Composting Bacteria.

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Dear Gardeners,
My church concerns about environment, and I'm interested in composting.
This is my composting bin.

This is anaerob I think because hatch is not opened, only when we throw waste in it then we open the upper hatch, throw garbage and close it.
Now, to make this composter works, we have to introduce composter bacteria in it.
And after that we have to spray the BCP (bio active compound bacteria) occasionally.
This is my BCP


Some of the consortium bacteria in my BCP are:
- Xenorhabdus Japonica
- Bacillus Simplex
- Paenibacillus Amylolyticus

So what I want to ask is this:
Why we have to spray the bacteria everytime we put a new garbage on top? Bacteria if I'm not mistaken multiply by dividing. Some says every 9.5 mins, and also every 20 mins.
Let's say that the bacteria divide every 1 hour, so IF we start with just 1 cell in hour 0, then
Hour Number
0 1
1 2
2 4
3 8
4 16
5 32
6 64
7 128
8 256
9 512
10 1024
In 24 hour, there will be 16 milions bacteria.
In 1 week there will be, I don't know. My calculator can't count it. But for those who read this question should get the point.
Why we should spray the bin occasionally?
Don't the bcp bacteria will be abundant in the bin?
Where do they go?
Who eat them?

Thanks for your help.

Steven

[applestar]

The way I understand the process, you want to more-or-less evenly distribute the bacteria in the "garbage" or kitchen scraps so that they are digested/processed by the bacteria and the enzymes they produce at the same time. The bacteria may multiply but they can only spread to cover more area at rate of microns.

Remember, too, that as fast as they multiply, they also die off of "old age" in their short life span. So how lively they remain will depend on if they still have enough good food for the bacterial population to eat until you add more fresh garbage.

Another reason to apply more of the intended bacteria each time you open and add ingredients is that you are unintentionally introducing OTHER bacteria and mold spores (some of which may in fact eat your good bacteria) from the surrounding air, shedding from your skin, falling from your hair, etc. So you want to fortify the number of GOOD bacteria to out compete them, and keep them from gaining foothold in the rich environment.

Some people say you should stir (mix top to bottom) the entire bin as well as add more, wearing clean gloves. I have also read arguments that that could contaminate the bacterial colony. The whole thing is really like any kind of lacto-fermenting or even yeast fermenting, or fungal culture process you may be familiar with -- pickles, yogurt, cheese, bread, wine, beer, ale, mushrooms.... You want to only encourage the specific micro-organisms to grow in the food you give them, and protect them from competing micro-organisms. (I always wondered if stirring might introduce air and oxygenate the mix, but you ARE supposed to press all air bubbles out.... I don't know -- I think I tried stirring once or twice, but stopped because it seemed like there were more mold growth, but I can't say for sure that it was specifically due to stirring since it was in the early days.)

Anyway, this is also the reason you should wipe clean the sides and inside lid of the bin when you open to add more ingredients, and thoroughly clean the bin after the process is finished and you empty it, before starting a new batch.

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Thank you very much applestar.
You have (been) giving me invaluable advices.