In the past I've posted on the sludge digger, a simple low cost pit emptying device ($20?) that can handle thick or thin sludge, with or without trash. I've recently put together and posted a much better video on this device. In particular, the new video shows

That the sludge digger can be produced with a neat finished look,

That is can be durable. In the video I throw it to the ground, step on it, then pick it up and start using it,

That it really shines in thick sludge, and it is demonstrated in simulated thick sludge. In thin sludge a simple scoop works just as well.

The link to the video is:



A still of the sludge digger is below


In a few days I will finish a manual for how to build a sludge digger.

Contact me for more information.

Dale Andreatta, Ph.D., P.E.
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My original statement

"Encourage people to throw trash into pits, and then use tools that can deal with both sludge and trash".

was intentionally provocative. Perhaps a better way to say it would be in three parts that are less provocative:

1. Getting people to change behavior and not throw trash into pits is difficult.
2. Tools that are easily defeated by trash, and therefore require people to not throw trash into pits are unlikely to succeed.
3. A better option might be to have tools that can handle trash, then let people do what they want with their trash.

My sludge digger and sludge dipper tools (references to videos below, and previous videos were linked earlier in this thread) were designed to handle trash. They work well when tested in my test pit latrine, and in limited testing in Africa seem to work well in actual latrines.

My barrel latrine idea (reference to video below) also works well under test conditions, using potting soil, leaves, trash, and water to simulate actual conditions.

What to do with the solid waste after it gets out of the pit is an open question. I'm thinking that at least getting the stuff out of the pit properly is a step in the right direction.

Regarding Elisabeth's idea of 2 pits side by side, I observed this in Mzuzu, Malawi, and seems to be a common practice there. Kitchen waste and trash go in a shallow pit next to the outhouse.

Regarding the burning skip of trash in South Africa, perhaps people thought its purpose was to burn trash. Providing trash skips could work if there was some infrastructure for emptying them regularly. Although, I expect some flying toilets and diapers (nappies) would get in there.

The latest video showing the sludge digger and the sludge dipper is at:



And the barrel toilet video is at:



The barrel toilet is intended to be a solution for places with high water tables or collapsing soil, as no pit is used. It's easy to empty with or without trash. Perhaps they would be good in refugee camps too?

Thanks,

Dale

Dear Dale,
dear Elisabeth,

I have a lot of ideas about such tools, but most of them are unproven.

Dale, I propose that you first prove the viability of your ideas how to retrieve solid waste (SW) together with FS from pits. We have tested recently three different pumps (gulper, eVac, Flexcravator) on pits in Lusaka and they all had serious challenges with SW and especially with plastic bags. Thus, if you can develop something which overcomes these challenges it will be highly appreciated.

And we must not forget that the FS & SW retrieved from pits also requires combined treatment for re-use or at least for safe disposal of the mix!

Currently in Lusaka, FS & SW is retrieved manually from pits, then the two are separated by sieving and a lot of water to clean the SW from FS. Then the SW is dried and finally disposed on the solid waste dump site. Which are questionable procedures altogether as we waste drinking water cleaning the SW, the FS is further diluted by the wash water, and the SW has to be handled several times (out of pit, cleaning, drying, transport to disposal) where the SW from pits may still pose a health hazard to scavengers.

Thus a combined processing of SW and FS would be more economical BUT do not forget, that it is not enough to get it out of the pits but it must also be treated and re-used/disposed. Proven ideas are also required here.

ciao
Hajo

That's indeed a radical idea that you proposed:

Encourage people to throw trash into pits, and then use tools that can deal with both sludge and trash.

It's a bit sad if that ends up as the only option we have or can offer people. It's far from ideal because it means the general trash is unnecessarily contaminated with pathogens from fecal matter.

How about encouraging people to have two pits: one for the toilet and one for other solid waste? But who would want to dig two holes.

