| 1. |
- Regmi, P., et al.
(författare)
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The future of WRRF modelling - Outlook and challenges
- 2019
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 79:1, s. 3-14
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Carstensen, J., et al.
(författare)
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Objective Functions for Wastewater Treatment Design and Operation
- 1995
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Ingår i: COST 682 Environment: Optimizing the Design and Operation of Biological Wastewater Treatment Plants through the use of Computer Programmes based on Dynamic Modelling of the Process: Report 1992-95. - 9282743446 ; , s. 105-108
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Bokkapitel (refereegranskat)
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| 3. |
- Jeppsson, Ulf, et al.
(författare)
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Benchmark simulation models, quo vadis?
- 2013
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 68:1, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- As the work of the IWA Task Group on Benchmarking of Control Strategies for wastewater treatment plants (WWTPs) is coming to an end, it is essential to disseminate the knowledge gained. For this reason, all authors of the IWA Scientific and Technical Report on benchmarking have come together to provide their insights, highlighting areas where knowledge may still be deficient and where new opportunities are emerging, and to propose potential avenues for future development and application of the general benchmarking framework and its associated tools. The paper focuses on the topics of temporal and spatial extension, process modifications within the WWTP, the realism of models, control strategy extensions and the potential for new evaluation tools within the existing benchmark system. We find that there are major opportunities for application within all of these areas, either from existing work already being done within the context of the benchmarking simulation models (BSMs) or applicable work in the wider literature. Of key importance is increasing capability, usability and transparency of the BSM package while avoiding unnecessary complexity.
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| 4. |
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| 5. |
- Olsson, Gustaf, et al.
(författare)
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Instrumentation, control and automation in wastewater – from London 1973 to Narbonne 2013
- 2014
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 69:7, s. 1373-1385
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Tidskriftsartikel (refereegranskat)abstract
- Key developments of instrumentation, control and automation (ICA) applications in wastewater systems during the past 40 years are highlighted in this paper. From the first ICA conference in 1973 through to today there has been a tremendous increase in the understanding of the processes, instrumentation, computer systems and control theory. However, many developments have not been addressed here, such as sewer control, drinking water treatment and water distribution control. It is hoped that this review can stimulate new attempts to more effectively apply control and automation in water systems in the coming years.
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| 6. |
- Vanrolleghem, P., et al.
(författare)
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Simulators for Modelling of WWTP
- 1995
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Ingår i: COST 682 Environment : Optimizing the Design and Operation of Biological Wastewater Treatment Plants through the use of Computer Programmes based on Dynamic Modelling of the Process. - 9282743446 ; , s. 67-78
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Bokkapitel (refereegranskat)
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| 7. |
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| 8. |
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| 9. |
- Jeppsson, Ulf, et al.
(författare)
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Benchmark simulation model no 2: general protocol and exploratory case studies
- 2007
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 56:8, s. 67-78
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Tidskriftsartikel (refereegranskat)abstract
- Over a decade ago, the concept of objectively evaluating the performance of control strategies by simulating them using a standard model implementation was introduced for activated sludge wastewater treatment plants. The resulting Benchmark Simulation Model No 1 (BSM1) has been the basis for a significant new development that is reported on here: Rather than only evaluating control strategies at the level of the activated sludge unit (bioreactors and secondary clarifier) the new BSM2 now allows the evaluation of control strategies at the level of the whole plant, including primary clarifier and sludge treatment with anaerobic sludge digestion. In this contribution, the decisions that have been made over the past three years regarding the models used within the BSM2 are presented and argued, with particular emphasis on the ADM1 description of the digester, the interfaces between activated sludge and digester models, the included temperature dependencies and the reject water storage. BSM2-implementations are now available in a wide range of simulation platforms and a ring test has verified their proper implementation, consistent with the BSM2 definition. This guarantees that users can focus on the control strategy evaluation rather than on modelling issues. Finally, for illustration, twelve simple operational strategies have been implemented in BSM2 and their performance evaluated. Results show that it is an interesting control engineering challenge to further improve the performance of the BSM2 plant (which is the whole idea behind benchmarking) and that integrated control (i.e. acting at different places in the whole plant) is certainly worthwhile to achieve overall improvement.
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| 10. |
- Nopens, I., et al.
