(I have just sent this to the German e-mail list for people in development cooperation called Aqua Mailserver, but I think it also deserves to be copied to here)

Dear all,

We often hear about the great strides that eThekwini Municipality (Durban) in South Africa is making in regards to access to sanitation for low-income areas.

This 10 minute Video in Afrikaans which was shown on South African TV – and is amazingly detailed for general TV - , explains very well what is going on in sanitation in Durban:



Particularly interesting is the part about the new sludge pelletising machine (starts in the video around minute 5:41). This machine actually will be winning an award at IWA Kuala Lumpur Development Congress, as well as the eThekwini Community ablution blocks.



GIZ colleagues of mine who work in Sub-Saharan Africa will say to me “but Elisabeth, South Africa is different, not comparable to the rest of Africa”. Of course they are right, however it helps to know what CAN be done if there is political will (and better governance and a higher tax revenue than elsewhere in Sub-Saharan Africa). I find it particularly impressive how this is all done by an African municipality and without external donor support. Seems to me to be a very sustainable set-up.

And I am very curious to see what comes out of their two Gates-Foundation-funded research projects in urine diversion as well (one of them is also explained in the video, the one with EAWAG called VUNA).

(we also have two SuSanA case studies on two of their programmes, see www.susana.org/case-studies, click on South Africa)

Regards,
Elisabeth

Thanks Elisabeth for this nice video (and congratulations to the team from eThekwini)!
Do you have an idea what kind of sludge they are using for producing the pellets at the moment – i.e. how they are tackling the problem of material other than fecal matter in the sludge and quality control (from an agricultural point of view) for the pellets?
Best Dorothee

Dear Dorothee,

Good questions. I will try to find out - have just e-mailed Chris Buckley and will encourage him to reply directly here (or else to send me his reply by e-mail).
My guesses are that it is mainly sludge from VIP latrines, and that they probably have some manual sorting to take out large items and a mechanical sieving process. And the question is whether the pellets are reused in agriculture or not.

From what our South African colleagues have told us about VIP latrine sludges, it is full of solid waste, as the people often have no other means for solid waste management, so the solid waste is dumped into the pit of the VIP latrine. - This should be one advantage of UDDTs where it is not so easy to dump large objects and if you do, then YOU have to take them out again almost immediately because the chamber is full straight away!

Regarding reuse, when we worked on the eThekwini UDDT case study I asked the question whether the people in the peri-urban areas need any fertiliser for their gardening activities, but I was told they don't do any gardening (urine is infiltrated and dried faeces is buried there, no reuse). This surprised me.

Hopefully, we will have some detailed input from our South African colleagues here soon, I will try to alert them to this discussion!

Regards,
Elisabeth

Hi Elisabeth and all,
They have many different projects on many different types of "sanitation user interfaces".
As mentioned in the film, urine reuse was not the motivation at the beginning, but they are doing research on it now (as I remember including technology option for producing fertiliser, as well as the whole logistics and economics behind).
If the pellets are not used in agriculture – but as a fuel for instance (I do not have an idea of the final TS of the pellets) – solid waste will probably more be a problem for the process of producing the pellets than the reuse.
Looking forward to the feedback from the eThekwini people.
Dorothee

Dear Dorothee and Elisabeth,
Dorothee, the TS might be above 80% (I guess). The process has been describe (very) shortly here
www.susana.org/lang-en/library?view=ccbk...p;type=2&id=1243 p. 28.
Actually it seems to me as sludge drying and each sludge drying process would give a pathogene and ascaris free sludge. The way of heating seems to be the only way to tackle the hygienic aspects safely in scale.
Elisabeth, thank you for the link to the viedeo, it is really worth to see it and the automatic resume link for the Forum. It really helps.
I really appreciate the enormous effort of the Durban people (tariff payers, researchers and employees). I got the impression they might be able to charge for visits and therefore have a third source of money?
Coming back to the hygienic aspects…. I think solar drying should be looked at for the sludge because the way presented (in this case still worse as it is a diesel generator) is not very energy friendly.

