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  • 1.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Diehl, Stefan
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Analyses of Activated Sludge Processes Consisting of a Plug-Flow Reactor and a Non-ideal Settler2015In: Proc. 9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015Conference paper (Other academic)
    Abstract [en]

    An activated sludge process (ASP) consisting of a plug-flow reactor (PFR) and a non-ideal settler is modelled and analysed. One soluble substrate component and one particulate biomass are assumed. The biomass growth rate is described by a Monod function. The settler model includes hindered settling and compression. A model describing the steady-state behaviour of the ASP is derived which constrains the settler to work with a fixed sludge blanket height in the thickening zone. The model provides new understanding for these types of ASPs and may be used for novel design schemes. The numerical example suggests that the steady-state solutions of the ASP give a one-parameter family of solutions, where the parameter is the recycle ratio r.

  • 2.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Analysis of simple bioreactor models: A comparison between Monod and Contois kinetics2014In: Proc. IWA Conference on Activated Sludge – 100 Years and Counting, IWA Publishing, 2014Conference paper (Refereed)
    Abstract [en]

    In this paper, an analysis of simple bioreactors in series is presented. The bioreactors are analysed for growth kinetics of the biomass described by a Monod and a Contois function. In particular, it is studied how the effluent substrate concentration is depending on the influent substrate concentration during steady state. It is shown that by going from one to two bioreactors in series completely changes the process behaviour when the growth kinetics is described by a Monod function. It is also shown that a bioreactor described by Contois kinetics has a completely different behaviour compared with the Monod case.

  • 3.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Fault detection and isolation of sensors in aeration control systems2016In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 73, no 3, p. 648-653Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of fault detection (FD) and isolation in the aeration system of an activated sludge process. For this study, the dissolved oxygen in each aerated zone is assumed to be controlled automatically. As the basis for an FD method we use the ratio of air flow rates into different zones. The method is evaluated in two scenarios: using the Benchmark Simulation Model no. 1 (BSM1) by Monte Carlo simulations and using data from a wastewater treatment plant. The FD method shows good results for a correct and early FD and isolation.

  • 4.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Fault detection and isolation of sensors in aeration control systems2014In: Proc. IWA World Water Congress: 2014, IWA Publishing, 2014Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider the problem of fault detection and isolation in the aeration system of an activated sludge process. The purpose is to detect and localize possible faults in dissolved oxygen and air flow sensors. The dissolved oxygen in each aerated zone is assumed to be controlled automatically. As the basis for a fault detection algorithm we use the ratio of air flow rates into different zones. The method is evaluated in two scenarios: using the Benchmark Simulation Model nº 1 by Monte Carlo simulations, and using data from a wastewater treatment plant. The fault detection method shows good results for a correct and early fault detection and isolation.

  • 5.
    Carlsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Fault detection of sensors in aeration control systems: the airflow ratio method2013In: 11th IWA conference on Instrumentation, Control and Automation, 2013Conference paper (Refereed)
    Abstract [en]

    A fault detection method, ARM, has been proposed for detection of faults in DOsensors in a serie of aerated zones. The DO in each zone is assumed to be controlled. In a simulation study, ARM shows promising results for correct and early fault detection. Eventually, it will not be possible to distinguish between a fault in a DOsensor and in air flow rate sensor. In this study, we have, for simplicity, used KLa as a measure of the air flow rate. In practice an air flow rate sensor should be used. An interesting alternative is to use the air valve position instead of the airflow rate.

  • 6.
    Chistiakova, Tatiana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Samuelsson, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Binary classifiers applied to detect DO sensor faults during washing events2015In: Proc. 2nd IWA Conference on New Developments in IT & Water, IWA Publishing, 2015Conference paper (Other academic)
    Abstract [en]

    In this paper, several classication techniques are applied for monitoring the status of DO sensors in wastewater treatment plants. In particular, DO sensors during washing events are studied and indication parameters from these events are used. The methods considered are the following: k-Nearest Neighbours, Radial Basis Function and Random Forest classiers. The result shows the comparison and the eligibility of the methods to detect a clogged DO-sensor.

  • 7.
    Chistiakova, Tatiana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Application of machine learning methods for fault detection in wastewater treatment plants2014In: Reglermöte, 2014Conference paper (Other academic)
  • 8. Diehl, Stefan
    et al.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Steady-state Analysis and Design of Activated Sludge Processes Including Compressive Settling2015In: Proc. 9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015Conference paper (Other academic)
  • 9. Diehl, Stefan
    et al.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Steady-state analysis of activated sludge processes with a settler model including sludge compression2016In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 88, p. 104-116Article in journal (Refereed)
    Abstract [en]

    A reduced model of a completely stirred-tank bioreactor coupled to a settling tank with recycle is analyzed in its steady states. In the reactor, the concentrations of one dominant particulate biomass and one soluble substrate component are modelled. While the biomass decay rate is assumed to be constant, growth kinetics can depend on both substrate and biomass concentrations, and optionally model substrate inhibition. Compressive and hindered settling phenomena are included using the Bürger-Diehl settler model, which consists of a partial differential equation. Steady-state solutions of this partial differential equation are obtained from an ordinary differential equation, making steady-state analysis of the entire plant difficult. A key result showing that the ordinary differential equation can be replaced with an approximate algebraic equation simplifies model analysis. This algebraic equation takes the location of the sludge-blanket during normal operation into account, allowing for the limiting flux capacity caused by compressive settling to easily be included in the steady-state mass balance equations for the entire plant system. This novel approach grants the possibility of more realistic solutions than other previously published reduced models, comprised of yet simpler settler assumptions. The steady-state concentrations, solids residence time, and the wastage flow ratio are functions of the recycle ratio. Solutions are shown for various growth kinetics; with different values of biomass decay rate, influent volumetric flow, and substrate concentration.

