The Sludge Digger (a device I’ve developed for emptying pit latrines, septic tanks, and similar tanks) New Video

  • dandreatta
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The Sludge Digger (a device I’ve developed for emptying pit latrines, septic tanks, and similar tanks) New Video

Introducing the Sludge Digger

Some of my past posts have talked about a device I’ve developed for emptying pit latrines, septic tanks, and similar tanks. I’ve shared links to some preliminary videos, but here finally is a link to a proper video showing what the device can really do. It now has a proper name, and I’m calling it the Sludge Digger. The video is at:



If the link to the video doesn't work, one can do a youtube search for my name and find it easily.

The video starts with a long still scene while I narrate, but it eventually gets moving, and there is some comic relief at the end.

The sludge digger is a pivoting bucket on a stick, with a rope. It is intended to replace the direct use of shovels and buckets, while still retaining the simplicity of buckets. It can easily pick up just about any kind of trash in the sludge, and a wide range of thick or thin sludge.

The video shows prototype 3 or 4, in the attached still photo is prototype 5 or 6, with a much sleeker design, more durable and more suitable for production. Also attached is a manual for how to build the sludge digger.

My goal here is to keep people out of pits and tanks. This is only the first step of the sludge management chain, of course, but I think this device would fit well into a low-tech, low-capital system. In a village the sludge could be carted to a central waste management facility (possibly composting, or vermicomposting) using a human or animal drawn cart that fits through narrow streets if necessary. In a city the sludge could be carted to transfer stations spaced perhaps a kilometer apart (maximum travel distance for the cart therefore is 500 meters) then the tanks at the transfer station could be emptied by tanker trucks, which would carry the waste to larger facilities. If traffic were heavy, the trucks might only come during a time of day when the traffic is lighter. (On my trip to Chennai in August I gained a profound respect for how difficult the traffic can be in a big city.) If trunk sewer lines are present, perhaps instead of transfer stations, the carts could be emptied at selected inlet points to the trunk sewer lines.

The only down side to the sludge digger, in my opinion, is that it requires a hole of about 25 cm diameter to get into the pit. (Of course, to send a human into the pit would require an even bigger hole.) I am currently working on similar devices that will go in through the squatting hole, though these will probably only work in fairly thin sludge. More on this later, with similar videos coming in a few months.

Dale Andreatta

Dale Andreatta, Ph.D., P.E.
Mechanical Engineer

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  • dandreatta
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Re: Develop new innovation for pit latrine emptying in peri-urban Mzuzu (Malawi)

Note by moderator: this post used to be in this thread about research in Mzuzu, Malawi:
forum.susana.org/forum/categories/99-fae...n-mzuzu-malawi#17559

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This is not specific to Mzuzu or Freetown, but another manual pit emptying device is the Sludge Digger. It can be seen at



The attached photo shows the latest all-metal version (except for the handle and rope) of the Sludge Digger, which is more slender and more durable than the original that is in the youtube video.

This device is a bucket on a handle, with a pivot and a rope, allowing the pit emptier to work above ground. He can use the same device to lift thick or thin sludge, even with loads of trash in the pit. It was designed to retain the simplicity and low cost of hand tools, but to also be able to handle trash in the sludge and most importantly of all, keep the man out of the pit! With a shallow pit and thin sludge one man with one sludge digger can work at up to 2.2 cubic meters per hour, though under most conditions it would be slower. Two men with two sludge diggers would be a possibility, with even faster speeds. The digger adapts to a range of pit depths, and can be extended by using longer handles.

The Sludge Digger is currently set to be tried in a refugee camp in Myanmar soon, and various field experiments are started in Africa.

Thanks,

Dale Andreatta

Dale Andreatta, Ph.D., P.E.
Mechanical Engineer
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  • hajo
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Re: Develop new innovation for pit latrine emptying in peri-urban Mzuzu (Malawi)

Dear Dale,

It seems to me that the digger has possibly two limitations of use: a standard squat hole will rarely be big enough to let a 5L (dia 20cm) or even 20 L (dia 30cm) bucket pass through. Thus it requires an extra opening big enough for the bucket. What is the size of your bucket?

And, it will not be possible to extend the handle beyond the inside height of the latrine if you want to dig deeper. This will require that the access hole to the pit is outside of the latrine.

And a question: does the bucket tips over and fills when you ‘dump’ it into relatively thick sludge or do you have to force it down vertically for filling? The latter requires quite some strength and puts lots of force on the structure/bucket.

Looking forward to hear more of your observations and experiences with the digger.

Ciao Hajo

We can't solve problems by using the same kind of thinking we used when we created them.
Albert Einstein
Any intelligent fool can make things bigger and more complex... It takes a touch of a genius - and a lot of courage to move in the opposite direction.
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Everything should be made as simple as possible, but not simpler. :-)
Albert Einstein
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Re: Fecal Sludge Management and Pit Emptying (Mzuzu, Malawi)

Hajo,

I wanted to do a few more tests before responding to your second question.

If working under a ceiling, if the pit depth is only a little greater than the ceiling height (and therefore the handle length is a little greater than the ceiling height) it is possible to angle the handle so that it doesn't hit the ceiling. You need to hold the handle and the rope in just the right way, but this is easy to figure out. To dump the bucket you would need to go outside so that you can lift the bucket and the handle, but hopefully the room is only small and it's only a couple steps to the outside.

If the pit is much deeper than the ceiling height, then you can use a 2-piece hinged handle as seen in my youtube video. In that situation I was working over a railing and it was very slow, but with no railing and a little practice, it would be much faster.

Regarding your first question, the intention in not to have the bucket fit down through the squatting hole. Typically, the bucket will be about 22 cm, and the handle adds a couple cm, so the hole needs to be about 24 cm. My intention is to keep men from going down into pits, so any hole into which they could go is already more than big enough. Clearly my Sludge Digger is not a universal solution, but should be useful in many places.

I'm currently working on a similar device that is thin enough to go through the squatting hole. I'll post videos when that is done. It will only work for thin sludge.

Regarding your final question, if the sludge is very thick it does take some force to push the digger down into the sludge. The youtube video shows about the thickest (simulated) sludge in which the device will work. Emptying the bucket is not a problem with just turning it upside down. I'm also working on a similar device with more of a digger on the end rather than a bucket.

Thanks for your interest and for the sharp questions,

Dale Andreatta

Dale Andreatta, Ph.D., P.E.
Mechanical Engineer
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  • psewor
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Re: Develop new innovation for pit latrine emptying in peri-urban Mzuzu (Malawi)

Dear Sir,

Thank you for your innovation
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