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  • 1.
    Amaral, Andreia
    et al.
    Ghent University, Belgium; Universidade de Lisboa, Portugal.
    Gillot, Sylvie
    Irstea, France.
    Garrido-Baserba, Manel
    University of California, USA.
    Filali, Ahlem
    Irstea, France.
    Karpinska, Anna
    Southern Water, UK.
    Plósz, Benedek
    University of Bath, UK.
    De Groot, Christopher
    Western University, Canada.
    Bellandi, Giacomo
    Ghent University, Belgium.
    Nopens, Ingmar
    Ghent University, Belgium.
    Takács, Imre
    Dynamita, France.
    Lizarralde, Izaro
    Universidad de Navarra, Spain; Ceit, Spain.
    Jimenez, Jose
    Brown and Caldwell, USA.
    Fiat, Justine
    Irstea, France.
    Rieger, Leiv
    CTRL Solutions Inc, Canada.
    Arnell, Magnus
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi. Lund University, Sweden.
    Andersen, Mikkel
    DHI, Denmark.
    Jeppsson, Ulf
    Lund University, Sweden.
    Rehman, Usman
    Ghent University, Belgium.
    Fayolle, Yannick
    Irstea, France.
    Amerlinck, Youri
    Ghent University, Belgium.
    Rosso, Diego
    University of California, USA.
    Modelling gas-liquid mass transfer in wastewater treatment: when current knowledge needs to encounter engineering practice and vice versa2019Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 80, nr 4, s. 607-619Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gas-liquid mass transfer in wastewater treatment processes has received considerable attention over the last decades from both academia and industry. Indeed, improvements in modelling gas-liquid mass transfer can bring huge benefits in terms of reaction rates, plant energy expenditure, acid-base equilibria and greenhouse gas emissions. Despite these efforts, there is still no universally valid correlation between the design and operating parameters of a wastewater treatment plant and the gas-liquid mass transfer coefficients. That is why the current practice for oxygen mass transfer modelling is to apply overly simplified models, which come with multiple assumptions that are not valid for most applications. To deal with these complexities, correction factors were introduced over time. The most uncertain of them is the α-factor. To build fundamental gas-liquid mass transfer knowledge more advanced modelling paradigms have been applied more recently. Yet these come with a high level of complexity making them impractical for rapid process design and optimisation in an industrial setting. However, the knowledge gained from these more advanced models can help in improving the way the α-factor and thus gas-liquid mass transfer coefficient should be applied. That is why the presented work aims at clarifying the current state-of-the-art in gas-liquid mass transfer modelling of oxygen and other gases, but also to direct academic research efforts towards the needs of the industrial practitioners.

  • 2.
    Arnell, Magnus
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Systemomställning och tjänsteinnovation. Lund University, Sweden.
    Ahlström, Marcus
    RISE Research Institutes of Sweden, Samhällsbyggnad, Systemomställning och tjänsteinnovation.
    Wärff, Christoffer
    RISE Research Institutes of Sweden, Samhällsbyggnad, Systemomställning och tjänsteinnovation. RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande. Lund University, Sweden.
    Saagi, Ramesh
    Lund University, Sweden.
    Jeppsson, Ulf
    Lund University, Sweden.
    Plant-wide modelling and analysis of WWTP temperature dynamics for sustainable heat recovery from wastewater2021Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 84, nr 4, s. 1023-1036Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 3.
    Hansson, Mikael
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Nordberg, Åke
    RISE., SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Sundh, I.
    Mathisen, Berit
    RISE., SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Early warning of disturbances in a laboratory-scale MSW biogas process.2002Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 45, nr 10, s. 255-260Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of near-infrared spectroscopy (NIR) to monitorthe dynamics of a biogas process was evaluated using multivariate data analysis. The digester was a completely stirred 8 I tank reactor fed with the organic fraction of source-sorted MSW. Intermittently the digester was overloaded with feed. Before and after overload on-line monitoring of NIR spectra and off-line analysis in the liquid and the gas phase of traditional chemical variables and microbial biomass, determined as total concentration of phospholipid fatty acids (PLFA and PLEL), were done. The dynamics that occurred due to overloading could be followed using principal component analysis of the obtained NIR-spectra. In addition, the response to changes in the digester fluid was reproducible and could be detected within five minutes, which can be considered as real-time monitoring. Selected wavelengths in the region 800-2,000 nm were used to make a PLS1 -regression with propionate. The regression resulted in a good correlation for propionate (R= 0.94 and RMSEP of 0.21 g/l in the range of 0.3-3 g/l). The results indicate the possibility to develop an early warning biogas control system based on near-infrared spectroscopy monitoring of propionate.

