Thermophilic Aerobic Digestion

[diesel]

Hi, Does anyone know how Thermophilic Aerobic Digestion proccess works. We have cattle slurry and chicken manure that would give a good NPK fertilizer. Just thinking if we could reduce the volume of slurry and increase the the value through this process it could be come a valuable product for our farm. Any information on how this proccess work would eb appreciated.

[velacreations]

Basically, you mix manure with straw, cardboard, wood chips, sawdust, or other carbon materials, wet it down well, and keep it aerated. It does the rest by itself! You know it is working because within a few days, it gets real hot.

I do it like this:
4-6 inches of brown material (straw, etc), 1 inch of manure. Then keep making those layers until it is 3-4 ft tall.

I like to make my stacks about 4 ft by 4 ft. I aerate it (turn and mix it up) every week or two. It should be done in a month or so. Keep it moist.

[diesel]

Basically, you mix manure with straw, cardboard, wood chips, sawdust, or other carbon materials, wet it down well, and keep it aerated. It does the rest by itself! You know it is working because within a few days, it gets real hot.

I do it like this:
4-6 inches of brown material (straw, etc), 1 inch of manure. Then keep making those layers until it is 3-4 ft tall.

I like to make my stacks about 4 ft by 4 ft. I aerate it (turn and mix it up) every week or two. It should be done in a month or so. Keep it moist.

Thanks velacreations for your reply. I was talking to a person that knows of a machine that can do this. He had not alot of information for me though. Basically you put the waste liquid into a rotating barrel it is heated to 50 degrees to burn of any bacteria and within a few days the liquid is reduced to a dry solid ready for the land.

I was thinking of building a demo myself. If I got a 50 gal barrel put in a heating element with a temperature gauge, heat it to 50 deg and also install a small motor to linked to an agitator with in the barell. Then give it a few days and see.

[velacreations]

if you let the bacteria do it themselves, they will get it to 50 degrees within a few days on their own, no energy required. In fact, you can use the heat from the pile to heat water or air for your home.

As long as you have the proper feed for the bacteria and moisture levels, they will do the rest.

[velacreations]

I just make a pile and wet it down really good, and it hits 50 degrees in 3-4 days without any effort.

A few years back, we made a long pile, 4 ft tall, 5 ft wide, against the back wall of our house. We wet it down, and covered it with a tarp, leaving a few tubes for aeration. Within 4 days it was up to temp, and lasted for over a month. The heat went through the brick wall into the house, and the wall was 35 degrees day and night. That was a lot of nice, free heat for the house.

[diesel]

I just make a pile and wet it down really good, and it hits 50 degrees in 3-4 days without any effort.

A few years back, we made a long pile, 4 ft tall, 5 ft wide, against the back wall of our house. We wet it down, and covered it with a tarp, leaving a few tubes for aeration. Within 4 days it was up to temp, and lasted for over a month. The heat went through the brick wall into the house, and the wall was 35 degrees day and night. That was a lot of nice, free heat for the house.

We are looking to increase the dry matter of the product that is why we are looking to put it into a rotating barrel that is well sealed. I know there will be some gases from it so we will have to leave some vent. One of the products we are looking to put in is only 12%Dm. We want to increase this to 85-90% we will be also be adding waste that will be between 40-50% Dm. I am trying to do as much research as possible before a build. any info is well appreciated.

[velacreations]

I'm not sure I understand what you are trying to do. It sounds like you want to cook compostable materials with energy input to produce something you can easily produce without energy input. What am I missing?

[diesel]

I'm not sure I understand what you are trying to do. It sounds like you want to cook compostable materials with energy input to produce something you can easily produce without energy input. What am I missing?

From what I understand cooking is the only way to vaporise most of the liquids. We want to have a high dm content so that we can bag it. In some of the waste we want to use there are 80-88% liquid mainly compromising of water. Pig slurry has a high water content because of the water used for washing the floors and stalls. Forgive me if i sound confusing, just trying the best way to figure this concept out.

Thanks for your input.

[velacreations]

From what I understand cooking is the only way to vaporise most of the liquids. We want to have a high dm content so that we can bag it. In some of the waste we want to use there are 80-88% liquid mainly compromising of water. Pig slurry has a high water content because of the water used for washing the floors and stalls. Forgive me if i sound confusing, just trying the best way to figure this concept out.

Thanks for your input.

If you mix dry, carbon material with your slurry, your water will be used as the moisture in the compost process. For example, if you have sawdust or straw at 90% DM and mix with your slurry at 12% DM 1:1, the resulting mix is 51% DM. If you mix 2 parts sawdust to one part slurry, you have a resulting mix with 64% DM. Let that compost for a few weeks, and then let it dry out on it's own (the composting process uses water). Your result will be compost around 80-90% DM.

Cooking it is not the only way to do it, and really, it is less desirably, because of the energy input (and required closed vessels). The compost will reach the 50 degrees on it's own and boil out a lot of water vapor by itself. You just need a proper mix of dry material to match your wet material.

