Towards a generalized physicochemical framework

Abstract

Process models used for activated sludge, anaerobic digestion and in general wastewater treatment plant process design and optimization have traditionally focused on important biokinetic conversions. There is a growing realization that abiotic processes occurring in the wastewater (i.e. 'solvent') have a fundamental effect on plant performance. These processes include weak acid-base reactions (ionization), spontaneous or chemical dose-induced precipitate formation and chemical redox conversions, which influence pH, gas transfer, and directly or indirectly the biokinetic processes themselves. There is a large amount of fundamental information available (from chemical and other disciplines), which, due to its complexity and its diverse sources (originating from many different water and process environments), cannot be readily used in wastewater process design as yet. This position paper outlines the need, the methods, available knowledge and the fundamental approaches that would help to focus the effort of research groups to develop a physicochemical framework specifically in support of whole-plant process modeling. The findings are that, in general, existing models such as produced by the International Water Association for biological processes are limited by omission of key corrections such as non-ideal acid-base behavior, as well as major processes (e.g., ion precipitation). While the underlying chemistry is well understood, its applicability to wastewater applications is less well known. This justifies important further research, with both experimental and model development activities to clarify an approach to modeling of physicochemical processes.

Modeling the low pH limit of Nitrosomonas eutropha in high-strength nitrogen wastewaters

“…The model by Hellinga et al (1999) included pH calculations based on acid-base equilibria only. However, for a realistic modeling of pH in high strength wastewaters ion activity and complex formation have to be considered as well (Batstone et al, 2012). This is definitely the case for source-separated urine (Udert et al, 2003b).…”

The Potential Phosphorus Crisis: Resource Conservation and Possible Escape Technologies: A Review

“…A good example of such approach can be found in Vaneeckhaute et al [90] that developed a generic nutrient model in order to optimize nutrient (N, P) and energy recovery of treatment facilities with a focus on fertilizer quality and quantity. Batstone et al [91] showed that there is a serious need of improvement on current physicochemical models for them to be applied for nutrients recovery purposes.…”

“…Sewage treatment using MFC systems in European Union could save up to 1 M tonne/year, and a considerable amount of sludge disposal costs [100,101]. Bio-electrochemical systems could also be implemented for the integration of energy and nutrients recovery: there have been, in fact, interesting studies on the possibility of phosphorus recovery in the form of struvite by MFC systems [91,102]. Studies suggest that phosphorus could be removed up to 82% by MFC systems, 40% of which it could be recovered as struvite [103].…”

Assessing Nutrient Use Efficiency and Environmental Pressure of Macronutrients in Biobased Mineral Fertilizers

“…In this respect, the use of mathematical models for nutrient and energy recovery can be very valuable for optimization of both process performance and fertilizer quality. As up to date an adequate integrated biological-physicochemical modelling approach for resource recovery is lacking (Batstone et al, 2012), the development and use of such prototype models will be aspect of further research.…”