What is FOS, TAC and FOS / TAC?
FOS - the abbreviation comes from German and means Flüchtigen Organischen Säuren or volatile organic acids (C2-C6). They are compounds formed during the second and third phase of the methane fermentation process. In English-language literature, the abbreviation FOS is VFA or volatile fatty acids.
The FOS value is determined by titration and is the sum of all volatile acids calculated as acetic acid. The most commonly used unit to determine it is mg / l or g / l.
TAC - this abbreviation also comes from German and means Total Alkalischen Carbonaten. The TAC determines the total inorganic carbonate buffer solution. The value of the TAC parameter is also determined by titration and means the sum of all substances of buffering nature (i.e. protecting against a decrease in pH). carbonates, ammonium ions and phosphates. The TAC value is expressed in the form of carbonate (CaCO3), the unit used is mg / l or g / l.
FOS / TAC - is a parameter that characterizes the equilibrium between volatile organic acids (FOS) and buffering substances (TAC). It is presented as a decimal fraction, where the nominative value is TAC [mg / l] and in the FOS counter. [mg / l].
Manual FOS/TAC titration kit
Automatic titrator TitraLab AT1000