A4 Use of the Rotating Drum Bioreactor Model

This section gives advice about the use of the model for the rotating-drum bioreactor that was presented in Chap. 22. The following steps should be followed.

First use a text editor to edit the input data file. An input data file (text file) has been supplied with the name "input.txt". The contents and format of this file are shown in Fig. A.2. Change the values as appropriate, save the file (as a text file) and exit the file editor.

Then click twice on "RotatingDrum.exe". A "DOS window" will appear on the screen. Several questions will appear, one after the other.

• What is the name of the OUTPUT file?

• What is the name of the COOLING CONTRIBUTIONS file?

After you answer the last question, the program will run automatically. When the instruction "Press any key to continue" appears, press a key (for example, the space bar).

Inspect the output files. Assuming that you have called the three output files "output.txt", "cooling.txt", and "echo.txt", respectively:

• Output.txt will have 15 columns with the headings shown in Table A.4. The number of rows will depend on the "number of outputs" that was selected in the input file.

1.2 Diameter of drum (m)

1. Air flow in vvm (m3-air/m3-total-bioreactor-volume/minute)

30. %fill = percentage of total volume of the bioreactor occupied by the bed

.99 Awso - initial water activity of the solids (0 to 1)

0.95 AwSP - solids water activity that triggers water addition

0.5 Initial water activity of the inlet air (0 to 1)

0.9 Water activity of the inlet air when T>38 celsius (0 to 1)

35. Tin - temperature of air entering the headspace (deg C) (in absence of control scheme)

35. Tsurr = temperature of the bioreactor surroundings

0.001 binoc kg of dry biomass per kg of dry solids

0.25 bmax = maximum concentration of biomass (kg-biomass/kg INITIAL dry solids)

0.236 Uopt = value of the specific growth rate constant at Topt (h-1)

38.0 Topt = temperature at which the specific growth rate is optimal (deg C)

387. rhobed = packing density of the bed (must know for the given water content!!!) (kg/m3)

0.005 Thickness of the metal wall of the drum (m)

35. Initial temperature of the bed (deg C)

35. Initial temperature of the headspace gases (deg C)

35. Initial temperature of the drum body (deg C)

0.5 Ybd = kg of dry biomass produced per kg of dry substrate consumed

0.0 emd = kg of dry solids eaten per kg of dry biomass present per SECOND (maintenance)

8.37D6 Yqb = J liberated per kg of dry biomass produced

0.0 emq = J liberated per kg of dry biomass present per SECOND (maintenance)

0.3 Ywb = kg of water produced per kg of dry biomass produced

0.0 emw = kg of water liberated per kg of dry biomass present per SECOND (maintenance)

10.0 enfactor = increase in mass and heat transfer (substrate to headspace) due to rotation

100.0 Time at which the simultion is to finish (h)

100 Number of outputs INTEGER

1 Type of organism (integer) "1"= A. niger type "2" = R.oligosporus

Fig A.2. Appearance of the input file (input.txt) for the rotating-drum bioreactor model

Table A.4. Significance of the column headings in the "OUTPUT" file generated by the ro-tating-drum bioreactor model

No. Heading Significance

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