CHAPTER 4
What is a Composite Variable?
In GPS-X, a group of state variables (such as oxygen, heterotrophic biomass, nitrate, ammonia, soluble substrate, particulate substrate, etc.) are calculated for each connection point in the plant layout. These state variables are the fundamental components that are acted upon by the processes in the models in each library.
These particular state variable components are not always easily measurable or interpretable in practical applications. Therefore, a series of composite variables are calculated from the state variables. The composite variables combine the state variables into forms that are typically measured, such as total suspended solids (TSS), BOD, COD and Total Kjeldahl Nitrogen (TKN).
Stoichiometry Settings
The way that the composite variables are calculated from state variables changes from library to library and to a great degree from model to model.
Composite variables are calculated from state variables with the use of stoichiometric constants. These constants describe the relationships between various states and composites, and depend on the type of composite calculations used.
Stoichiometry Calculations
Nomenclature
In this chapter, diagrams and tables are used to depict the relationships between the state and composite variables included in a library.
Box-and-arrow Diagrams
The nomenclature used in the box-and-arrows diagrams is explained in Figure 4‑1.
Figure 4‑1 – Diagram Nomenclature
The variables in the boxes and above the connection lines are known (either previously calculated or user input). The variables in BOLD CAPITALS represent the composite variables which are to be calculated. The connection line shows the direction of calculation and always begins from a known or boxed variable. Multiple lines converging to one unknown variable imply a summation operator. In the example shown above, the variable Y1 is calculated by multiplying the variable x1 by the stoichiometry parameter k and summing it with variable x2. If no stoichiometry parameter appears above the connection line, it implies a default value of 1. When a broken line circle is drawn on the lines, it indicates that the stoichiometry parameters for these lines are model dependent. In certain situations, two or more calculated composite variables are used to calculate an additional composite variable. For example, Y3 is calculated by adding the calculated composite variables of Y1 and Y2.
In addition to diagrams which explain the general way composite variables are calculated, composite variable tables are used to explain model-specific calculations. The nomenclature used in the composite variables tables is explained in Table 4‑1:
Table 4‑1 – Example Composite Variable Calculations
|
|
SCOMP |
XCOMP |
TCOMP |
|
sa |
1 |
|
1 |
|
sb |
ksb |
|
ksb |
|
xa |
|
1 |
1 |
|
xb |
|
kxb |
kxb |
The composite variables being calculated are shown across the top of each column. The state variables used in the calculations are shown down the left side of the table. To calculate the composite variable, each state variable is multiplied by the coefficient in the table for that particular composite variable, and then summed down the column.
For the example data given in Table 4‑1, the calculations for SCOMP, XCOMP, and TCOMP are:
SCOMP = 1*sa + ksb*sb +
0*xa + 0*xb = sa + ksb*sb
XCOMP = 0*sa + 0*sb + 1*xa + kxb*xb = xa + kxb*xb
TCOMP = 1*sa + ksb*sb + 1*xa + kxb*xb = sa + ksb*sb +
xa + kxb*xb
Composite Variables in MANTIS2LIB
The composite variable calculation schemes in MANTIS2LIB are shown in Figure 4‑2 to Figure 4‑6. Figure 4‑2 shows the scheme for estimation of soluble BOD5 (SBOD), particulate BOD5 (XBOD), BOD5 (BOD), soluble ultimate BOD (SBODU), particulate ultimate BOD (SBODU), ultimate BOD (BODU), soluble COD (SCOD), particulate COD (XCOD) and COD (COD). The list of stoichiometric parameters used in the estimation of composite variables is provided in Table 4‑2.
Table 4‑2 - Stoichiometry Parameters used in Estimation of Composite Variables MANTIS2LIB
|
Stoichiometry Parameter |
Default Value |
Description |
|
yhglobal |
0.666 |
Heterotrophic biomass yield |
|
fuu |
0.206 |
Fraction of unbiodegradable residue in biomass |
|
fssbodtosscod |
0.717 |
BOD5 to COD ratio of soluble substrate |
|
fpsbodtopscod |
0.58 |
BOD5 to COD ratio of particulate substrate |
|
fbbodtobcod |
0.566 |
BOD5 to COD ratio of biomass |
|
icodtovssxbt |
1.674 |
xCOD/VSS ratio of PHA |
The default value of the stoichiometry parameters can be changed in the System > Input Parameters > Biochemical Model Settings menu.
