Hi John,

Firstly, thank you very much for the detailed description of the management structure of your pit latrine service chain.

I would be very much interested to promote such a pit service chain in our town of Moshi, Tanzania where we are currently trying to improve sanitation governance and services.

Therefore some comments and further questions relating to your presentation, I hope you will again find the time for a reply.

1) Emptying pits free of charge every 5 years (or whatever) is beyond the finance and the sanitation policy in Tanzania. But people are used to pay for the emptying, thus an improved service will be appreciated and hopefully paid.

2) You say EWS owns one LADEPA and leases three more. In your Hanoi presentation you quoted the price of a 2000 m3/year plant at 6.5 million ZAR (about 550,000 USD). Is that still valid about? 2000 m3 stands for 2000 m3 sludge input into LADEPA? How many kg is that?

3) Since lease and maintenance by PSS would be not possible for Tanzania (or?) we would have to find other ways for maintenance. Also in Moshi neither municipality nor utility would be able to maintain the plant.

4) You are lucky in SA that you can tender out a management contract for pit emptying and LADEPA operation. In Tanzania we probably will have to consider an additional capacity development plan for such contractor. But that should not be an obstacle. I guess PSS would also provide O&M training?

5) You differentiate ‘wet’ and ‘dry’ pits. Do you envisage problems that some pits may be too dry to be pumped, but at the same time still too wet to go into the LADEPA. Do you have figures to judge which sludge can still be pumped, and what maximum moisture content is acceptable for the LADEPA process?

6) The previous question is also of interest because we had discussed to moisture/dilute the sludge to make it ‘pumpable’ which may then prohibit its LADEPA processing.

7) Who is going to market the pellets, EWS or contractor? Do you have a possible sales price / market value from your previous production?

Looking forward to your response, if you feel like also off-line and to my email,
Ciao
Hajo

Hi,

We, at eThekwini are about to start the next cycle of pit emptying – the city has undertaken to empty pits free of charge once every five years, and we are already overdue for the second round. What we are aiming to do this round, is the following:

In short we are going out on two contracts; a five year lease contract for the lease of the Ladepa plants, and a management contract to operate the Ladepa plant and empty the pits.

We own one Ladepa plant but we require four to run the pit emptying on a continuous basis, so we intend to lease three more from the manufacturer, on a five year lease basis. The manufacturer is happy to lease and maintain the plants, but not operate them. We are going the lease route purely as a consequence of the Municipality’s supply chain management system, which is not geared up to deal with plant failure that may need to be repaired in a hurry in order to keep an independent contractor operational.

The Management Contract will cover the pit emptying, transporting sludge to the Ladepa plants, plant operating and the overall co-ordination and management of the operation. The Ladepa plants will be established at four of our wastewater treatment works for security and reduced environmental licencing requirements. The management Contractor will be encouraged to subcontract with private Small, Medium and Micro Enterprises (SMMEs), who in turn will be required to employ labour local to where the pits are being emptied, in order to empty the pits and do any other unskilled work that is required.

We classify pits into “wet pits” and “dry pit”. Dry pits are ones with sludge that is dry enough to be processed through the Ladepa machine and wet pits as those that need to be pumped out and disposed with our septic tank sludge. We are still of the opinion that dry pits are easier to deal with than wet ones, and certainly cheaper if one is considering the mass of dry solids removed. (This is due to the transport costs due to the added volume of water). At the moment we still think dry pits are most easily emptied by hand, using long handled spades etc.; limited access to pits and the “stickiness” of the sludge seems to frustrate any mechanical solution.

Some features of the operation:

• Health and hygiene of both the community and the workers is a high priority, and as far as we are concerned, the main means of dealing with this issue, practically, is education and awareness, so this will be emphasised. Providing people with personal protection equipment does not solve the problem without the users understanding how transmission of disease happens, and how to reduce the risks. So workers will have to pass both a theoretical and a practical examination.
• On the last round of pit emptying we suspect that a lot of the sludge that was removed from the pits was dumped back into the environment. This happened because we paid per pit emptied. This time round we will pay primarily on volume of sludge processed through the plant, which should force the contractor to deliver the sludge to the plant and thereby overcome this problem.

