Alkalinity measurement: Part 3 - A 5 pH point titration method to determine the carbonate and SCFA weak acidlbases in aqueous solution containing also known concentrations of other weak acid/bases

Abstract

The theoretical basis for a 5 pH point acid titration method is described that allows the determination of H 2 CO 3 * alkalinity, total carbonatespecies concentration (C T ) and total short-chain fatty acid (SCFA) concentration in anaerobic digestor liquids also containing known concentrations of other weak acid/bases, e.g. ammonium and phosphate. The known concentrations of the other weak acid/bases are incorporated in the algorithm employed to calculate the H 2 CO 3 * alkanity, C T and SCFA, i.e. their alkalinity contributions are removed the measurements in the 5 pH point acid titration to give C T , H 2 CO 3 * alkalinity and SCFA. The method also provides an estimate of any systematic pH measurement error, provided the carbonate subsystem dominates over the SCFA subsystem, i.e. C T as CaCO 3 > 2 SCFA as acetic acid