File contents

package Krebs "Secondary settling tank modelling by Krebs (ASM1)" 
  extends Modelica.Icons.Library;
  
  annotation (
    Coordsys(
      extent=[0, 0; 442, 386], 
      grid=[2, 2], 
      component=[20, 20]), 
    Window(
      x=0.45, 
      y=0.01, 
      width=0.44, 
      height=0.65, 
      library=1, 
      autolayout=1), 
    Documentation(info="This package contains an ASM1 secondary clarifier model and an Interfaces sub-library
based on Krebs conceptional model [1].
The settler model consists of two compartments, a \"sludge-bed\" and a clear water zone above.

Main Author:
   Gerald Reichl
   Technische Universitaet Ilmenau
   Faculty of Informatics and Automation
   Department Dynamics and Simulation of ecological Systems
   P.O. Box 10 05 65
   98684 Ilmenau
   Germany
   email: gerald.reichl@tu-ilmenau.de

References:

[1] P. Krebs and M. Armbruster and W. Rodi: Numerische Nachklaerbeckenmodelle. Korrespondenz Abwasser. 47 (7)
    2000. pp 985-999.

This package is free software; it can be redistributed and/or modified under the terms of the Modelica license, see the license conditions and the accompanying
disclaimer in the documentation of package Modelica in file \"Modelica/package.mo\".

Copyright (C) 2003, Gerald Reichl
"));
  package Interfaces "Partial models for Secondary Clarifier Model by Krebs" 
    
    extends Modelica.Icons.Library;
    
    partial model SCVar "partial models providing variables" 
      package WWU = WasteWater.WasteWaterUnits;
      WWU.MassConcentration Xf "total sludge concentration";
      WWU.MassConcentration XB "sludge concentration in sludge layer";
      WWU.MassConcentration XR "sludge concentration of return";
      
      WWU.MassConcentration Si1 
        "Soluble inert organic matter in first stirrer tank of the excess layer"
        ;
      WWU.MassConcentration Ss1 
        "Readily biodegradable substrate in first stirrer tank of the excess layer"
        ;
      WWU.MassConcentration So1 
        "Dissolved oxygen in first stirrer tank of the excess layer";
      WWU.MassConcentration Sno1 
        "Nitrate and nitrite nitrogen in first stirrer tank of the excess layer"
        ;
      WWU.MassConcentration Snh1 
        "Ammonium nitrogen in first stirrer tank of the excess layer";
      WWU.MassConcentration Snd1 
        "Soluble biodegradable organic nitrogen in first stirrer tank of the excess layer"
        ;
      WWU.Alkalinity Salk1 
        "Alkalinity in first stirrer tank of the excess layer";
      
      WWU.MassConcentration Si2 
        "Soluble inert organic matter in second stirrer tank of the excess layer"
        ;
      WWU.MassConcentration Ss2 
        "Readily biodegradable substrate in second stirrer tank of the excess layer"
        ;
      WWU.MassConcentration So2 
        "Dissolved oxygen in second stirrer tank of the excess layer";
      WWU.MassConcentration Sno2 
        "Nitrate and nitrite nitrogen in second stirrer tank of the excess layer"
        ;
      WWU.MassConcentration Snh2 
        "Ammonium nitrogen in second stirrer tank of the excess layer";
      WWU.MassConcentration Snd2 
        "Soluble biodegradable organic nitrogen in second stirrer tank of the excess layer"
        ;
      WWU.Alkalinity Salk2 
        "Alkalinity in second stirrer tank of the excess layer";
      annotation (
        Coordsys(
          extent=[-100, -100; 100, 100], 
          grid=[2, 2], 
          component=[20, 20]), 
        Window(
          x=0.45, 
          y=0.01, 
          width=0.35, 
          height=0.49), 
        Documentation(info="partial models providing ASM1 variables"));
    end SCVar;
    partial model ratios "partial model for ratios of solid components" 
      // ratios of solid components
      Real rXi;
      Real rXs;
      Real rXbh;
      Real rXba;
      Real rXp;
      Real rXnd;
      annotation (
        Coordsys(
          extent=[-100, -100; 100, 100], 
          grid=[2, 2], 
          component=[20, 20]), 
        Window(
          x=0.45, 
          y=0.01, 
          width=0.35, 
          height=0.49), 
        Documentation(info="partial model for ASM1 ratios of solid components")
        );
    end ratios;
    annotation (
      Coordsys(
        extent=[0, 0; 442, 386], 
        grid=[1, 1], 
        component=[20, 20]), 
      Window(
        x=0.45, 
        y=0.01, 
        width=0.44, 
        height=0.65, 
        library=1, 
        autolayout=1), 
      Documentation(info="This package contains partial models for ASM1 secondary clarifier models.

