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Table 3 pH value, ammonium-nitrogen (NH4–N), VFA/TIC, TOC, and TN of digestates from the primary digester

From: Process upsets in a full-scale anaerobic digestion bioreactor: over-acidification and foam formation during biogas production

Time (d)

pH

VFA (mg/L)

TIC (mg/L)

VFA/TIC (−)

TOC (mg/L)

TN (mg/L)

NH4–N (mg/L)

81

7.90

1606

12,073

0.13

19,570

4570

1550

88

7.94

1871

11,073

0.17

16,652

4144

1316

95

8.05

3311

10,179

0.33

17,710

4270

1230

102

7.03

9196

5441

1.69

21,316

4273

1483

109

8.09

4034

10,861

0.37

18,610

4233

1494

116

8.19

3731

9,485

0.39

17,055

4169

1198

123

7.91

2154

11,815

0.18

15,914

3784

1080

130

7.99

1627

9,005

0.18

18,148

4312

1541

137

7.73

2133

10,814

0.20

17,996

4422

1261

144

7.93

1884

10,440

0.18

16,700

4064

1217

151

7.70

2017

11,525

0.18

17,689

4297

1443

158

7.64

2291

10,906

0.21

10,490

3433

1194

  1. The data from the over-acidification period are marked in bold and those from the foaming period in bold and italics