Backyard Aquaponics
A place to discuss aquaponics

Hi Daniel,



Yes, I have done lots of different things.

The upside is that I don't spend a lot of time regretting that I haven't done something.

The downside is little superannuation and no Long Service Leave.

Rupert,

That site has some excellent material on it. Thanks!


Gary

DDM, have you seen this bio digestor, I read where you have a steer or two and could benefit from a small version like this.
http://biorealis.com/digester/construction.html
I've seen the bladder type storage units but I was thinking a refridgerator compressor could safely compress the gas to be stored in 5 gallon propane bottles, those little compressors can pump up to 400 psi., so it would have to be regulated. I know you are an experimenter type, what do you think?

I did some searching a while back on the same subject. If you have animals and land with some excess materials to use, you could probably make a nice rig. For us with only two people and 4 chickens, humanure composting works well enough for us. I didn't think I could really justify the effort/space to build a digester for our small scale. With the output of an extended family plus some large animals, I think it might be worth while to collect some fuel while processing the effluent.

I don't think I saved any bookmarks from that past search but I did find several different methods from as small as a 55 gallon drum and an innertube as a gas collector on up to the big plastic tube or dome over pit continuous digesters. All dooable though some effort involved.

I agree TC, not worth while for me. But a family of 4 with a couple of steer, a couple of dogs and a little organic waste could produce a couple dollars worth of gas per day. Easy calculator below.
http://biorealis.com/wwwroot/digester_revised.html

If anybody's interested there's a big biodigester in NSW called Camellia. (or that's the location)
and a new one going in at Jack's Gully.
I've had a bit to do with both these projects.
The new one's aim is to take standard landfill, and reduce it to 10%.
It's pretty ambitious and hasn't been done outside of Israel so far.
I googled for publuic info, and only found a pdf here. These guys are pretty secretive about their IP, so I can't really say much that isn't public
Also, I have a bandwidth cap atm and can't tell if the pdf barely mentions them or if it's interesting.

NSW has apparently run out of landfill, so a heap of money is being spent on efficient waste management.
This new site will sort all metals, food products, remove plastic bags, biodigest anything organic, produce methane for power, send out all recyclables to other plants, and only put 10% in the ground. This to me is fantastic... but it's scary the control systems that are installed there, it's collosal.
Meanwhile or super composter there is doing very well, whilst the biodigester is taking it's time getting to full production.

The top rusted off of my septic tank,(my house was built in 1958, and I should be installing somthing new. I can just put a new top on it but once I'm there the options are open. Some of the new local systems have two tanks. The second tank is the effluent/grey water tank and is pumped thru an inground lawn sprinkler system at night. The fermenter tank has an airation pump on it to help break down the solids. This would be bad for a methane system as it would create an explosive atmosphere. I have a lot of trees on my little 3/4 acre, and from what I read that while not as good as manure, the leaves and grass clipping can be digested. But it is a waste of a lot of good compost for a little methane.

Bill, if you bubble water through it, it becomes an aerobic process, which produces little methane. So I doubt, unless osmething was designed poorly, an explosive atmosphere would be created.

How about bubbling air?

yeah OK, thanks OB... damn my not reading through what I wrote!
Please substitute water for air in my above post.

It requires 95 deg. F to maintain the conversion of poop and all to methane. So the gas may be required just to keep her perking at least with my nighttime temps. I may not have any surplus gas to use. Nonetheless it will be worthwhile to process affluent from composting toilet and animal wastes into good fertilizer. It is to dry here to keep a compost pile going. I have tried several methodes and all failed. Currently storing biolet affluent in sealed drums and putting animal waste on as mulch. After mulching like this for years my soil is still lacking in nutrients and dirt gardens are poor producers.
I have a four ft. diameter 1000 gal steel tank that I will cut the end off and float a fiber glass tank in to catch the gas. I will build a water containment around the steel tank for heating. Will use solar and thermosyphon with methane booster to heat. Will probaly require opening and cleaning out annually. Looking for volenters for that part. Anyone?

I'm not brilliant with biodigesters, but I do know with composters, that one key point is keping the pile cool. Compost Winrows have been known to spontaneously combust when not managed correctly. Compost readily sits @ 80 deg C. I had assumed methane production also produced heat, but perhaps not.

What I'm trying to get at, is that if you cool the system enough, you'll kill it... sure... but if your temps are so extreme, perhaps some kind of insulation would help.
Or surround your biodigester with a compost heater

What's your lowest average temp over there? I'll see if anybody at work has an opinion on you running a composter successfully, and how...
What methods have you tried so far?

All biological activity produces heat as far as I am aware, the greater the activity the more the heat
Spirit
Providing the bacterial action is complete, the waste is not unpleasant smelling, relatively sterile and good soil conditioner.
Unfortunately you probably need to build two, so you can be letting one taper off and still have somewhere to put the fresh waste. ie running two out of sync.

Here is some of the best info you can get about making methane: http://66.76.55.66/naphtha/images/posted/methane.PDF

It does not compress well. It much like natural gas, no wait... It is real natural gas, lol.. If you can compress it to 3000 psi then you can do well, otherwise you need large tanks at low pressure to store much. A cheaper method is using large weather balloons that cost only $5 each.

I have tried piles of material turned and wet daily. I have tried patented tumblers turned and damped daily. I have tried wire screens and hinged pokers wetting daily. They all have worked for me in other climates. Even when the material was bedding and rabbit pan gleanings which was soggie with urine composting failed here. We have 20 to 30 deg. F temp drop at night and often have less than 20% humidity.
The digestor requires lots of water to make a slurrey of the feed in. Best if warm water is used. some heat is produced in digesting but with a steel tank most of that will be lost to cooler ambient. By putting a water jacket around the bottom third of the vertical tank much of that heat is retained. Heating water in the jacket will be required here. My fish tank temps in the green house are currently 59 deg. F even with a solar collector.