Yours
Christoph

As the person who is being obliquely referred to in much of this blogging, I would like to speak about the pelletiser and our intentions.
The pelletiser was specifically designed to process pit toilet sludge that is heavily contaminated with garbage. The machine first separates the sludge from the rags, boots, spoons, sheeps heads, etc. It then treats the sludge by heating it to a temperature in excess of 100 deg celcius for about 8 minutes - this renders it pathogen free and produces dry pellets that can be used as fertilizer. The garbage component is sent to a landfill site for disposal.
In Durban we provide one emptying of a VIP toilet every 5 years as a basic sanitation service. At present it takes us 3 years to empty the 35 000 VIP toilets in our area of operations - it is this sludge we process in the pelletiser. We do not empty the UD toilets at this stage, but the pelletiser has the potential to recover nutrients from that sludge as well
We recognise faeces and urine as potential sources of nutrients and energy, rather than as material to be 'avoided at all costs' and kept as far away from people as possible. This pelletiser is part of a series of interventions that we are working on to recover nutrients from human waste and then recover energy from what is left. The interventions have the potential to create many small businesses who will collect and process the waste and the fertilizer will also support food security.
I do not agree with the implied view that these solutions would only work in South Africa - all of Africa has a need for plant nutrients and energy and we are working on solutions that are practical and which can be used in any country in Africa and elsewhere in the world.
The flush toilets we use today were invented in 1860 and pit toilets have been around for millennia - the time has come for new technology that works for everyone and that is sustainable in every sense of the word(I call it a 4G toilet, using the mobile phone analogy)

Dear all,

Extremly interesting research you're carrying here !
It looks like it's early to say but could you please give us an approximation of the potencial business model of this kind of installation.

Roughly, what is the price of the pelletiser, the cost of use and maintenance, how much do you expect to sell a kg of downstream product and how much is the VIP emptying cost ?
You said you emptied 35000 VIP in 3 years, can we consider you are emptying latrines of almost a 300 000 people area (5 people / latrine / emptied every 5 years) or the pelletiser has even a higher productivity ?

I know this is reducing the problem a lot to just turn this massive health problem into cost figures but that would be very interesting to see how much we could sell this idea to private entrepreneurs in developing world.

Congratulations again, great work and thanks for sharing !

Ben

Dear Neil

Thank you for your post. I agree with you on the fact that this technology can be adapted where necessary and used in other African countries. But would hastily add that the success in other African countries that do not have an efficient tax collection authority like SARS and stable municipal infrastructure in terms of processes and procedures like eThekwini, would only be a success and sustainable if you as the pioneers are able to make a break-even business case. As if an interested African social entrepreneur knows that it is possible to break even with a sludge pelletising business, innovation will result to ensure that the social entrepreneur can make a bit of profit to pay the bills and sustain his small social enterprise. I would love to know your thoughts and ideas in this regard!

I shall continue to follow your progress with great enthusiasm.
Kind regards
Trevor

I have seen the video and also the comments posted by various members.
I think while designing the pellet machine which uses lot of energy, we should explore the possibility of Solar Heat which is abundantly available in African Countries.
I would also like to suggest that the roof area of toilet blocks which remains only as a shelter cover can be advantageously used for heating and drying of excreta,which is kept in sealed and well ventilated metal containers. What we require is a temperature of about 50 to 60 degrees Celsius for killing of pathogens.
So by collecting the urine separately and treating the ablution water in reed beds etc the problem of excreta treatment can be effectively tackled.
we are working on such solutions in India which are at experimental stage and we hope that a sustainable solution would be found soon.

Prof.Shrikant Bhate.
Architect and Social Entrepreneur.
India.

Dear Shrikant,
Your post sounds very interesting. The energy problem is really a tricky one. Thanks for sharing this interesting aspect. From what I understand…you are heating a UDDT chamber? I thought this because you mentioned drying as well. Could you tell us some more or is it too early? (Size of the chamber, temperature achieved, retention time in the chamber, the heating is done in the walls of the container? Do you mix the material? If so, how do you do that? Do you have a picture?)Sorry lots of questinons.
It would be nice if you could give us some more ideas.
Christoph Platzer
Brazil

(note by forum administrator: I have moved the recent post of Rein to here, as it belongs to this thread on the sludge pelletiser)
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Topic: Processing Pit Latrine Waste into pasteurized saleable fertiliser

For those interested parties please have a look at the Ladepa Process
( Latrine Dehydration and Pasteurization Process)
This is a new technology which separates Pit latrine Bio solids from detritus,
and forms the bio-solids into extrusions which are then dried under Medium Wave Infrared Radiation under a negative pressure.
A 1,5 m3/hr pilot plant is currently being successfully tested by the Durban Ethekwini Municipality, South Africa.

