Modelling multiple mineral precipitation in anaerobic digester liquor

Rensburg, Pierre van; Musvoto, E. V.; Wentzel, M. C.; Ekama, G. A.

doi:10.1016/s0043-1354(03)00173-8

Cited by 73 publications

(56 citation statements)

References 4 publications

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“… pH is modelled through a combined kinetic/equilibrium with kinetic/equilibrium approach for limited weak acid-base reactions without further ion pairing;  Phosphorus removal with alum or ferric in the preliminary treatment is modelled using an equilibrium approach;  Spontaneous mineral precipitation is described with kinetic equations based on previous work (Ekama et al 2006a, Maurer et al 1999, Musvoto et al 2000a, van Rensburg et al 2003.  Gas stripping is represented by kinetic equations.…”

Section: Limitations In Current Biological Modelsmentioning

confidence: 99%

“…Some studies (Ekama et al 2006a, Musvoto et al 2000a, van Rensburg et al 2003 have applied a fully kinetic approach for both fast reactions (e.g. acid-base systems) and slow reactions (e.g.…”

Section: Model Time Constant Issues: Kinetics Vs Equilibriummentioning

confidence: 99%

“…Several studies have used mathematical modelling to improve the understanding of chemical precipitation mechanisms in wastewater treatment (Barat et al 2009, Maurer et al 1999, Musvoto et al 2000a, van Rensburg et al 2003. Typically, unique modelling approaches have been applied to specific experimental datasets.…”

Section: Introductionmentioning

confidence: 99%

“…an assumption that precipitation reactions are occurring at sufficiently rapid rates to be effectively at equilibrium (Hanhoun et al 2011, Loewenthal et al 1995, Ohlinger et al 1998, Scott et al 1991, Wrigley et al 1992 or instead treating them as kinetic reactions in the dynamic state equation set (Maurer et al 1999, Musvoto et al 2000a, van Rensburg et al 2003);…”

Section: Introductionmentioning

confidence: 99%

“…Key precipitating species in wastewater treatment include carbonates and phosphates of calcium and magnesium (Barat et al 2011, Musvoto et al 2000a, van Rensburg et al 2003. Some of the minerals are also capable of forming a variety of different minerals, including amorphous and crystal polymorphs (Brečević and Nielsen 1989, Kralj et al 1997, Meyer and Weatherall 1982.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic modelling of minerals precipitation in wastewater treatment

Mbamba¹

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In wastewater treatment, there is an increasing focus on nutrient and energy recovery and a reduction in energy consumption to counter climate change. Because of this, integrated mathematical modelling platforms are required to support plant-wide developments making use of emerging, resilient and environmental-friendly technologies. A reliable model description of a wastewater treatment plant should include both biology and physico-chemistry. However, existing standard models used across the wastewater sector have a biological focus with over-simplified descriptions of important physicochemistry, especially with minerals precipitation which is a very important class of physicochemical reactions.As part of development of a more widely applicable physicochemical framework, this thesis sought to identify a suitable minerals precipitation modelling approach that could give reasonable results in mainstream use with wastewater treatment. This research aim was approached in three steps. Firstly a review of available modelling approaches suggested a simple equilibrium kinetic-based modelling approach could be feasible. This approach was then validated in a simple system of calcite in synthetic solutions using pH titration experiments with the reliable Constant Composition Method (CCM).Further statistical analysis focused on clarifying key environmental factors that influence calcite precipitation to determine whether these are necessary to include in a model. Secondly, the proposed model approach was further tested on different types of wastewater and for multiple parallel precipitation reactions. Experiments included dynamic titration or aeration with synthetic wastewater and real wastewater. Thirdly, the general physicochemical modelling approach was implemented in a plant-wide platform together with standard biological models, namely activated sludge model No 2 (ASM2d) and Anaerobic Digestion Model No. 1 (ADM1). The plant-wide model evaluation compared simulations with real data from a full-scale wastewater treatment plant, and used steadystate, dynamic and scenario analyses to test the model performance.Experimental evidence for calcite precipitating in synthetic aqueous solutions, suggested that minerals precipitation kinetics could be reliably described with a 1 st order dependency on mineral Further testing for multi-species systems in real wastewater indicated that precipitation was dominated by the mineral struvite, forming together with varied and minor amounts of calcium phosphate and some calcium carbonate. Kinetic rate coefficients (kcryst), which were statistically fitted, were generally in the range 0.35-11.6 h -1 with 95% confidence intervals of 10-80% relative.The results confirmed that the baseline model approach provided a statistically good fit of measured pH, dissolved calcium, magnesium, total inorganic carbon and phosphate. With this application, the precipitation modelling approach offered the advantage of only requiring a minimal number of empirical fitted parameters (kcryst values), res...

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Section: Limitations In Current Biological Modelsmentioning

confidence: 99%

Section: Model Time Constant Issues: Kinetics Vs Equilibriummentioning

confidence: 99%