  • 4.
    Levén, Lotta
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Wijnbladh, Erik
    SLU Swedish University of Agricultural Sciences, Sweden.
    Tuvesson, Malin
    SYVAB Himmerfjärdsverket, Sweden .
    Kragelund, Caroline
    Aalborg University, Denmark; Danish Technological Institute, Denmark.
    Hallin, Sara
    SLU Swedish University of Agricultural Sciences, Sweden.
    Control of Microthrix parvicella and sludge bulking by ozone in a full-scale WWTP2016Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 73, nr 4, s. 866-872Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bulking and rising sludge are common problems in wastewater treatment plants (WWTPs) and are primarily caused by increased growth of filamentous bacteria such as Microthrix parvicella. It has a negative impact on sludge settling properties in activated sludge (AS) process, in addition to being responsible for foam formation. Different methods can be used to control sludge bulking. The aim of this study was to evaluate the dosage of on-site generated ozone in the recycled AS flow in a fullscale WWTP having problems caused by M. parvicella. The evaluation of the experiment was assessed by process data, microscopic analysis and microbial screening on the experimental and control line before, during and after the period of ozone dosage. The ozone treatment resulted in decreased abundance of M. parvicella and improved the settling properties, without impairing the overall process performance. Both chemical oxygen demand (COD)-and N-removal were unaffected and the dominant populations involved in nitrification, as analysed by fluorescent in situ hybridization, remained during the experimental period. When the ozone treatment was terminated, the problems with sludge bulking reappeared, indicating the importance of continuous evaluation of the process.

  • 5.
    Lindblom, Erik
    et al.
    Lund University, Sweden; Stockholm Vatten, Sweden.
    Arnell, Magnus
    RISE., SP – Sveriges Tekniska Forskningsinstitut. Lund University, Sweden.
    Flores-Alsina, Xavier
    DTU Technical University of Denmark, Denmark.
    Stenström, Fredrik
    Lund University, Sweden; VA-Ingenjörerna AB, Sweden.
    Gustavsson, D.J.I.
    VA SYD, Sweden; Sweden Water Research, Sweden.
    Yang, Jiannan
    KTH Royal Institute of Technology, Sweden; IVL Swedish Environmental Research Institute, Sweden.
    Jeppsson, Ulf
    Lund University, Sweden.
    Dynamic modelling of nitrous oxide emissions from three Swedish sludge liquor treatment systems2016Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 73, nr 4, s. 798-806Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this paper is to model the dynamics and validate the results of nitrous oxide (N2O) emissions from three Swedish nitrifying/denitrifying, nitritation and anammox systems treating real anaerobic digester sludge liquor. The Activated Sludge Model No. 1 is extended to describe N2O production by both heterotrophic and autotrophic denitrification. In addition, mass transfer equations are implemented to characterize the dynamics of N2O in the water and the gas phases. The biochemical model is simulated and validated for two hydraulic patterns: (1) a sequencing batch reactor; and (2) a moving-bed biofilm reactor. Results show that the calibrated model is partly capable of reproducing the behaviour of N2O as well as the nitritation/nitrification/denitrification dynamics. However, the results emphasize that additional work is required before N2O emissions from sludge liquor treatment plants can be generally predicted with high certainty by simulations. Continued efforts should focus on determining the switching conditions for different N2O formation pathways and, if full-scale data are used, more detailed modelling of the measurement devices might improve the conclusions that can be drawn.

