Biogas & RNG Online – March 2026
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Total VFAs Monitoring
Total VFAs Monitoring
Hi. What is the Best way to measure Total VFAs . Is two point titration of pH from 5 to 4.4 (Nordman Method) is good enough? Any One cross checked its error with GC Values of VFA profiling? Please share your experiences on this.
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We’ve regularly compared spot-VFA estimates by titrations vs total and speciated VFA analysis via split testing. The field-expedient titration is only ever an estimate and the buffering chemistry involved, including ammonia and other pH-sensitive minerals, means if you’re looking for a strict VFA concentration, then you will likely be misled.
The good news is that it practice, it rarely matters. The rapid field test is enough to inform operators about their system’s stability. Instability can then be a trigger for more costly, slower, off-site lab testing for speciated VFAs.
Measuring Total VFAs (Volatile Fatty Acids) in a biogas plant can be done by several methods. The two-point titration method (Nordmann ) is widely used in biogas plants because it is fast, inexpensive, and suitable for daily plant monitoring. However, it is not the most accurate scientific method for total VFA quantification.
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