Integrated Influent Specifier
The Influent Specifier Interface
Click on the red flask icon on the Main toolbar to open the Influent Specifier tool. The Influent Specifier main window consists of four main parts.
• Menu
• Toolbar
• Numbered Steps of Wastewater Characterization
• Display pane
Menu The various menus available in the main window are located at the top of the window. They include:
• File
• Setting
• View
• Stoichiometry
• About
Each menu may be accessed by either of two methods:
1. Click on the text of the menu, or;
2. Hold down the Alt key on your keyboard and press the letter on the keyboard corresponding to the first letter in the menu title name. For example, Alt+F will access the File menu.
File Menu Item
The File menu contains commands to manipulate files such as:
• New: Create and open a new file.
• Open: Open an existing influent specifier file (.ets).
• Save: Save an existing influent specifier file under the same name.
• Save as: Save an influent specifier file under a name to be specified.
• Export to Excel: Export the influent specifier data to excel.
• Exit: Exit and close the Influent specifier.
Setting Menu Item
The Setting menu contains commands to manipulate the default concentrations and fractions to represent typical municipal raw or settled wastewater. They include:
• Set typical (Raw)
• Set typical (Settled)
Note that the typical settled fraction set is based on a typical raw wastewater strength (i.e. COD of 500 mg/L, TKN of 40 mg/L) and fractionation (i.e. soluble readily degradable fraction of 16%, particulate undegradable fraction of 13%) passing through a primary settling tank achieving 55% solids capture.
View Menu Item
• The View menu contains commands to access different display options such as:
• Input Measurement View Format
o Table View: Change the Input Measurement display view to a table view of parameters.
o Picture View: Change the Input Measurement display view to a picture view of parameters.
• Tree Views: Open a window to access tree views of COD, N, P and ISS fractionation. The COD, N, and P fractionation can be modified in this view.
• Balance Checking: Launch TP balance checking dialog, followed by TKN balancing checking dialog.
Tree Views
Click View > Tree Views or use the Tree Views short cut icon to open tree views of COD, N, P and ISS speciation. Click on the COD, N, P and ISS tabs to toggle views between each parameter. Various fractions appear in red text within the tree view displays. These COD, N, and P fractions can be manually adjusted by either overwriting the red text within the text box, or by clicking and dragging the slider that appears to the right of some of the fractions. When adjustments are made to the parameters in red, any corresponding fractions affected by the change will be shown highlighted in green as the value is updated. Any adjustments that are made to fractions and/or parameters in the tree views will automatically appear in the Adjust Fractions display for COD and BOD or in the Stoichiometry > Fractions window for N and P.
The COD tab contains additional sliders for modifying k1 for CODc – Xsc and k2 for CODp – Xsp for the cBOD calculations. Changing these k values will help bring the calculated cBOD values in line with measured cBOD estimates (see the Adjust Fractions). The k1 for CODc – Xsc slider can be used to adjust both cBOD5 and fcBOD5 (GFC); this slider is generally used to obtain a match for fcBOD5 (GFC). The k2 for CODp – Xsc slider can be used to adjust only cBOD5.
Balance Checking Mass balance checking is performed for TP and TKN by clicking View > Balance Checking. The TP balancing checking window opens first. Once this window is closed, the TKN balancing checking window opens. If the calculated TP and TKN values match the measured values then the balance checking window will show ‘No warnings’ and indicate that the TP or TKN balance checking is completed. The formulas for the calculated TP and TKN are shown in the window display. Click the Close button to exit the TKN balance checking window.
If the calculated TP or TKN do not match measured values, the balance checking window will display a warning message indicating that a problem with the TP or TKN value exists. A hint will appear at the bottom of the window with a suggestion to consider changing one of the contributing fractions in the influent specifier i.e. the fraction of P associated with the unbiodegradable particulate COD (FupP) or the fraction of N associated with the unbiodegradable particulate COD (FupN). A text box is provided beside the hint to specify a change in the FupP or FupN fraction. Once a value is entered click the Set button to update this fraction in the specifier and recalculate the TP or TKN. If changing the FupP or FupN does not help to close the mass balance, a note will appear indicating that balance checking is not complete and other P or N fractions should be checked to ensure calculated values match measured values. This requires manually editing the P or N values under Input Measurements or changing the P and N stoichiometry found in Stoichiometry > Fractions (see Stoichiometry Menu Item). The windows below show an example of the balance checking dialogs that appear for a problem with the Total P value.
