SuSanA - Forum Kunena Site Syndication Mon, 25 May 2015 01:19:48 +0000 Kunena 1.6 SuSanA - Forum en-gb Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on? - by: themessenger I have spent years rabbitting - since late 2010 during Haiti - on about the potential benefits of mobile, flatpack raised latrines.
Contain the waste effectively in the first place and it is easier to come up with local resource maintenance/extraction/processing.
I presented the idea as a CAD at a UNESCO water meet in Holland in 2012.
Now my company, AirCell Structures, is finalising pre-production samples of a complete flatpack latrine and raised latrine 800litre tank kit that flatpacks onto a standard 120*80cms pallet.
The latrine structure can accept a direct drop squat or sit-on plate or a proprietary loo and the tank box can utilise standard 240L oil drums or our custom 800L bag. Extraction is design for either vac-sucking through a rear hatch or you can slide the oil drums out and drag them off on our 'sludge-sledge'.
It is designed to work anywhere and to provide a robust and dignified solution to the major problem in world sanitation!]]>
Faecal sludge management Mon, 18 May 2015 12:06:43 +0000
Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on? - by: jsauer
Great ideas. However, what I am looking / hoping for is something that gives the experience of the pour flush toilet and that also is off set, so not a direct drop like these models you mentioned. Ideas?

Faecal sludge management Mon, 18 May 2015 10:53:20 +0000
Information about septic tanks, emptying frequency, and Wikipedia article - by: muench
Yes, please.
So far we only have some information about regulations for septic tanks in England and Wales:

(and I don't know how good that part is)

It would be great to have the additional information about prefabricated septic tanks sold in the EU added to the Wikipedia article. When you do (or when you tell me what to add), it is very important that we provide some sort of reference (source) for the information. Otherwise someone will add the {{citation needed}} tag (sometimes I add that tag myself just as a reminder that a source is still needed). It can be better than nothing.


P.S. Just wanted to stress again that the Wikipedia article on septic tanks is not yet that good. I have only done some bare minimum work on it but I hope that others will improve the article further.]]>
Faecal sludge management Sun, 17 May 2015 09:45:02 +0000
Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on? - by: stilmans
Regarding your mobile septic idea, I would advocate for household-level container-based sanitation, as practiced by x-runner in Peru, SOIL in Haiti, CleanTeam in Ghana, and Sanivation in Kenya as the right way to provide service to residents who have transient or uncertain land tenure. The toilets that all these services use are easy to transport to a new home for uninterrupted service.

Initial results from the pilot service we at re.source helped set up with SOIL can be found in this open-access peer-reviewed paper just published, and another one by Kory Russel that will be published in October.

Faecal sludge management Sun, 17 May 2015 04:26:35 +0000
Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on? - by: erkkisantala
it is good that you have made some additions to the Wikipedia article on septic tanks. But one important aspect is still missing there, concerning regulations. Since July 2013 all prefabricated septic tanks sold in European Union countries must have a CE-mark and fulfill certain requirements based on European standards EN 12566-1 or EN 12566-4. I´ll try to persuade a British colleague from the standardization working group to write an addition to that Wikipedia article, he will do it more concisely than I could do.

Erkki Santala]]>
Faecal sludge management Sat, 16 May 2015 20:15:16 +0000
Re: LaDePa is a faecal sludge pelletising machine in eThekwini (Durban) - by: SeptienS
I attach here the poster presented during the Conference FSM3, which presents the results obtained in a laboratory-scale LaDePa machine from the Pollution Research Group of the University of KwaZulu-Natal,in Durban, South Africa. These results include: drying kinetics and faecal sludge composition as a function of the MIR emitter intensity; the pasteurization extent concerning Ascaris eggs, as a function of the MIR emitter intensity; the thermal properties (calorific value), chemical composition (P,K) of the the dried sludge in order to evaluate its potential use as a fertilizer or biofuel.

