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Kirim G, Torfs E, Vanrolleghem PA. An improved 1D reactive Bürger-Diehl settler model for secondary settling tank denitrification. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2022; 94:e10825. [PMID: 36518000 DOI: 10.1002/wer.10825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/22/2022] [Accepted: 11/26/2022] [Indexed: 06/17/2023]
Abstract
An improved 1D reactive settler model is pursued in order to increase the understanding of reactive settling processes and obtain a better prediction of the nitrogen mass balance in wastewater treatment systems. The developed model is based on the 1D Bürger-Diehl settler model with compression function and the Activated Sludge Model No. 1 biological reactions. Specific attention was paid in the model development phase to optimal selection of settling velocity functions and integration of the correct clarifier geometry. A unique measurement campaign was carried out with different operational scenarios to quantify the denitrification in a secondary settling tank. A detailed step-wise calibration effort demonstrated that by choosing an appropriate settling velocity function (power-law structure) and considering the true clarifier geometry allows to accurately capture the biomass concentration profile, total sludge mass, sludge blanket height, and the reaction rates. The resulting model is able to accurately describe total suspended solids (TSS) and nitrate concentration profiles throughout a settling tank under different operational conditions. As such the model can be applied in further scenario analysis and system optimization. PRACTITIONER POINTS: A unique measurement campaign was carried out to obtain detailed data for a reactive settler model development. A 1-D reactive settler model is developed based on the Bürger-Diehl framework including ASM1 biokinetics and the clarifier geometry. An extensive calibration and model selection effort was performed. The model accurately predicts measured concentration profiles in the settling tank. The developed model can be integrated in a plant-wide model to properly calculate the nitrogen mass balance of a WRRF.
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Affiliation(s)
- Gamze Kirim
- modelEAU, Université Laval, Québec, Québec, Canada
- CentrEau, Quebec Water Research Centre, Québec, Québec, Canada
| | - Elena Torfs
- modelEAU, Université Laval, Québec, Québec, Canada
- BIOMATH, Department of Data Analysis and Mathematical Modelling, Ghent University, Ghent, Belgium
- CentrEau, Quebec Water Research Centre, Québec, Québec, Canada
- Centre for Advanced Process Technology for Urban Resource recovery (CAPTURE), Ghent, Belgium
| | - Peter A Vanrolleghem
- modelEAU, Université Laval, Québec, Québec, Canada
- CentrEau, Quebec Water Research Centre, Québec, Québec, Canada
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2
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Bürger R, Careaga J, Diehl S, Pineda R. A model of reactive settling of activated sludge: comparison with experimental data. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.118244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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3
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Modelling filamentous bacteria in activated sludge systems and the advancements of secondary settling tank models: A review. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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4
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Design of Feedback Control Strategies in a Plant-Wide Wastewater Treatment Plant for Simultaneous Evaluation of Economics, Energy Usage, and Removal of Nutrients. ENERGIES 2021. [DOI: 10.3390/en14196386] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Simultaneous removal of nitrogen and phosphorous is a recommended practice while treating wastewater. In the present study, control strategies based on proportional-integral (PI), model predictive control (MPC), and fuzzy logic are developed and implemented on a plant-wide wastewater treatment plant. Four combinations of control frameworks are developed in order to reduce the operational cost and improve the effluent quality. As a working platform, a Benchmark simulation model (BSM2-P) is used. A default control framework with PI controllers is used to control nitrate and dissolved oxygen (DO) by manipulating the internal recycle and oxygen mass transfer coefficient (KLa). Hierarchical control topology is proposed in which a lower-level control framework with PI controllers is implemented to DO in the sixth reactor by regulating the KLa of the fifth, sixth, and seventh reactors, and fuzzy and MPC are used at the supervisory level. This supervisory level considers the ammonia in the last aerobic reactor as a feedback signal to alter the DO set-points. PI-fuzzy showed improved effluent quality by 21.1%, total phosphorus removal rate by 33.3% with an increase of operational cost, and a slight increase in the production rates of greenhouse gases. In all the control design frameworks, a trade-off is observed between operational cost and effluent quality.