Figure 4‑3 shows the scheme for estimation of Volatile Suspended Solid (VSS), Inorganic Suspended Solid (XISS) and Total Suspended Solid (TSS) concentration. In the estimation of VSS, each biomass concentration is multiplied by a corresponding VSS to COD factor. For example, ivsstocodxbh is the VSS to COD ratio for heterotrophic biomass, xbh. The VSS to COD ratio for each biomass type are calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu.
As the composition of xs and xi are not well known, the VSS to COD ratios for these states ivsstocodxs and ivsstocodxi are provided as direct inputs. These ratios can be accessed and changed in System > Input Parameters > Biochemical Model Settings menu. The state variable of xns is included in the calculation of VSS for being consistent with the practice of considering the N fraction in biomass as part of VSS. A stoichiometry factor of 17.0/14.0 is used to convert N to NH3.
In the calculation of Inorganic Suspended Solid (XISS), each biomass concentration is multiplied by the inorganic fraction in the biomass. The inorganic fraction for each biomass is estimated by subtracting the VSS to SS ratio for each individual biomass from one. The VSS to SS ratio for each individual biomass type is calculated by using the set biomass composition, for example ivsstossxbh is the VSS to SS ratio calculated for the xbh biomass type.
The composite variable of XISS also includes the contribution from the inorganic states in the model. The mass contributions from the xpp and xps states are calculated by using a stoichiometry factor of 95/31. The factor reflects the conversion from molecular weight of P to molecular weight of PO43-. For all the other inorganic states a stoichiometry ratio of 1 is used.
The Total Suspended Solid (TSS) concentration is calculated by the sum of estimated VSS and XISS.
Figure 4‑4 shows the scheme for estimation of soluble part of Total Kjeldahl Nitrogen (STKN), particulate part of Total Kjeldahl Nitrogen (XTKN), Total Kjeldahl Nitrogen (TKN), Total Nitrogen (TN) and Total Nitrogen including dissolved Nitrogen (TN & dissolved gas). In the estimation of STKN, the stoichiometry ratio of, insi is used to estimate the organic nitrogen present in the si state variable. In the estimation of XTKN, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the N content in the corresponding biomass. For example, inxbh is the stoichiometry factor representing the N content in the heterotrophic biomass, xbh. The N fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. In the calculation of XTKN, the N contained in the MgNH4PO4 is also included. Although, in strict sense this is not a part of the organic nitrogen, it is assumed that the ammonia contained in the precipitate shall reflect in the analytical measurement of TKN.
Figure 4‑5 shows the scheme for estimation of soluble part of Total Phosphorus (STP), particulate organic part of Total Phosphorus (XTOP), particulate inorganic part of Total Phosphorus (XTIP) and Total Phosphorus. In the estimation of STP, the stoichiometry ratio of, ipnsi is used to estimate the phosphorus present in the si state variable. In the estimation of XTOP, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the P content in the corresponding biomass. For example, ipxbh is the stoichiometry factor representing the P content in the heterotrophic biomass, xbh. The P fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. In the calculation of XTIP, the P contained in various P- precipitates is included. The stoichiometry factor for each precipitate are estimated based on the composition of the precipitate. These stoichiometry factors are also available in Biochemical Model Settings menu. The composite variable of XTP is estimated by the sum of XTOP and XTIP. The TP is estimated by the sum of STP and XTP.
Figure 4‑6 shows the scheme for estimation of soluble part of Total Organic Carbon (STOC), particulate part of Total Organic Carbon (XTOC), and Total Organic Carbon. In the estimation of STOC, the stoichiometry ratio of icsac, icsmet, icspro are estimated based on the substrate compositions. The stoichiometry factor of icscol, icsi and icss on the other hand needs to be set by direct user input. These factors can be accessed and changed in System > Input Parameters > Biochemical Model Settings menu. In the estimation of XTOC, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the C content in the corresponding biomass. For example, icxbh is the stoichiometry factor representing the C content in the heterotrophic biomass, xbh. The C fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. For the particulate states of xi and xs, the user can directly enter the C content in the System > Input Parameters > Biochemical Model Settings menu. The composite variable of TOC is estimated by the sum of XTOC and STOC.
Table 4‑3 presents the summary of the stoichiometry parameters used in the MANTIS2LIB and access menus for changing the default values.
