Biogas Digester for Dog Kennel wastes on Cyprus?

Digester design and construction info

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Biogas Digester for Dog Kennel wastes on Cyprus?

Post by Bob » Sun Oct 29, 2000 5:53 pm

The following was copied here from email. Thanks for the inquiry, Peter!

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Dear Sir,

Your site is of considerable interest. My attempt at downloading the Netscape Viewer did not work so no calculation was possible of the size and cost of the system needed.If I may explain the need please kindly give some idea of the costs of the system so that I can put it to the management committee of the kennels.

Here I am one of many volunteer helpers at these kennels which are run to home stray dogs on the island and actively home many in the process. We have about 120 dogs with daily solid waste collection of about 6 buckets (c 30 kgs) per day. At present the waste is buried in pits which is not wise for water table and no benefit results. The site is not on mains electricity. Bottled gas is used for heating water plus a solar collector.

A system that could produce some methane for bottling and output treated waste suitable for garden manure etc would be excellent.

I look forward to hearing from you.

With Regards

Peter Gibbs
<HR></BLOCKQUOTE>

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Post by Bob » Sun Oct 29, 2000 5:58 pm

copied here from email...

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Hello,

Attached is a file showing results with your parameters (i.e. waste from 120 dogs) plugged in. I'm also including a second version, showing the effect of adding some additional carbon source (i.e. scrap paper, leaves or sawdust -- or kennel bedding?). This increases the C/N ratio, substantially improving the performance -- more than doubling the output.

May I ask what trouble you ran into with the Netscape plugin?

You should be able to download it from ftp://biorealis.com/f1net32s.exe . Then, after downloading, just double-clicking on the file and following the prompts should install it. Can you tell me where it failed? If I have a better understanding of problems that people are having, it would help me to be able to correct or improve it. You can also use the program to ask "what-if" questions, try more variations, beyond what I can do for you...

Thanks for your interest. Good luck.

Bob Crosby<HR></BLOCKQUOTE>

(edited to add pointers to attached files:dog_methane-1.PDF
dog_methane-2.PDF)


[This message has been edited by Bob (edited 10-30-2000).]

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Post by Bob » Sun Oct 29, 2000 6:00 pm

copied from email...
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
Many thanks for the calculations. The trouble I have is that having downloaded the software it came up with the message "Could Not create a destination file C:\windows\temp\setup.exe"Followed by next message ?xtract failed". Maybe because I cannot use the software I could not print out the spread sheets you prepared. The information is there to view and I thought I would copy it to a floppy disk and take the disk to a computer agent in town.

Are the figures quoted the cost of the tank made locally in US or does it include all piping and fittings? I still do not have a feel for the amount of physical work required to empty the tank from time to time of sludge and put the sludge to a drying area for use as compost. Also is it possible to pressurise the methane gas in bottles for use in stoves or do you generally use low pressure tubes etc? Still interested and learning!

Regards

Peter Gibbs

<HR></BLOCKQUOTE>

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Post by Bob » Sun Oct 29, 2000 6:03 pm

copied here from email...
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
Hi Peter,

Would you mind moving this conversation from private email, to "The Forum" on my website? http://www.biorealis.com/Forum/cgi/Ultimate.cgi

One of my goals for the website has been to create a place for a public dialogue, and, ultimately, a repository of collective wisdom: a place where people can ask & answer questions, share experiences with each other, etc. Right now it is brand new (or newly repaired, that is, after moving the website over to a new hosting service), and I'm looking to "seed" it with relevant conversation.

Check it out, and let me know.

"Many thanks for the calculations. The trouble I have is that having downloaded the software it came up with the message "Could Not create a destination file C:\windows\temp\setup.exe" Followed by next>message Extract failed".

Hmm... I can't explain that one (nor duplicate it on my machine). When you click on the "download for free" link, do you get a "Save As" dialogue box? And then, after it has downloaded, can you confirm whether or not it actually downloaded, and to where?

"Maybe because I cannot use the software I could not print out the spread sheets you prepared. The information is there to view and I thought I would copy it to a floppy disk and take the disk to a computer agent in town."

That sounds like a separate problem. The files I sent you are in .pdf format, readable by Acrobat Reader. Do you have Acrobat Reader?

"Are the figures quoted the cost of the tank made locally in US or does it include all piping and fittings?"

The costs are just for the tank. (I originally built this tool for my own use to help select the best tank(s) to fit the job.)