Plese follow the you tube link to see this unique technology.






Thank you
Rein

I have been asked by Elizabeth to respond to some of your questions and comments.

Ben asks about costing information. The prototype pelletiser can process 12 tons per day of wet pit toilet sludge. A comprehensive financial analysis of the viability of this pelletiser has been done by John Harrison in my organisation and he is to present the resiluts at the WISA 2012 conference in South Africa,in a few months time. The analysis compares disposal of the unprocessed sludge at a landfill site with the sale in a pellet form. We can sell the pellets at R15 per 30 cu dm bag or about R500 per cu m (at 80% solids) The cost of disposal on landfill is R1012 per ton. Overall, taking into account all the costs of operating the pelltiser, it is financially competetive. ($1 converts to about R8)
We agree that the prototype plant is not energy efficient and there is considerable scope to improve its performance and reduce costs

Trevor asks about entrepreneurial opportunities. We are not only looking at pelletising VIP toilet sludges, but also UD toilet faecal matter. In addition we are working as partners in a Gates Foundation research project to look at a model for processing urine and recovering nutrients. One of the outcomes of that research will be a logistics model that will enable utilities to work out how best to design collection systems that will minimise processing costs (balancing reactor and pelletiser costs with transport and other collection costs and comparing this to potential revenue). Once that model has been tested we expect that it could be used anywhere, with the variables being adjusted to local situations. We will then have a tool that will tell us where the collection and processing of human excreta, from non- piped systems,will be financially viable or what level of subsidy will be required to make it attractive to private investors

Prof Bhata asks about alternative energy sources. The prototype was designed to be portable and is housed in two shipping containers, with a diesel generator as the power source. We agree that there may be better and more efficient ways of drying the sludge and that is where our attention has moved to now that we know the pellets are pathogen free and they are being used in agriculture. As with all new ideas, the initial attempt is an over-design and then efficiencies are introduced as the process unfolds. We were not sure at the start, what level of heating would be required to produce pathogen free pellets - we now know the power source is about double what it needed to be for the 12 ton/day plant. Solar may be a possibility, as he suggests.

Underneath I have included the data for the Ladepa Prototype dryer. We are refining this process and will release the new data when compiled.

DEM – 1 – LADEPA PROTOTYPE DATA:

Ladepa plant
Durban Ethekwini Municipality

Details of plant

Belt width : 950 mm
Dryer width : 1350 mm
Dryer length : 11000 mm
Dryer height : 1200 mm
Belt Apertures : 300 micron
Belt drive : 0.75 kW
Screw drive : 1.50 kW (2 off)
Blower : 5.5 kW
MIR : 3 x 48 kW = 144 kW
Total Ladepa : 151.75 kW

Engine required 160 kW (engine installed JD 406 x HD – 310 kW – (much too big)

Fuel diesel 7 – 8 ℓ/hr = R80/hr (USD 10.66/hr)(E 7.30/hr)

Feed : 1000 kg/hr @ 30 – 35 % Solids
Detritus : 15 % 150 kg/hr
Product : ± 300 kg/hr @ 80 – 85 % Solids
Evaporation Rate :1000 – (150 + 300)/154 kW = 3.64 ℓ/kwh
Residence time : 8 minutes (4 minutes gas 4 minutes MIR)
Product temperature : 180 – 220 ºC
Bagging : 20 x 15 kg/hr (value R400/hr) (USD 53.33/hr) (E 36.36/hr)

Future changes:

Single Screw Compactor/Extruder with height adjustment
192 kW MIR (Total power installed 199.75 kW)
220 kW Engine
Exhaust gas only
Radiator cooling gas to atmosphere

OPEX

95 % of cost is electricity/diesel
(10 – 11 ℓ/hr) - for a 192 kW Ladepa plant

REIN BUISMAN
Director
Particle Separation Systems Technologies (Pty) Ltd

LADEPA – JOINT PATENTED TECHNOLOGY BETWEEN DURBAN ETHEKWINI MUNICIPALITY AND PSS

Short Biography of Particle Separation Systems (Pty) LTD (PSS) Company

The company has two directors 50/50 share ownership between Werner Altmann (Swiss) and Rein Buisman. (Dutch) and was formed in 1997. The company main business was to develop technologies using steel mesh and woven steel belts.

