Picture of Dog Waste Digester Bin
Having a dog and little kids means there is a lot of dog poo to be picked up to keep the yard clean and the kids safe from illness and parasites. I decided to use an old HDPE barrel to build a dog waste digester.  I'll place the dog poo in the digester and add bacteria from time to time to break the waste down.  Much like a home's septic system.
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Step 1: 55 gallon barrel

Picture of 55 gallon barrel
I started with an old 55 gallon HDPE barrel.  This one used to have soy sauce in it.  It was also used as a rain barrel and compost bin, so it's dirty inside, but it won't matter.

Step 2: Marking Door

Picture of Marking Door
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I marked out the size of the door I wanted using to "L" squares to make sure it was true. It needed to be big enough that a shovel dropping in waste wouldn't make a mess on the rim and also to fit a shovel in case I ever needed to clean it out. 

Then I tried drilling small diameter holes in a row to make a slot in one corner to start the jig saw. I ended up snapping off the little drill bit so that ended that method. 

I stepped back and thought about it and went and grabbed a BBQ lighter.  I decided I'd try to heat up the blade until it would slide into the barrel. It worked like a charm.  I didn't even have to get the blade red hot.

After I finished cutting the door out, I used the box knife to clean the rough edges.

Step 3: Cut the barrel in half

Picture of Cut the barrel in half
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Next I needed to cut the barrel in half.  I'm saving the other end for another project I have in mind.

The barrel has several ribs so I just measured halfway between them and marked every so often.

Then I took some wide masking tape and wrapped it around the barrel to give myself a guide.

I heated the blade again and plunged it in. I rotated the barrel as I cut.

It cut great and both ends came out super square.

This is great. I'm going to take this discussion thread and start from there. Lots of good information here. I really like what was said. Helps loads!

Bubbler10 months ago

The rights and wrongs of China and Germany trading waste etc; is a worry to me, as China wants to export market garden produce and fruit, and in Australia, traces of human feaces have been found in some of those foods imported from China. I live in South Australia, and we treat our sewerage water, then pump it to holding tanks in market gardens, where it is perfectly safe for use. However, to the device above. I would make another alongside of this one you have, and add composting worms to it. There are a good few varieties, so add them all, and you may find that they soon demolish a pile of animal waste. The only time not to use the worms would be after the animals have had a worming treatment period. Dig a hole deep under the drum, and add chunky gravel and stones, a few litres of fresh rain water each week, and then the worms can escape to the depths in hotter weather.

Thanks for posting this- it's exactly what I've been looking for! I love my animal friends, but not a poppy yard or full nasty trash cans :-)
paqrat2 years ago
Regardless of what you call it it appears to be a good idea and well executed. Congratulations on a good instructable. I think I will try it with cat waste. I don't like the idea of putting it in the trash and only so many places to dig holes in the yard.  For a single cat, could you make an estimate how large a digester I would need?  I am guessing a 55 gallon container would be overkill.  Thanks
ugreebo2 years ago
I have a Great Dane. Do you think a digester of this size would be sufficient?
erich_870 (author)  ugreebo2 years ago
It's hard to say. If you live in a warmer climate and keep adding septic tank bacteria and some water, it could probably handle it. I live in Alaska, so the bacteria take a long time to do their thing.
Tony27nine3 years ago
I've literally just finished building my dog-waste disposal system having bought a couple of dogs a year ago. Basically it comprises a channel 35 feet long dug under the lawn with a clay drainage pipe and gravel surround. At one end I've sunk a dustbin in the ground up to the rim. This bin has no bottom.
Into this I've slid a second bin. This bin has a ring of holes drilled into the sides so that it will act as a bucket up to the ring of holes but anything more than that can run through the holes. (I also put some much larger holes above this ring so that, if necessary I can flush larger solids out of the top bin).
I'll add water, septic starter and poo to the top bucket and see what happens. Each time I add poo I'll squirt a tiny amount of water and septic starter in as well.
In theory this should allow the waste that has broken down to simply leach away into the soil about 18 inches under the lawn…..
I've yet to start it off though!
hilary0073 years ago
I just made one from a 5 gallon bucket. I have to Corgi's and it is filling up fast. I think they are stealing the chicken eggs, as I don't over feed them. So if I add the septic additive, how fast can this keep up with the input? I buried it and put lots of holes, and no bottom.

Wish me luck!
erich_870 (author)  hilary0073 years ago
I'm not sure how fast the septic tank additive cuts down the waste yet. I just added some and it's been dry here, so I'm waiting to see it speed up when the rain returns.
erich_870 (author) 3 years ago
Atombomb is right, this is intended to be more of a septic tank. That kind of system is anaerobic and should have less oxygen so the bacteria can continue to do their thing.
Well, you called it a "Compost Bin," not a Septic Tank.
erich_870 (author)  bruc33ef3 years ago
That's true, I guess I could have called it a "septic / compost bin". I've never heard of adding bacteria to yard/kitchen waste compost bins (you let it populate on it's own) and it's not a true septic tank because it is neither completely air tight, nor does it have inlet pipes, a solid bottom, or a separate leach field. It is closer to a septic tank because it's not designed to take the composted material out for use in the garden and the draining of liquids out the bottom is like a leach field.