<I>"I still do not have a feel for the amount
of physical work required to empty the tank from time to time of sludge and put the sludge to a drying area for use as compost."</I>

A system could be designed to pump the sludge from the tank. It could even be automated.

"Also is it possible to pressurise the methane gas in bottles for use in stoves or do you generally use low pressure tubes etc?"

Yes, it's possible, but probably not practical. The cost and energy required to compress the gas would exceed the value of the gas itself. Also, for safety reasons, it is best if you can burn it (e.g. in a water heater) as it is generated -- or, accumulate only small amounts in an inflatable bag. (In my prototype, I have used a car inner tube to generate just enough pressure to feed the gas burner.
<HR></BLOCKQUOTE>


[This message has been edited by Bob (edited 10-31-2000).]

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Post by Bob » Sun Oct 29, 2000 6:05 pm

copied here from email...
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
Dear Bob,
Hopefully this will go on the "Forum" having registered. Thanks for your e-mail reply of Monday 15 October.

First, downloading tried again with the same message "Could not create a destination file". But having found that I have Adobe Acrobat I was able to read and print the two methane files that you produced a few days ago. Success!

You confirm that the costs quoted are just for the tank. (For the benefit of others Option 1 was a digester to handle the dog feces of 120 dogs with no additional other input and this is priced (tank only at $842). Option 2 had additional input of 20 kgs scrap paper and sawdust and this tank would cost $1442. Option 2 had about twice the output of gas and used 3 times more water).

Now I want to move on to know the estimated cost of a complete tank and all piping and fittings for Option 1 plus estimated shipping to Cyprus. That may seem absurd due to the distance Alaska to Cyprus! The alternative is to have complete drawing plans and find a local contractor to build it. So far I have come up with a blank for any provider in Cyprus or even Greece. I am going for option 1 on cost grounds and the fact that extra gas is not an advantage as it is cheap to buy in here and ther asmount of gas produced may even do the cooking for the dogs on this option. It is an environmentally good solution rather than burying the waste!

If you have any firms you work with in the Mediteranean area do let me know.
I go on a 2 month tour of Australia and NZ in a week or so and will be out of e-mail link then.

Thanks for information to date and good progress with the site and objectives!

Yours

Peter Gibbs
<HR></BLOCKQUOTE>

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Post by Bob » Tue Feb 13, 2001 6:54 pm

Hi Peter,

I'm wondering if you are back from your trip yet. I've been thinking about your project, and have a proposal. From what you've said, I don't think it would make economic sense for me to build a custom unit for you, and ship it from Alaska.

If you can find a local source for the tank (see following link for example) and send me the exact dimensions, I'll develop a set of drawings and how-to instructions you can build from, and provide support information as required.

Depending on "local" (i.e. closer than Alaska or USA -- UK?, Italy? Greece?) cost & availability of the materials (e.g. a 300 gal plastic tank plus misc plastic pipe & fittings) you should be able to build the Option 1 digester for $2,000 - $3,000 in materials and 2-3 days labor.

The only requirement I ask is that we do it all here on the Forum, and that, after it is completed, you agree to help others with similar questions, based on what you (we) learn doing this one.

What do you think?
http://www.chemtainer.com/products.asp? ... &category=

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Post by Darrell » Mon Oct 22, 2001 10:08 am

Hi Bob:
I am having trouble with the design tool.
Have installed Netscape 6.1 and installed the plugin from you site. I still have a blank window.

I am very appreciative of the site and the information on a very important subject as I am in the planning stage of a very small farm community.

Methane digesters are to human quality of life off the grid as compost piles are to the soil off the chemical products.

Thank you.
Darrell

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Post by Bob » Tue Oct 23, 2001 3:55 pm

Hi Darrell,

Yeah, I know. The design tool is rather dated -- as is this whole site, for that matter. I'm working on a new version. But, as its a labor of love, it's slow going.

In the meantime, what are your parameters? I can plug them in and send you a printout.

Glad you're here.