Stoichiometry Menu Item
The Stoichiometry menu item opens a window containing stoichiometric P, N, Ca, Mg and ISS values used for fractionating P, N, Ca, Mg and ISS. The values that appear in a blue text box can be modified. Any changes that are made in this window will automatically get updated in the Tree Views display. A mass balance check can be performed for TKN and TP by clicking the Balance Checking button (see Balance Checking).
About Menu Item
The about menu item shows the Influent Specifier version and licensing information.
Toolbar The toolbar shows several buttons.
Main Description
New File: Click this button to close the current influent specifier setup and start a new one. A confirmation window may appear.
Open File: Click this button to open an influent specifier file from disk.
Save File: Click this button to save the current influent specifier setup to disk.
Tree Views:Click this button to open tree views of the COD, N, P and ISS fractionation.
Export to Excel: Click this button to export the influent specifier data to Excel.
Data Validation: Click this button to show any calculation warnings resulting from the data specified. A warning will appear if a negative value is calculated.
Set to Default Values: Click this button to reset the influent specifier to default values (either Raw or Settled as specified in the Setting menu).
Numbered Steps of Wastewater Characterization
Input Measurements
The specifier opens on the first step - Input Measurements (denoted by a clickable circle with a number 1 inside) highlighted in blue. The display shows an area where users can input measured and/or assumed influent data into the blue textboxes beside each parameter name. Click on the Table View button from Picture View or the Picture View button from Table View to change the displayed view for entering information. This measured and/or assumed influent data will be used to determine influent wastewater fractions (See Adjust Fractions).
Adjust Fractions
Click the number 2 circle labelled Adjust Fractions to proceed to the next step. This display contains the Fraction/Parameter Estimates and the Fraction Calculation Results. The Fraction/Parameter Estimates highlighted in blue serve as inputs to the specifier. Users can adjust the estimates highlighted in blue via trial and error to improve the match status between measured and calculated influent values. The impact of changing each fraction/parameter is explained in the table below.
The following table explains the impact of changing each of the fraction/parameter estimates in blue:
Fraction/Parameter Estimate Description and Impact
Fbiomass The fraction of COD associated with influent biomass.
Increasing this fraction will reduce the degradable fraction of the COD (slowly degradable COD (Fxs) decreases; slowly degradable particulate COD (Fxsp) decreases and slowly degradable colloidal COD (1 – Fxsp) increases). This is reflected by a decrease in the total cBOD and an increase in the VSS. These changes in turn will result in a higher TSS, a lower CODp:VSS, and a higher total COD:cBOD.
Fup The unbiodegradable particulate fraction of COD.
Increasing this fraction will reduce the degradable fraction of the COD (slowly degradable COD (Fxs) decreases; slowly degradable particulate COD (Fxsp) decreases and slowly degradable colloidal COD (1 – Fxsp) increases). This is reflected by a decrease in the total cBOD and an increase in VSS. These changes in turn will result in a higher TSS, a lower CODp:VSS, and a higher total COD:cBOD.
Cellulose The fraction of unbiodegradable particulate COD that is associated with cellulose.
Increasing this fraction reduces the fraction of non-cellulose unbiodegradable particulate COD. This increases the VSS and in turn results in higher TSS and a lower CODp:VSS.
Particulate Biodegradable COD:VSS
The COD:VSS ratio of slowly biodegradable particulate COD.
Increasing this ratio will reduce the VSS and in turn result in a lower TSS and a higher CODp:VSS.
Particulate Inert COD:VSS The COD:VSS ratio of the non-cellulose unbiodegradable particulate COD.
Increasing this ratio will reduce the VSS and in turn result in a lower TSS and a higher CODp:VSS.
Cellulose COD:VSS The COD:VSS ratio of cellulose.
Increasing this ratio will reduce the VSS and in turn result in a lower TSS and a higher CODp:VSS.
k1 for CODc - Xsc BOD calculation rate constant for degradation of slowly biodegradable colloidal COD (Xsc) [Time constant used to calculate BOD versus time change due to colloidal material; see BOD Calculations in BioWin].
Increasing this ratio will increase both the filtered and total cBOD. This results in a lower total COD:cBOD.
k2 for CODp - Xsp BOD calculation rate constant for slowly biodegradable particulate COD (Xsp) [Time constant used to calculate BOD versus time change due to particulate degradable material; see BOD Calculations in BioWin].
Increasing this ratio will increase the total cBOD. This results in a lower total COD:cBOD.
Some general rules of thumb for determining which of the above parameters to modify for typical municipal wastewater are listed below. Two examples are also provided below.
