Titrimetric Monitoring Of Anaerobic Digestion: VFA, Alkalinities and More

Volatile fatty acids and bicarbonate measurements are important to assess a digester’s stability and to control it. Titration methods are the most likely cost-effective methods to determine those variables with acceptable accuracy. In this paper, titrimetic methods will be classified and evaluated. Two titrimetric sensors are compared for their potential on-line use. One sensor uses advanced interpretation techniques to quantify almost any buffering system while the other uses approximate methods that assume bicarbonate and VFA are the dominating buffers. A specific experiment was performed to run the two sensors during an overload situation of a 1 m fixed bed anaerobic reactor with the aim to assess their accuracy. Also, the results show the dynamic evolution of bicarbonate and VFA in the digester during overload conditions. In addition to VFA and bicarbonate, lactate was determined titrimetrically during the overload conditions.