Table 4‑3 - Access Menus for Different Stoichiometry Parameters in MANTIS2LIB
|
Stoichiometry Parameter |
Access Menu |
|
yhglobal |
System > Input Parameters > Biochemical Model Settings |
|
fuu |
System > Input Parameters > Biochemical Model Settings |
|
fssbodtosscod |
System > Input Parameters > Biochemical Model Settings |
|
fpsbodtopscod |
System > Input Parameters > Biochemical Model Settings |
|
fbbodtobcod |
System > Input Parameters > Biochemical Model Settings |
|
COD to VSS ratio for biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
COD to VSS ratio for xs and xi |
System > Input Parameters > Biochemical Model Settings |
|
VSS to SS ratio for biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
N fraction in biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
N fraction in xi, si |
Influent Characterization menu of influent object |
|
P fraction in biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
P fraction in xi, si |
Influent Characterization menu of influent object |
|
C fraction in biomass and sac, spro, smet |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass/substrate composition) |
|
C fraction in xcol, xss, si, xi, xs |
System > Input Parameters > Biochemical Model Settings |
Figure 4‑2 – MANTIS2LIB – Calculation
Procedure for Composite Variables SCOD, COD, SBOD, BOD, SBODU and
BODU
Figure 4‑3 - MANTIS2LIB - Calculation
Procedure for Composite Variables VSS, TSS
Figure 4‑4 - MANTIS2LIB - Calculation Procedure for Composite Variables STKN and TKN
Figure 4‑5 - MANTIS2LIB - Calculation Procedure for Composite Variables STP, XTP, and TP
Figure 4‑6 - MANTIS2LIB - Calculation Procedure for Composite Variables STOC and TOC
Displaying Composite Variables
All of the composite variables, including the most common ones such as X (total suspended solids), TKN (Total Kjeldahl Nitrogen), BOD, COD, etc., can be accessed by selecting the Output Variables > Concentrations menu. These variables (and those found by clicking on the More... button) can be tagged and placed on output graphs.
Composite Variables in MANTIS3LIB
Mantis3 library shares the same composite variable calculation with Mantis2 for the COD, TSS, TN, TP, and TOC. Please refer to Composite Variables in MANTIS2LIBsection for more information.
Composite Variables in MANTIS2SLIB
The composite variable calculation schemes in MANTIS2LIB are shown in Figure 4‑7 to Figure 4‑13. Figure 4‑7 shows the scheme for estimation of soluble BOD5 (SBOD), particulate BOD5 (XBOD), BOD5 (BOD), soluble ultimate BOD (SBODU), particulate ultimate BOD (SBODU), ultimate BOD (BODU), soluble COD (SCOD), particulate COD (XCOD) and COD (COD). The list of stoichiometric parameters used in the estimation of composite variables is provided in Table 4‑4.
Table 4‑4 - Stoichiometry Parameters used in Estimation of Composite Variables in MANTIS2SLIB
|
Stoichiometry Parameter |
Default Value |
Description |
|
yhglobal |
0.666 |
Heterotrophic biomass yield |
|
fuu |
0.206 |
Fraction of unbiodegradable residue in biomass |
|
fssbodtosscod |
0.717 |
BOD5 to COD ratio of soluble substrate |
|
fpsbodtopscod |
0.58 |
BOD5 to COD ratio of particulate substrate |
|
fbbodtobcod |
0.566 |
BOD5 to COD ratio of biomass |
|
icodtovssxbt |
1.674 |
xCOD/VSS ratio of PHA |
|
frsulfurinmes |
0.3647 |
Ratio of sulfur to metal-sulfur precipitate |
The default value of the stoichiometry parameters can be changed in the System > Input Parameters > Biochemical Model Settings menu. Additional state variables like sulfate reducing biomass variables (xbsr1, xbsr2, xbsr3, xbsr4) are introduced in this library to capture the reaction of sulfur and selenium.
Figure 4‑8 shows the scheme for estimation of Volatile Suspended Solid (VSS), Inorganic Suspended Solid (XISS) and Total Suspended Solid (TSS) concentration. In the estimation of VSS, each biomass concentration is multiplied by a corresponding VSS to COD factor. For example, ivsstocodxbh is the VSS to COD ratio for heterotrophic biomass, xbh. The VSS to COD ratio for each biomass type are calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu.
As the composition of xs and xi are not well known, the VSS to COD ratios for these states ivsstocodxs and ivsstocodxi are provided as direct inputs. These ratios can be accessed and changed in System > Input Parameters > Biochemical Model Settings menu. The state variable of xns is included in the calculation of VSS for being consistent with the practice of considering the N fraction in biomass as part of VSS. A stoichiometry factor of 17.0/14.0 is used to convert N to NH3.