Whatever it's called, I'm going to put dog poo in it and hopefully never have to touch it after that point! LOL!
Yeah, it's ashame you don't want to create useful resource as is compost, which doesn't require any bacterial inoculants at all, and just want to get rid of what you term "waste." The definition of waste, though, is an output that you haven't found a use for yet. Fortunately, there is a good use for manure, though. Too bad you want to look a gift dog in the mouth.
erich_870 (author)  bruc33ef3 years ago
I appreciate your point about not wasting a resource, but I'm not comfortable with the idea of using compost with dog waste in it. Humans can contract many kinds of parasites from dog waste and I don't live in a region that is conducive to composting. If I tried to keep up a compost bin large enough to assimilate the waste, it would be huge and only functional for a short time each year.

First, proper composting reaches a temperature of 160-170 F and kills the parasites. Second, fertilizing soil with aged manure is standard practice in agriculture. All across China they even use humanure in agriculture to good effect. Ashame we don't as well. Third, all it takes is a handful of sawdust, dried leaves, or wood chips, for example, for each deposit, to handle dog manure. Finally, I know of no region where composting is not effective.
erich_870 (author)  bruc33ef3 years ago

"If you have dogs, you have poop. And how to dispose of that poop is an issue. Traditional composting theory and most agricultural extension offices will tell you that dog manure may not be added to compost bins.

However, in a cooperative study between mushers and the Fairbanks Soil and Water Conservation District in Alaska, researchers are finding that with some special precautions, dog waste can be successfully composted. It’s important that you follow the compost recipe closely. The additive to the dog waste must be a carbon source such as sawdust. You can’t just add dog manure to your regular compost bins or piles and expect to get good, safe results. You must also make sure the recipe gets to the temperature specified. A long-stemmed thermometer is useful for this. If you do not reach the "magic number" of 140 degrees F, you may not kill the pathogens present in the dog waste.

At this point, the Natural Resources Conservation Service is not sure the compost gets hot enough to kill Toxicara canis, or large roundworms (one of the most heat-resistant pathogens found in dog manure). The researchers in the study were not able to find dog waste samples infected with roundworm because mushers are so good at controlling it. It is not known whether roundworms will be killed during the process. For that reason, only use the resulting compost on non-food plantings such as flower beds and shrubs."

As I said before, it's a risk I'm not willing to take and I don't have the time to manage a true composter.
Yes, lot's of things are dangerous if you don't do them correctly.  But you don't need a "true composter," whatever that is; just a pile on the ground and about 10 minutes every couple of days.

If you live in Alaska, the following might be of interest:
"In 1991, the Fairbanks Soil and Water Conservation District started a study which showed that dog waste composting is practical in Interior Alaska. On-site composting systems can be used by any kennel. Interested mushers composted dog waste under different conditions. They took the internal temperature of the compost and recorded their results. Their experiences were very positive and most felt their composting systems worked well. "It was much simpler than I expected" was a common reaction. Good composting on-site, eliminates transporting dog waste to a disposal facility. This saves time, energy and landfill space. Good composting is essentially odorless and reduces the volume of waste by over 50%."

erich_870 (author)  bruc33ef3 years ago
I live in Southeast Alaska, in the worlds largest temperate rain forest. We get 100 inches of rain a year, 30 days of sun shine a year, and our average summer day time temps are comparable to winter lows in most of the lower 48. We are incredibly wet, damp and mildewy here, compared to the Alaskan Interior or lower 48.

I could probably keep a compost pile working for a couple months a year, but it's not worth the time or effort on my part.

Thanks for the concern about the semantics of "compost" and "septic", but I don't see this line of back and forth being necessary for this simple instructable.
Yeah, I think I'll sign off with this one, too, but I think it's been "instructable" to walk down this road of composting problems and solutions. I think you'd be surprised, though, at how well composting can work in humid environments. After the disaster in Haiti, recently, Joe Jenkins, author of the Humanure Handbook, went down there with other experts to teach composting. His videos are on YouTube if you're ever interested.
erich_870 (author)  bruc33ef3 years ago
The more I've thought about it, I've decided that "composter" isn't the right word. "Digester" is the proper term for what this process is. It's the very same process that takes place in the digesters at every municipal sewage treatment facility in America, so I've made the changes to the instructable.

Just for the record, the term "dog waste composter" is how a bunch of the products on the market label themselves, so you might go after them for the improper use of the term... ;)
Yep, that's more accurate, but I would think you'd want to stay well away from what takes place in our municipal sewage treatment facilities... and also what some products in the marketplace are called. After all, they're taking a resource -- an increasingly valuable one given the denuding of agriculture land in this country -- and doing nothing with it. And they're spending a lot of tax dollars just to get rid of it. What a waste.
erich_870 (author)  bruc33ef3 years ago
This back and forth seems to have turned into a game of "who has the last word".

