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Wärff, C. (2023). Operational digital twins for water resource recovery facilities – Rationale, components, and case studies.
Open this publication in new window or tab >>Operational digital twins for water resource recovery facilities – Rationale, components, and case studies
2023 (English)Report (Other academic)
Abstract [en]

Digital twins (DT) for water resource recovery facilities (WRRF) are different from regular process models. They require 1) a physical plant twin; 2) automatic data exchange with the real plant; 3) possibility to dynamically update models when or if required. Their use has the potential to improve understanding of plant behaviour and unmeasured variables; move towards proactive decision making at the plants when including influent forecasts; improve data quality control when comparing simulation results to measured values; and be used for predictive maintenance. The model used in a DT can be mechanistic (i.e., describing underlying mechanisms/physics), data driven (empirical, based on observed relationships between variables) or a combination of both (hybrid model). Most of the commercially available (mechanistic) wastewater process simulators include the option to use them in (near) real time as digital twins. Fault detection is important for DTs to avoid use of faulty input data. Methods range from dimensional reduction techniques to process models and statistical control charts. Automated methods for gap filling and corrections of sensor values based on laboratory measurements can be used to correct faulty data. Forecasts of influent flow rate and concentration of pollutants can be useful for optimization and “what if”-scenarios. Forecast models can be data driven (e.g., many examples with time series models and artificial neural networks available in the literature) or detailed mechanistic models. Common for most examples is that weather forecasts (temperature and precipitation) are used, and the model accuracy of course depend on the quality of the forecast. Automatic calibration can be used for both data driven/hybrid models (i.e., re-training) and mechanistic models. For mechanistic models, examples in the literature include simple changing of measured influent fractions or settler solids separation efficiency to global optimization of multiple variables over a plant-wide model. Automatic calibration can be done at fixed intervals or based on performance evaluation. Model predictive control (MPC) has been widely studied in simulated settings, with few real examples for WRRFs. For digital twins, the possibility to combine a mechanistic model with influent forecasts and numerical optimisation for, e.g., setpoints over a future time interval to achieve a certain goal is promising. The faster control applications can then be handled using regular PID-controllers. Few examples of implemented digital twins for WRRFs have so far been published in the literature. Here, one example of a digital twin is presented. It includes automatic data transfer, automatic calibration, and forecasts, but is (at the time of writing based on the available literature) only used as an advisory tool and not for direct control. Digital twins of water resource recovery facilities are complex with many different parts and models that work together. They can be used for fault detection, predictions, and optimization/control. This report summarizes some of the components that can be used to build digital twins, which ones to include of course depends on the scope and goals of the specific project. In all cases, the flow of data from collection to use must be well designed to avoid unnecessary interruptions in operation.

Publisher
p. 33
Series
RISE Rapport ; 2023:105
National Category
Control Engineering
Identifiers
urn:nbn:se:ri:diva-67558 (URN)978-91-89821-85-9 (ISBN)
Note

Digital twins for water resource recovery facilities/wastewater treatment plants are an emerging technology with large potential benefits to plant operations. This report is written as part of the project Digital twin for sustainable and resource efficient operation of wastewater treatment plants (Formas 2020-00222), with the aim to summarize the rationale for using digital twins, describe the different components that will be important for implementation of a digital twin, and describe available case studies.

Available from: 2023-10-23 Created: 2023-10-23 Last updated: 2024-05-17Bibliographically approved
Saagi, R., Arnell, M., Wärff, C., Ahlström, M. & Jeppsson, U. (2022). City-wide model-based analysis of heat recovery from wastewater using an uncertainty-based approach. Science of the Total Environment, 820, Article ID 153273.
Open this publication in new window or tab >>City-wide model-based analysis of heat recovery from wastewater using an uncertainty-based approach
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2022 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 820, article id 153273Article in journal (Refereed) Published
Abstract [en]

Around 90% of the energy requirement for urban water systems management is for heating domestic tap water. In addition, the energy content of wastewater is mainly in the form of heat (85%). Hence, there is an obvious interest in recovering a large portion of this heat. However, city-wide scenario analyses that evaluate heat recovery at various locations while considering impacts on wastewater treatment plant (WWTP) performance are currently very limited. This study presents a comprehensive model-based city-wide evaluation considering four different heat recovery locations (appliance, household, precinct and WWTP effluent) for a Swedish city with varying degrees of implementation using an uncertainty-based approach. Results show that heat recovery at the appliance level, with heat exchangers installed at 77% of the showers at domestic households, leads to a mean energy recovery of 127 MWh/day with a 0.25 °C reduction in mean WWTP inlet temperature compared to the default case without heat recovery. The highest mean temperature reduction compared to the default case is 1.5 °C when heat is recovered at the precinct level for 77% of the domestic wastewater flow rate. Finally, the impact on WWTP nitrification capacity is negligible in this case due to its large existing capacity and design. © 2022 The Authors