[diesel]

If you mix dry, carbon material with your slurry, your water will be used as the moisture in the compost process. For example, if you have sawdust or straw at 90% DM and mix with your slurry at 12% DM 1:1, the resulting mix is 51% DM. If you mix 2 parts sawdust to one part slurry, you have a resulting mix with 64% DM. Let that compost for a few weeks, and then let it dry out on it's own (the composting process uses water). Your result will be compost around 80-90% DM.

Cooking it is not the only way to do it, and really, it is less desirably, because of the energy input (and required closed vessels). The compost will reach the 50 degrees on it's own and boil out a lot of water vapor by itself. You just need a proper mix of dry material to match your wet material.

Thanks velacreations. Is there a cut off point in the Dm that can be used for composting. In other word can it be to low or to high. I wanted to use heat to speed up the process is there a danger in doing this ? Most of the imput products we have are low DM and are waste materials. Was searching the net last night I couldn't find to much much info on equipment but came across the following. Rotary Composters, LLC and ASM Group, Organic Recyclates

[velacreations]

Thanks velacreations. Is there a cut off point in the Dm that can be used for composting. In other word can it be to low or to high. I wanted to use heat to speed up the process is there a danger in doing this ? Most of the imput products we have are low DM and are waste materials. Was searching the net last night I couldn't find to much much info on equipment but came across the following. Rotary Composters, LLC and ASM Group, Organic Recyclates

For moisture content, I will have to look it up. I think 40-60% is best (40-60% DM).

Basically moist to the touch, but not dripping wet. Particle size also matters, the smaller the size, the better. So, if you have slurry, it is a small particle already, mix it with sawdust, instead of wood chips.

Do some small tests, like in buckets or something to see how it works for you.

There is a danger of heating it too much and killing the bacteria. You won't speed it up much, anyway. A better option would be to insulate your container really well, so the heat stays in there. If you could set up multiple bins that share a wall, the first pile will get hot, and will help heat the second pile when you add it.

Aeration can affect the speed of composting. If you turn it every other day, mix it up really well, it will go fast. Barrel composters are good for this, because you just turn it and it aerates. The downside is that you are limited to the size of the vessel.

Google hot composting, and you will get tons of low tech and easy ways to do it without adding energy.

Personally, I don't see the point of adding energy to it. I can start a pile today, one tomorrow, etc, etc, and by the time the first one is ready, I will have a daily supply without any added energy.

[velacreations]

here's a contraption for producing heat energy for heating water or whatever. It is basically a rotating compost bin. http://mb-soft.com/public3/globalzl.html

Lots of ways to do it. I prefer the easy, low tech way of just making a pile.

[dutchdivco]

I understand

WHAT you are wanting to do, just not WHY; If your going to put the 'stuff' in an airtight container, and heat it, WHY in the world would you want to 'vent' the gas produced to the aptnosphere? It is methane gas, the SAME gas people pay to have piped to their house; USE it. In addition, the resulting liquidy product can be pumped, which is an easier, less labor intensive way of spreading fertiliser; Go to Mother Earth news, (website), and look in their index, for articles on 'Methane Digestion'. I believe they have an article on a pig farmer, (1000 head) in (I believe) South Africa, who ran a diesel engine, 24/7, on the gas produced. he used it to produce electricity, and to run pumps to distribute the liquid fertiliser. Said the MAIN reason he originally did it, was to deal with the fly problem; all the eggs layed in the fertiliser get 'digested' in the process, and the 'odor' is in the GAS, not the fertiliser; hence, no more fly's! And, the odor in the gas means you'll notice if their are any gas leaks, which is good, cause methane is flammable/explosive.
Anywa, just my thoughts,....I seem to recall their are 2 different bacteria; 1 'operates' at about 90-110 degrees, (F.), and the other at about 120-140F. (going by memory here). You can use the gas to heat the unit, or use the exhaust from the infernal combustion engine you use to burn the gas, take your pick.Jim

[velacreations]

Methane production is not aerobic digestion, it is anaerobic.

[dutchdivco]

Your right;

And Diesel, who started this thread said earlier,

"We are looking to increase the dry matter of the product that is why we are looking to put it into a rotating barrel that is well sealed. I know there will be some gases from it so we will have to leave some vent."

Once you 'seal' the container, and start talking about venting the resulting gasses, aren't you moving from aerobic to anerobic? (Fancy term for with oxygen (arerobic) vs. without oxygen (anerobic) speelings probably wrong, but a clarification for any unfamiliar with the terms.

Anyway, based on my reading of Diesels questions, sounds like you are up to your *ss in pigsh*t, and other such materials, and are trying to figure out a way to utilise it. So, should at least keep an open mind, and consider anaerobic digestion as well; certainly worked out well for that pig farmer in South Africa!

Methane gas IS a 'geenhouse gas', and there is more 'greenhouse gasses' produced and released to the aptnosphere every year by livestock operations in the U.S., than by ALL the cars and trucks,....or so i have heard.Jim