Nuestros investigadores

Paloma Grau Gumbau

Publicaciones científicas más recientes (desde 2010)

Autores: Elduayen Echave, Beñat (Autor de correspondencia); Azcona Calero, Mikel; Grau Gumbau, Paloma; et al.
ISSN 2214-7144  Vol. 38  2020  págs. 101657
Controlled struvite precipitation is a promising solution for phosphorus recovery in wastewater treatment plants. Particle size distribution of recovered struvite affects its efficacy as a fertilizer, so should be considered in the design and operation of struvite recovery reactors. This contribution analyzes the effect of varying the average shear rate (between 150 s(-1) and 876 s(-1)) and saturation index (between 0.76 and 2.96) in two different experimental set-ups. Solution pH and particle number and size measurements using an electric zone sensing method are used to monitor the process. In addition, photomicrographs are used to observe the shape of the precipitated particles. Interestingly, for identical thermochemical conditions, a higher mixing intensity, associated with the shear rate, leads to shorter induction times, faster precipitation and a greater particle density. On the other hand, for similar mixing conditions, a higher saturation index is also linked with shorter induction times, faster precipitation and a greater particle density. From the experimental data it is concluded that the effect of the fluid shear rate cannot be ignored and should be further studied in the precipitation process.
Autores: Elduayen Echave, Beñat (Autor de correspondencia); Lizarralde Aguirrezabal, Izaro; Sánchez Larraona, Gorka; et al.
ISSN 0043-1354  Vol. 155  2019  págs. 26 - 41
Mathematical models describing precipitation processes in one step need to be upgraded. Particle size distribution is a crucial variable and its inclusion in the modelling libraries is necessary if the technology wants to be optimized through simulation. With this objective, a mass based population balance model is presented in this contribution. The model has been constructed using a stoichiometric matrix and a kinetic vector and using mass as the internal coordinate, as it is usually done in wastewater treatment modelling. Identifiability of the parameters of the model was evaluated using a sensitivity and a collinearity analysis for six simulation case studies of struvite precipitation. In addition, parameters in the model were calibrated to represent data from two batch tests in the laboratory. The results of the analysis showed that the identifiability of the parameters depends on the available experimental data and explored scenarios. Identifiability of the parameters could be the reason behind the shifting parameter values describing mechanisms of precipitation in the literature. This contribution helps to understand the possibilities and limitations that the population balance model approach offer.
Autores: Lizarralde Aguirrezabal, Izaro (Autor de correspondencia); Fernández Arevalo, Tamara; Manas, A. ; et al.
ISSN 0043-1354  Vol. 153  2019  págs. 39 - 52
Phosphorus has been considered as a pollutant to be removed from the wastewater. In the last years, however, it has been considered a valuable asset that needs to be recovered due to its shortage in nature. The study of optimum phosphorus management in wastewater treatment plants is not straightforward, due to the complexity of technologies and configurations that may be applied for phosphorus removal and recovery. In this context, plant-wide mathematical modelling and simulation tools are very useful for carrying out these studies. This paper introduces a study carried out at the Sur WWTP (Madrid) to assess optimum phosphorus management strategies based on the PWM. The mathematical model made it possible to describe the phosphorus flux and its characterization throughout the plant. Finally, an exploration by simulation with WEST (TM) was carried out to analyse different plant configurations and different operational strategies to optimize phosphorus management strategies in the Sur WWTP.
Autores: Muñoz Villamizar, Andrés Felipe; Santos García, Javier; Garcia Sabater, Julio; et al.
ISSN 1741-0401  Vol. 3  2019  págs. 608 - 625
Autores: Muñoz Villamizar, Andrés Felipe (Autor de correspondencia); Santos García, Javier; Grau Gumbau, Paloma; et al.
ISSN 0007-070X  Vol. 121  Nº 5  2019  págs. 1140 - 1153
Purpose-The purpose of this paper is to analyze gaps and trends, as well suggest approaches andmethodologies that should be addressed by future studies for implementing the lean and green managementin the agri-food sector. Design/methodology/approach-Based on a sample with 117 papers, this paper presents a systematicreview on the integration of lean and green in the agri-food sector. Findings-Key findings indicate that research on lean and greentopics has increased in recent years, an importantgapintheintegrationofleanandgreenintheagri-foodsector has been identified. Two paths that remain open forfurther research are detected: the lack of theoretical, prescriptive and quantitative research and the possibility ofintegrating the two most used tools of lean (i.e. value stream mapping) and green (i.e. life-cycle assessment). Practical implications-This study does not only advance the theoretical knowledge of the lean and greenfield, but it is also beneficial for agri-food companies who aim to effectively deploy lean and green in theirprocesses in order to improve both operational and environmental performances. Social implications-No other industry matches in such a complete way the agri-food industry¿s challengeof sustainability that is due to the amount of resources it consumes and its interrelatedness with thewell-being of humanity. Originality/value-There are separate streams of established research on lean and green management inthe agri-food sector,
Autores: Regmi, P.; Stewart, H.; Amerlinck, Y.; et al.