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Giberti M, Dereli RK, Flynn D, Casey E. Predicting wastewater treatment plant performance during aeration demand shifting with a dual-layer reaction settling model. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 81:1365-1374. [PMID: 32616689 DOI: 10.2166/wst.2019.262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Demand response (DR) programmes encourage energy end users to adjust their consumption according to energy availability and price. Municipal wastewater treatment plants are suitable candidates for the application of such programmes. Demand shedding through aeration control, subject to maintaining the plant operational limits, could have a large impact on the plant DR potential. Decreasing the aeration intensity may promote the settling of the particulate components present in the reactor mixed liquor. The scope of this study is thus to develop a mathematical model to describe this phenomenon. For this purpose, Benchmark Simulation Model No.1 was extended by implementing a dual-layer settling model in one of the aerated tanks and combining it with biochemical reaction kinetic equations. The performance of this extended model was assessed in both steady-state and dynamic conditions, switching the aeration system off for 1 hour during each day of simulation. This model will have applications in the identification of potential benefits and issues related to DR events, as well as in the simulation of the plant operation where aerated tank settling is implemented.
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Affiliation(s)
- Matteo Giberti
- School of Chemical and Bioprocess Engineering, University College Dublin, Ireland E-mail:
| | - Recep Kaan Dereli
- School of Chemical and Bioprocess Engineering, University College Dublin, Ireland E-mail:
| | - Damian Flynn
- School of Electrical and Electronic Engineering, University College Dublin, Ireland
| | - Eoin Casey
- School of Chemical and Bioprocess Engineering, University College Dublin, Ireland E-mail:
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Muoio R, Palli L, Ducci I, Coppini E, Bettazzi E, Daddi D, Fibbi D, Gori R. Optimization of a large industrial wastewater treatment plant using a modeling approach: A case study. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 249:109436. [PMID: 31454637 DOI: 10.1016/j.jenvman.2019.109436] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/14/2019] [Accepted: 08/18/2019] [Indexed: 06/10/2023]
Abstract
The objective of this paper is to find the optimum solid retention time (SRT) of a wastewater treatment plant (WWTP), which minimizes operating costs, using a modeling approach with WEST software by MIKE DHI®. For the determination of the kinetic and stoichiometric parameters (used for the correct calibration of the model implemented), respirometric and kinetic batch tests were carried out. Each Oxidation ditch was modeled by a sequence of four aerated activated sludge units (ASUs) and four anoxic ASUs with recirculation. The model is able to simulate the separation efficiency of the secondary settler, which is generally quite low: in fact, the industrial origin of the wastewater induces the formation of small flocs, the dimensions of which can be further reduced by the presence of surface aerators. The nitrification/denitrification process is also accurately predicted. Using data obtained from the model, mass balances at the steady state for COD and N were made and compared to the ones obtained using measured data. After calibration and validation of the model, steady-state simulations were carried out by increasing and decreasing the SRT of the system under two different operational conditions used by the managing company and by evaluating the costs related to the water treatment line and the sludge treatment line for each scenario. It is interesting to note how the total costs are lower in summer than in winter (7.2 €cent/m3 in summer and 8.7 €cent/m3 in winter, in scenario 0). In general, the increase in the SRT led to a decrease in the total management costs. In fact, differences between scenario 0 and the scenario with the lowest total treatment costs (corresponding to an SRT of 11.4 d in winter and 10.0 d in summer) could give rise to total savings of about 44·000€/year in summer and 93·000€/year in winter.
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Affiliation(s)
- Roberta Muoio
- Department of Civil and Environmental Engineering, University of Florence, Via Santa Marta 3, Florence, Italy
| | - Laura Palli
- Department of Civil and Environmental Engineering, University of Florence, Via Santa Marta 3, Florence, Italy.
| | - Iacopo Ducci
- Department of Civil and Environmental Engineering, University of Florence, Via Santa Marta 3, Florence, Italy
| | | | | | | | | | - Riccardo Gori
- Department of Civil and Environmental Engineering, University of Florence, Via Santa Marta 3, Florence, Italy
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Solon K, Flores-Alsina X, Kazadi Mbamba C, Ikumi D, Volcke EIP, Vaneeckhaute C, Ekama G, Vanrolleghem PA, Batstone DJ, Gernaey KV, Jeppsson U. Plant-wide modelling of phosphorus transformations in wastewater treatment systems: Impacts of control and operational strategies. WATER RESEARCH 2017; 113:97-110. [PMID: 28199867 DOI: 10.1016/j.watres.2017.02.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/02/2017] [Accepted: 02/03/2017] [Indexed: 05/06/2023]
Abstract