  • 6.
    Nordberg, Åke
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Edström, Mats
    RISE., SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Co-digestion of energy crops and the source-sorted organic fraction of municipal solid waste2005Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 52, nr 1-2, s. 217-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biological and technical performance during co-digestion of energy crops and the source-sorted organic fraction of municipal solid waste has been investigated at laboratory and pilot scale. A 50:50 (TS-based) mixture of energy crops and organic waste reached a loading rate of 6.0 gVS L -1d -1 with a methane yield of 0.33-0.38 LgVS -1, while a 80:20 mixture showed elevated levels of volatile fatty acids at 5.5 gVS L -1d -1 The better performance of the 50:50 mixture can partly be explained by a better nutritional composition. Mincing the ley crop reduced viscosity and reduced problems with fibre floating and scum-blanket formation. The electricity consumed for mincing and stirring at a full-scale plant corresponds to ca 3% of the energy produced. Calculations of the costs for full-scale plants indicate that the price of the upgraded biogas has to be at least 0.078 Euro/kWh in order to balance the costs. © IWA Publishing 2005.

  • 7.
    Regmi, P.
    et al.
    Brown and Caldwell, USA.
    Miller, M.
    Brown and Caldwell, USA.
    Jimenez, J.
    Brown and Caldwell, USA.
    Stewart, H.
    Jacobs, USA.
    Johnson, B.
    Jacobs, USA.
    Amerlinck, Y.
    Ghent University, Belgium.
    Volcke, E. I. P.
    Ghent University, Belgium.
    Arnell, Magnus
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi. Lund University, Sweden.
    García, P. J.
    Atkins, UK.
    Maere, T.
    Université Laval, Canada; Québec Water Research Center, Canada.
    Torfs, E.
    Université Laval, Canada; Québec Water Research Center, Canada.
    Vanrolleghem, P. A.
    Université Laval, Canada; Québec Water Research Center, Canada.
    Miletić, I.
    InCTRL Solutions Inc, Canada.
    Rieger, L.
    InCTRL Solutions Inc, Canada.
    Schraa, O.
    InCTRL Solutions Inc, Canada.
    Samstag, R.
    Bainbridge Island, USA.
    Santoro, D.
    Trojan Technologies, Canada.
    Snowling, S.
    Hydromantis ESS Inc, Canada.
    Takács, I.
    Dynamita, France.
    The future of WRRF modelling - Outlook and challenges2019Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 79, nr 1, s. 3-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 8.
    Saagi, R.
    et al.
    Lund University, Sweden.
    Arnell, Magnus
    RISE Research Institutes of Sweden, Samhällsbyggnad, Systemomställning och tjänsteinnovation. Lund University, Sweden.
    Reyes, D.
    Lund University, Sweden.
    Wärff, Christoffer
    Lund University, Sweden.
    Ahlström, Marcus
    RISE Research Institutes of Sweden, Samhällsbyggnad, Systemomställning och tjänsteinnovation.
    Jeppsson, U.
    Lund University, Sweden.
    Modelling temperature dynamics in sewer systems – Comparing mechanistic and conceptual modelling approaches2021Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 84, nr 9, s. 2335-2352Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9. Schnurer, A.
    et al.
    Nordberg, Åke
    RISE., SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Ammonia, a selective agent for methane production by syntrophic acetate oxidation at mesophilic temperature2008Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 57, nr 5, s. 735-740Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In biogas processes, methane production from acetate proceeds by either aceticlastic methanogenesis or through syntrophic acetate oxidation (SAO). In the present study, the pathway for methane production from acetate was analysed; i) during a gradual increase of the ammonia concentration (final concentration 7 g NH4+ - N/L) in a semi-continuous lab-scale anaerobic digester (4.3 L), operating at mesophilic temperature (37°C) or ii) in diluted enrichment cultures (100 ml) experiencing a gradual increase in ammonia, sodium, potassium and propionic acid. The pathway for methane formation was determined by calculating the 14CO2/14CH 4 ratio after incubating samples with 14C-2-acetate. In the anaerobic digester, as well as in the enrichment cultures, the 14CO2/14CH4 ratio clearly increased with increasing ammonium-nitrogen concentration, i.e. as the ammonia concentration increased, a shift from the aceticlastic mechanism to the syntrophic pathway occurred. The shift was very distinct and occurred as the NH4+ - N concentration rose above 3 g/l. No shift in pathway was seen during increasing concentrations of sodium, potassium or propionic acid. The shift to SAO in the biogas digester resulted in a twofold decrease in the specific gas and methane yield. © IWA Publishing 2008.