ISSN 0273-1223  Vol. 79  Nº 1  2019  págs. 3 - 14
The wastewater industry is currently facing dramatic changes, shifting away from energy-intensive wastewater treatment towards low-energy, sustainable technologies capable of achieving energy positive operation and resource recovery. The latter will shift the focus of the wastewater industry to how one could manage and extract resources from the wastewater, as opposed to the conventional paradigm of treatment. Debatable questions arise: can the more complex models be calibrated, or will additional unknowns be introduced? After almost 30 years using well-known International Water Association (IWA) models, should the community move to other components, processes, or model structures like `black box¿ models, computational fluid dynamics techniques, etc.? Can new data sources ¿ e.g. on-line sensor data, chemical and molecular analyses, new analytical techniques, off-gas analysis ¿ keep up with the increasing process complexity? Are different methods for data management, data reconciliation, and fault detection mature enough for coping with such a large amount of information? Are the available calibration techniques able to cope with such complex models? This paper describes the thoughts and opinions collected during the closing session of the 6th IWA/WEF Water Resource Recovery Modelling Seminar 2018. It presents a concerted and collective effort by individuals from many different sectors of the wastewater industry to offer past and present insights, as well as an outlook into the future of wastewater modelling.
Autores: Lizarralde Aguirrezabal, Izaro (Autor de correspondencia); Fernández Arevalo, Tamara; Beltrán Calaff, Sergio; et al.
ISSN 0043-1354  Vol. 129  2018  págs. 305 - 318
This paper introduces a new mathematical model built under the PC-PWM methodology to describe the aeration process in a full-scale WWTP. This methodology enables a systematic and rigorous incorporation of chemical and physico-chemical transformations into biochemical process models, particularly for the description of liquid-gas transfer to describe the aeration process. The mathematical model constructed is able to reproduce biological COD and nitrogen removal, liquid-gas transfer and chemical reactions. The capability of the model to describe the liquid-gas mass transfer has been tested by comparing simulated and experimental results in a full-scale WWTP. Finally, an exploration by simulation has been undertaken to show the potential of the mathematical model. (C) 2017 Elsevier Ltd. All rights reserved.
Autores: Fernández Arevalo, Tamara; Lizarralde Aguirrezabal, Izaro; Maiza, M.; et al.
ISSN 0273-1223  Vol. 75  Nº 3  2017  págs. 518 - 529
Given the shift in perception of wastewater treatment plants as water resource recovery facilities, conventional mathematical models need to be updated. The resource recovery perspective should be applied to new processes, technologies and plant layouts. The number and level of models proposed to date give an overview of the complexity of the new plant configurations and provides a wide range of possibilities and process combinations in order to construct plant layouts. This diversity makes the development of standard, modular and flexible tools and model libraries that allow the incorporation of new processes and components in a straightforward way a necessity. In this regard, the plant-wide modelling (PWM) library is a complete model library that includes conventional and advanced technologies and that allows economic and energetic analyses to be carried out in a holistic way. This paper shows the fundamentals of this PWM library that is built upon the above-mentioned premises and the application of the PWM library in three different full-scale case studies.
Autores: Fernández Arevalo, Tamara; Lizarralde Aguirrezabal, Izaro; Fdz-Polanco, F.; et al.