One solution I've seen is council supplied skips dotted around the informal settlements which then get picked up and emptied regularly by council workers. Sometimes their content also get set alight though. Not sure why. Vandalism? Or to create new space in the skip? Very protracted problems indeed!

Here's a photo I took of such a skip in an informal settlement in Johannesburg, South Africa in 2006:

Burning solid waste (low income area of Johannesburg) by SuSanA Secretariat , auf Flickr

We really need to get closer to colleagues working in the solid waste sector. If we could get them to join the forum we could learn a lot!

Regards,
Elisabeth

Elisabeth, and others,

I haven't gotten much response to my postings, so I'm still looking for people to connect with. Before thinking about commercialization, I think the devices need further testing.

Perhaps the people I need to reach are not NGOs who are currently working with some sanitation technology, but rather NGOs (perhaps church-based?) who are working directly with pit latrine emptiers who currently have no technology. Perhaps some organization that is currently not doing much in sanitation, but recognizes the plight of the men who work in filthy pit latrine conditions.

I'm generally following the posts about the Flexcrevator and other vacuum-based tools, and I see my devices as things that will work well where the more complex tools don't work, particularly thick sludge and trash-filled sludge. We tested the sludge digger under these conditions in Malawi and it worked well. In Nairobi the sludge is thin so the sludge digger is not necessary, and a simple bucket on a stick works fine. My devices are not as clean or tidy as the vacuum tools, but they are a lot cleaner than men climbing into pits, and they are very inexpensive. As I like to say, every tool works well somewhere, no tool works well everywhere.

I've also been following the posts about keeping trash out of pit latrines and I'll throw out a radical idea that most people probably won't like: Encourage people to throw trash into pits, and then use tools that can deal with both sludge and trash. I have a lot of ideas about such tools, but most of them are unproven.

Thanks,

Dale Andreatta
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Dear Dale,

In November you asked the question "Who do I contact to try to get these tools to the people who seem to need them most?". Is that still your question or have you found some answers in the meantime, perhaps via Rochelle in Malawi?

Are you asking how to commercialise this tool and mass produce it, or how to get in touch with NGOs who could test and develop it further?

Regarding the topic of trash in pit latrines, did you see this thread which Hajo started:
forum.susana.org/99-faecal-sludge-transp...aste-in-pit-latrines

As well as this thread about the Flexcrevator (do you see that one as a competing or a complimentary product to yours?):
forum.susana.org/99-faecal-sludge-transp...hnology-flexcrevator

Regards,
Elisabeth

Previously on this Forum I've introduced two sludge handling tools, the Sludge Digger and the Sludge Dipper, but they have now been developed further and field tested. Both are simple and inexpensive, and both pick up trash with the sludge since they are based on buckets. The Sludge Digger is now a very general purpose device that can handle thick or thin sludge, deep or shallow pits, works outdoors or under a roof, and goes through large or small openings, down to the typical size of a drop hole. The Sludge Dipper is simpler, lighter, and faster, and it handles all the same conditions except it is limited to thin sludge.

The Sludge Digger was tested in several locations in Africa in September, 2017 and worked well. Both devices can be seen at:



and much of this video was shot in Africa.

A manual is attached for building both of these devices, along with tips for using them.

And now for the question. My original goal in developing these devices was to keep pit emptiers from climbing down into the pits. I'm told this still happens, but I've not seen this in my travels to India or Africa. Who do I contact to try to get these tools to the people who seem to need them most?

Dale Andreatta
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Hi Dale,

thanks for your reply.

I wouldn't imagine that the bucket needs to be tipped (open end down) in order to push it into the sludge. The upward thrust shouldn't be that large that it cannot be pushed in 'bottom first'. 1.5 kg/litre, Or? I can't judge from experience or observation because the pit emptiers I have observed in Lusaka open the pit from the side, just below the concrete platform and enter with their buckets from the side, not from the top. The squat holes are too small (15 cm) to enter with a bucket and the toilets are not high enough for their long handles (2.5m).

