, and +  means increase