Main Author:
   Gerald Reichl
   Technische Universitaet Ilmenau
   Faculty of Informatics and Automation
   Department Dynamics and Simulation of ecological Systems
   P.O. Box 10 05 65
   98684 Ilmenau
   Germany

This package is free software; it can be redistributed and/or modified under the terms of the Modelica license, see the license conditions and the accompanying
disclaimer in the documentation of package Modelica in file \"Modelica/package.mo\".

Copyright (C) 2003, Gerald Reichl
"));
  end Interfaces;
  model SecClarModKrebs "ASM1 Secondary Settling Tank Model based on Krebs" 
    
    extends WasteWater.Icons.SecClarKrebs;
    package WWSC = WasteWater.ASM1.SecClar.Krebs.Interfaces;
    extends WWSC.SCVar;
    extends WWSC.ratios;
    
    package SI = Modelica.SIunits;
    package WI = WasteWater.ASM1.Interfaces;
    package WWU = WasteWater.WasteWaterUnits;
    parameter SI.Length hsc=4.0 "height of secondary clarifier";
    parameter SI.Area Asc=1500.0 "area of secondary clarifier";
    parameter WWU.SludgeVolumeIndex ISV=130 "Sludge Volume Index";
    Real te "thickening time in sludge layer in [d]";
    SI.Length hs "height of sludge layer";
    SI.Length he "height of excess layer";
    WI.WWFlowAsm1in Feed annotation (extent=[-110, 4; -90, 24]);
    WI.WWFlowAsm1out Effluent annotation (extent=[92, 47; 112, 67]);
    WI.WWFlowAsm1out Return annotation (extent=[-40, -106; -20, -86]);
    WI.WWFlowAsm1out Waste annotation (extent=[20, -106; 40, -86]);
    annotation (
      Coordsys(
        extent=[-100, -100; 100, 100], 
        grid=[2, 2], 
        component=[20, 20]), 
      Window(
        x=0.45, 
        y=0.01, 
        width=0.35, 
        height=0.49), 
      Documentation(info="This component models an ASM1 secondary clarifier based on Krebs conceptional model.
It consists of two compartments: a \"sludge-bed\" and a clear water zone above.

Parameters:
  hsc -  height of clarifier [m]
  Asc -  surface area of secondary clarifier [m2]
  ISV -  Sludge Volume Index [ml/g]
"), 
      Diagram(
        Rectangle(extent=[-90, 80; 92, 14], style(thickness=2)), 
        Rectangle(extent=[-90, 14; 92, -86], style(thickness=2)), 
        Polygon(points=[-8, -20; -8, -38; -16, -38; 0, -48; 16, -38; 8, -38; 8
              , -20; -8, -20], style(pattern=0, fillColor=48)), 
        Polygon(points=[-8, 34; -8, 54; -16, 54; 0, 64; 16, 54; 8, 54; 8, 34; -
              8, 34], style(pattern=0, fillColor=69)), 
        Text(extent=[-90, 78; -34, 66], string="top_layer"), 
        Text(extent=[-90, 20; -30, -16], string="bottom_layer"), 
        Line(points=[-90, 48; 92, 48], style(pattern=2))), 
      Icon);
  equation 
    
    // total sludge concentration in clarifier feed
    Xf = 0.75*(Feed.Xs + Feed.Xbh + Feed.Xba + Feed.Xp + Feed.Xi);
    
    // ratios of solid components
    rXs = Feed.Xs/Xf;
    rXbh = Feed.Xbh/Xf;
    rXba = Feed.Xba/Xf;
    rXp = Feed.Xp/Xf;
    rXi = Feed.Xi/Xf;
    rXnd = Feed.Xnd/Xf;
    
    
      //following expression is only for steady state initial equation of XB and is necessary
    
      //to calculate hs, if there would be problems with "initial()" in your modelica version 
    //leave out this term and initial XB (or hs) manually e.g. via script-file
    if initial() then
      XB = Feed.Q/(0.7*(-(Return.Q + Waste.Q)))*Xf;
    end if;
    
    //thickening time in sludge layer in [d]
    te = 5/7*Asc*hs/(-(Return.Q + Waste.Q));
    
    //sludge concentration in sludge layer (unit of time in [h]) in [g/m3]
    XB = (1000/ISV*((te*24)^(1/3)))*1000;
    
