Backyard Aquaponics
A place to discuss aquaponics

bio-digesters have been thrown around a lot on this forum (edit: not physically, just mentioned ) and I am not sure what they are, what do they do? Can they be built? Are they used in parliament etc. Please help...

It is a method of treating sewage, but I have never seen one in use, nor had I heard of them outside of this forum. I had assumed they were a composting toilet, but it looks like they are designed to handle waste from multiple sources. Here's a nice animation.

http://www.biodigester.co.uk/biodigeste ... 6.asp?id=7

Often used in villages in India on a small scale to convert waste into methane gas via anaerobic fermentation which can then be used for cooking.

In large sewage farms they can run generators on the gas.

They work great and can be built for less than $30.00 US. We used one in Honduras. The caretakers of the hog farm simply dumped a 5 gallon bucket of poo in each day and they had gas too cook three meals and heat water. Sometimes we had to burn gas off. The other side of it was that the effluent running out of the system was odorless and loaded with nutrients to spread on the garden. They had wonderful squash, papaya, and passion fruit. Plenty to go around.

Hi,

On a backyard scale, the effluent from the digester is the main benefit since the amount of gas will be negligible.

The little home brew kit fitted with an airlock is a simple batch digester.
Do a search on "bio-digesters" or "bio-gas" and you'll find more information on them.

Back in the '70's, I operated digesters with a capacity of several megalitres and I've seen plenty of smaller ones. If you need more information, PM me.

Gary

actually they can be set up as lawn torches with kind of an "eternal flame". Use the effluent in the garden and use the light at night.

Hi,

I can see where this might work in third world situations.

I think if you expose an open flame just about anywhere in Australia, at the moment, you may get to meet a lynching party. We're working through one of the worst bushfire seasons in memory.

I like the cheap plastic bio-digesters that Vietnamese farmers use, too.

If I was on acreage.....and I had animals.....I'd definitely be using a digester. As I said earlier, the effluent is very useful.

Gary

ah yes, brush fires. I guess maybe not such a good idea in your neck of the woods. I wasn't thinking. You got a pic of one of those vietnamese things?

I have seen one in action in Aus, at boliva sewerage treatment plant.
They had this huge metal container, with a couple of hundred tonnes metal lid, on a sort of thread that was lifted up by the gas produced (eg, as the gas pressure build, the lid rose and turned) They used the gas to power the turbines for electricity, when we were there they were burning off excess gas in a flame like you see on oil rigs.
Well i didn't really know about biodigesters at the time to ask our "tour guide" but it seems to match a biodigester


but yeah a backyard system would prob cause lynching...

Hi Daniel,

I worked as a plant operator at Bolivar from 1977 to 1980. There are six of the digesters that you referred to and the methane gas powered 5 dual fuel engines. At the time that I worked at Bolivar, the entire plant was self-sufficient in electricity.

Gary

Cool! I really like that idea

Wow gary, Seems you are experienced in alot of things, biodigesters, thermosyphons....

Ahhh! now I know. I have seen these alluded to in the self-sufficiency book a while back.

Thanks for all the help, does anyone have a link to a homemade job on the net (had a look but nothing concrete), it sounds like it could deal with our dog, chicken crap nicely. I'd be a little concerned about the pressure build-up so I would start small with a trusted design. Live on 20acres and have had three fires on the block in 4 years! (I didn't light one!)

Asitis, haven't read through, but remembered bookmarking this page....

hope it helps Methane Digesters

whole site's worth a read actually

Cheers RoOZ, have a look now (I'm so bloody lazy on the net )