ISSN 0043-1354  Vol. 118  2017  págs. 272 - 288
The growing development of technologies and processes for resource treatment and recovery is offering endless possibilities for creating new plant-wide configurations or modifying existing ones. However, the configurations¿ complexity, the interrelation between technologies and the influent characteristics turn decision-making into a complex or unobvious process. In this frame, the Plant-Wide Modelling (PWM) library presented in this paper allows a thorough, comprehensive and refined analysis of different plant configurations that are basic aspects in decision-making from an energy and resource recovery perspective. In order to demonstrate the potential of the library and the need to run simulation analyses, this paper carries out a comparative analysis of WWTPs, from a techno-economic point of view. The selected layouts were (1) a conventional WWTP based on a modified version of the Benchmark Simulation Model No. 2, (2) an upgraded or retrofitted WWTP, and (3) a new Wastewater Resource Recovery Facilities (WRRF) concept denominated as C/N/P decoupling WWTP. The study was based on a preliminary analysis of the organic matter and nutrient energy use and recovery options, a comprehensive mass and energy flux distribution analysis in each configuration in order to compare and identify areas for improvement, and a cost analysis of each plant for different influent COD/TN/TP ratios. Analysing the plants from a standpoint of resources and energy utilization, a low utilization of the energy content of the components could be observed in all configurations. In the conventional plant, the COD used to produce biogas was around 29%, the upgraded plant was around 36%, and 34% in the C/N/P decoupling WWTP. With regard to the self-sufficiency of plants, achieving self-sufficiency was not possible in the conventional plant, in the upgraded plant it depended on the influent C/N ratio, and in the C/N/P decoupling WWTP layout self-sufficiency was feasible for almost all influents, especially at high COD concentrations. The plant layouts proposed in this paper are just a sample of the possibilities offered by current technologies. Even so, the library presented here is generic and can be used to construct any other plant layout, provided that a model is available.
Autores: Lizarralde Aguirrezabal, Izaro; Fernández Arevalo, Tamara; Brouckaert, C; et al.
ISSN 0043-1354  Vol. 74  2015  págs. 239 - 256
This paper introduces a new general methodology for incorporating physico-chemical and chemical transformations into multi-phase wastewater treatment process models in a systematic and rigorous way under a Plant-Wide modelling (PWM) framework. The methodology presented in this paper requires the selection of the relevant biochemical, chemical and physico-chemical transformations taking place and the definition of the mass transport for the co-existing phases. As an example a mathematical model has been constructed to describe a system for biological COD, nitrogen and phosphorus removal, liquid gas transfer, precipitation processes, and chemical reactions. The capability of the model has been tested by comparing simulated and experimental results for a nutrient removal system with sludge digestion. Finally, a scenario analysis has been undertaken to show the potential of the obtained mathematical model to study phosphorus recovery. (C) 2015 Elsevier Ltd. All rights reserved.
Autores: Albizuri, J.; Grau Gumbau, Paloma; Christensson, M.; et al.
ISSN 0273-1223  Vol. 69  Nº 7  2014  págs. 1552 - 1557
The paper presents a systematic study of simulations, using a previously calibrated Colloid model, from which it was found that: (i) for pure moving-bed biofilm reactor (MBBR) processes with tertiary nitrification conditions (no influent chemical oxygen demand (COD)), dissolved oxygen = 5 mg/L and residual NH4-N > 4 mgN/L, a nitrification rate of 1.2 gN/(m(2)d) was obtained at 10 W C. This rate decreases sharply when residual NH4-N is lower than 2 mgN/L, (ii) for MBBR systems with predenitrification-nitrification zones and COD in the influent (soluble and particulate), the nitrification rate (0.6 gN/(m(2)d)) is half of that in tertiary nitrification due to the effect of influent colloidal X-S (particulate slowly biodegradable COD) and (iii) for integrated fixed-film activated sludge (IFAS) processes the nitrification rate in the biofilm (0.72 gN/(m(2)d)) is 20% higher than for the pure MBBR due to the lower effect of influent X-S since it is adsorbed onto flocs. However, it is still 40% lower than the tertiary nitrification rate. In the IFAS, the fraction of the nitrification rate in suspension ranges from 10 to 70% when the aerobic solids retention time varies from 1.4 to 6 days.
Autores: Fernández Arevalo, Tamara; Lizarralde Aguirrezabal, Izaro; Grau Gumbau, Paloma; et al.
ISSN 0043-1354  Vol. 60  2014  págs. 141 - 155
This paper presents a new modelling methodology for dynamically predicting the heat produced or consumed in the transformations of any biological reactor using Hess's law. Starting from a complete description of model components stoichiometry and formation enthalpies, the proposed modelling methodology has integrated successfully the simultaneous calculation of both the conventional mass balances and the enthalpy change of reaction in an expandable multi-phase matrix structure, which facilitates a detailed prediction of the main heat fluxes in the biochemical reactors. The methodology has been implemented in a plant-wide modelling methodology in order to facilitate the dynamic description of mass and heat throughout the plant. After validation with literature data, as illustrative examples of the capability of the methodology, two case studies have been described. In the first one, a predenitrification-nitrification dynamic process has been analysed, with the aim of demonstrating the easy integration of the methodology in any system. In the second case study, the simulation of a thermal model for an ATAD has shown the potential of the proposed methodology for analysing the effect of ventilation and influent characterization. (C) 2014 Elsevier Ltd. All rights reserved.
