Table 4 Characteristics of the steady states during continuous fermentation experiments with in situ acids removal by REED

Operating features

 HRT (d)

1

1

1

2

 Influent glucose concentration (g L⁻¹)

50

38

54

54

 Influent xylose concentration (g L⁻¹)

22

34

34

Steady state characteristics

 Glucose concentration (g L⁻¹)

<0.45

<0.45

15.16

<0.45

 Xylose concentration (g L⁻¹)

–

9.62

20.16

3.93

 Butyric acid concentration (g L⁻¹)

5.21

4.08

2.76

2.79

 Acetic acid concentration (g L⁻¹)

1.25

1.73

0.93

0.95

 Glucose consumption rate (g L⁻¹ h⁻¹)

¹2.08

¹1.64

1.81

1.17^a

 Xylose consumption rate (g L⁻¹ h⁻¹)

–

0.65

0.72

0.65

 Acetic acid production rate (g L⁻¹ h⁻¹)

0.23

0.39

0.45

0.27

 Acetic acid yield (g g⁻¹ sugars)

0.11

0.17

0.18

0.15

 Butyric acid production rate (g L⁻¹ h⁻¹)

0.79

0.78

0.85

0.55

 Butyric acid yield (g g⁻¹ sugars)

0.38

0.34

0.34

0.30

 Butyric acid selectivity (g g⁻¹ acids)

0.78

0.67

0.65

0.67

 Hydrogen production rate (L L⁻¹ h⁻¹)

0.50

0.51

0.62

NM^b

 REED extraction efficiency  (%)

72.2

84.59

89.86

93.3