Place, publisher, year, edition, pages
Elsevier B.V., 2022
Keywords
City-wide modelling, Heat recovery, Uncertainty analysis, Wastewater, Effluents, Heating, Recovery, Waste heat, Wastewater treatment, City-wide modeling, Energy content, Energy requirements, Management IS, Model-based analysis, Systems management, Tap water, Uncertainty, Urban water systems, Waste water treatment plants, article, effluent, energy recovery, flow rate, household, nitrification, waste water treatment plant
National Category
Water Engineering
Identifiers
urn:nbn:se:ri:diva-58497 (URN)10.1016/j.scitotenv.2022.153273 (DOI)2-s2.0-85123381630 (Scopus ID)
Note

Funding details: LU 2020/2-32; Funding details: Svenska Forskningsrådet Formas, 942-2016-80; Funding details: Svenskt Vatten, SWWA, 16-106; Funding text 1: The authors acknowledge the financial support provided by the Swedish research council Formas ( 942-2016-80 ), Swedish Water ( 16-106 ), Sweden Water Research , and Tekniska Verken i Linköping for the project HÅVA (‘Sustainability analysis for heat recovery from wastewater’). Tekniska Verken i Linköping is also gratefully acknowledged for their financial support and for supporting measurement campaigns. The computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) through the Center for Scientific and Technical Computing at Lund University (LUNARC) under project LU 2020/2-32.; Funding text 2: The authors acknowledge the financial support provided by the Swedish research council Formas (942-2016-80), Swedish Water (16-106), Sweden Water Research, and Tekniska Verken i Link?ping for the project H?VA (?Sustainability analysis for heat recovery from wastewater?). Tekniska Verken i Link?ping is also gratefully acknowledged for their financial support and for supporting measurement campaigns. The computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) through the Center for Scientific and Technical Computing at Lund University (LUNARC) under project LU 2020/2-32.

Available from: 2022-02-18 Created: 2022-02-18 Last updated: 2024-05-17Bibliographically approved
Arnell, M., Ahlström, M., Wärff, C., Miltell, M. & Vahidi, A. (2021). Digitalisering av den svenska VA-branschen.
Open this publication in new window or tab >>Digitalisering av den svenska VA-branschen
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2021 (Swedish)Report (Other academic)
Abstract [sv]

Rapporten ska ge VA-branschen en kunskapsbas för arbetet med digitalisering inom vatten och avlopp. Den beskriver potentialen och pekar ut framgångsfaktorer för omställningen. Den tar också upp utmaningar med kompetensförsörjning, datahantering och cybersäkerhet. En inspirationskatalog ger tio exempel på lyckade digitala tillämpningar ur verkligheten.

Abstract [en]

The report provides a knowledge base on the digital transformation in the water industry, its visionand potential. Key success factors are pointed out and challenges with workforce competence,data management and cybersecurity is outlined. A catalogue with ten examples of successful digitalapplications is provided for inspiration.

Publisher
p. 93
Series
Svenskt vatten rapport ; 2021:21
Keywords
Digitalization, water industry, water, wastewater, stormwater, Digitalisering, VA-sektorn, vatten, avlopp, dricksvatten, dagvatten
National Category
Environmental Sciences
Identifiers
urn:nbn:se:ri:diva-58297 (URN)
Note

Finns att hämta hem som pdf från Vattenbokhandeln. https://vattenbokhandeln.svensktvatten.se/   Projektnummer 19-108. Projektets namn: State of Knowledge – Digitalisering av den svenska VA-sektorn. Projektets finansiering: Svenskt Vatten Utveckling.