In the calculation of Inorganic Suspended Solid (XISS), each biomass concentration is multiplied by the inorganic fraction in the biomass. The inorganic fraction for each biomass is estimated by subtracting the VSS to SS ratio for each individual biomass from one. The VSS to SS ratio for each individual biomass type is calculated by using the set biomass composition, for example ivsstossxbh is the VSS to SS ratio calculated for the xbh biomass type.
The composite variable of XISS also includes the contribution from the inorganic states in the model. The mass contributions from the xpp and xps states are calculated by using a stoichiometry factor of 95/31. The factor reflects the conversion from molecular weight of P to molecular weight of PO43-. For all the other inorganic states a stoichiometry ratio of 1 is used.
The Total Suspended Solid (TSS) concentration is calculated by the sum of estimated VSS and XISS.
Figure 4‑9 shows the scheme for estimation of soluble part of Total Kjeldahl Nitrogen (STKN), particulate part of Total Kjeldahl Nitrogen (XTKN), Total Kjeldahl Nitrogen (TKN), Total Nitrogen (TN) and Total Nitrogen including dissolved Nitrogen (TN & dissolved gas). In the estimation of STKN, the stoichiometry ratio of, insi is used to estimate the organic nitrogen present in the si state variable. In the estimation of XTKN, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the N content in the corresponding biomass. For example, inxbh is the stoichiometry factor representing the N content in the heterotrophic biomass, xbh. The N fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. In the calculation of XTKN, the N contained in the MgNH4PO4 is also included. Although, in strict sense this is not a part of the organic nitrogen, it is assumed that the ammonia contained in the precipitate shall reflect in the analytical measurement of TKN.
Figure 4‑10 shows the scheme for estimation of soluble part of Total Phosphorus (STP), particulate organic part of Total Phosphorus (XTOP), particulate inorganic part of Total Phosphorus (XTIP) and Total Phosphorus. In the estimation of STP, the stoichiometry ratio of, ipnsi is used to estimate the phosphorus present in the si state variable. In the estimation of XTOP, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the P content in the corresponding biomass. For example, ipxbh is the stoichiometry factor representing the P content in the heterotrophic biomass, xbh. The P fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. In the calculation of XTIP, the P contained in various P- precipitates is included. The stoichiometry factor for each precipitate are estimated based on the composition of the precipitate. These stoichiometry factors are also available in Biochemical Model Settings menu. The composite variable of XTP is estimated by the sum of XTOP and XTIP. The TP is estimated by the sum of STP and XTP.
Figure 4‑11 shows the scheme for estimation of soluble part of Total Organic Carbon (STOC), particulate part of Total Organic Carbon (XTOC), and Total Organic Carbon. In the estimation of STOC, the stoichiometry ratio of icsac, icsmet, icspro are estimated based on the substrate compositions. The stoichiometry factor of icscol, icsi and icss on the other hand needs to be set by direct user input. These factors can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. In the estimation of XTOC, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the C content in the corresponding biomass. For example, icxbh is the stoichiometry factor representing the C content in the heterotrophic biomass, xbh. The C fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. For the particulate states of xi and xs, the user can directly enter the C content in the System > Input Parameters > Biochemical Model Settings menu. The composite variable of TOC is estimated by the sum of XTOC and STOC.
Figure 4‑12 shows the scheme for estimation of soluble part of Total Sulfur (sulfursoluble), particulate part of Total Sulfur (sulfurpart) and Total Sulfur (sulfurtotal). Soluble sulfur is being estimated by summing up the sulfate sulfur (sso4), sulfite sulfur (sso3) and part of the soluble sulfide sulfur (stssul). The soluble sulfide sulfur can involve in gas/liquid transfer and produce some Hydrogen Sulfide gas (H2S). In the estimation of particulate sulfur, the mass contributions from the iron sulfide states are calculated by using a stoichiometry factor of 32/87.48, and the stoichiometry parameters frsulfurinmes is used to estimate the sulfur concentration from particulate heavy metal sulfide.
Figure 4‑9 shows the scheme for estimation of soluble part of Total Selenium, particulate part of Total Selenium and Total Selenium, where the particulate selenium is only estimated from the elemental selenium. The soluble selenium is being estimated by summing up selenate selenium and slenite selenium.
Table 4‑5 presents the summary of the stoichiometry parameters used in the MANTIS2SLIB and access menus for changing the default values.
