Home >  CE 421/521 Biowin Assignment 2 Diurnal flow effects and the VIP process Part I – Diurnal Flow Begin with the activated sludge plant model develo

CE 421/521 Biowin Assignment 2 Diurnal flow effects and the VIP process Part I – Diurnal Flow Begin with the activated sludge plant model develo

CE 421/521 Biowin Assignment 2

Diurnal flow effects and the VIP process

Part I – Diurnal Flow

Begin with the activated sludge plant model developed for in-class assignment one, and available as “In class biowin file” at www.public.iastate.edu/~eevans/ce521.htm .� Open the file in Biowin.

Examine the effect of dynamic flow conditions on performance of this activated sludge plant.� Download the “Diurnal Flow” file available on the website.� This file gives a sample diurnal flow pattern for a city.� Change the Input type in the BOD influent to Variable under the properties menu.� Choose From File and browse to the .bif file given.� You may view the influent flow data by choosing Edit data, but do not change the values.

The simulation will need to be plotted to see the results of the flow pattern.� Go to View-Album and add three pages to the album.� On one of the new pages insert a chart.� To the chart add a series.� Under Time Series change Element name to Discharge Effluent and under State variables choose ammonia, listed as NH3-N.� Under Plot selected choose Fast line, but uncheck 3D.� Add another series to the same page.� Under time series, once again choose discharge effluent, but now select BODt.

Under the second added page insert another chart.� Right click and add series, but this time choose Composite.� Choose Discharge Effluent for Elements selected.� Choose ammonia as the compound to monitor.� Make this plot a bar chart.� Add another series to this same plot.� This time monitor composite samples of total BOD (BODt) in another bar chart.

Run the simulation.� Choose a dynamic simulation.� Click the play button.� The dynamic simulator window should pop up.� Under Simulate from choose to start from November 13th, 2003 at 12:00am.� Simulation duration should be set to simulate for 3 days.� Select close and the simulation should proceed.� Once finished, hit the stop button and choose yes to terminate the simulation.

View the results on the recently added pages of your album.� On the first page added, notice the oscillating effluent concentrations.� On the second page added, note the resulting flow weighted concentrations from composite sampling.� Answer the following.

The effluent ammonia and total BOD concentrations oscillate throughout the day.� What limitations exist from assuming steady-state conditions versus dynamic.

Compare the composite sample concentrations for the dynamic simulation to the effluent concentrations for steady-state conditions performed in the first in-class assignment.� How do they differ and what does that imply?�

Part II – Virginia Initiative Plant

Begin with the activated sludge plant model developed for the in-class assignment, and available as “In class biowin file” at www.public.iastate.edu/~eevans/ce521.htm .� Open the file in Biowin.� Use the wastewater characteristics and flow specified in the in-class problem, but modify the plant into a VIP process.

A VIP process is useful for removing BOD, ammonia-nitrogen, nitrate-nitrogen, and phosphorus.� Modify the traditional activated sludge plant from the file so that it matches the following VIP process.

Note that the following items will need to be added:

An anaerobic tank

������������� 14 feet deep

������������� HRT = 90 minutes

An anoxic tank

������������� 14 feet deep

������������� HRT = 90 minutes

An anoxic recycle (AR) splitter, pipe

A mixed liquor recycle (MLR) splitter, pipe, and mixer

Remember to add the new tanks to total mass of SRT calculated under project SRT.� Simulate the plant under steady state conditions.� Find the effluent BOD, ammonia, nitrate, and phosphorus concentrations on page one of the album.

What was the system SRT?

Did the plant successfully remove ammonia, nitrates, and phosphorus?

How could the operations of the plant been adjusted to reduce the effluent nitrate concentration?

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