Autores: Maiza Galparsoro, Mikel; Bengoechea García, Asier; Grau Gumbau, Paloma; et al.
ISSN 0273-1223  Vol. 68  Nº 2  2013  págs. 296 - 302
This paper summarizes part of the research work carried out in the Add Control project, which proposes an extension of the wastewater treatment plant (WWTP) models and modelling architectures used in traditional WWTP simulation tools, addressing, in addition to the classical mass transformations (transport, physico-chemical phenomena, biological reactions), all the instrumentation, actuation and automation & control components (sensors, actuators, controllers), considering their real behaviour (signal delays, noise, failures and power consumption of actuators). Its ultimate objective is to allow a rapid transition from the simulation of the control strategy to its implementation at full-scale plants. Thus, this paper presents the application of the Add Control simulation platform for the design and implementation of new control strategies at the WWTP of Mekolalde.
Autores: Lizarralde Aguirrezabal, Izaro; Claeys, F.; Ordoñez, R.; et al.
ISSN 0273-1223  Vol. 65  Nº 11  2012  págs. 1929 - 1938
The increasing costs associated with water supply and the disposal of wastewater has stimulated industries to seek more efficient water management systems. Mathematical modelling and simulation can be a very valuable tool for the study of the multiple alternatives available whilst assessing optimum solutions for water management in industry. This study introduces a new steady state model library able to reproduce industrial water circuits. It has been implemented in a novel software framework for the representation, simulation and optimization of industrial water networks. A water circuit representing a paper mill has been modelled and simulated showing the capability to reproduce real case studies. Alternative scenarios for the water network have also been tested to assess the capability of the models to optimize water circuits minimizing total cost.
Autores: Batstone, D.J.; Amerlinck, Y.; Ekama, G.; et al.
ISSN 0273-1223  Vol. 66  Nº 6  2012  págs. 1147 - 1161
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.
Autores: de Gracia, M.; Grau Gumbau, Paloma; Ayesa Iturrate, Eduardo José; et al.
ISSN 0273-1223  Vol. 64  Nº 3  2011  págs. 557 - 567
This paper presents the characterisation procedure of different types of sludge generated in a wastewater treatment plant to be reproduced in a mathematical model of the sludge digestion process. The automatic calibration method used is based on an optimisation problem and uses a set of mathematical equations related to the a priori knowledge of the sludge composition, the experimental measurements applied to the real sludge, and the definition of the model components. In this work, the potential of the characterisation methodology is shown by means of a real example, taking into account that sludge is a very complex matter to characterise and that the models for digestion also have a considerable number of model components. The results obtained suit both the previously reported characteristics of the primary, secondary and mixed sludge, and the experimental measurements specially done for this work. These three types of sludge have been successfully characterised to be used in complex mathematical models.
Autores: Elduayen Echave, Beñat; Ochoa de Eribe, A.; Lizarralde Aguirrezabal, Izaro; et al.
Libro:  Frontiers in Wastewater Treatment and Modelling. Lecture Notes in Civil Engineering
Vol. 4  2017  págs. 614 - 621
Struvite precipitation has raised as a promising solution to recover phosphorous in wastewater treatment plants (WWTP). Struvite is a fertilizer that varies its performance depending on its size. This shows the need to upgrade one-step classic kinetic precipitation models by new frameworks as the Population Balance Model (PBM). In this abstract a mass-based Discretized Population Balance Model (DPBM) used to predict struvite precipitation is presented. The model includes primary nucleation, growth and aggregation mechanisms as a function of supersaturation index and kinetic parameters. Main advantage of the mass-based definition is that mass continuity is guaranteed and that it is fully compatible with other chemical and physicochemical reactions. A sensitivity analysis performed reveals exponents of nucleation and growth as the most relevant parameters in the pH evolution during precipitation and final Particle Size Distribution (PSD). Experimental data was used to calibrate the model employing Bayesian Inference. Selected values of the parameters showed good agreement with reality.