Abstract
Titrimetric methods are considered to be useful for the study of biological wastewater treatment processes, particularly those processes that have negligible influence on the dissolved inorganic carbon pool. However, the application of titrimetric methods for studying biological processes that produce/consume carbon dioxide is not straightforward as microbial activity affects the total amount of dissolved inorganic carbon with a proportioned change (determined by pH) in the concentration of every species of inorganic carbon. In this work, the impact of adjustments to the inorganic carbon pool on titrimetric data was assessed by considering a pH-stat titration of heterotrophic carbon oxidation. It was confirmed that at typical operating conditions (pH 7.5 and KLaCO2 . 22.5 h-1) carbon oxidation causes a marked increase in the rate of carbon dioxide transfer and consequently has impact on titrimetric data. Model simulation was used to quantify the impact for a wide range of operating conditions. It was found that only when a titration is operated at pH > 8 with a KLaCO2 < 10 h-1 can the interference that results from action of the bicarbonate system be neglected (< 5% error induced). Outside these operating conditions it is suggested that the interference be accounted for by either measurement or modelling of carbon dioxide transfer.
Highlights
Microbial activity has a wide-ranging effect on pH
Titrimetric methods are considered to be useful for the study of biological wastewater treatment processes, those processes that have negligible influence on the dissolved inorganic carbon pool
The application of titrimetric methods for studying biological processes that produce/consume carbon dioxide is not straightforward as microbial activity affects the total amount of dissolved inorganic carbon with a proportioned change in the concentration of every species of inorganic carbon
Summary
The effect is a consequence of the action of acid-base buffering systems, whereby the biological consumption or production of components of these systems results in a change in hydrogen ion concentration (Pratt et al, 2003). H when volatile fatty acids (VFA) are produced/consumed during anaerobic digestion acid dissociation/formation results in a change in hydrogen ion concentration consumed during biological activity the carbonic acid concentration is altered, which again results in a change to the hydrogen ion concentration: HCO3 r2C O3 H CO32. Ficara et al (2000), Massone et al (1998) and Gernaey et al p mmol H+ is released when ammonia is assimilated for biomass (1997), in developing and applying a titrimetric method for exam- growth: ining ammonia oxidation, addressed the effect of background physico-chemical processes by proposing that the carbon dioxide transfer rate (CTR) is constant throughout an experiment, i.e. Ficara et al (2000), Massone et al (1998) and Gernaey et al p mmol H+ is released when ammonia is assimilated for biomass (1997), in developing and applying a titrimetric method for exam- growth: ining ammonia oxidation, addressed the effect of background physico-chemical processes by proposing that the carbon dioxide transfer rate (CTR) is constant throughout an experiment, i.e. p
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