(författare)
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Benchmark Simulation Model No 2: finalisation of plant layout and default control strategy
- 2010
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 62:9, s. 1967-1974
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Tidskriftsartikel (refereegranskat)abstract
- The COST/IWA Benchmark Simulation Model No 1 (BSM1) has been available for almost a decade. Its primary purpose has been to create a platform for control strategy benchmarking of activated sludge processes. The fact that the research work related to the benchmark simulation models has resulted in more than 300 publications worldwide demonstrates the interest in and need of such tools within the research community. Recent efforts within the IWA Task Group on "Benchmarking of control strategies for WWTPs" have focused on an extension of the benchmark simulation model. This extension aims at facilitating control strategy development and performance evaluation at a plant-wide level and, consequently, includes both pretreatment of wastewater as well as the processes describing sludge treatment. The motivation for the extension is the increasing interest and need to operate and control wastewater treatment systems not only at an individual process level but also on a plant-wide basis. To facilitate the changes, the evaluation period has been extended to one year. A prolonged evaluation period allows for long-term control strategies to be assessed and enables the use of control handles that cannot be evaluated in a realistic fashion in the one week BSM1 evaluation period. In this paper, the finalised plant layout is summarised and, as was done for BSM1, a default control strategy is proposed. A demonstration of how BSM2 can be used to evaluate control strategies is also given.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Solon, K., et al.
(författare)
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Plant-wide modelling of phosphorus transformations in wastewater treatment systems : Impacts of control and operational strategies
- 2017
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354. ; 113, s. 97-110
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Tidskriftsartikel (refereegranskat)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 (SNHX ) and total suspended solids (XTSS) control strategy (A1) better adapts the system to influent dynamics, improves phosphate (SPO4 ) accumulation by phosphorus accumulating organisms (XPAO) (41%), increases nitrification/denitrification efficiency (18%) and reduces aeration energy (Eaeration) (21%). The addition of iron XFeCl3 ) 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 (GH2S) 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 (XMgNH4PO4 ) recovery ranging from 69 to 227 kg.day−1 depending on: (1) airflow (Qstripping); and, (2) magnesium (QMg(OH)2 ) 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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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Villez, K, et al.
(författare)
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Comparison of two wavelet-based tools for data mining of urban water networks time series
- 2007
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 56:6, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, two approaches to data mining of time series have been tested and compared. Both methods are based on the wavelet decomposition of data series and allow the localization of important characteristics of a time series in both the time and frequency domain. The first method is a common method based on the analysis of wavelet power spectra. The second approach is new to the applied field of urban water networks and provides a qualitative description of the data series based on the cubic spline wavelet decomposition of the data. It is shown that wavelet power spectra indicate important and basic characteristics of the data but fail to provide detailed information of the underlying phenomena. In contrast, the second method allows the extraction of more and more detailed information that is important in a context of process monitoring and diagnosis
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| 20. |
- Volcke, E.I.P, et al.
(författare)
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Plant-wide (BSM2) evaluation of reject water treatment with a SHARON-Anammox process
- 2006
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 54:8, s. 93-100
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Tidskriftsartikel (refereegranskat)abstract
- In wastewater treatment plants (WWTPs) equipped with sludge digestion and dewatering systems, the reject water originating from these facilities contributes significantly to the nitrogen load of the activated sludge tanks, to which it is typically recycled. In this paper, the impact of reject water streams on the performance of a WWTP is assessed in a simulation study, using the Benchmark Simulation Model no. 2 (BSM2), that includes the processes describing sludge treatment and in this way allows for plant-wide evaluation. Comparison of performance of a WWTP without reject water with a WWTP where reject water is recycled to the primary clarifier, i.e. the BSM2 plant, shows that the ammonium load of the influent to the primary clarifier is 28% higher in the case of reject water recycling. This results in violation of the effluent total nitrogen limit. In order to relieve the main wastewater treatment plant, reject water treatment with a combined SHARON-Anammox process seems a promising option. The simulation results indicate that significant improvements of the effluent quality of the main wastewater treatment plant can be realized. An economic evaluation of the different scenarios is performed using an Operating Cost Index (OCI).
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Corominas, L., et al.
(författare)
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Performance evaluation of fault detection methods for wastewater treatment processes
- 2011
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 108:2, s. 333-344
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Tidskriftsartikel (refereegranskat)abstract
- Several methods to detect faults have been developed in various fields, mainly in chemical and process engineering. However, minimal practical guidelines exist for their selection and application. This work presents an index that allows for evaluating monitoring and diagnosis performance of fault detection methods, which takes into account several characteristics, such as false alarms, false acceptance, and undesirable switching from correct detection to non-detection during a fault event. The usefulness of the index to process engineering is demonstrated first by application to a simple example. Then, it is used to compare five univariate fault detection methods (Shewhart, EWMA, and residuals of EWMA) applied to the simulated results of the Benchmark Simulation Model No. 1 long-term (BSM1_LT). The BSM1_LT, provided by the IWA Task Group on Benchmarking of Control Strategies, is a simulation platform that allows for creating sensor and actuator faults and process disturbances in a wastewater treatment plant. The results from the method comparison using BSM1_LT show better performance to detect a sensor measurement shift for adaptive methods (residuals of EWMA) and when monitoring the actuator signals in a control loop (e.g., airflow). Overall, the proposed index is able to screen fault detection methods. Biotechnol. Bioeng. 2011;108: 333–344. © 2010 Wiley Periodicals, Inc.