The objective of this paper is to report the effects that control/operational strategies may have on plant-wide phosphorus (P) transformations in wastewater treatment plants (WWTP). The development of a new set of biological (activated sludge, anaerobic digestion), physico-chemical (aqueous phase, precipitation, mass transfer) process models and model interfaces (between water and sludge line) were required to describe the required tri-phasic (gas, liquid, solid) compound transformations and the close interlinks between the P and the sulfur (S) and iron (Fe) cycles. A modified version of the Benchmark Simulation Model No. 2 (BSM2) (open loop) is used as test platform upon which three different operational alternatives (A1, A2, A3) are evaluated. Rigorous sensor and actuator models are also included in order to reproduce realistic control actions. Model-based analysis shows that the combination of an ammonium ( [Formula: see text] ) and total suspended solids (XTSS) control strategy (A1) better adapts the system to influent dynamics, improves phosphate [Formula: see text] accumulation by phosphorus accumulating organisms (XPAO) (41%), increases nitrification/denitrification efficiency (18%) and reduces aeration energy (Eaeration) (21%). The addition of iron ( [Formula: see text] ) for chemical P removal (A2) promotes the formation of ferric oxides (XHFO-H, XHFO-L), phosphate adsorption (XHFO-H,P, XHFO-L,P), co-precipitation (XHFO-H,P,old, XHFO-L,P,old) and consequently reduces the P levels in the effluent (from 2.8 to 0.9 g P.m-3). This also has an impact on the sludge line, with hydrogen sulfide production ( [Formula: see text] ) reduced (36%) due to iron sulfide (XFeS) precipitation. As a consequence, there is also a slightly higher energy production (Eproduction) from biogas. Lastly, the inclusion of a stripping and crystallization unit (A3) for P recovery reduces the quantity of P in the anaerobic digester supernatant returning to the water line and allows potential struvite ( [Formula: see text] ) recovery ranging from 69 to 227 kg.day-1 depending on: (1) airflow (Qstripping); and, (2) magnesium ( [Formula: see text] ) addition. All the proposed alternatives are evaluated from an environmental and economical point of view using appropriate performance indices. Finally, some deficiencies and opportunities of the proposed approach when performing (plant-wide) wastewater treatment modelling/engineering projects are discussed.
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Affiliation(s)
- K Solon
- Division of Industrial Electrical Engineering and Automation, Department of Biomedical Engineering, Lund University, Box 118, SE-221 00, Lund, Sweden
| | - X Flores-Alsina
- CAPEC-PROCESS Research Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, DK-2800, Kgs. Lyngby, Denmark
| | - C Kazadi Mbamba
- Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia
| | - D Ikumi
- Water Research Group, Department of Civil Engineering, University of Cape Town, Rondebosch, 7700, South Africa
| | - E I P Volcke
- Department of Biosystems Engineering, Ghent University, Coupure Links 653, B-9000, Gent, Belgium
| | - C Vaneeckhaute
- BioEngine, Department of Chemical Engineering, Université Laval, Québec, QC, G1V 0A6, Canada
| | - G Ekama
- Water Research Group, Department of Civil Engineering, University of Cape Town, Rondebosch, 7700, South Africa
| | - P A Vanrolleghem
- modelEAU, Département de Génie Civil et de Génie des Eaux, Université Laval, Québec, QC, G1V 0A6, Canada
| | - D J Batstone
- Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia
| | - K V Gernaey
- CAPEC-PROCESS Research Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, DK-2800, Kgs. Lyngby, Denmark
| | - U Jeppsson
- Division of Industrial Electrical Engineering and Automation, Department of Biomedical Engineering, Lund University, Box 118, SE-221 00, Lund, Sweden.
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8
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Bürger R, Careaga J, Diehl S, Mejías C, Nopens I, Torfs E, Vanrolleghem PA. Simulations of reactive settling of activated sludge with a reduced biokinetic model. Comput Chem Eng 2016. [DOI: 10.1016/j.compchemeng.2016.04.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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de Araujo ACB, Gallani S, Mulas M, Skogestad S. Sensitivity Analysis of Optimal Operation of an Activated Sludge Process Model for Economic Controlled Variable Selection. Ind Eng Chem Res 2013. [DOI: 10.1021/ie4006673] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Antonio C. B. de Araujo
- Department
of Chemical Engineering, Federal University of Campina Grande, 58429-900 Campina Grande, Paraiba, Brazil
| | - Simone Gallani
- Department
of Chemical Engineering, Federal University of Campina Grande, 58429-900 Campina Grande, Paraiba, Brazil
| | - Michela Mulas
- Department of Civil and Environmental
Engineering, Aalto University, P.O. Box
15200, FI-00076 Aalto, Finland
| | - Sigurd Skogestad
- Department of Chemical Engineering, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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10
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Guerrero J, Flores-Alsina X, Guisasola A, Baeza JA, Gernaey KV. Effect of nitrite, limited reactive settler and plant design configuration on the predicted performance of simultaneous C/N/P removal WWTPs. BIORESOURCE TECHNOLOGY 2013; 136:680-688. [PMID: 23579003 DOI: 10.1016/j.biortech.2013.03.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 03/02/2013] [Accepted: 03/06/2013] [Indexed: 06/02/2023]
Abstract
This paper describes a modelling study where five new benchmark plant design configurations for biological nutrient removal (A(2)/O, UCT, JHB, MUCT and BDP-5 stage) are simulated and evaluated under different model assumptions. The ASM2d including electron dependent decay rates is used as the reference model (A1). The second case (A2) adds nitrite as a new state variable, describing nitrification and denitrification as two-step processes. The third set of models (A3 and A4) considers different reactive settlers types (diffusion-limited/non limited). This study analyses the importance of these new model extensions to correctly describe the nitrification behaviour and the carbon source competition between ordinary heterotrophic organisms (OHO) and polyphosphate accumulating organisms (PAO) under certain operation conditions. The economic and environmental aspects when meeting the P discharge limits by adding an external carbon source are also studied.