I'm curious to know more about your level of technical expertise when it comes to municipal sewage treatment facilities. You say that they are taking a "resource" and doing "nothing" with it. Which resource might that be?

Is it the dangerous and highly contagious pathogens that sicken and kill millions of people a day around the planet who don't have access to properly designed and managed sewage facilities?

Or are you talking about sludge, the remnants of the bacteria that cleansed the dissolved solids and reduced the organic compounds that cause low oxygen levels and fish kills if untreated sewage was discharged directly into streams and lakes?

Sludge has been used for composting purposes, and it works just fine if you have the technology to remove enough water and a cost effective source of carbon such as wood waste from mills or tree trimming services. Many municipalities struggle with what to do with their sludge because there is no market for it. That's where a huge amount of the cost is, the tax dollars you talk about. Maybe you could buy a truck and drive around and pick up the sludge and take it home! Most towns will give it away for free!

If you see a profitable resource that is being under utilized, why doesn't anyone else?

Here's some info on the uses and risks to the public of sewage sludge:

Most sewage treatment in the US is pretty backward compared to, say, what they do in Australia and China where they run it through successive natural filtration ponds and produce pure water. China actually pays Germany for its sewage it's so valuable. New York dumping of sewage into the sea (last I heard they were trying to make them stop) kills an estimated 700 miles of the seabed each year. With a worldwide shortage of pure water and soil, we can't afford to ignore a resource like this "waste" anymore.

As to why they don't do anything with it in the US? My guess is because it requires retooling and rethinking and the fact that no one has forced them to do it yet. But there are pockets of hope.
erich_870 (author)  bruc33ef3 years ago
You obviously don't know the first thing about how a sewage treatment plant works. You still didn't explain what the "valuable waste" is that China supposedly buys from Germany.

I'm not sure why you keep touting China as a leader in environmental protection!? They are one of the most egregious polluters in the developed world.

There are many sewage treatment plants in the US that discharge PARTIALLY treated waste water into wetlands that they own to allow the local flora and fauna to reclamate it naturally. If a town has the room for such a faculty, it makes fiscal AND environmental sense to let the plants and animals in the ponds break down the remaining organicl compounds. The trouble in a lot of cases is that the sewage treatment plants that once were on the edge of town have now been built around and cannot expand. At that point they have to use mechanical methods to treat the waste water.

If what you say about New York dumping sewage is true, then you need to turn your aggression at the EPA and start sending them letters because they're wasting precious time nickel and dime-ing to death reasonable projects with insane permitting requirements. They should be going after "Big Fish" like New York!

If you'd like to continue this lesson on sewage treatment plant design, I'd be happy to discuss it with you through PM's. I'll pull out my text books and we can go chapter by chapter.

This will be the last off topic response I have on this instructable.
Responding only to your few substantive points, first, China certainly is an egregious industrial polluter, but they have innovative ways of using some "wastes," (and also in their development of solar energy by the way) and that was the extent of my comments.

Second, I'm glad we can agree that "it makes fiscal and environmental sense to let the plants and animals in ponds break down... organic compounds."

Third, the lack of adequate sewage treatment plants, in terms of size, number, and type, reflects a lack of political will. I'm not sure what "can't" means here. We certainly can and, indeed, we must if we don't want to further the destruction of the environment.
SweetPea_13 years ago
This looks like it will work great! Good job! Thanks for sharing.

Bruc33ef, what is up with being so technical about the name. Whatever the name, it is great way to eliminate dog poo and way better than throwing it away. Give the guy a pat on the back for posting a good idea. It is here for you to use, not criticize.
Nice write up, but I do have one suggestion that may make this a little more efficiant. Try drilling or cutting a few holes up each side to allow the "waste" to seep into the ground at different levels. Also, on a side note, where ever you decide to bury this, it is going to make what ever is growing there nice and strong. Just an FYI.
erich_870 (author)  atombomb19453 years ago
I'll remember the holes at different levels when I install it, thanks!
bruc33ef3 years ago
Setting up a compost system is definitely a great idea, but you don't have to separate dog poop from other compostable matter. And a closed bin will just delay the composting process. It requires air and moisture.

There is a lot of information out there now on how to do this. Basically, you need to add carbon-rich material such as twigs, branches, dried leaves, wood chips, sawdust, etc., to balance the nitrogen-rich manure, green grass clippings, food scraps, etc.

There are hot/active methods (eg the Berkley Method) which will make compost in 18 days or less, or the slow/passive methods which take a year or more. Your choice.
I believe that you are mis-interpenetrating the meaning of his instructable. The term "Compost" being that the bin is just breaking it down. This is actually more like a septic tank that some homes have verses a sewer system. Keeping the material in the bin wet, in the ground, and the addition of the bacteria will just break it down and then the water will just carry it into the surrounding soil.
I have seen the same thing done with large PVC pipes buried in the ground also.