Hi Team.

As part of an introduction to the site wastewater plant for production employees

I want to build a simple, portable and consistently repeatable and replicable demonstration kit to show bacterial and fungal activity.

I want to encourage exponential growth with foaming. Growth needs to be as rapid as possible - take slides of lifeless starting solution at the beginning of the presentation and come back to it at the end of the day for observation.

Only needs to get to the stage where the start up foam begins to turn brown and the exponential growth stage has completed. (Up to flagellates, hyphae etc, no higher life forms necessary.)

Is the foam changing from white to brown a reliable indicator of completion of exponential growth?

Speed of growth is a requirement so BOD will be simple sugars.

A single environment that will encourage an abundance of both bacteria and fungi - but that still exhibits foaming would be ideal, but can make a kit or each if necessary.

For each organism what is the ideal:
BOD source
BOD N P ratio
BOD load to ensure foaming (per litre of water)
pH
Temperature (I want all organisms to be mesophilic).
Organic N P and trace element source would be ideal for demo. (In keeping with the green technology on display)
Is there an air cfm to BOD/litre ratio or similar to ensure DO is 2.0 or higher? (Air input will be non variable so will start high and hopefully finish at 1.5- 2.0.)
I want mininmal/zero anaerobes.

I don't want to need to do any testing aside from at the start to establish
pH (which will not be controlled). Temp will be controlled with simple aquarium heaters.

In essence I want the foaming so non-industry people can observe microbial activity without a microscope. When the foam starts to colour (and the microbial life is at its maximum concentration in the solution) I will take a sample which will hopefully contain abundant bacteria, flagellates and fungi for display.

I lot to ask I know!

Thanks for your expert input everyone

Hi JKD,
I heard one time about someone who was scheduled to give an outdoor class to a group of Botany students, and wanted to show them an Acorn grow into a tree, with the tree sprouting leaves and then with the leaves turning golden, and then falling from the tree so that they could see the splendor of fully grown Oak tree and appreciate the various stages of development of the plant.
I understand that the project was developed successfully, but the only problem was that the time allocated for the lecture was only 40 minutes, and the project time took 40 years.
I fear you may be facing a somewhat similar difficulty.