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Affiliation(s)
- Javier Guerrero
- Center for Process Engineering and Technology (PROCESS), Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, DK-2800 Kgs. Lyngby, Denmark.
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11
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Ostace GS, Cristea VM, Agachi PŞ. Cost reduction of the wastewater treatment plant operation by MPC based on modified ASM1 with two-step nitrification/denitrification model. Comput Chem Eng 2011. [DOI: 10.1016/j.compchemeng.2011.03.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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12
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de Araújo ACB, Gallani S, Mulas M, Olsson G. Systematic Approach to the Design of Operation and Control Policies in Activated Sludge Systems. Ind Eng Chem Res 2011. [DOI: 10.1021/ie101703s] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Antonio C. B. de Araújo
- Department of Chemical Engineering, Federal University of Campina Grande, 58429-140 Campina Grande, Paraiba, Brazil
| | - Simone Gallani
- Department of Chemical Engineering, Federal University of Campina Grande, 58429-140 Campina Grande, Paraiba, Brazil
| | - Michela Mulas
- Department of Civil and Environmental Engineering, Aalto University, P.O. Box 15200, FI-00076 Aalto, Finland
| | - Gustaf Olsson
- Department of Measurement Technology and Industrial Electrical Engineering, Lund University, SE-22100 Lund, Sweden
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Flores-Alsina X, Gallego A, Feijoo G, Rodriguez-Roda I. Multiple-objective evaluation of wastewater treatment plant control alternatives. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2010; 91:1193-1201. [PMID: 20167418 DOI: 10.1016/j.jenvman.2010.01.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 12/15/2009] [Accepted: 01/10/2010] [Indexed: 05/28/2023]
Abstract
Besides the evaluation of the environmental issues, the correct assessment of wastewater treatment plants (WWTP) should take into account several objectives such as: economic e.g. operation costs; technical e.g. risk of suffering microbiology-related TSS separation problems; or legal e.g. accomplishment with the effluent standards in terms of the different pollution loads. For this reason, the main objective of this paper is to show the benefits of complementing the environmental assessment carried out by life cycle assessment with economical, technical and legal criteria. Using a preliminary version of the BSM2 as a case study, different combinations of controllers are implemented, simulated and evaluated. In the following step, the resulting multi-criteria matrix is mined using multivariate statistical techniques. The results showed that the presence of an external carbon source addition, the type of aeration system and the TSS controller are the key elements creating the differences amongst the alternatives. Also, it was possible to characterize the different control strategies according to a set of aggregated criteria. Additionally, the existing synergies amongst different objectives and their consequent trade-offs were identified. Finally, it was discovered that from the initial extensive list of evaluation criteria, only a small set of five are really discriminant, being useful to differentiate within the generated alternatives.
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Affiliation(s)
- Xavier Flores-Alsina
- Laboratory of Chemical and Environmental Engineering, University of Girona, Montilivi Campus s/n 17071, Girona, Spain.