Available from: 2022-01-21 Created: 2022-01-21 Last updated: 2024-05-17Bibliographically approved
Saagi, R., Arnell, M., Reyes, D., Wärff, C., Ahlström, M. & Jeppsson, U. (2021). Modelling temperature dynamics in sewer systems – Comparing mechanistic and conceptual modelling approaches. Water Science and Technology, 84(9), 2335-2352
Open this publication in new window or tab >>Modelling temperature dynamics in sewer systems – Comparing mechanistic and conceptual modelling approaches
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2021 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 84, no 9, p. 2335-2352Article in journal (Refereed) Published
Abstract [en]

The vast majority of the energy consumed for urban water services is used to heat tap water. Heat recovery from wastewater is consequently an area of rapidly growing concern, both in research and by commercial interest, promoting the path towards a circular economy. To facilitate a system-wide evaluation of heat recovery from wastewater, this paper compares two one-dimensional models (mechanistic and conceptual) that can describe wastewater temperature dynamics in sewer pipe systems. The models are applied to successfully predict downstream wastewater temperature for sewer stretches in two Swedish cities (Linköping and Malmö). The root mean squared errors for the mechanistic model (Linköping Dataset1 – 0.33 °C; Linköping Dataset2 – 0.28 °C; Malmö – 0.40 °C) and the conceptual model (Linköping Dataset1 – 0.32 °C; Linköping Dataset2 – 0.20 °C; Malmö – 0.44 °C) indicate that both models have similar predictive capabilities, encouraging the use of conceptual models to reduce data requirements and model calibration efforts. Both models are freely distributed and can be easily integrated with wastewater generation and treatment models to facilitate system-wide wastewater temperature dynamics analysis. © 2021 The Authors.

Place, publisher, year, edition, pages
IWA Publishing, 2021
Keywords
Heat recovery, Heat transfer, Modelling, Sewer system, Temperature dynamics, Dynamics, Sewers, Waste heat, Wastewater treatment, Conceptual model, Energy, Mechanistic models, Model temperatures, Modeling, Modeling approach, Urban water services, Wastewater temperature, Mean square error, calibration, data, model, temperature, wastewater, article, city, energy recovery, sewer
National Category
Water Engineering
Identifiers
urn:nbn:se:ri:diva-57338 (URN)10.2166/wst.2021.425 (DOI)2-s2.0-85120440444 (Scopus ID)
Note

Funding details: Svenska Forskningsrådet Formas, 942-2016-80; Funding details: Svenskt Vatten, SWWA, 16-106; Funding text 1: The authors acknowledge the financial support provided by Swedish research council Formas (942-2016-80), The Swedish Water and Wastewater Association (16-106) and Sweden Water Research for the project HÅVA (‘Sustainability analysis for heat recovery from wastewater’). VA Syd (Malmö) and Tekniska Verken (Linköping) are also gratefully acknowledged for their financial support, providing various details about the sewer network and supporting measurement campaigns.

Available from: 2021-12-23 Created: 2021-12-23 Last updated: 2024-05-17Bibliographically approved
Arnell, M., Ahlström, M., Wärff, C., Saagi, R. & Jeppsson, U. (2021). Plant-wide modelling and analysis of WWTP temperature dynamics for sustainable heat recovery from wastewater. Water Science and Technology, 84(4), 1023-1036
Open this publication in new window or tab >>Plant-wide modelling and analysis of WWTP temperature dynamics for sustainable heat recovery from wastewater
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2021 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 84, no 4, p. 1023-1036Article in journal (Refereed) Published
Abstract [en]

Wastewater heat recovery upstream of wastewater treatment plants (WWTP) poses a risk to treatment performance, i.e. the biological processes. In order to perform a sustainability analysis, a detailed prediction of the temperature dynamics over the WWTP is needed. A comprehensive set of heat balance equations was included in a plant-wide process model and validated for the WWTP in Linköping, Sweden, to predict temperature variations over the whole year in a temperate climate. A detailed model for the excess heat generation of biological processes was developed. The annual average temperature change from influent to effluent was 0.78°C with clear seasonal variations, wherein 45% of the temperature change arose from processes other than the activated sludge unit. To address this, plant-wide energy modelling was necessary to predict in-tank temperature in the biological treatment steps. The energy processes with the largest energy gains were solar radiation and biological processes, while the largest losses were from conduction, convection, and atmospheric radiation. Tanks with large surface areas showed a significant impact on the heat balance regardless of biological processes. Simulating a 3°C lower influent temperature, the temperature in the activated sludge unit dropped by 2.8°C, which had a negative impact on nitrogen removal

Place, publisher, year, edition, pages
IWA Publishing, 2021
Keywords
Energy and heat balance, Mathematical modelling, Resource recovery, Temperature, Wastewater heat recovery, Wastewater treatment plant, activated sludge, biological method, climate prediction, heat balance, performance assessment, seasonal variation, solar radiation, Sweden
National Category
Water Engineering
Identifiers
urn:nbn:se:ri:diva-56693 (URN)10.2166/wst.2021.277 (DOI)2-s2.0-85114170209 (Scopus ID)
Note