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| 26. |
- Flores-Alsina, Xavier, et al.
(författare)
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Benchmarking strategies to control GHG production and emissions : Chapter 9
- 2022
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Ingår i: Quantification and Modelling of Fugitive Greenhouse Gas Emissions from Urban Water Systems: A report from the IWA Task Group on GHG. - : IWA Publishing. - 9781789060461 - 9781789060454 ; , s. 213-228
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Benchmarking has been a useful tool for unbiased comparison of control strategies in wastewater treatment plants (WWTPs) in terms of effluent quality, operational cost and risk of suffering microbiology-related total suspended solids (TSS) separation problems. This chapter presents the status of extending the original Benchmark Simulation Model No 2 (BSM2) towards including greenhouse gas (GHG) emissions. A mathematical approach based on a set of comprehensive models that estimate all potential on-site and off-site sources of COinf2/inf, CHinf4/inf and Ninf2/infO is presented and discussed in detail. Based upon the assumptions built into the model structures, simulation results highlight the potential undesirable effects on increased GHG emissions when carrying out local energy optimization in the activated sludge section and/or energy recovery in the anaerobic digester. Although off-site COinf2/inf emissions may decrease in such scenarios due to either lower aeration energy requirement or higher heat and electricity production, these effects may be counterbalanced by increased Ninf2/infO emissions, especially since Ninf2/infO has a 300-fold stronger greenhouse effect than COinf2/inf. The reported results emphasize the importance of using integrated approaches when comparing and evaluating (plant-wide) control strategies in WWTPs for more informed operational decision-making.
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| 27. |
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| 28. |
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| 29. |
- Flores, Xavier, et al.
(författare)
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Including greenhouse gas emissions during benchmarking of wastewater treatment plant control strategies
- 2011
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Ingår i: Water Research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 45:16, s. 4700-4710
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Tidskriftsartikel (refereegranskat)abstract
- The main objective of this paper is to demonstrate how greenhouse gas (GHG) emissions can be quantified during the evaluation of control strategies in wastewater treatment plants (WWTP). A modified version of the IWA Benchmark Simulation Model No 2 (BSM2G) is hereby used as a simulation case study. Thus, the traditional effluent quality index (EQI), operational cost index (OCI) and time in violation (TIV) used to evaluate control strategies in WWTP are complemented with a new dimension dealing with GHG emissions. The proposed approach is based on a set of comprehensive models that estimate all potential on-site and off-site sources of GHG emissions. The case study investigates the overall performance of several control strategies and demonstrates that substantial reductions in effluent pollution, operating costs and GHG emissions can be achieved when automatic control is implemented. Furthermore, the study is complemented with a scenario analysis that examines the role of i) the dissolved oxygen (DO) set-point, ii) the sludge retention time (SRT) and iii) the organic carbon/nitrogen ratio (COD/N) as promoters of GHG emissions. The results of this study show the potential mechanisms that promote the formation of CO2, CH4 and N2O when different operational strategies are implemented, the existing synergies and trade-offs amongst the EQI, the OCI and TIV criteria and finally the need to reach a compromise solution to achieve an optimal plant performance.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
- Jeppsson, Ulf, et al.
(författare)
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Status and future trends of ICA in wastewater treatment--a European perspective.
- 2002
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Ingår i: Water Science and Technology. - 0273-1223. ; 45:4-5, s. 485-494
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Tidskriftsartikel (refereegranskat)abstract
- The status of instrumentation, control and automation (ICA) within the European wastewater community is reviewed and some major incentives and bottlenecks are defined. Future trends of ICA are also discussed. The information is based on a COST 624 workshop and a non-exhaustive survey with regard to ICA carried out in 13 European countries during March 2001. The level of instrumentation (type of sensors, usage frequency, etc.) and how these instruments are used for on-line control purposes are presented for each individual country (Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Netherlands, Romania, Slovenia, Spain, Sweden and Switzerland). The most common types of applied real-time control in wastewater treatment plants are given. One conclusion of the paper is that sensors no longer represent the main bottleneck for on-line control, rather the lack of plant flexibility is more troublesome. Moreover, the current transitional phase of the wastewater industry in Europe represents a unique opportunity to apply ICA on a large scale. The driving forces are simply too strong to ignore.
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| 35. |
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| 36. |
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| 37. |
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| 38. |
- Rosén, Christian, et al.
