Abstract:
Anaerobic digesters are often not operated to full capacity and are recurrently subjected to
adverse operational practices due to: temperature fluctuations, inconstant feeding regimes,
variable solids content on the feed, changes in loading rates etc. The use of standard online
monitoring indicators (pH, alkalinity, gas production and compositions)is insufficient
to detect the perturbation at an early stage as these parameters are linked to the final
product of the process, causing delays when diagnosing digester imbalances. On the other
hand, volatile fatty acids (VFA) have been widely recognized as a key parameter for
understanding and controlling anaerobic processes as they are intermediate products and
real time indicators of the digester stability. Application of on-line instrumentation for VFA
measurement has been limited as all developed instrumentations are based on expensive
equipments (Gas Chromatograpy, High Performance Liquid Chromatography, Fourier
Transform Infra-Red spectrometer etc.) and require. sample preparations involving the use
of filtration, membranes, chemical additions, therefore triggering extensive maintenance. Cont/d.