We wait and see what we learn from the next round of pit emptying.

Regards
John Harrison, eThekwini Municipality (EWS)

hello eThekwini,

I follow with much interest all your activities around sanitation and also the LADEPA. Although I hope that we can overcome the pit latrines in urban environment and replace them all with UDDT or similar system, we have to live with pit latrines for some years to come. In Tanzania about 60% of (peri-) urban and close to 90% of rural population depend on pit latrines. Thus in the urban environment we have to find ways to deal with the sludge from the pits as they cannot be relocated when full. LADEPA is definitely an answer.

In the presentation by Dave and John it is said that the emptying of the VIPs is subcontracted. Are these services supervised/monitored by eThekwini? Do you know in detail how your subcontractors empty the pits? I am asking because we have several threads on this forum where difficulty of pit emptying seems not yet resolved. And I think also your KwaZulu University is researching the very varying properties of pit contents which makes it difficult to find one effective way of pit emptying.

ciao, Hajo

For those interested in the LaDePa process, I would like to highlight a presentation from the recent FSM3 Conference:

Towards a Sustainable Pit Latrine Management strategy Through LaDePa technology, Dave Wilson and John Harrison, Department of Water and sanitation, the eThekwini Municipality, Durban, South Africa
www.susana.org/images/documents/07-cap-d...-2/2-2-3-5Wilson.pdf

The basis for needing something like the LaDePa process was:

• Council had approved that the pits would be emptied on a 5 year cycle
• Any additional emptying required would be to owners account
• Only VIPs would be emptied (this has now changed, also UDDTs are being emptied free of charge every two years).

Therefore, they needed a process to render this faecal sludge safe for reuse, otherwise it would have taken up valuable space in landfills.

Some notes that I took while listening to this presentation in Hanoi (I hope they are all correct):

1. LaDePa is pronounced like this: "LaDeehPa" and it stands for Latrine Dehydration and Pelletisation.
2. The incoming material is 25% solids, the outgoing material is 75% solids
3. It is not meant to process faecal material from UDDTs as that is too dry for this processs.
4. The cost for one machine is currently 640,000 USD (that sounds like quite a lot).
5. The energy requirements are 0.5 L of diesel per year and per person (i.e. they must have calculated how much VIP sludge one person produces per year)
6. The commercialisation of this process is ongoing with an Australian company called LaDePa Global.

I am going to follow further develpments with interest. Anything that comes out of eThekwini municipality, kwaZulu Natal University etc. is worth keeping an eye on!

Regards,
Elisabeth

Dear colleagues,

I have posted a couple of videos from LaDePa process plant and its laboratory pilot.

1 - The LaDePa (Latrine Dehydrtation Pasteurization) machine has been installed in Tongaat wastewater treatment plant, located in the eThekwini municipality (Durban, South Africa), in order to process feacal sludge collected from ventilated improved pit latrines. The product target consist in dried and pasteurized pellets which can be used in agriculture or as a biofuel.




2 - The laboratory scale LaDePa, located in the experimental facilities from the Pollution Research Group, in the University of KwaZulu-Natal (Durban, South Africa), is the prototype of a full scale machine in Tongaat wastewater treatment plant, for the drying and pasteurization of faecal slugde from improved pit latrines. Its objectives are to better understand the phenomenology and optimize the process, and to evaluate the product for agriculture use or as a biofuel.




If you have comments about the videos, please let me know.

I wish you a lovely day.

Best regards,
Dr. Santiago Septien Stringel

Please be advised that PSS has supplied 1 Ladepa to the Kwazulu Natal University (University of KZN) for test work.

A second pilot plant is under construction for TU Delft. This pilot plant is designed to make use of waste heat and medium wave infrared radiation. This plant will also go to University of KZN for research.