Table 4‑5 - Access Menus for Different Stoichiometry Parameters in MANTIS2LIB
|
Stoichiometry Parameter |
Access Menu |
|
yhglobal |
System > Input Parameters > Biochemical Model Settings |
|
fuu |
System > Input Parameters > Biochemical Model Settings |
|
fssbodtosscod |
System > Input Parameters > Biochemical Model Settings |
|
fpsbodtopscod |
System > Input Parameters > Biochemical Model Settings |
|
fbbodtobcod |
System > Input Parameters > Biochemical Model Settings |
|
frsulfurinmes |
System > Input Parameters > Biochemical Model Settings |
|
COD to VSS ratio for biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
COD to VSS ratio for xs and xi |
System > Input Parameters > Biochemical Model Settings |
|
VSS to SS ratio for biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
N fraction in biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
N fraction in xi, si |
Influent Characterization menu of influent object |
|
P fraction in biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
P fraction in xi, si |
Influent Characterization menu of influent object |
|
C fraction in biomass and sac, spro, smet |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass/substrate composition) |
|
C fraction in xcol, xss, si, xi, xs |
System > Input Parameters > Biochemical Model Settings |
Figure 4‑7 - MANTIS2SLIB – Calculation Procedure for Composite Variables SCOD, COD, SBOD, BOD, SBODU and BODU
Figure 4‑8 - MANTIS2SLIB - Calculation Procedure for Composite Variables VSS, TSS
Figure 4‑9 - MANTIS2SLIB - Calculation Procedure for Composite Variables STKN and TKN
Figure 4‑10 - MANTIS2SLIB - Calculation Procedure for Composite Variables STP, XTP, and TP
Figure 4‑11 - MANTIS2SLIB - Calculation Procedure for Composite Variables STOC and TOC
Figure 4‑12 - MANTIS2SLIB - Calculation Procedure for Composite Variables Particulate Sulfur, Soluble Sulfur and Total Sulfur
Figure 4‑13 - MANTIS2SLIB - Calculation Procedure for Composite Variables Particulate Selenium, Soluble Selenium and Total Selenium
Composite Variables in PROCWATERLIB
The composite variable calculation schemes in PROCWATERLIB are shown in Figure 4‑14 to Figure 4‑18. The PROCWATERLIB uses a simpler method to estimate the composite variables. Figure 4‑14 shows the scheme for estimation of soluble BOD5 (SBOD), particulate BOD5 (XBOD), BOD5 (BOD), soluble ultimate BOD (SBODU), particulate ultimate BOD (SBODU), ultimate BOD (BODU), soluble COD (SCOD), particulate COD (XCOD) and COD (COD). The list of stoichiometric parameters used in the estimation of composite variables is provided in Table 4‑6.
Table 4‑6 - Stoichiometry Parameters used in Estimation of Composite Variables in PROCWATERLIB
|
Stoichiometry Parameter |
Default Value |
Description |
|
yhglobal |
0.666 |
Heterotrophic biomass yield |
|
fuu |
0.206 |
Fraction of unbiodegradable residue in biomass |
|
fssbodtosscod |
0.717 |
BOD5 to COD ratio of soluble substrate |
|
fpsbodtopscod |
0.58 |
BOD5 to COD ratio of particulate substrate |
|
fbbodtobcod |
0.566 |
BOD5 to COD ratio of biomass |
|
icodtovssxbt |
1.674 |
xCOD/VSS ratio of PHA |
The default value of the stoichiometry parameters can be changed in the System > Input Parameters > Global Fixed stoichiometry menu.
Figure 4‑15 shows the scheme for estimation of Volatile Suspended Solid (VSS), Inorganic Suspended Solid (XISS) and Total Suspended Solid (TSS) concentration. In the estimation of VSS, each biomass concentration is multiplied by a corresponding VSS to COD factor. For example, ivsstocodxbh is the VSS to COD ratio for heterotrophic biomass, xbh. The VSS to COD ratio for each biomass type are calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Global Fixed Stoichiometry menu.
As the composition of xs and xi are not well known, the VSS to COD ratios for these states ivsstocodxs and ivsstocodxi are provided as direct inputs. These ratios can be accessed and changed in System > Input Parameters > Biochemical Model Settings menu. The state variable of xns is included in the calculation of VSS for being consistent with the practice of considering the N fraction in biomass as part of VSS. A stoichiometry factor of 17.0/14.0 is used to convert N to NH3.