In 1997 Werner Altmann and Rein Buisman started PSS and invented the Pansep Screen in joint partnership with Anglo American. Due to development costs, politics and other interference PSS was forced to abandon the Pansep Screen and close the company in 2002 and restart as Particle Separation Systems Technologies (Pty) Ltd (PSST).


Rein Buisman (HNDT Extractive Metallurgy - Wits Technikon)

Born in Amsterdam in February 1956. Immigrated to South Africa in February 1972. Studied and qualified as a metallurgist in 1980 (HNDT in extractive metallurgy). Worked for De Beers Diamonds in Namibia and Angola, Goldfields and Delkor Technik in Belt Filter filtration and the Linear Screen development. Started Buismet in 1986, importing heavy duty industrial textiles from Sweden and Germany. Sold Buismet in 1994 to GKD Kufferath Germany.


Werner Altmann (BSc Mech Design Engineering – University of Ipswitch)

Born in Germany in May 1944. Immigrated to South Africa in 1968.

Worked for Everite, Pentech Services, Bechtel International and finally Delkor Technick as Engineering Director and shareholder until 1998. Resident in Switzerland since 1998. Started PSS in 1997.

Particle Separation Systems Technologies (Pty) LTD (PSS)

In 2002 PSS restarted the company under a new name Particle Separation Systems Technologies (Pty) Ltd. (PSST).

PSST invented and patented the following technologies:

• The dehydration filter (2004)
• The Parsep dryer (2008)
• The drying of ferric salts (ferric sulphate) (2009)
• The Commett mill (2011)
• The Ladepa Process with Ethekwini Municipality (2011)
• The recycling and recovery of foundry sands (2012)
 
Ladepa Process

In May 2010 PSS was approached by the Ethekwini Municipality represented by Dave Wilson and John Harrison to assist with the latrine sludge problem.

Whereas the drying technology was proven in the mining and minerals industry, the separation of detritus from latrine sludge and presenting the sludge in such a form whereby fast, efficient and economical evaporation can take place was a major challenge. After test work and pilot trials the principle of the Ladepa was patented. Ethekwini then raised the finance and ordered the prototype scale of the patented model from PSST.

The Ladepa (Latrine Dehydration and Pasteurisation) plant utilises three patents:

1. The dehydration of a substrate on an unsupported filter media. (SBF)
2. The use of medium wave infrared radiation under a negative pressure,
(Parsep drying)
3. The extrusion of sludge in a form ideal for drying and simultaneously separating the detritus. (Ladepa)

After several modifications and redesigns the Ladepa is now available in modular form to treat any sludge between 20 – 35 % solids and pasteurise to 80 – 90 % solid product.

The model adopted to supply the technology is on a rental basis whereby ownership will remain with PSS and the rentals are for the use of the technology. PSS would supply the plant at an establishment fee (P&G), a rental and a maintenance contract.

The product is a pasteurised bagged fertiliser currently being registered as GrowEthek which can be sold to cover the cost of Ladepa and collection of the Pit Latrine sludge.

PSS/PSST is involved in ongoing research to improve the process by development of a direct Biogas fired MIR system. (i.e. not Biogas to Electrical and then convert to MIR)

PSS/PSST is also investigating a Solar magnification process which when linked to the MIR optical sensor reduces electricity consumption (fuel) when the sun shines and re–applies MIR when it becomes cloudy. (NOT quite a solar powered technology)

PSS will update developments on a continual and ongoing basis.

Ladepa 2

PSS, Ethekwini and the Gates Foundation are in negotiation to develop the Ladepa 2 with improved design features, efficiency and affordability, duration of this development is 2 – 3 years.

