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  1. #1
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    Small community Composting Machines

    Over the years I have been toying with the idea of obtaining or building a small scale community composter that can be used to turn village organic waste into compost a little quicker than my compost heaps.

    I happen to have come across this site recently showing a Cowtec Compost machine and biogas generator. The CT-10 looks to be about the right size for a small scale composter. Not sure how to store the biogas or what to do with it, other than run an electrical generator.

    Cowtec composting machine and biogas ??????????????????? ??? ?????????? cowtec composting Machine ????????? ?????? ????????? ?????????????????? ????????????

    Has anyone come across these machines and are they any good?

    Any ideas on building one?

  2. #2
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    You could try your local colleges. I know the Rajabhat where I am has done work on developing bio-digesters.
    Last edited by Zooheekock; 14-10-2012 at 06:36 PM.

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    You could use the biogas to run an engine for a generator, but first you jave to modify the engine to run the fuel and then you have to safley collect, compress and store the gas.

    You will need to know how much bio-gas is needed to properly run the engine. If your little composting machine only produces enough gas to run the engine for 30 minutes, well, what good is that ?

    There are companies that operate small power stations, here in the US (and I'm certain elsewhere) that operate off of the methane and other combustible gases generated in a landfill. A landfill is a very large area with a lot of buried, decomposing trash. The power stations do not produce a lot of power from all that gas generated.

    It looks like there are 1-2 electric motors tucked underneath the inlet. How much electrical power will it use. After all, to compost in 24 hours, it is speeding up what takes Mother Nature weeks or months to do. That's a cost to consider.

    Interesting idea though.

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    Still thinking about the storage and use of the biogas.

    I saw this septic tank product from China...not sure if it is safe or worthwhile though...
    I was thinking more in terms of compost making as the soil in our area could do with it...

    PUXIN septic tank biogas system - Detailed info for PUXIN septic tank biogas system,septic tank biogas system,PUXIN septic tank biogas system,2M3 on Alibaba.com

    Any thoughts anyone?

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    How does the waste flow from one tank to the next? if it's natural, then what happens to the biogas being produced as the waste fills up the first tank to overflow into the second tank?

    The biogas is stored in a 1m3 bag? How does the biogas get from the tanks to the bag? At what pressure is it stored ? How does it flow into the biogas double stove burner ? Does the stove require a minimum pressure to operate properly?

    How long does the desulfurizer last? How much for a replacement desulfurizer?

    Does the liquid fertiliser pit smell ? I've been near hog farms with "liquid fertilizer" and it's a pretty overpowering stench, even from a distance. Even worse in warm weather.

    Even if it does work, the components look like simple things you could source in Thailand on your own. But too many questions and it sounds very dubious in my book.
    Last edited by stevefarang; 15-10-2012 at 02:40 AM.

  6. #6
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    Steve is correct, needs looking into regarding odour's and gas storage, just to be sure, but still a very interesting concept.
    Finding some one in Thailand with some metal fabrication skills might be difficult. I would say to purchase a unit from China would be the cheapest.

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    Finding some one in Thailand with some metal fabrication skills might be difficult.
    I don't see why. The Elephant Conservation Centre near Lampang has (had? - last time I went there I seem to remember it wasn't being used) a biodigester for producing gas from the centre's copious supply of elephant dung. I doubt they got it made in China.

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    ^^^ Not being made in China might be the problem, no doubt there would be more to it than meets the eye. The Thai's might have put together a box like thing that looks similar and wonder why it does'nt work.

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    Quote Originally Posted by Mozzbie47 View Post
    ^^^ Not being made in China might be the problem, no doubt there would be more to it than meets the eye. The Thai's might have put together a box like thing that looks similar and wonder why it does'nt work.
    Well I doubt that the Chinese version will work either. There's too many holes in the system description.

    To be practical, that biogas has to be "pumped" into a storage vessel. It's going to flow into the 1m3 bag and when they equalize pressure, it stops flowing. And with that, I truly doubt one would have a useful volume of biogas to do anything, except maybe cool little gas explosions (if that's even possible).