The Ladepa technology (www.parsep.co.za) pasteurises pit latrine sludge at 180 - 240 degrees celcius but the performance has not yet been optimised. We hope to have much more information once testing commences next year.

Rein Buisman

Further to my last post, Delft University have now placed an order for a Lab scale LaDePa plant. It is to befitted with a full recycling waste heat system, to test for efficiency with regards using waste heat to dry and pasteurize the waste, as opposed to our MIR's. The design includes recycling heat that has been used, putting it through a hot box to reheat, and forcing this through the system again. It has multiple test and monitoring instrumentation points, which would not normally be found on a commercial unit, but will give a good indication on efficiency, and possible, where we could make improvements to our design. More to follow....

Thanks Massimo for the information. I sent you a mail and will be grateful for a brochure.

Robert.

Good day Robert, in response to your questions:-
1) The moisture content of the current LaDePa production plant running in KZN is less than 10%. We have achieved less than 5% moisture in test work, but the product will absorb moisture from the air, back up to around 10% anyway, so drying it any more than that is a waste of energy.
2) The pellets are currently being bagged and transported. They seem to hold up well to the man-handling, but do break up if pressed between the fingers.
3) We have had test work done on some of the output pellets, but we were not convinced that the original feed material was mainly sludge, as the source material has been stockpiled for some time, and the loading method does tend to pick up a lot of soil at the same time. We are planning to rerun the tests soon. (The UKZN research team will be doing similar tests, so we may await their feedback).
4) Some independent test-work was done on a small patch of lettuce. The section planted with the LaDePa output product did perform better than that without, but this was not a scientific test, so no real conclusion could be reached (not for reference anyway). I will attach pictures here.
We have also done test work on drying of waste food, waste abattoir products, pith (from a paper mill / sugar mill), and various other products, with mixed success.
Some of the products need the addition of a small amount of moisture absorbing material (like coco-peat) to get the initial moisture levels down to around 65-70% before we can extrude and dry them.

If you want more information, brochures, etc. please email me at This email address is being protected from spambots. You need JavaScript enabled to view it..

Dear All,
This is an interesting solution to sludge disposal challenges. Congrats!
I need clarity on these;
1. The moisture content of the pellets just after production
2. How strong are the pellets (for transportation and general handling)
3. The nutrient composition of the pellets. This is very important if we are considering the pellets as potential fertilizers (may be soil conditioners may be more appropriate).
4. Trials conducted on crops

Robert

Good day everyone, The LaDePa machine for the University of KwaZulu-Natal is finally on its way. Installation planned for tomorrow, and they can start with their test work by Monday.
We are currently in discussions with Delft University for a similar machine, that they plan to do rest work with.
All the information collected during testing will revert to us, so that we can use it to improve our design, and make the machine more accessible to a bigger market.
I have also made contact with K.R. Sundaravaradarajan, Head of the Department of Agricultural Economics, Annamalai University, following an article I found on the web, where I see there is a renewed interest in using human waste for agricultural purposes.
Chat soon.....

Dear Trevor
My apologies for taking almost 2 years to reply to your post! I had not seen it before. Our philosophy is one of becoming a facilitator or regulator, rather than an active player in the faecal sludge processing business in the medium to long term.
If phosphorous prices rise over time as we all expect them to, a point will be reached where the nutrient recovery business is self sustaining. At present we are promoting nutrient recovery to reduce the cost to us of disposing of faecal sludge - in other words reduce the subsidy that we have to pay to small businesses to collect faecal sludge and deliver it to us for processing or safe disposal. I guess that is what differentiates us from many other developing countries - we are expected to ensure the safe disposal of human excreta and our citizens have this expectation as a Constitutional right.
If we reach the point where the value of the nutrients makes for a sustainable business, then people will enter the market whether the government is effective or not. What may develop in future is a 'fight' between operators over the right to work in a given area if there is no effective regulator allocating these rights to empty toilets and access the nutrients