• Fbiomass
o Can be measured and should be modified only when information is known about the nature of the influent wastewater or the collection system.
o If no information is known then this value can likely stay at default.
• Fup
o Should be used for tweaking the VSS and BOD when both parameters need to be modified.
o Adjusting the Fup will only slightly modify the VSS and BOD; adjusting the COD:VSS ratio will provide a bigger change in the VSS.
• Cellulose
o If no information is known then this value can likely stay at default.
• Particulate biodegradable COD:VSS
o Should be less than 4. For an organic substance to be particulate (i.e. have a VSS) it generally requires carbon chains. Pure methane has a COD to mass ratio of 4 gO/gCH4. Wastewater containing benzene, toluene, xylene, ethane or methane may have a particulate biodegradable COD:VSS ratio around 3.
o Should be higher than the particulate inert COD:VSS. The particulate biodegradable material is in a more reduced form and hence has a higher electron donating capacity (i.e. COD is higher per unit mass).
o Should be changed when a significant adjustment in VSS (i.e. more than 1 or 2 mg/L) is required. This parameter is typically adjusted first before the particulate inert COD:VSS.
• Particulate inert COD:VSS
o Should be less than the particulate biodegradable COD:VSS (see description under particulate biodegradable COD:VSS).
o Should be changed when a significant adjustment in VSS (i.e. more than 1 or 2 mg/L) is required.
• Cellulose COD:VSS
o Should not increase above 1.4 unless measured data is available to support this change.
o This value can be used to fine tune the VSS calculation and is typically lowered to increase the VSS. The theoretical COD:VSS of pure cellulose is 1.18; hence this ratio should not be decreased below approximately 1.1.
• k1 for CODc – Xsc
o Should be modified to match the filtered cBOD
o Generally greater than zero.
• k2 for CODp – Xsp
o Should be modified to match the total cBOD
Match status criteria is as follows:
COD, VSS, TSS parameters
Match Status Percent Difference
Excellent < 5%
Acceptable 5 - 10%
Unacceptable > 10%
BOD parameters
Match Status Percent Difference
Excellent < 10%
Acceptable 10 - 20%
Unacceptable > 20%
The match status of any ratios of the parameters above (i.e. COD:VSS or COD:BOD) uses the largest percent difference criteria from the parameters being compared. For example, the total COD:cBOD ratio uses the BOD percent difference criteria. Users should take into consideration the reproducibility of laboratory measurements for a particular parameter when assessing the match status between the measured and calculated values. Users should also verify that the fraction and parameter estimates are reasonable given the nature of the influent wastewater. If adjustments to the fraction/parameter estimates in blue do not improve the match status between measured and calculated parameters then measured/assumed inputs may need to be adjusted or reconfirmed.
Parameter values can also be adjusted via the Tree Views display. The tree views display allows users to observe which parameters will be affected by changing any of the modifiable parameters.
Calculated COD fractions are defined as follows (note fractions in blue are specified and not calculated):
𝐹"# =𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡𝐹𝐹𝐶𝑂𝐷 − 𝐸𝑓𝑓𝑙𝑢𝑒𝑛𝑡𝐹𝑖𝑙𝑡𝑒𝑟𝑒𝑑𝐶𝑂𝐷
𝑇𝑜𝑡𝑎𝑙𝐶𝑂𝐷
𝐹89 =𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡𝐴𝑐𝑒𝑡𝑎𝑡𝑒𝐹"# ∗ 𝑇𝑜𝑡𝑎𝑙𝐶𝑂𝐷
𝐹=#> = 1 −(𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡𝐹𝑖𝑙𝑡𝑒𝑟𝑒𝑑𝐶𝑂𝐷 − 𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡𝐹𝐹𝐶𝑂𝐷)(1 − 𝐹"# − 𝐹B# − 𝐹C"D − 𝐹B>) ∗ 𝑇𝑜𝑡𝑎𝑙𝐶𝑂𝐷
𝐹B# =𝐸𝑓𝑓𝑙𝑢𝑒𝑛𝑡𝐹𝑖𝑙𝑡𝑒𝑟𝑒𝑑𝐶𝑂𝐷
𝑇𝑜𝑡𝑎𝑙𝐶𝑂𝐷
𝐹B>,FGFHIJKKLKGMJ = 1 − 𝐹B>,IJKKLKGMJ
𝐹=# = 1 − 𝐹"# − 𝐹B# − 𝐹B> − 𝐹NOGPQMM
Fractionation Example #1
The following example shows influent data collected from a municipal plant with a typical influent COD:cBOD ratio.