    //sludge concentration of return
    XR = 0.7*XB;
    
    //ODE of height of sludge layer
    der(hs) = (Feed.Q*Xf - (-(Return.Q + Waste.Q))*XR)/(Asc/2*XB);
    
    //height of excess layer
    he = hsc - hs;
    
    // ODE of soluble components in first stirrer tank of the excess layer
    der(Si1) = (Feed.Q*Feed.Si - (-Effluent.Q)*Si1 - (-(Waste.Q + Return.Q))*
      Si1)/(Asc*he/2);
    der(Ss1) = (Feed.Q*Feed.Ss - (-Effluent.Q)*Ss1 - (-(Waste.Q + Return.Q))*
      Ss1)/(Asc*he/2);
    der(So1) = (Feed.Q*Feed.So - (-Effluent.Q)*So1 - (-(Waste.Q + Return.Q))*
      So1)/(Asc*he/2);
    der(Sno1) = (Feed.Q*Feed.Sno - (-Effluent.Q)*Sno1 - (-(Waste.Q + Return.Q))
      *Sno1)/(Asc*he/2);
    der(Snh1) = (Feed.Q*Feed.Snh - (-Effluent.Q)*Snh1 - (-(Waste.Q + Return.Q))
      *Snh1)/(Asc*he/2);
    der(Snd1) = (Feed.Q*Feed.Snd - (-Effluent.Q)*Snd1 - (-(Waste.Q + Return.Q))
      *Snd1)/(Asc*he/2);
    der(Salk1) = (Feed.Q*Feed.Salk - (-Effluent.Q)*Salk1 - (-(Waste.Q + Return.
      Q))*Salk1)/(Asc*he/2);
    
    // ODE of soluble components in second stirrer tank of the excess layer
    der(Si2) = ((-Effluent.Q)*Si1 - (-Effluent.Q)*Si2)/(Asc*he/2);
    der(Ss2) = ((-Effluent.Q)*Ss1 - (-Effluent.Q)*Ss2)/(Asc*he/2);
    der(So2) = ((-Effluent.Q)*So1 - (-Effluent.Q)*So2)/(Asc*he/2);
    der(Sno2) = ((-Effluent.Q)*Sno1 - (-Effluent.Q)*Sno2)/(Asc*he/2);
    der(Snh2) = ((-Effluent.Q)*Snh1 - (-Effluent.Q)*Snh2)/(Asc*he/2);
    der(Snd2) = ((-Effluent.Q)*Snd1 - (-Effluent.Q)*Snd2)/(Asc*he/2);
    der(Salk2) = ((-Effluent.Q)*Salk1 - (-Effluent.Q)*Salk2)/(Asc*he/2);
    
    // volume flow rates
    Feed.Q + Effluent.Q + Return.Q + Waste.Q = 0;
    
    // effluent, solid and soluble components (ASM1)
    Effluent.Si = Si2;
    Effluent.Ss = Ss2;
    Effluent.So = So2;
    Effluent.Sno = Sno2;
    Effluent.Snh = Snh2;
    Effluent.Snd = Snd2;
    Effluent.Salk = Salk2;
    Effluent.Xi = 0.0*XR;
    Effluent.Xs = 0.0*XR;
    Effluent.Xbh = 0.0*XR;
    Effluent.Xba = 0.0*XR;
    Effluent.Xp = 0.0*XR;
    Effluent.Xnd = 0.0*XR;
    
    // return sludge flow, solid and soluble components (ASM1)
    Return.Si = Si1;
    Return.Ss = Ss1;
    Return.So = So1;
    Return.Sno = Sno1;
    Return.Snh = Snh1;
    Return.Snd = Snd1;
    Return.Salk = Salk1;
    Return.Xi = rXi*XR;
    Return.Xs = rXs*XR;
    Return.Xbh = rXbh*XR;
    Return.Xba = rXba*XR;
    Return.Xp = rXp*XR;
    Return.Xnd = rXnd*XR;
    
    // waste sludge flow, solid and soluble components (ASM1)
    Waste.Si = Si1;
    Waste.Ss = Ss1;
    Waste.So = So1;
    Waste.Sno = Sno1;
    Waste.Snh = Snh1;
    Waste.Snd = Snd1;
    Waste.Salk = Salk1;
    Waste.Xi = rXi*XR;
    Waste.Xs = rXs*XR;
    Waste.Xbh = rXbh*XR;
    Waste.Xba = rXba*XR;
    Waste.Xp = rXp*XR;
    Waste.Xnd = rXnd*XR;
  end SecClarModKrebs;
end Krebs;