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Post by petermgibbs » Fri Nov 09, 2001 8:05 am

Dear Bob,
I have had to change mu username and password and also my e-mail address and hope this now works. First I will just see if this message goes through and then mention some relevant queries.
Peter

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Post by petermgibbs » Fri Nov 09, 2001 8:12 am

Dear Bob,
Another attempt with new password and user name. There was an Internal Server Error last time. Just see if this goes.
Peter

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Post by petermgibbs » Sun Nov 11, 2001 7:57 pm

Hello Bob,
We note with interest that you have finished a design on the new tank.
The architect for the new dogs kennels now wants to know the space to allow for the tank and the sludge drying beds. This depends on what area to allow for the sludge drying and the smell factor. Can you include a design for the sludge drying beds?
Generally we are getting 30 kgs of dogs waste per day + any other material we add to it. For 9 months of the year it is pretty dry with temps +29-34C and sunny. For the rainy season +12-20C and periodically wet.
We must get an idea of total cost and labour. Also confirmation that processed dogs waste is free of pathogens for use on gardens as manure. Can you comment on that?
Best regards
Peter

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Post by Bob » Thu Nov 15, 2001 1:39 pm

We note with interest that you have finished a design on the new tank.

Er. I don't know if finished is the right word, but, yes, I have some ideas on how to modify your tank to make it work. What I have in mind will require cutting the top, and inserting some components. Drawings to follow shortly. Can your tank supplier or someone else locally do some custom fabrication -- i.e. weld plastic?

The architect for the new dog kennels now wants to know the space to allow for the tank and the sludge drying beds. This depends on what area to allow for the sludge drying and the smell factor. Can you include a design for the sludge drying beds?

I have not dried sludge before, but can offer some estimate of quantities. And If I knew more about your site and climate, I could maybe offer some suggestions. Is drying of sludge your only option? Do you have any pumper truck service that could come and pump it out and dispose of it, say, 2-3 times/year? Or other ways of dealing with it. I know so very little about your overall site, infrastructure and circumstances.

I'm also wondering now if you mean sludge, (the solids which accumulate rather slowly in the bottom of the tank, and are only periodically removed), or effluent (which is the liquid that flows out of the tank daily, at the same rate as what enters, e.g. approx. 100 liter/day). This can be disposed of and/or used in various ways, depending, again, on your site, needs and circumstances, which I know little about.

Generally we are getting 30 kgs of dog waste per day + any other material we add to it.

What is the nature and quantity of this "other material"? Bedding? Dirt? Biodegradable or non-organic?

For 9 months of the year it is pretty dry with temps +29-34C and sunny. For the rainy season +12-20C and periodically wet.

For optimum performance, the digester temperature should be maintained at a pretty constant 35degC. Fluctuations in temperature can lead to instability, and unpredictable performance. The tank would need to be insulated, and some kind of regulated heat source provided. This could be hot water, heated with biogas, or electricity, heat mat wrapped around the tank.

We must get an idea of total cost and labour.

The estimate I provided above was for the just the digester (and, of course, I didn't have any idea of the size and shape of the tank you ultimately found). The complete system will also require some method of preparing the wastes and getting them into the tank, some method of handling and using the biogas, and some method of disposing of and/or using the effluent and the sludge.

For preparing the wastes, I would suggest a large service sink or laundry tub, draining to a holding tank with a sewage pump in it. The goal is to macerate the waste material, mix with water, and, ideally, eliminate non-organic debris (rocks, fibrous bedding?) that could damage the pump, or be difficult to remove from the digester. Provide a work area that is readily cleanable (durable, washable hard surfaces), with hot and cold running water and spray wand. Wild guess is US$2,000 - $US3,000.

Of course there are other options. I offer this suggestion without knowing any more about your situation, or desired degree (and cost) of automation vs maintenance/volunteer labor. The cost of a supply pump, for example will vary widely, depending on what it has to handle.

For example, for wastes that are adequately prepared (i.e. nothing but feces & water), I have successfully and reliably used a marine holding tank diaphram hand pump that costs less than $100.

Biogas can be handled by venting into a gas bag (truck inner tube, for example) with a weight on it (to provde minimum pressure), and a pressure switch on the gastube wired in series with the gas valve on a hot water heater. Again, many options, and a wide variety of costs. For the hot water heating option presented, say $1,500 - $3,000.

Re sludge & effluent treatment, use and/or disposal: I need to know more about your options.

Also confirmation that processed dogs waste is free of pathogens for use on gardens as manure.

It certainly can be made safe, possibly by heating with biogas generated by digester, or electricity (I don't have any idea about your utility costs or availability of different fuels). But there are also different degrees of safety. You could put less-treated wastes on ornamentals and/or trees and/or berry bushes, for example, that you wouldn't want to put on lettuce or carrots.