In the calculation of Inorganic Suspended Solid (XISS), each biomass concentration is multiplied by the inorganic fraction in the biomass. The inorganic fraction for each biomass is estimated by subtracting the VSS to SS ratio for each individual biomass from one. The VSS to SS ratio for each individual biomass type is calculated by using the set biomass composition, for example ivsstossxbh is the VSS to SS ratio calculated for the xbh biomass type.
The composite variable of XISS also includes the contribution from the inorganic states in the model. The mass contributions from the xpp and xps states are calculated by using a stoichiometry factor of 95/31. The factor reflects the conversion from molecular weight of P to molecular weight of PO43-. For all the other inorganic states a stoichiometry ratio of 1 is used.
The Total Suspended Solid (TSS) concentration is calculated by the sum of estimated VSS and XISS.
Figure 4‑16 shows the scheme for estimation of soluble part of Total Kjeldahl Nitrogen (STKN), particulate part of Total Kjeldahl Nitrogen (XTKN), Total Kjeldahl Nitrogen (TKN), Total Nitrogen (TN) and Total Nitrogen including dissolved Nitrogen (TN & dissolved gas). In the estimation of STKN, the stoichiometry ratio of, insi is used to estimate the organic nitrogen present in the si state variable. In the estimation of XTKN, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the N content in the corresponding biomass. For example, inxbh is the stoichiometry factor representing the N content in the heterotrophic biomass, xbh. The N fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Global Fixed Stoichiometry menu. In the calculation of XTKN, the N contained in the MgNH4PO4 is also included. Although, in strict sense this is not a part of the organic nitrogen, it is assumed that the ammonia contained in the precipitate shall reflect in the analytical measurement of TKN.
Figure 4‑17 shows the scheme for estimation of soluble part of Total Phosphorus (STP), particulate organic part of Total Phosphorus (XTOP), particulate inorganic part of Total Phosphorus (XTIP) and Total Phosphorus. In the estimation of STP, the stoichiometry ratio of, ipnsi is used to estimate the phosphorus present in the si state variable. In the estimation of XTOP, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the P content in the corresponding biomass. For example, ipxbh is the stoichiometry factor representing the P content in the heterotrophic biomass, xbh. The P fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Global Fixed Stoichiometry menu. In the calculation of XTIP, the P contained in various P- precipitates is included. The stoichiometry factor for each precipitate is estimated based on the composition of the precipitate. These stoichiometry factors are also available in Biochemical Model Settings menu. The composite variable of XTP is estimated by the sum of XTOP and XTIP. The TP is estimated by the sum of STP and XTP.
Figure 4‑18 shows the scheme for estimation of soluble part of Total Organic Carbon (STOC), particulate part of Total Organic Carbon (XTOC), and Total Organic Carbon. In the estimation of STOC, the stoichiometry factor of icscol, icsi and icss needs to be set by direct user input. These factors can be accessed and changed in System > Input Parameters > Global Fixed Stoichiometry menu. In the estimation of XTOC, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the C content in the corresponding biomass. For example, icxbh is the stoichiometry factor representing the C content in the heterotrophic biomass, xbh. The C fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Global Fixed Stoichiometry menu. The composite variable of TOC is estimated by the sum of XTOC and STOC.
Table 4‑7 presents the summary of the stoichiometry parameters used in the PROCWATERLIB and access menus for changing the default values.
