One-dimensional modelling of the secondary clarifier-factors affecting simulation in the clarification zone and the assessment of the thickening flow dependence

Plósz, Benedek G.; Weiß, Michael; Printemps, C.; Essemiani, Karim; Meinhold, Jens

doi:10.1016/j.watres.2007.03.007

Cited by 41 publications

(20 citation statements)

References 20 publications

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“…This leads to severe faulty predictions of MLSS in the bioreactor as shown in Figure 5. This corresponds with recent findings in literature (Plosz et al, 2007;Bürger et al, 2011). Therefore, the Bürger model was adopted for the sludge removal system of the Eindhoven WWTP.…”

Section: Modelling the Wwtp In Wet Weather Conditions Secondary Settlersupporting

confidence: 77%

Integrated model-based optimisation at the WWTP of Eindhoven

Keyser

Hulle

Plano

et al. 2012

Water Practice and Technology

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The current model of the full-scale wastewater treatment plant model in Eindhoven uses a state-of-the-art model for the biological processes (ASM2d) and is calibrated for C-and N-removal in dry weather. However, for the "Kallisto" project, which is an innovation programme aiming at a smart improvement of the surface water quality of the river Dommel by applying cost effective integrated system measures, the WWTP model needs to be improved to predict the WWTP performance under all conditions foreseen in the scenarios (e.g. storm events). A project approach was developed with parallel improvements in the different submodels, based on the interaction between submodels and the availability of several on-line sensors in influent, in-process and effluent. This is in contrast to most WWTP modelling studies, where focus is only on one submodel. It should lead to a well-balanced dynamic model that is able to predict WWTP behaviour under various conditions and that will be included in the integrated model, which will serve as an important decision support tool. Keywords urban wastewater system, dynamic modelling, WWTP optimization INTRODUCTIONOverall improvement of efficiency, increasingly stringent effluent discharge limits, the aim for a better surface water quality, minimization of energy use and greenhouse gas emissions are current drivers for the optimization of urban wastewater systems and operational strategies of wastewater treatment plants (WWTPs). In this respect, the use of dynamic models has already proven to be of great value. Indeed, a model with high predictive power allows testing of different optimisation strategies without disrupting the actual operation of the plant i.e. without the risk of losing biomass or violating discharge permits. Waterboard De Dommel (WDD, The Netherlands) has shown long-term interest in the development and use of dynamic models, which resulted in a calibrated dynamic model (including COD, N and P removal) of WWTP Haaren (Sin et al.,2008). Building further on the gained knowledge, a full-scale model of Eindhoven was calibrated and validated for dry weather including C and N removal (Nopens et al., 2010). This model is used as basis in the wastewater treatment plant modelling part of the current "Kallisto" project, which studies the integrated urban water system in the water cluster Eindhoven.

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Section: Modelling the Wwtp In Wet Weather Conditions Secondary Settlersupporting

confidence: 77%

Integrated model-based optimisation at the WWTP of Eindhoven

Keyser

Hulle

Plano

et al. 2012

Water Practice and Technology

View full text Add to dashboard Cite

show abstract

“…Batch settling curves were measured using a SettloMeter (Applitek NV, Belgium; Vanrolleghem et al 1996), and further information on the experimental techniques used is presented by Pló sz et al (2007).…”

Section: Batch Settling Experimentsmentioning

confidence: 99%

“…Despite the progress made in the last two decades in the field (Watts et al 1996;Diehl & Jeppsson 1998;Bü rger et al 2005;Pló sz et al 2007;De Clercq et al 2008), the 1-D SST model developed by Taká cs et al (1991) is still the most widely used. This can, in part, be explained by the fact that most of the software packages provide only the Taká cs model, and that WWTP process modellers either ignore the settler performance in their assessment studies or may not be aware of the development in the field.…”

Section: Introductionmentioning

confidence: 99%

Shall we upgrade one-dimensional secondary settler models used in WWTP simulators? – An assessment of model structure uncertainty and its propagation

Plósz

Clercq

Benedetti

et al. 2011

Water Science and Technology

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In WWTP models, the accurate assessment of solids inventory in bioreactors equipped with solid-liquid separators, mostly described using one-dimensional (1-D) secondary settling tank (SST) models, is the most fundamental requirement of any calibration procedure. Scientific knowledge on characterising particulate organics in wastewater and on bacteria growth is well-established, whereas 1-D SST models and their impact on biomass concentration predictions are still poorly understood. A rigorous assessment of two 1-DSST models is thus presented: one based on hyperbolic (the widely used Takács-model) and one based on parabolic (the more recently presented Plósz-model) partial differential equations. The former model, using numerical approximation to yield realistic behaviour, is currently the most widely used by wastewater treatment process modellers. The latter is a convection-dispersion model that is solved in a numerically sound way. First, the explicit dispersion in the convection-dispersion model and the numerical dispersion for both SST models are calculated. Second, simulation results of effluent suspended solids concentration (XTSS,Eff), sludge recirculation stream (XTSS,RAS) and sludge blanket height (SBH) are used to demonstrate the distinct behaviour of the models. A thorough scenario analysis is carried out using SST feed flow rate, solids concentration, and overflow rate as degrees of freedom, spanning a broad loading spectrum. A comparison between the measurements and the simulation results demonstrates a considerably improved 1-D model realism using the convection-dispersion model in terms of SBH, XTSS,RAS and XTSS,Eff. Third, to assess the propagation of uncertainty derived from settler model structure to the biokinetic model, the impact of the SST model as sub-model in a plant-wide model on the general model performance is evaluated. A long-term simulation of a bulking event is conducted that spans temperature evolution throughout a summer/winter sequence. The model prediction in terms of nitrogen removal, solids inventory in the bioreactors and solids retention time as a function of the solids settling behaviour is investigated. It is found that the settler behaviour, simulated by the hyperbolic model, can introduce significant errors into the approximation of the solids retention time and thus solids inventory of the system. We demonstrate that these impacts can potentially cause deterioration of the predictive power of the biokinetic model, evidenced by an evaluation of the system's nitrogen removal efficiency. The convection-dispersion model exhibits superior behaviour, and the use of this type of model thus is highly recommended, especially bearing in mind future challenges, e.g., the explicit representation of uncertainty in WWTP models.

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“…CFD models are based on the NaviereStokes equations and are computationally demanding. Nevertheless, they are cost effective because validated CFD models can be employed instead of field experiments to generate data for the calibration and validation of simpler one-dimensional (1-D) SST models for WWTP simulations under a range of boundary conditions (De Clercq, 2003;Pl osz et al, 2007).…”

Section: Introductionmentioning

confidence: 99%