 Funding details: Svenska Forskningsrådet Formas, 942-2016-80; Funding details: Svenskt Vatten, SWWA, 16-106; Funding text 1: The authors acknowledge the financial support provided by the Swedish research council Formas (942-2016-80), The Swedish Water and Wastewater Association (16-106), Sweden Water Research, Käppalaförbundet and Tekniska Verken in Linköping for the project HÅVA (‘Sustainability analysis for heat recovery from wastewater’). Tekniska Verken in Linköping, is also gratefully acknowledged for their financial support and for supporting measurement campaigns.; Funding text 2: The authors acknowledge the financial support provided by the Swedish research council Formas (942-2016-80), The Swedish Water and Wastewater Association (16-106), Sweden Water Research, K?ppalaf?rbundet and Tekniska Verken in Link?ping for the project H?VA ('Sustainability analysis for heat recovery from wastewater'). Tekniska Verken in Link?ping, is also gratefully acknowledged for their financial support and for supporting measurement campaigns.

Available from: 2021-09-28 Created: 2021-09-28 Last updated: 2024-05-17Bibliographically approved
Arnell, M., Saagi, R., Wärff, C., Ahlström, M. & Jeppsson, U. (2021). Värmeåtervinning ur avloppsvatten: Energiåtervinning och påverkan på avloppssystemet.
Open this publication in new window or tab >>Värmeåtervinning ur avloppsvatten: Energiåtervinning och påverkan på avloppssystemet
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2021 (Swedish)Report (Other academic)
Abstract [sv]

Uppvärmning av tappvarmvatten utgör lejonparten av den totala energianvändningen i den urbana vattencykeln, upp till 90 procent. Uppskattningar visar att 780 till 1 150 kWh per person och år används i svenska hushåll i form av varmvatten. Denna energi hamnar huvudsakligen i avloppsvattnet. Variationerna i varmvattenanvändning är stora och det går att göra besparingar på brukarnivå. Ändå finns det stor potential för energieffektivisering genom värmeåtervinning ur avloppsvatten med värmeväxlare och värmepumpar.

Abstract [en]

Heating of tap water makes up the lion share of the total energy used in the urban water cycle, up to 90 %. Estimates show that 780 to 1,150 kWh per person and year is used in Sweden for heating water. This energy mainly ends up in the sewers. Even if variations in energy use for this purpose are large and savings are possible, wastewater heat recovery, using heat exchangers or heat pumps, has a large potential.

Publisher
p. 61
Series
Svenskt vatten rapport ; 2021:26
Keywords
Energy balance, mathematical modelling, simulation, resource recovery, temperature dynamics, wastewater heat recovery, wastewater treatment plant, Energibalans, matematisk modellering, simulering, resursåtervinning, temperaturdynamik, värmeåtervinning från avloppsvatten, avloppsreningsverk
National Category
Energy Engineering
Identifiers
urn:nbn:se:ri:diva-58295 (URN)
Note

Finns att hämta hem som pdf från Vattenbokhandeln. https://vattenbokhandeln.svensktvatten.se/. 

Projektnummer 16-106. Projektets namn: Hållarhetsanalys av värmeåtervinning ur avloppsvatten (HÅVA). Projektetsfinansiering: Svenskt Vatten Utveckling, FORMAS, Sweden Water Research, Käppalaförbundet, Tekniska Verken iLinköping, AB Stångåstaden

Available from: 2022-01-21 Created: 2022-01-21 Last updated: 2024-05-17Bibliographically approved
Wärff, C. (2020). Household Wastewater Generation Model.
Open this publication in new window or tab >>Household Wastewater Generation Model
2020 (English)Report (Other academic)
Abstract [en]

This is an internal report in the research project Sustainability Analysis of Wastewater (WW) HeatRecovery (WWHR) - Hållbarhetsanalys av värmeåtervinning ur avloppsvatten (HÅVA), in Swedish - coordinated by the Division of Industrial Electrical Engineering and Automation at Lund University,Lund, Sweden. Key partners in the project are RISE Research Institutes of Sweden, the wastewaterutilities VA Syd, Tekniska Verken in Linköping and Käppalaförbundet, and the real estate companyStångåstaden.

In the project a system-wide sustainability analysis will be performed using process models. The modelwill include components from the origin of domestic wastewater in buildings through WWHR units andsewers to the impact of temperature changes on the wastewater treatment plant (WWTP). Theliterature review on WWHR identified wastewater characteristics as a key variable for the model(Arnell et al., 2017). This document contains a description of a stochastic model for generatingwastewater from households over the course of one day, which was calibrated based onmeasurements from a case study in Linköping, Sweden, and validated with literature data.