Table 4‑7 - Access Menus for Different Stoichiometry Parameters in PROCWATERLIB
|
Stoichiometry Parameter |
Access Menu |
|
yhglobal |
System > Input Parameters > Global Fixed Stoichiometry |
|
fuu |
System > Input Parameters > Global Fixed Stoichiometry |
|
fssbodtosscod |
System > Input Parameters > Global Fixed Stoichiometry |
|
fpsbodtopscod |
System > Input Parameters > Global Fixed Stoichiometry |
|
fbbodtobcod |
System > Input Parameters > Global Fixed Stoichiometry |
|
COD to VSS ratio for biomass |
System > Input Parameters > Global Fixed Stoichiometry (Calculated based on biomass composition) |
|
COD to VSS ratio for xs and xi |
System > Input Parameters > Global Fixed Stoichiometry |
|
VSS to SS ratio for biomass |
System > Input Parameters > Global Fixed Stoichiometry (Calculated based on biomass composition) |
|
N fraction in biomass |
System > Input Parameters > Global Fixed Stoichiometry (Calculated based on biomass composition) |
|
N fraction in xi, si |
Influent Characterization menu of influent object |
|
P fraction in biomass |
System > Input Parameters > Global Fixed Stoichiometry (Calculated based on biomass composition) |
|
P fraction in xi, si |
Influent Characterization menu of influent object |
|
C fraction in biomass and sac, spro, smet |
System > Input Parameters > Global Fixed Stoichiometry (Calculated based on biomass/substrate composition) |
|
C fraction in xcol, xss, si, xi, xs |
System > Input Parameters > Global Fixed Stoichiometry |
Figure 4‑14 - PROCWATERLIB – Calculation Procedure for Composite Variables SCOD, COD, SBOD, BOD, SBODU and BODU
Figure 4‑15 - PROCWATERLIB - Calculation Procedure for Composite Variables VSS, TSS
Figure 4‑16 - PROCWATERLIB - Calculation Procedure for Composite Variables STKN and TKN
Figure 4‑17 - PROCWATERLIB - Calculation Procedure for Composite Variables STP, XTP, and TP
Figure 4‑18 - PROCWATERLIB- Calculation Procedure for Composite Variables STOC and TOC
Composite Variables in MANTISIWLIB
The composite variable calculation schemes in MANTISIWLIB are shown in Figure 4‑19 to Figure 4‑23. Figure 4‑19 shows the scheme for estimation of soluble BOD5 (SBOD), particulate BOD5 (XBOD), BOD5 (BOD), soluble ultimate BOD (SBODU), particulate ultimate BOD (SBODU), ultimate BOD (BODU), soluble COD (SCOD), particulate COD (XCOD) and COD (COD). The state variables of aromatic compounds (sarm, sarp, sarh), sorbed oil (xoil) and other content exists in the petrochemical wastewater are also included in the estimation. The list of stoichiometric parameters used in the estimation of composite variables is provided in Table 4‑8.
Table 4‑8 - Stoichiometry Parameters used in Estimation of Composite Variables in MANTISIWLIB
|
Stoichiometry Parameter |
Default Value |
Description |
|
yhglobal |
0.666 |
Heterotrophic biomass yield |
|
ypglobal |
0.666 |
Heterotrophic Yield on VOCs |
|
fuu |
0.206 |
Fraction of unbiodegradable residue in biomass |
|
fssbodtosscod |
0.717 |
BOD5 to COD ratio of soluble substrate |
|
fpsbodtopscod |
0.58 |
BOD5 to COD ratio of particulate substrate |
|
fbbodtobcod |
0.566 |
BOD5 to COD ratio of biomass |
|
icodtovssxbt |
1.674 |
xCOD/VSS ratio of PHA |
The default value of the stoichiometry parameters can be changed in the System > Input Parameters > Biochemical Model Settings menu.
Figure 4‑20 shows the scheme for estimation of Volatile Suspended Solid
(VSS), Inorganic Suspended Solid (XISS) and Total
Suspended Solid (TSS) concentration. In the estimation of
VSS, each biomass concentration is multiplied by a
corresponding VSS to COD factor. For example,
ivsstocodxbh is the VSS to COD ratio
for heterotrophic biomass, xbh. The VSS to
COD ratio for each biomass type are calculated based on the
biomass composition. The default composition of biomass can be
accessed and changed in the
System > Input Parameters > Biochemical Model
Settings menu.
As the composition of xs and xi are not well known, the VSS to COD ratios for these states ivsstocodxs and ivsstocodxi are provided as direct inputs. These ratios can be accessed and changed in System > Input Parameters > Biochemical Model Settings menu. The state variable of xns is included in the calculation of VSS for being consistent with the practice of considering the N fraction in biomass as part of VSS. A stoichiometry factor of 17.0/14.0 is used to convert N to NH3.
In the calculation of Inorganic Suspended Solid (XISS), each biomass concentration is multiplied by the inorganic fraction in the biomass. The inorganic fraction for each biomass is estimated by subtracting the VSS to SS ratio for each individual biomass from one. The VSS to SS ratio for each individual biomass type is calculated by using the set biomass composition, for example ivsstossxbh is the VSS to SS ratio calculated for the xbh biomass type.
The composite variable of XISS includes only the contribution from the inorganic inert particulate states (xii) in the model. For all the other inorganic states a stoichiometry ratio of 1 is used.
The Total Suspended Solid (TSS) concentration is calculated by the sum of estimated VSS and XISS.
