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Water SA

On-line version ISSN 1816-7950
Print version ISSN 0378-4738

Water SA vol.48 n.1 Pretoria Jan. 2022 



Integration of complete elemental mass-balanced stoichiometry and aqueous-phase chemistry for bioprocess modelling of liquid and solid waste treatment systems -Part 5: Ionic speciation



CJ BrouckaertI; BM BrouckaertI; GA EkamaII

IWASH R&D Centre, School of Engineering, University of KwaZulu-Natal, Durban 4041, South Africa
IIWater Research Group, Department of Civil Engineering, University of Cape Town, Rondebosch 7700, South Africa





Where aqueous ionic chemistry is combined with biological chemistry in a bioprocess model, it is advantageous to deal with the very fast ionic reactions in an equilibrium sub-model, as was frequently mentioned in the preceding papers in this series. This last paper in the series presents details of how such an equilibrium speciation sub-model can be implemented, based on well-known open-source aqueous chemistry models. Specific characteristics of the speciation calculations which can be exploited to reduce the computational burden are highlighted. The approach is illustrated using the ionic equilibrium sub-model of a plant-wide wastewater treatment model as an example.

Keywords: equilibrium speciation, modelling, tableau representation, computational efficiency, primary search variables, pH, alkalinity