  • 10.
    Sylwan, Ida
    et al.
    Mälardalen University, Sweden.
    Bergna, D.
    University of Oulu, Finland.
    Runtti, H.
    University of Oulu, Finland.
    Westholm, L. J.
    Mälardalen University, Sweden.
    Thorin, E.
    Mälardalen University, Sweden.
    Primary and digested sludge-derived char as a Cd sorbent: Feasibility of local utilisation2023Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 88, nr 11, s. 2917-2930Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cadmium (Cd) is a highly toxic metal, occurring in municipal wastewater and stormwater as well as in wastewater from various industries. Char derived from the pyrolysis of municipal sewage sludge has the potential to be a low-cost sorption media for the removal of Cd. However, the balance between possible local char production and demand has not been assessed previously. In this study, the Cd sorption capacities of chars derived from primary (PSC) and secondary sludge (DSC), as well as the feasibility of char production for Cd sorbent purposes, and the pyrolysis energy balance were evaluated. Results showed that the sorption capacity of PSC (9.1 mg/g; 800 C, 70 min) was superior to that of DSC (6.0 mg/g; 800 C, 70 min), and increased with a higher pyrolysis temperature. Pyrolysis of primary sludge had a more favourable energy balance compared with the pyrolysis of digested sludge; however, when accounting for loss of biogas production the energy balance of primary sludge pyrolysis was negative. Assessment of the regional demand (Västeras, Sweden) indicated that PSC or DSC may cover the local Cd sorbent demand. However, it was estimated that large char volumes would be required, thus making the use of DSC/PSC less feasible. 

  • 11.
    Willén, Agnes
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Junestedt, C.
    IVL Swedish Environmental Research Institute, Sweden.
    Rodhe, Lena
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Pell, M.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Jönsson, H.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Sewage sludge as fertiliser - Environmental assessment of storage and land application options2017Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 75, nr 5, s. 1034-1050Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sewage sludge (SS) contains beneficial plant nutrients and organic matter, and therefore application of SS on agricultural land helps close nutrient loops. However, spreading operations are restricted to certain seasons and hence the SS needs to be stored. Storage and land application of SS are both potential sources of greenhouse gases and ammonia, leading to global warming, acidification and eutrophication. Covering the stored SS, treating it with urea and choosing the correct time for land application all have the potential to reduce emissions from the system. Using life cycle assessment (LCA), this study compares storage and land application options of SS in terms of global warming potential (GWP), acidification potential, eutrophication potential and primary energy use. The system with covered storage has the lowest impact of all categories. Systems with autumn application are preferable to spring application for all impact categories but, when nitrate leaching is considered, spring application is preferable in terms of eutrophication and primary energy use and, for some SS treatments, GWP. Ammonia addition reduces nitrous oxide and ammonia emissions during storage, but increases these emissions after land application. Storage duration has a large impact on GWP, while amount of chemical nitrogen fertiliser substituted has a large impact on primary energy use.

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