For more information please check www.parsep.co.za or contact the writer:

Rein: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Tel: 011-412-2100

Dear all,

I recently had the opportunity to see the LaDePa sludge pelletiser in Durban and listen to a presentation about it (we had discussed it earlier on the forum, please scrol up).

It is a very interesting process, where part of the technology is actually taken from the mining industry.

The energy consumption per person is similar to that needed in an activated sludge plant, we were told (it needs electricity).

I suspect that for a country like South Africa this could be a promising sludge treatment process, making the sludge safe for reuse and even sellable probably. But for other African countries in the region it is probably too complex and energy intensive.

I noticed also some small pieces of plastics remaining in the final product. Not much and probably unavoidable given the amount of plastic going in (menstrual pads). Interestingly, also in Durban they have a research project on menstrual cups which would reduce the amount of plastic in faecal sludge (I will encourage the researchers to share about this in our forum in the MHM section).

The amount of "reject sludge" should also not be ignored, as not all of it goes through the extruder properly. It seemed in the order of 30% (I think one of the persons mentioned this number). See photos below.

You can read more about the process in the attached paper which was presented at the conference. Also John Harrison, one of the people behind it, has promised me to answer questions here if I alert him to them. So please feel free to ask!



I must congratulate eThekwini Water and Sanitation for having the guts and willingness to innovate and find practical solutions in a step-wise manner! Keep up the great work.

Some visual impressions below (click on the link below the photos to get to my entire photo set from the field trip on 1 November):

Sludge pellets after LaDePa process by Sustainable sanitation, on Flickr

The reject which cannot be processed (not the right moisture content) by Sustainable sanitation, on Flickr

Faecal sludge after some drying (stock piling) by Sustainable sanitation, on Flickr

LaDePa sludge pelletising plant by Sustainable sanitation, on Flickr

Regards,
Elisabeth

Dave Wilson from eThekwini Water and Sanitation (EWS) sent me the following further information by e-mail in response to my posting:
+++++++++

Hi Elisabeth,
The 30% that would remain behind should only be the detritus (rags, plastic etc). The problem here is that the sludge is too dry as we need sludge with a solids content of about 25-30% and this is old sludge with solids content of about 40-45%.

Another way of quantifying the energy requirement is with a machine this size and serving approx 50,000 people the cost to process would be 0.5 litres of diesel per person per annum.

The equipment is not complex as there is very little that can go wrong and the beauty about the new ones is that they are remotely checked for performance and condition.
Your pictures are fine with the comments.

Regards
Dave
+++++++++++

Really interesting. Hope that Abigail Brown, PHLUSH rep to World Toilet Summit in Durban can learn about this.

Good day SuSanA members,

Just an update on the progress we are making with the LaDePa plant. Apart from ongoing modifications and improvements to the existing plant at eThekwini, in conjunction with the gentlemen responsible for that service delivery, we are also now in the completion phase for a lab sized plant which will be issued to the University of KZN.

The purpose for this lab plant is for the university, in conjunction with the members from the eThekwini Water services department, to do more comprehensive studies of the total LaDePa plant functionality. They will assess it's efficiency, monitor the gasses (if any) which may be coming off the machine due to the drying process, and also do test work on the output product to access actual content with regards the minerals, heavy metals, etc. All the information that is gathered, and all reports will revert to PSS as the owners of the technology, and we will then be in a position to further improve on the inefficiencies of the LaDePa plant.

Further to the above, we are also working on making the plant cheaper, thereby making it easier for poorer countries / communities to make use of it. We have also made inroads in other markets with this plant, specifically in the waste food space, as well as animal waste products. Ultimately all of these "waste" products have further value to give when returned to the earth, but also can contain pathogens / bacteria, etc. which need to be eliminated before they can safely be used in agriculture, and this is where the LaDePa is making its mark.

Anyone wanting more information on the plant can contact us either through this site, or on our web page at www.parsep.co.za.

Have a sanitary safe day!

Hi there, we did have representation at the WTS in Durban. If Abigail did not get to meet and chat with us, please ask her to contact us via our website, and we can discuss the LaDePa plant and it's value add.
Thank you