Faecal sludge management Thu, 14 May 2015 00:59:58 +0000
Re: Dissertation at SLU "Sanitisation of Faecal Sludge by Ammonia - Treatment Technology for Safe Reuse in Agriculture " - live streaming on 7 May at 13:00 CET - by: jorgenfidjeland
The slides from my presentation are available on the link below:

Faecal sludge management Wed, 13 May 2015 13:55:20 +0000
question about Ladepa and pit emptying on the forum - by: johnha
Sorry about the delay in my response. I was very nervous about answering some of the questions as there are a number of students doing post graduate work very closely aligned to the answers to some of the question that were asked and I did not want to publish things that they were about to publish. So I just needed to clear with them first. There was also a minor issue that I am still chasing deadlines. So please accept my apologies.

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.

This is a comment more than a question and I have no experience in Tanzania so cannot comment further, except to say that Ladepa is not financially self-sustaining. By this I mean that the income from the sale of the product does not cover the cost of the operation of the machine, let alone the cost of emptying the pits. The Ladepa has a positive balance in the case of eThekwini and most of the cities in South Africa, because the alternative legal disposal method is to a hazardous land fill site. There are very few of these in the country and the cost of transport and disposal to landfill, consequently makes the Ladepa viable.

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.

These two questions are best answered by PSSH, who I asked to make comment on but have not followed up to see if it was done. However the maintenance in general is not difficult, but certain spares would need to be held in stock in Tanzania. If there are a few Ladepas then the cost of holding stock can be shared, which is one of the reason that we chose to lease from PSSH, so that they would be responsible for holding the stock which cost they can off -set if they get more customers.

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?

The operation of the ladepa Plant is very simple for anyone with an aptitude for operating mechanical plant. PSSH is going to provide training for our pit emptying management contractor.

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.

Here in eThekwini we generally have a very strong binary system, in that the VIP sludge is either "wet" or "dry". The "dry" sludge is stiff enough to form "spaghetti" on extrusion through the ports in the barrel of the screw conveyor. These spaghettis form an open voided matrix when it falls onto the belt. These voids allow the air to pass through the pile; this is the deciding factor as to whether it can be treated through a Ladepa Plant. (Wet sludge forms a "cow pat" that does not hold up in a form with voids when it falls onto the belt).

As far as the moisture contents are concerned we generally operate on visual triggers as to whether an open voided matrix will be achieved, and because of the clear distinction between wet and dry sludge it is generally clear which sludge can be treated by the Ladepa and which cannot. Whether a sludge is too dry or not is a far more difficult question and is generally based on what you are prepared to live with.

If the sludge is too dry, there is not a good separation between the detritus and the sludge and the dryer the sludge the more sludge passes through the barrel of the extruder with the detritus, hence my remark about what you are prepared to live with. We have only found the phenomenon of sludge being too dry, on sludge that has been left in the open and has air-dried to a degree. Sludge coming out of the pits and then directly into the machine does not seem to have this problem.

Chris Buckley and his team are busy with a report to our Water Research Commission on trying to determine the moisture content relative to the rheology of the sludge, so I will wait until that is published before commenting on the moisture content. But again based on my experience of the behaviour of wastewater sludge I would guess that the lower solids limit of what can be treated through a Ladepa would be about 22% solids.

As far as pumping is concerned that is an open question and it depends on what sort of pumps are being used. I have seen peristaltic pumps pumping 16% solids waste activated sludge, thickened in a centrifuge with a heavy dose of polyelectrolyte. The problem though is getting the sludge into the pump, because it is well into the sticky phase by then. From Ladepa perspective, as a general rule, if you are able to pump then it is probably too wet for Ladepa.

With regards to the clear distinction between wet and dry sludge, Lungi Zuma and Chris Buckley pointed out is that they have found two different types of "wet" VIPs, the "crust-liquid-settled solids" type and a type where the "liquid" forms pockets or lenses within the more dense sludge.

I have untested hypothesis as to why there is distinct separation between "wet" and "dry" pits based on the mass balance and movement of the liquid into and out of pit. (For simplification of explanation, we can exclude the liquid lost through evaporation). The rate that water leaves the pit is governed by the product of the transmission rate through the wetted surface, and the area of the wetted surface. (This implies that the transmission rate through the surface is rate limiting as opposed to the rate through the soil being rate limiting).