Figure 4‑4 shows the scheme for estimation of soluble part of Total Kjeldahl Nitrogen (STKN), particulate part of Total Kjeldahl Nitrogen (XTKN), Total Kjeldahl Nitrogen (TKN), Total Nitrogen (TN) and Total Nitrogen including dissolved Nitrogen (TN & dissolved gas). In the estimation of STKN, the stoichiometry ratio of, insi is used to estimate the organic nitrogen present in the si state variable. In the estimation of XTKN, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the N content in the corresponding biomass. For example, inxbh is the stoichiometry factor representing the N content in the heterotrophic biomass, xbh. The N fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu.
Figure 4‑5 shows the scheme for estimation of soluble part of Total Phosphorus (STP), particulate organic part of Total Phosphorus (XTOP), particulate inorganic part of Total Phosphorus (XTIP) and Total Phosphorus. In the estimation of STP, the stoichiometry ratio of, ipnsi is used to estimate the phosphorus present in the si state variable. In the estimation of XTOP, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the P content in the corresponding biomass. For example, ipxbh is the stoichiometry factor representing the P content in the heterotrophic biomass, xbh. The P fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. In the calculation of XTIP, the P contained in various P- precipitates is included. The stoichiometry factor for each precipitate is estimated based on the composition of the precipitate. These stoichiometry factors are also available in Biochemical Model Settings menu. The composite variable of XTP is estimated by the sum of XTOP and XTIP. The TP is estimated by the sum of STP and XTP.
Figure 4‑6 shows the scheme for estimation of soluble part of Total Organic Carbon (STOC), particulate part of Total Organic Carbon (XTOC), and Total Organic Carbon. In the estimation of STOC, the stoichiometry ratio of icsac, icsmet, icspro are estimated based on the substrate compositions. The stoichiometry factor of icscol, icsi and icss on the other hand needs to be set by direct user input. These factors can be accessed and changed in System > Input Parameters > Biochemical Model Settings menu. In the estimation of XTOC, each biomass concentration is multiplied by a corresponding stoichiometry factor representing the C content in the corresponding biomass. For example, icxbh is the stoichiometry factor representing the C content in the heterotrophic biomass, xbh. The C fraction for each biomass type is calculated based on the biomass composition. The default composition of biomass can be accessed and changed in the System > Input Parameters > Biochemical Model Settings menu. For the particulate states of xi and xs, the user can directly enter the C content in the System > Input Parameters > Biochemical Model Settings menu. The composite variable of TOC is estimated by the sum of XTOC and STOC.
Table 4‑9 presents the summary of the stoichiometry parameters used in the MANTISIWLIB and access menus for changing the default values.
Table 4‑9 - Access Menus for Different Stoichiometry Parameters in MANTISIWLIB
|
Stoichiometry Parameter |
Access Menu |
|
yhglobal |
System > Input Parameters > Biochemical Model Settings |
|
ypglobal |
System > Input Parameters > Biochemical Model Settings |
|
fuu |
System > Input Parameters > Biochemical Model Settings |
|
fssbodtosscod |
System > Input Parameters > Biochemical Model Settings |
|
fpsbodtopscod |
System > Input Parameters > Biochemical Model Settings |
|
fbbodtobcod |
System > Input Parameters > Biochemical Model Settings |
|
COD to VSS ratio for biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
COD to VSS ratio for xs and xi |
System > Input Parameters > Biochemical Model Settings |
|
VSS to SS ratio for biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
N fraction in biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
N fraction in xi, si |
Influent Characterization menu of influent object |
|
P fraction in biomass |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass composition) |
|
P fraction in xi, si |
Influent Characterization menu of influent object |
|
C fraction in biomass and sac, spro, smet |
System > Input Parameters > Biochemical Model Settings (Calculated based on biomass/substrate composition) |
|
C fraction in xcol, xss, si, xi, xs |
System > Input Parameters > Biochemical Model Settings |
Figure 4‑19 - MANTISIWLIB – Calculation Procedure for Composite Variables SCOD, COD, SBOD, BOD, SBODU and BODU
Figure 4‑20 - MANTISIWLIB - Calculation Procedure for Composite Variables VSS, TSS
Figure 4‑21 - MANTISIWLIB - Calculation Procedure for Composite Variables STKN and TKN
Figure 4‑22 - MANTISIWLIB - Calculation Procedure for Composite Variables STP, XTP, and TP
Figure 4‑23 - MANTISIWLIB- Calculation Procedure for Composite Variables STOC and TOC