    It just seems with everything listed, all of that could be easily sourced right in Thailand, except for the desulfurizer. Although, I'm sure someone might have them or can fabricate one that would do the trick.

  10. #10
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    I think the above were referring to the Cowtec machine rather than the Septic Tank. The latter did seem a bit dubious when I first saw it, which is why I posted it.

    The Cowtec machine looks as if it is being used in Thailand, or at least research has been carried out of some sort. I will check the local Uni and Agricultural college as advised. I thought float tanks were still best for gas storage...

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    When I lived in Phichit provience, my neighbor had a hog finishing operation for CP. He was feeding about 500 hogs for about 5 to 6 months then cleaning his barn before starting a new batch. CP had installed his system for him at no cost. There were 2,5 meter tanks buried with just the top exposed. There was no external heat applied to the tanks.

    He would wash down the barn daily with all waste going in to tank #1 and then into tank #2. After tank #2 was full it ran out into an open lagoon #1 and then into lagoon #2 and from there into the klong. In the 2 years I lived there I never saw it go into the klong. He used the gas to run one of those Thai diesel engines that ran 6 large exhaust fans. For the most part, there was very little odor from his operation.

    Another man a few km away had a hog farrowing operation, also for CP, and he had the same type of methane digestor.
    “The inherent vice of capitalism is the unequal sharing of blessings; the inherent virtue of socialism is the equal sharing of miseries.”

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    I compost the wastes from our pig farm with farm residuals, biochar and probiotics. This compost is ready in 18 to 21 days. I looked into building a dome biodigester but decided against the biogas option. Two main issues. Firstly the nature of the gas, low heat value methane, small or irregular supply, and the corrosive nature of the impurities. The second issue is the real issue, the methane is generated at the expense of useful forms of nitrogen. To me the trick is to trap the nitrogen before it volatises.
    I looked at the composting machines, especially the ones that use bacteria to decompose the material. The heating requirement and other power usage costs to much to run against the outputs commercial value. I cannot see how you could make a profit from selling the gas and compost etc.. If they are to be used in a village community then who is going to pay the power bill?

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    IsaanAussie,
    I would be interested to know which composting machines you looked at. I am more interested in the compost and making it using organic refuse rather than animal manure. What sort of input power requirements were they? I was thinking in terms of 1kW and running it on a weekly basis (or as dictated by the load and time to completion).

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    Troy,
    I now understand the scale you are looking at, very small. The machines I was looking at involved megawatts and would compost in a day the requirements of a provincial town, like mine in Isaan.
    What you are looking at is more at my own scale. Happy to talk more about probiotics and pitchforks, three stage compost bins, hammermills, rice bran, rock phosphate and other minerals, biochar and minimising external expenditure. Soil remediation.

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    Thanks, that would be great!
    Let me give you a low down on what I have been doing and what I was hoping to achieve with a community composter. You may have some ideas that would help me greatly without having to resort to such machinery.

    I am in a village with around 100-120 households, say 300-400 people. Next to the house I have a 1 rai vegetable patch and small fishpond (20mx20m). The vegetable patch consists of 12 20ftx5ft raised beds that have been double dug. The local soil is acidic (ph of 4.0 - 4.5) and clayey (requires slow watering and cracks easily in drought conditions). Every couple of years I double dig and add lime and the early beds are about 6.5 - 7.0 now (best way to cope with ants IMO).

    I have three main compost heaps built using layers of rice chaff/banana trunks/corn stalks for the "brown" layer.. soil+manure for the manure layer and household waste/greens for the "green" layer. I have another heap that is basically chopped up leaves and harder twigs that I add as extra for the "brown" from time to time. Anyway, compost takes about 3 months to make and I never seem to have enough for myself let alone others. I use on all but two beds...that are rotated each year.

