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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