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Flores-Alsina X, Comas J, Rodriguez-Roda I, Gernaey KV, Rosen C. Including the effects of filamentous bulking sludge during the simulation of wastewater treatment plants using a risk assessment model. WATER RESEARCH 2009; 43:4527-4538. [PMID: 19695661 DOI: 10.1016/j.watres.2009.07.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 07/26/2009] [Accepted: 07/31/2009] [Indexed: 05/28/2023]
Abstract
The main objective of this paper is to demonstrate how including the occurrence of filamentous bulking sludge in a secondary clarifier model will affect the predicted process performance during the simulation of WWTPs. The IWA Benchmark Simulation Model No. 2 (BSM2) is hereby used as a simulation case study. Practically, the proposed approach includes a risk assessment model based on a knowledge-based decision tree to detect favourable conditions for the development of filamentous bulking sludge. Once such conditions are detected, the settling characteristics of the secondary clarifier model are automatically changed during the simulation by modifying the settling model parameters to mimic the effect of growth of filamentous bacteria. The simulation results demonstrate that including effects of filamentous bulking in the secondary clarifier model results in a more realistic plant performance. Particularly, during the periods when the conditions for the development of filamentous bulking sludge are favourable--leading to poor activated sludge compaction, low return and waste TSS concentrations and difficulties in maintaining the biomass in the aeration basins--a subsequent reduction in overall pollution removal efficiency is observed. Also, a scenario analysis is conducted to examine i) the influence of sludge retention time (SRT), the external recirculation flow rate (Q(r)) and the air flow rate in the bioreactor (modelled as k(L)a) as factors promoting bulking sludge, and ii) the effect on the model predictions when the settling properties are changed due to a possible proliferation of filamentous microorganisms. Finally, the potentially adverse effects of certain operational procedures are highlighted, since such effects are normally not considered by state-of-the-art models that do not include microbiology-related solids separation problems.
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Affiliation(s)
- Xavier Flores-Alsina
- Laboratory of Chemical and Environmental Engineering, University of Girona, Montilivi Campus s/n, Girona, Spain.
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15
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Flores-Alsina X, Rodríguez-Roda I, Sin G, Gernaey KV. Multi-criteria evaluation of wastewater treatment plant control strategies under uncertainty. WATER RESEARCH 2008; 42:4485-4497. [PMID: 18804255 DOI: 10.1016/j.watres.2008.05.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 05/13/2008] [Accepted: 05/29/2008] [Indexed: 05/26/2023]
Abstract
The evaluation of activated sludge control strategies in wastewater treatment plants (WWTP) via mathematical modelling is a complex activity because several objectives; e.g. economic, environmental, technical and legal; must be taken into account at the same time, i.e. the evaluation of the alternatives is a multi-criteria problem. Activated sludge models are not well characterized and some of the parameters can present uncertainty, e.g. the influent fractions arriving to the facility and the effect of either temperature or toxic compounds on the kinetic parameters, having a strong influence in the model predictions used during the evaluation of the alternatives and affecting the resulting rank of preferences. Using a simplified version of the IWA Benchmark Simulation Model No. 2 as a case study, this article shows the variations in the decision making when the uncertainty in activated sludge model (ASM) parameters is either included or not during the evaluation of WWTP control strategies. This paper comprises two main sections. Firstly, there is the evaluation of six WWTP control strategies using multi-criteria decision analysis setting the ASM parameters at their default value. In the following section, the uncertainty is introduced, i.e. input uncertainty, which is characterized by probability distribution functions based on the available process knowledge. Next, Monte Carlo simulations are run to propagate input through the model and affect the different outcomes. Thus (i) the variation in the overall degree of satisfaction of the control objectives for the generated WWTP control strategies is quantified, (ii) the contributions of environmental, legal, technical and economic objectives to the existing variance are identified and finally (iii) the influence of the relative importance of the control objectives during the selection of alternatives is analyzed. The results show that the control strategies with an external carbon source reduce the output uncertainty in the criteria used to quantify the degree of satisfaction of environmental, technical and legal objectives, but increasing the economical costs and their variability as a trade-off. Also, it is shown how a preliminary selected alternative with cascade ammonium controller becomes less desirable when input uncertainty is included, having simpler alternatives more chance of success.
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Affiliation(s)
- Xavier Flores-Alsina
- Laboratory of Chemical and Environmental Engineering, University of Girona, Girona, Spain.
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16
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Flores X, Rodríguez-Roda I, Poch M, Jiménez L, Bañares-Alcántara R. Systematic Procedure to Handle Critical Decisions during the Conceptual Design of Activated Sludge Plants. Ind Eng Chem Res 2007. [DOI: 10.1021/ie061426a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xavier Flores
- Laboratory of Chemical and Environmental Engineering, University of Girona, Montilivi Campus s/n 17071 Girona, Spain
| | - Ignasi Rodríguez-Roda
- Laboratory of Chemical and Environmental Engineering, University of Girona, Montilivi Campus s/n 17071 Girona, Spain
| | - Manel Poch
- Laboratory of Chemical and Environmental Engineering, University of Girona, Montilivi Campus s/n 17071 Girona, Spain
| | - Laureano Jiménez
- Department of Chemical Engineering, University of Barcelona, Martí Franquès 1, 08028 Barcelona, Spain
| | - René Bañares-Alcántara
- Department of Engineering Science, Oxford University, Parks Road, OX1 3PJ, Oxford, United Kingdom
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