(författare)
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Adding realism to simulated measurements and actuators
- 2008
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 57:3, s. 337-344
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a statistical theoretical framework for incorporation of sensor and actuator faults in dynamic simulations of wastewater treatment operation. Sensor and actuator faults and failures are often neglected in simulations for control strategy development and testing, although it is well known that they represent a significant obstacle for realising control at full-scale facilities. The framework for incorporating faults and failures is based on Markov chains and displays the appealing property of easy transition of sensor and actuator history into a model for fault generation. The paper briefly describes Markov theory and how this is used together with models for sensor and actuator dynamics to achieve a realistic simulation of measurements and actuators.
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| 39. |
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| 40. |
- Rosén, Christian, et al.
(författare)
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Adding realism to simulated sensors and actuators.
- 2008
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 57:3, s. 337-344
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a statistical theoretical framework for incorporation of sensor and actuator faults in dynamic simulations of wastewater treatment operation. Sensor and actuator faults and failures are often neglected in simulations for control strategy development and testing, although it is well known that they represent a significant obstacle for realising control at full-scale facilities. The framework for incorporating faults and failures is based on Markov chains and displays the appealing property of easy transition of sensor and actuator history into a model for fault generation. The paper briefly describes Markov theory and how this is used together with models for sensor and actuator dynamics to achieve a realistic simulation of measurements and actuators.
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| 41. |
- Torfs, Elena, et al.
(författare)
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Concentration-driven models revisited: Towards a unified framework to model settling tanks in WWTPs
- 2016
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Ingår i: Proceedings 5th IWA/WEF Wastewater Treatment Modelling Seminar (WWTmod2016). ; , s. 109-118
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Konferensbidrag (refereegranskat)abstract
- This contribution introduces a new perspective on the modelling of settling behaviour aimed at providing a unified description of the processes taking place both in primary and secondary settling tanks for a more detailed operation and control in Water and Resource Recovery Facilities (WRRFs). First, experimental evidence is provided pointing out the flocculation state of sludge as an important common source of distributed behavior in different settling processes. Subsequently, a unified model framework considering several particle classes is proposed in order to describe this distributed settling behaviour as well as the effect of variations in flocculation state on the settling process. The result is a set of PDEs that are valid from dilute concentrations where they correspond to discrete settling to concentrated suspensions where they correspond to compression settling and can thus be used to model both primary and secondary settling tanks.
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| 42. |
- Vanrolleghem, P A, et al.
(författare)
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Continuity-based interfacing of models for wastewater systems described by Petersen matrices
- 2005
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Ingår i: Water Science and Technology. - 0273-1223. ; 52:1-2, s. 493-500
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the Petersen and composition matrices that modellers are now familiar with are used as a basis to construct interfacing models between subsystems considered in wastewater treatment. Starting from continuity considerations and a set of transformation reactions between components used in the two models of the subsystems to be interfaced, a set of linear algebraic equations needs to be solved. The theoretical development is illustrated using a simplified integrated model of an activated sludge system coupled to an anaerobic digester. Continuity-guaranteed interfacing of subsystems will facilitate optimization studies of the within-the-fence process units of a wastewater treatment plant or of the integrated urban wastewater system.
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| 43. |
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| 44. |
- Vanrolleghem, P., et al.
(författare)
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Integration of WWT Plant Design and Operation - a Systematic Approach Using Cost Functions
- 1996
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Ingår i: Water Science and Technology. - 0273-1223. ; 34:3-4, s. 159-171
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Tidskriftsartikel (refereegranskat)abstract
- A general framework for the formulation and analysis of an overall decision support index is discussed. It is indicated that such an index allow evaluation of the combined effects of both design and operation (i) during the planning phase of new WWTPs, as well as (ii) for the evaluation of new operational strategies versus traditional expansions of plants already in operation. Attention is drawn to the problems of incorporating such factors as plant flexibility and robustness against failures in the index. These factors become especially relevant when decisions are to be made that affect the life span of a WWTP. Spatial and temporal separation of the optimisation problem are proposed to make the approach operational. It is not the intention of the authors to provide an exhaustive list of objective criterion functions, but rather to give the reader some examples illustrating the approach.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Villez, K, et al.
(författare)
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Qualitative representation of trends: An alternative approach to process diagnosis and control
- 2008
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Ingår i: Water Science And Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 57, s. 1525-1532
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Konferensbidrag (refereegranskat)abstract
- The potential for qualitative representation of trends in the context of process diagnosis and control is evaluated in this paper. The technique for qualitative description of the data series is relatively new to the field of process monitoring and diagnosis and is based on the cubic spline wavelet decomposition of the data. It is shown that the assessed qualitative description of trends can be coupled easily with existing process knowledge and does not demand the user to understand the underlying technique in detail, in contrast to, for instance, multivariate techniques in Statistical Process Control. The assessed links can be integrated straightforwardly into the framework of supervisory control systems by means of look-up tables, expert systems or case-based reasoning frameworks. This in turn allows the design of a supervisory control system leading to fully automated control actions. The technique is illustrated by an application to a pilot-scale SBR.
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