Cmnv. Almeida et al., Automatic flow titrator based on a multicommutated unsegmented flow systemfor alkalinity monitoring in wastewaters, ANALYT CHIM, 438(1-2), 2001, pp. 291-298
A full automatic flow system based on potentiometric titration for alkalini
ty monitoring in wastewater treating plants is presented. Titration to an e
nd-point of pH 5.75 partial alkalinity CPA) and then to pH 4.3 intermediate
alkalinity CIA) allows to distinguish the relative buffering contributions
of both bicarbonate and volatile acids in anaerobic digesters and, thus, t
he attainment of a IA:PA ratio which is a sensitive parameter of digestion
monitoring that increases rapidly with the process upset.
The titration approach is based on a time-based sequential introduction of
increasing titrant and decreasing titrand volumes into a mixing chamber The
theoretical model for the titration process already presented and discusse
d was used to determine the titrand concentration without prior calibration
.
The interface between the analytical system and the anaerobic digester was
also developed, allowing completely automated on-line monitoring of alkalin
ity.
The results obtained were reproducible (R.S.D. lower than 2.4 and 5.1% for
repeatability and reproducibility, respectively) and in good agreement with
those given by the comparative method. (C) 2001 Elsevier Science B.V. All
rights reserved.