    The villagers like it but never bother to try themselves...usual reasons that I shan't bother to go into....

    Problem is that the villagers just burn their rubbish and organic waste. I have tried numerous ways to try and get them to adopt composting but to no avail..."Not Invented here" syndrome seems to be the main reason. They are quite happy to moan about the poor state of the soil though...and where I am it is single season rain fed irrigation so not the most ideal of conditions.

    No-one in the village keeps pigs but I can get buffalo and cow manure in small quantities...villagers have stopped laughing at me cleaning the road from time to time with my wheelbarrow and spade :-).

    I was thinking of a community composter where household waste could be collected /dumped and fed to the monster in order to make compost on a larger scale that could be used by more then me alone. Ultimately, the goal would be a way of making enough to use on each of the farms (up to 20 rai each)...before it all turns to dust and gets blown away.

    Hope that puts it in perspective....

    =====================================
    edit:

    Last bit is possibly written confusingly for some...I mean the soil on the farms turning to dust. They have planted rice year after year for 100's of years. Leave it fallow for all but the single growing season but it is in a really poor state...I cannot get them to grow legumes (foot long beans would be ideal local answer) just after the rice harvest. So it is chemical fertiliser every year and a yield I think could be nearly doubled with better techniques.
    Last edited by Troy; 17-10-2012 at 12:48 AM.

  16. #16
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    Troy,
    One thing you can do is to make some carbonised rice hulls (pyrolisis) and incorporate that instead of or with the lime. It will raise the pH as does lime but its effect is long term and you are putting heaps of carbon into the soil as well.
    You could try intensive planting of marum which you cut at about 500mm high and use the leaves for cow and buffalo feed. You cut every month and as it is a legume it is nitrogen fixing. When you prep for the next rice crop just plough it in. Drought tolerant as well.
    In my village there are three of four times a year they all get out and clean up the roadside, trimming the tress and bushes. If you had a serious chipper/shredder that would be a good time to gather a lot of greens for your compost.
    The machine idea is good but if my neighbours are anything to go on, they will give you all the rubbish or none. Don't fancy sorting that out myself.

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    Thanks for the info. When you talk about carbonised rice husks what do you mean exactly? The village mills de-husk peoples' rice for free and sell the husks for animal feed. I thrash our rice in my garden and make a rice husk heap with the spillage that's on the net. I set fire to a small pile, cover it with the rest to make a heap about 1/2 to 1m high and leave it for a day or two. I apply this directly to new beds. Is this what you mean? I didn't realise the full extent of its value, if this is correct, just thought it might be good.

    Is Marum common and easily sourced? I thought about clover as a green manure in the past but could never find any in bulk. Did not know about Marum and it looks to be a very good idea. Thanks for that tip. In fact, that may be the best way to go.

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    Marum is also known as Moringa and I would be surprised if there isnt a tree in a garden near you. The seed pods are dry now so just go get some.
    I use a large thinner tin with a hole cut in the top and the bottom removed. Punch heaps of holes in the sides and stand a cement pipe on top for a chimney. Light a small fire inside the tin and heap the rice hulls in a steep pyramid around it. Takes about 4 hours to pyrolisize 10 bags of hulls. The trick is to extinguish the burn before the husk burns to ash.
    Bio char in the compost (thin layer on top) of each load is great. You get the carbon ratio up and it traps the ammonia gas as usable nitrogen so reducing smell and increasing N levels. As a soil improver it acts like lime (raising pH) but lasts a lot longer as well as adding carbon back to the soil and improving moisture retention.

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    Charcoal also improves the soil by itself.
    It has the ability to bind minerals which otherwise can be washed out by water and plants are able to release the minerals when needed.
    This was long ago used by the indigenous people in the Amazon basin, making humus out of sandy soils. The knowledge disappeared for centuries and has just been rediscovered by analyzing the still existent humus of the ruin areas.
    So adding ground charcoal to the soil itself adds a bonus on the long term.

    Bye,
    Derk

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