SBR Denitrification Calculations Spreadsheet

Where to Find an SBR Denitrification Calculations Spreadsheet

To obtain an SBR Denitrification Calculations Spreadsheet, click here to visit our spreadsheet store.  This Excel spreadsheet is intended for making design calculations for either pre-anoxic or post-anoxic denitrification in a sequencing batch reactor. You can buy a convenient SBR denitrification calculations spreadsheet for a very reasonable price.  It is available in either U.S. units or S.I. units.  Read on for background information about sequencing batch reactor denitrification process design calculations.

Background for an SBR Denitrification Calculations Spreadsheet

The sequencing batch reactor is a batch type, fill and draw alternative to the continuous flow activated sludge process for biological wastewater treatment, including BOD removal, nitrification and denitrification.  The typical components of a sequencing batch reactor operating cycle for BOD removal and nitrification are shown in the diagram below.

Typical SBR Cycle for SBR denitrification calculations spreadsheetAt least two tanks are typically used.  In that case, the length of the fill period would be equal to the sum of the times for the react, settle and decant periods.  Thus one tank would be filling while the other tank was going through the react, settle and decant periods and then the roles would be reversed.

In order to achieve denitrification, an anoxic period must be added.  A typical sequencing batch reactor cycle for a post-anoxic denitrification process is shown in the figure below.  A mixed anoxic react period is included after the aerobic react period.

post-anoxic SBR operating cycle for SBR denitrification calculations spreadsheetFor a pre-anoxic denitrification SBR process, some or all of the fill period would be anoxic and there would be no anoxic react period after the aerobic react period.

 Example SBR Denitrification Calculations Spreadsheet

An example SBR denitrification calculations spreadsheet is partially shown in the image below.  This Excel spreadsheet can be used to set the times for the different parts of the SBR operating cycle, calculate the required tank size and check on the adequacy for nitrification and for denitrification.  This Excel spreadsheet, as well as others for wastewater treatment process design calculations, is available in either U.S. or S.I. units for a very reasonable price in our spreadsheet store.

screenshot for SBR denitrification calculations spreadsheet

References:

1. Metcalf & Eddy, Inc, (Revised by Tchobanoglous, G, Burton, F.L, Stensel, H.D.), Wastewater Engineering, Treatment and Reuse, 4th Ed., New York, NY, 2003.

2. Metcalf & Eddy, Inc, (Revised by Tchobanoglous, G, Burton, F.L, Stensel, H.D.), Wastewater Engineering, Treatment and Resource Recovery, 5th Ed., New York, NY, 2014.

3. Bengtson, Harlan H.,  “Sequencing Batch Reactor Denitrification Calculations,” an online blog article.

A Spreadsheet for Choked Air Flow Calculation

Where to Find a Spreadsheet for Choked Air Flow Calculation

To obtain a spreadsheet for choked air flow calculations click here to visit our spreadsheet store.  Intended for use in making fanno flow calculations with adiabatic compressible flow of air, you can buy a convenient spreadsheet for choked air flow calculations for a very reasonable price.  This spreadsheet will also calculate the frictional pressure drop, and is available in either U.S. or S.I. units.  Read on for information about a choked air flow calculation spreadsheet for compressible pipe flow.

Conditions for Choked Air Flow Calculation with a Fanno Flow Excel Spreadsheet

For flow of air in a pipe with the frictional pressure drop less than 20% of the inlet air pressure, satisfactory results can be obtained using incompressible flow calculations with the Darcy-Weisbach equation.  For background information on that type of calculation, see the article, “Pipe Flow-Friction Factor Calculations with Excel Spreadsheets.”  If the frictional pressure drop is more than 20% of the incoming air pressure, then Fanno Flow equations should be used, as discussed here using a Fanno Flow Excel spreadsheet.

With adiabatic compressible flow conditions, the maximum air flow rate that can pass through a pipe is that which occurs when the exit Mach number is 1.0.  This is referred to as “choked flow.”

Equations for Choked Air Flow Calculations with a Fanno Flow Excel Spreadsheet

Shown below are the primary equations used in the fanno flow excel spreadsheet being discussed here for compressible flow of air in a pipe.  These equations are for compressible pipe flow with negligible heat transfer with the surroundings, but including effects of friction in the flow.

Fanno Flow Excel Spreadsheet EquationsThe parameters in these fanno flow equations are as follows:

  • f = Moody friction factor
  • L = pipe length
  • D = pipe diameter
  • k = adiabatic constant for the flowing air
  • M = mach number
  • T = air temperature
  • P = air pressure
  • ρ = air density

Parameters with an asterisk refer to conditions at the “choke point” in the pipe, where the Mach number is 1.

Screenshot for a Choked Air Flow Calculation Spreadsheet Using Fanno Flow Equations

The screenshot below shows part of a fanno flow excel spreadsheet for making compressible air flow calculations.  These calculations are for air flow in a pipe, in S.I. units. This Excel spreadsheet and others for compressible pipe flow calculations in a fanno flow excel spreadsheet are available in either U.S. or S.I. units at a very reasonable cost  in our spreadsheet store.Choked Air Flow Calculation Spreadsheet

Reference:

Bengtson, Harlan H.,  “Compressible Flow Pressure Drop Calculator Spreadsheet,” an online blog article