But as you say, different locations have different challenges.

ciao
Hajo

There are at least 2 reasons for pivoting the bucket.

If the sludge is thick, the bucket must be pivoted down (open end down) to be pushed into the sludge. The pivot is offset from the center of the bucket so that gravity tends to pivot the bucket down, unless the user is pulling up on the rope. Once the bucket is pushed down into the thick sludge, then the rope is pulled to pivot the bucket up and scoop the sludge, and then the bucket and handle are lifted out of the pit.

The second situation would be for thick or thin sludge if the pit is deep and the handle is long. Without a pivot you have to tip the whole handle, which gets awkward inside the pit latrine. I did not appreciate until I went to Africa, that the horizontal dimensions of the pit latrine are small. The current version of the sludge digger has a telescoping handle that can be as long as 2 meters, and it would be more difficult to tip this long of a handle up and down with each stroke.

It sounds like the conditions in Lusaka are similar to Nairobi, shallow pits and thin sludge. Under these conditions, a simple handle welded (or nailed) to a bucket is fine, The handle can be tipped such that the top of the handle is out the door of the latrine, if necessary.

As I like to say, every tool works well somewhere, no tool works well everywhere.

Thanks,

Dale

Hi Dale,

I had followed up your posts about the sludge digger for quite a while and have always wondered why the bucket needs to be hinged to the rod? What is the advantage of this construct compared to a bucket welded to the rod as we use it here in Lusaka?

ciao
Hajo

In the past I’ve announced the development of pit emptying tools, the sludge digger (for thick or thin sludge) the sludge dipper (for thin sludge) and a trash picking tool developed by my students that was called “The Crabtrap”. These devices have now been tested in Malawi and Nairobi.

The sludge digger is a simple bucket-based device that can handle trash. Some pictures of the sludge digger are below, and a video of an early version is at:



The sludge digger has been improved considerably since this video, and a new video will be made soon. The sludge digger works in thick or thin sludge, deep or shallow pits.

The sludge dipper is a simpler lighter version of the sludge digger and works only in thin sludge. It was not tested in Africa, but the basic idea can be seen at:



The crab trap is to clear out the trash in a pit or septic tank before using a more complex machine such as a gulper or an evacuator truck. The crab trap will be covered in a later post. The original prototype can be seen at



Modification have been made since this video was made.

The conditions in Malawi and Nairobi are very different from each other. The sludge is usually thick in the pit latrines in Malawi, and thin in Nairobi. The pits in Nairobi are also not very deep, or in some cases they are only emptied down to a certain depth. Septic tanks in Malawi have thin sludge.

The testing was limited, as the prototypes tested were quick prototypes not meant to be durable. Still, the devices were used in many different pit latrines and septic tanks, and local pit latrine emptiers were involved.

The sludge digger worked as intended, however the reaction of the pit emptiers was very different, based on the different conditions. In Malawi, where the sludge is thick, the tool worked well and would be a useful tool where the sludge is too thick to use a gulper or evacuator truck. The emptiers liked the sludge digger. The fact that the trash does not need to be removed in a separate step is a big plus. After the sludge is removed from the pit or septic tank, it is disposed of in the normal manner.

In Nairobi, where the sludge is thin and they don’t go down very far in the pit, the sludge digger also worked as intended, but it is not as fast as the current device. The current device is shown below, and is typically the lower half of a 10-liter jerry can nailed to a pole or stick. The pit emptiers are very skilled in using this in the tight spaces of a Nairobi pit latrine, and under Nairobi conditions it works well. Not surprisingly, they are not interested in the sludge digger.

In the future I will put together documents on building sludge diggers, sludge dippers, and crabtraps, along with putting together videos showing their use. Look for future posts on these topics.

Many thanks to Sanergy in Nairobi, and the University of Mzuzu in Malawi, for their considerable assistance with this field testing.

Dale Andreatta
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this field testing.