Publisher
p. 30
National Category
Engineering and Technology
Identifiers
urn:nbn:se:ri:diva-51015 (URN)
Available from: 2020-12-17 Created: 2020-12-17 Last updated: 2024-05-17Bibliographically approved
Wärff, C., Arnell, M., Sehlén, R. & Jeppsson, U. (2020). Modelling heat recovery potential from household wastewater. Water Sci Technol, 81(8), 1597-1605
Open this publication in new window or tab >>Modelling heat recovery potential from household wastewater
2020 (English)In: Water Sci Technol, Vol. 81, no 8, p. 1597-1605Article in journal (Refereed) Published
Abstract [en]

There is a strongly growing interest for wastewater heat recovery (WWHR) in Sweden and elsewhere, but a lack of adequate tools to determine downstream impacts due to the associated temperature drop. The heat recovery potential and associated temperature drop after heat recovery on a building level is modelled for a case study in Linköping, Sweden. The maximum temperature drop reaches 4.2 °C, with an annual recovered heat of 0.65 kWh · person(-1) · day(-1). Wastewater temperature out from the heat exchanger was 18.0 °C in winter at the lowest. The drinking water source type can be an important factor when considering wastewater heat recovery.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-45166 (URN)10.2166/wst.2020.103 (DOI)0273-1223 (Print) 0273-1223 (ISBN)
Available from: 2020-07-15 Created: 2020-07-15 Last updated: 2024-05-17Bibliographically approved
Wärff, C., Ahlström, M. & Arnell, M. (2020). Processmodelleringav avloppsreningsverk: Kunskapsspridning om ettkraftfullt verktyg för driftoch design.
Open this publication in new window or tab >>Processmodelleringav avloppsreningsverk: Kunskapsspridning om ettkraftfullt verktyg för driftoch design
2020 (English)Report (Other academic)
Abstract [sv]

Datorbaserade modeller för simulering av processer på avloppsreningsverk kan göra stor nytta för att optimera investeringar och drift, men de används bara på ett fåtal avloppsreningsverk i Sverige. Målet med projektet var att höja kunskapsnivån om nyttan med modellering hos svenska användare och beslutsfattare. Hittills har det funnits ytterst lite information på svenska om hur processmodellering kan användas. Projektet tog därför fram kunskapsportalen ModelleraARV som nu fi nns tillgänglig på Internet.

Abstract [en]

The aim of the project was to raise the awareness about the benefi ts of modeling at wastewater treatment plants by highlighting existing knowledge, showing good examples and disseminating knowledge about the practical use of models for simulation studies. A knowledge portal is available on-line (in Swedish).

Publisher
p. 24
Series
Stockholm Vatten Utveckling ; 2020-3
Keywords
Wastewater treatment plant, modelling, knowledge portal, Avloppsreningsverk, modellering, kunskapsportal
National Category
Engineering and Technology
Identifiers
urn:nbn:se:ri:diva-51014 (URN)
Available from: 2020-12-17 Created: 2020-12-17 Last updated: 2024-05-17
Wärff, C., Arnell, M., Jeppsson, U. & Sehlén, R. (2019). Modelling heat recovery potential from household wastewater. In: Proceedings of 10th IWA Symposium on Modelling and Integrated Assessment: . Paper presented at 10th IWA Symposium on Modelling and Integrated Assessment (Watermatex 2019), Copenhagen, Denmark.
Open this publication in new window or tab >>Modelling heat recovery potential from household wastewater
2019 (English)In: Proceedings of 10th IWA Symposium on Modelling and Integrated Assessment, 2019Conference paper, Published paper (Refereed)
Abstract [en]

There is a strongly growing interest for wastewater heat recovery (WWHR) in Sweden and elsewhere, but a lack of adequate tools to determine downstream impacts due to the associated temperature drop. The heat recovery potential and associated temperature drop after heat recovery on a building level is modelled for a case study in Linköping, Sweden. The maximum temperature drop reaches 4.2 °C, with an annual recovered heat of 0.65 kWh/person/day. Wastewater temperature out from the heat exchanger was 18.0 °C in winter at the lowest. The drinking water source type can be an important factor when considering wastewater heat recovery.

Keywords
wastewater; heat recovery; heat demand; energy use; heat exchanger; modelling
National Category
Water Treatment
Identifiers
urn:nbn:se:ri:diva-42437 (URN)
Conference
10th IWA Symposium on Modelling and Integrated Assessment (Watermatex 2019), Copenhagen, Denmark
Available from: 2019-12-30 Created: 2019-12-30 Last updated: 2024-05-17Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-4866-0262

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