Whew! A long rambling installment.

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Post by Bob » Thu Nov 15, 2001 1:56 pm

Hmmm... I just went back and read some of the older messages here, and see that there are answers to some of my questions -- that you don't have electricity on-site, for example.

Also, for the benefit of others, here is a picture of the tank you found.
Image

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Post by petermgibbs » Sat Dec 01, 2001 7:43 am

Dear Bob,
Thank you for the long answer and series of questions. Further information and comment is as follows:
1. Cutting and welding the plastic tank. Yes, I expect the expertise is here on Cyprus although I have not yet found it. There is a lot of fibreglassing to do with boats but I do not know if fibreglass resin sticks to plastic. Leave that one with me.

2. Sludge. Yes, I mean the slow accumulation of solids maybe 2 or 3 times per year to be removed. We could use a cess-pit emptier and may prefer that solution if drying it in beds and using the manure is too much work. In a way that defeats the object which is to make use of the waste beneficially. At least the biogass would be used for cooking the dog food and if the supply is more than enough we could heat hot water and help keep the tank near 35 deg with hotwater pipes around it .
3. Liquid waste. The plan in mind is to water the peripheral trees with it. If it is say 100 litres a day we could manage that by hand or with a via a small tank and hose on a buggy.
4. Other Material. We can add straw and paper if it helps the digestion process as you showed earlier. Unfortuantely the new dog pens are going to have some gravel yards the more compact the better. But if it has gravel pebbles the workers pick some up with the dog turds and trying to separate this would ne messy. So anticipate that some small size gravel stones will enter the tank and find their way to the sludge.

5. Tank temperature. Optimum 35C noted. The summer temperatures are around 30 and painted black the tank should get to that temperature pretty naturally. But for the winter when outside temperature averages 20C midday to 10C at night we will need to provide insulation and heating by means of heated pipes and insulation.

6. Truck tubes for gas. I note your estimates. Natural bottled gas here is cheap at about $5 per 60lb refill but still there may be a reasonable payback period to manufacture our own gas for cooking dog food. (There will be no elec on site at the new shelter).

Thanks for your thoughts to date. When we get your tank conversion design I will get some estimate from plumbers/welders.

As for getting the waste into the tank can we not just empty the buckets into the top? I do not like the idea of a pre-processing tub to prepare the waste. It is difficult to get unpaid volunteers as it is.

Regards
Peter

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Post by Bob » Tue Dec 04, 2001 6:26 pm

Peter, as I learn more about your site and its constraints and requirements, I'm thinking that an anaerobic digester may not be your best solution. I'm thinking maybe an aerobic composting process, with vermiculture (worms) instead???

Given that you have no on-site electricity source, would like to be able to have your volunteers just pick up and dump the dog turds into an open tank (without the hassle of adding water & making a slurry), and that your bottled fuel gas is so cheap, the cost and complexity of a digester may not be worth it. But I don't know yet. So here are a couple of more questions:

1. Do you have a source of running water? If so, how is it delivered and disposed of, (considering that you don't have electricity)?

2. Have you purchased your tank yet? (by the way, HDPE is welded with a hot air welder, looks something like an acetylene torch but has an electric heating element only. For use with a small air compressor & welding rod of same material as plastic being welded.)

3. How difficult would it be to find a source of leaves, grass clippings, sawdust, shredded paper or vegetable scraps to add to the dog turds, if necessary -- say, 3-5 kg/day, (depending on what you have)?

4. How often do you have to refill your $5.00 / 60 lb bottles of fuel gas? Our preliminary calcs show that the digester could produce about 2 lbs/day worth of fuel gas. Not a very quick payback at the prices you pay.

The vermiculture suggestion I have in mind (assuming it makes sense, depending on your other goals, constraints, of course...) would consist of an open, fenced, covered (for shade and/or to keep the rain off) leaf pile (or grass clippings, shredded paper, wood shavings, whatever you have available...) bin with worms (e.g. lumbricus rubellus, eisenia foetida, etc.). Much simpler, less expensive, and the finished compost would make an excellent soil amendment, & be safe and not unpleasant to handle...

Throw the bucket of dog turds on top of the pile, cover with bulking agent (leaves, etc), and let the worms mix & aerate it. If you have two piles, one could age while you add to the other. Every time material is added, monitor the moisture content, sprinkle the top if too dry, provide drain for "compost tea" at the bottom to prevent liquid from building up..