  • 10. Irizar, Ion
    et al.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Morrás, Mikel
    Aymerich, Enrique
    Robust tuning of bending-points detection algorithms in batch-operated processes: Application to autothermal thermophilic aerobic digesters2015In: Environmental Modelling & Software, ISSN 1364-8152, E-ISSN 1873-6726, Vol. 71, p. 148-158Article in journal (Refereed)
  • 11. Nájera, Silvano
    et al.
    Gil-Martínez, Montserrat
    Zambrano, Jesús A.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    ATAD control goals through the analysis of process variables and evaluation of quality, production and cost2015In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 71, no 5, p. 717-724Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to establish and quantify different operational goals and control strategies in autothermal thermophilic aerobic digestion (ATAD). This technology appears as an alternative to conventional sludge digestion systems. During the batch-mode reaction, high temperatures promote sludge stabilization and pasteurization. The digester temperature is usually the only online, robust, measurable variable. The average temperature can be regulated by manipulating both the air injection and the sludge retention time. An improved performance of diverse biochemical variables can be achieved through proper manipulation of these inputs. However, a better quality of treated sludge usually implies major operating costs or a lower production rate. Thus, quality, production and cost indices are defined to quantify the outcomes of the treatment. Based on these, tradeoff control strategies are proposed and illustrated through some examples. This paper's results are relevant to guide plant operators, to design automatic control systems and to compare or evaluate the control performance on ATAD systems.

  • 12.
    Samuelsson, Oscar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Zambrano, Jesús
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Björk, Anders
    Chistiakova, Tatiana
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Detecting anomalous air flow-ammonia load ratios, using Gaussian process regression2015In: Proc. 9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015Conference paper (Refereed)
  • 13.
    Zambrano, Jesús
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Fault detection of DO sensors subject to possible clogging2015In: Proc. 9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015Conference paper (Other academic)
  • 14.
    Zambrano, Jesús
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Optimizing zone volumes in bioreactors described by Monod and Contois growth kinetics2014In: Proc. IWA World Water Congress: 2014, IWA Publishing, 2014Conference paper (Refereed)
    Abstract [en]

    In this paper, an optimization study of simple bioreactors in series is presented. For a given total reactor volume, the zone volumes are optimized with respect to the effluent substrate. Also simple activated sludge models are considered. Both Monod and Contois functions are used for describing the growth kinetics. It is shown that the optimal zone volumes are very different depending on the choice of growth kinetics. In particular, it is studied how the influent steady state substrate concentration influence the optimal configuration.

  • 15.
    Zambrano, Jesús
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Steady-state analysis of simple activated sludge processes with Monod and Contois growth kinetics2014In: Proc. IWA Conference on Activated Sludge – 100 Years and Counting, IWA Publishing, 2014Conference paper (Refereed)
    Abstract [en]

    In this paper, simple activated sludge process (ASP) models with Monod and Contois biomass growth kinetics are compared. In particular, the cases of an ASP with one or two bioreactors are studied. Of particular concern in this study is to investigate how the effluent substrate concentration depends on the influent substrate concentration. It is shown that the results are very different dependingon the number of bioreactors and on the growth kinetics assumed.

  • 16.
    Zambrano, Jesús
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Diehl, Stefan
    Optimal steady-state design of zone volumes of bioreactors with Monod growth kinetics2015In: Biochemical engineering journal, ISSN 1369-703X, E-ISSN 1873-295X, Vol. 100, p. 59-66Article in journal (Refereed)
  • 17. Zambrano, Jesús
    et al.
    Samuelsson, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Machine learning techniques for monitoring the sludge profile in a secondary settler tank2019In: Applied water science, ISSN 2190-5487, E-ISSN 2190-5495, Vol. 9, no 6, article id 146Article in journal (Refereed)
  • 18.
    Zambrano, Jesús
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Samuelsson, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Chistiakova, Tatiana
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Liu, Hongbin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Gaussian process regression for monitoring a secondary settler2015In: Proc. 2nd IWA Conference on New Developments in IT & Water, IWA Publishing, 2015Conference paper (Other academic)
    Abstract [en]

    An approach based on Gaussian Process Regression for monitoring the sludge profile of a secondary settler is proposed. Gaussian Process is a probabilistic, nonparametric model with an uncertainty prediction. The approach is illustrated using data from a sensor measuring the sludge concentration in a settler as a function of the settler depth at Bromma wastewater treatment plant (WWTP). Results suggest that the approach is feasible for monitoring and fault detection of the sludge settling process.

1 - 18 of 18
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