With the above inputs, the calculation results below are found by clicking on “2 - Adjust Fractions”. Some match status results appear in yellow indicating these fraction/parameter estimates may be improved. In particular, the calculated filtered cBOD and VSS concentrations could be adjusted to achieve “Excellent” match status.
A trial and error approach is used to adjust certain fractions/parameters to achieve an excellent match status for all parameters. In this particular example, respirometry was performed to determine the influent biomass concentration. The Fbiomass was input as 0.09 as calculated using measured influent biomass and TCOD data. Increasing the Fbiomass from the Raw default of 0.0212 to 0.09 slightly increases the VSS and decreases the total cBOD. The calculated VSS needs to be reduced by more than 10 mg/L, so it is best to use the COD:VSS ratios to induce a big change in VSS. Generally, we start by changing the particulate biodegradable COD:VSS ratio. Decreasing the particulate biodegradable COD:VSS from the default of 1.6327 to 1.55 increases the VSS concentration. Since the particulate inert COD:VSS ratio should be less than the particulate biodegradable COD:VSS ratio, the particulate inert COD:VSS is lowered to 1.4. Finally, the filtered cBOD needs to be reduced. This can be done by decreasing k1 for CODc-Xsc from 0.5 to 0.3; this change also helps to bring the calculated total cBOD
closer to the measured value. With these adjustments, the match status of every parameter updates to “Excellent”.
Fractionation Example #2
The following example shows influent data collected from a municipal plant with an influent COD:cBOD ratio that is higher than typical.
With the above inputs, the calculation results below are found by clicking on “2 - Adjust Fractions”. Some match status results appear in red and yellow indicating these fraction/parameter estimates may be improved. In particular, changes to the calculated filtered cBOD and VSS concentrations are required.
A trial and error approach is used to adjust certain fractions/parameters to achieve an excellent match status for all parameters. The influent biomass was not measured so the Fbiomas fraction is kept at the default. The calculated VSS concentration needs to be reduced by more than 10 mg/L, so it is best to use the COD:VSS ratios to induce a big change in VSS. Again, we start by changing the particulate biodegradable COD:VSS ratio. Increasing the particulate biodegradable COD:VSS from the default of 1.6327 to 1.85 decreases the VSS concentration, achieving an excellent match status for VSS, TSS and influent CODp:VSS. Both the total and filtered cBOD calculated concentrations need to be reduced. This can be achieved by changing the model parameters k1 for CODc - Xsc and k2 for CODp - Xsp BOD. First, k1 is lowered to 0.05 to obtain an acceptable status for the filtered cBOD; this also helps to lower the total cBOD. Next, k2 is lowered to 0.22 to further reduce the total cBOD. With these adjustments, the match status has improved for all parameters. Note the match status for filtered cBOD shows acceptable indicating that the percent difference for the measured and calculated filtered cBOD is between 10-20%. Since the filtered cBOD is relatively low and k1 had to be significantly reduced to almost zero, we will leave this status as “acceptable” rather than further reduce k1.
View Results
Click the circle with number 3 to change the display to View Results. This display contains a summary of COD, BOD, N, P and ISS fractionation calculation results. The fractionation of COD and BOD is defined in the Adjust Fractions window or in the Tree View > COD tab. The fractionation of N, P and ISS are defined in Stoichiometry > Fractions or in the Tree View > N and P tabs. It is a good idea to click on the data
validation button to show any calculation warnings resulting from the data specified. A warning will appear if a negative value is calculated.
Export to BioWin
Click the circle with number 4 to change the display to Export to BioWin. This display contains a summary of values that can be exported into BioWin. Click on Copy Influent Values to copy the influent flow and load values to the clipboard. These values can be pasted into a COD influent element. Open the COD influent element and go to the Input Type tab, then specify type as “Constant” and click the Edit data button. Right click on the white flow value cell and then paste the influent values. Click on Copy Stoich. Values to copy the stoichiometric parameters to the clipboard. These values can then be pasted into their respective row in the BioWin menu Project > Parameters > Stoichiometric > Common. Click on the Copy Frac. Values to copy the influent wastewater fractions to the clipboard. These values can be pasted into the WW Fractions tab of a COD or BOD influent element. Click on Copy BOD Model Para. to copy the BOD calculation rate constants to the clipboard. These values can be pasted into their respective row in the BioWin menu Project > Parameters > Other.