Anyway, just some thoughts. We need to discuss further...

[This message has been edited by Bob (edited 12-04-2001).]

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Post by petermgibbs » Fri Dec 07, 2001 8:46 am

Dear Bob,
Funny you should say that. I too had been thinking I must find out more about a vermiculture solution (if that is the right name - worms). Composting bins helped by worms. I would have to find out first if there is any law against importing worms as I have seen none on the island.

To answer your queries. The new site will have a well and a pump with as header tank for gravity feed. I guess we use one bottle of gas of 60 lbs or so in 6 days cooking, about 10 lbs per day. It is a cheap fuel.
WE have not bought the tank but it is available here.

If you have ideas on the composting bins do let me have further thoughts. Meantime I will visit an ?xperimental Government Farm'near here and find out if they have used worms.
As you say we would achieve the compost with less outlay and work with worms doing the work!
Peter

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Post by Bob » Sat Dec 08, 2001 11:32 am

After thinking about it a little further, probably regular composting -- i.e. without worms -- might be better. The advantage of worms is that they do the work of turning the pile, to homogenize and aerate it, but the disadvantage is that you can't let the compost get hot enough to kill the pathogens. If you did, it would kill the worms too.

For rough sizing, I would think something like this commercial flowthru vermiculture unit from EPM would be about right -- say 3-4 cubic meters total volume?

Image

I don't know how much these commercial units cost, but I'm guessing you could probably site-build something that would work for you, for less.

[This message has been edited by Bob (edited 12-08-2001).]

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Post by petermgibbs » Sat Dec 29, 2001 6:54 am

Dear Bob,
Many thanks for the information on a suitable compost bin and the web site of the vermiculture firm which was very interesting. Yes, this is the solution we should best go for with worms if possible. My next move is to find out availability of worms in Cyprus and the law regarding import of worms from UK. Manufacture of a suitable bin should be no problem. I will try a small one in our garden here!

Before thanking you very much for your consultative expertise you may be able to help with local contacts who run huskies for sport or traditional transport. I am collecting for one of the 70 named pens in the new design and my breed is the HUSKY from fond association with travel in the Antarctic. I have to raise 1000 Cyprus pounds (about 1600 US$) over three years and am looking for some ten volunteer helpers. Photo of the dog of their choice and name will be mounted on the pen door; they will receive (at cost a few dollars) copy of my 1958 video of dog-driving in Antarctica and local scenes - penguins, the base etc.; a montage photo of the dogs in the CAPCA shelter; copies of the CAPCA newsletter and accounts. Just an idea, where you are Huskies are I think more common than on Cyprus and much appreciated.

Best wishes for 2002!
Peter

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Post by Bob » Mon Oct 14, 2002 7:47 am

Peter, It's been a while, so I don't know if you ever resolved your problems with the dog waste. I recently came across a design that looks like right up your alley. A low-tech, low-cost site built digester.

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Post by jed turtle » Thu Sep 02, 2004 8:00 pm

hi Bob,
you have a great site here. thanks.
i used to make methane 30 years ago in a 55 gal drum buried in a manure pile, continuous feed. stored the gas in inner tubes. after a month the scum buildup shut off escaping gas. anyways, that link to the low-cost digester was very interesting but why do you suppose the author cautioned against using chicken manure: "YOU SHOULD NEVER CHARGE THE BIOGAS PLANT WITH CHICKEN MANURE. This is not appropiate for biogas production"

any idea where to buy the kind of plastic sheeting tubes the author used?

i have just recently received a copy of an interview with Harold Bates, the gentleman in England that was made famous by articles in Mother Earth News 30 years ago, who made methane in a water-heater-sized digester and compressed the gas into cylinders (at 1200 psi...) and ran his car on it - for decades!

it is just a short 15 minute film / video but is a great testimonial to the benefits and practicality of home-made methane.

i have been toying with the idea of filling a 12' diameter above ground swimming pool with chicken manure and water, covering it with plastic and collecting the gas in a floating collector in an adjacent pool. i'd really like to copy Mr. Bate's example and run my vehicles with methane, but he no longer is around apparently and there appears to be no source for the "auto-converters" which he produced and sold that allowed him to connect the methane to the existing carburator.

i've run across comments in a discussion group that said his device wasn't safe, but seems like he used it for a couple of decades without incident...
are you aware of anyone currently using home-made methane in their vehicles?
TIA

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