If one considers the situation of water flowing into an empty pit, there is an automatic system of adjustment in that if the water is flowing into the pit faster than the rate that it is currently flowing out of the pit, the level of water in the pit will rise. This will increase the wetted surface area until such time that the product of the surface area and the rate of transmission through the wetted surface matches the inflow rate, (and vice versa, if there is a net loss of moisture).

If we now consider the same inflow rate but in the case where a pit is filled with sludge to a level above that of the level that the water would have risen to in the equilibrium state. In this situation there is more wetted surface area than the inflow rate requires, that is, there is potentially a net outflow of water from the pit or a net drying effect. Now the rate limiting factor is the rate that the water can be transmitted to the wetted surface. In most pits a "conical" top surface forms which moves the water to the sides of the pit. The water will then flow down the path of least resistance between the sludge and pit side, the soil and the sludge.

In most cases, I suspect that the line of most resistance is sludge and consequently the rate at which water ingresses into the sludge is far lower than it will move away from the interface. The time scale between wetting incidents and the relative rate of transmission of water into soil compared to the rate the water moves into the sludge is such that we land up with a "dry" sludge.

"Wet" pits occur when the rate of inflow is greater than the outflow, and this occurs when either there is very low permeability in the soil or the pit walls are blinded or when excessive amounts of water are being added to the pit (when people are bathing in the toilets and discharging wastewater into the pit).

Theoretically, one could find a situation where the sludge layer is exactly equal to the level that the water would rise to if the pit was in equilibrium, in which case the sludge may be somewhere in between "wet" and "dry", but the chances of obtaining this situation is remote particularly at the stage when people come to empty the pits.

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

At the moment we are not marketing the product, we are giving it to our parks department who are passing it on to their community gardens section, we sometimes get a gratuity from the parks department as it reduces their fertiliser costs. However, this is an interesting questions with many facets which we, the Engineering profession, are unable to answer. The accountants do not want sludge as it is a liability to them, however the moment this sludge is converted to a marketable product it becomes an asset to them. In terms of the Municipal Finance Management Act, the disposal of Municipal assets need to be done by public tender. However the question is who does the asset belong to? Does it belong to the Municipality who paid for its conversion, the community who produced the sludge or the owner of the technology that converts the waste into the asset? PSSH have a vested interest in how the product is marketed as this affects their Ladepa machine market. Fortunately it is not my problem.

I think this answers the question as best I can.

Regards John]]>
Faecal sludge management Wed, 13 May 2015 13:31:53 +0000
Re: question about Ladepa and pit emptying on the forum - by: Reinb
I lost my computer through an encrypting virus and with it somehow also the SuSanA mails and contacts.

I am getting back on track.

We build Ladepa plants although to date we have spent much of our time developing and testing the technology.

The Ladepa (Latrine Dehydration and Pasteurization) can accept sludges from between 16 – 35 % solids. If less than 16 % the extrusions become too wet and clog the belt and “wet” extrusions reform into a wet “pudding” which does not allow air through and so prevent the sludge from drying.

If too dry the extruder may have problems extruding.

The art is to form a layer of extrusions which allow air to pass between the extrusions to remove evaporated water.

We build Ladepa plants to requirements.

If you could give me an idea of volumes or kilograms then I can make a proposal (for sludge we generally work on 1 litre = 1 kilogram).

The Ladepa has standard belt widths 250 – 600 – 950- 1400 – 1900 – 2500 – 3000 mm.
We build in any length with multiples of arrays. No need to operate all arrays. You use as required and switch off some arrays when there is less product.

If the sludge is very wet I would suggest to place the sludge for a period in paddock until the consistency is better 25 – 30 % solids is ideal, and allows better belt loading.

Generally you can work on 3.0 – 3.5 litre of water evaporation/ kWatt hr. This way you can determine on how many kWatt/hr you need and we can then also size a Ladepa plant.

If you are paid for emptying latrines and you get an off take for the dried product then generally the operation pays for itself on a double shift and a profit on a 24/7 operation.
As for maintenance, we have dryers in operation in the DRC, Angola, Kazakhstan and very remote areas.

Maintenance is very simple and only requires a semi-skilled employee.

The wear items are the extruder flight and housing – extrusion head. Life ± 1 – 2 years, depending on the presence of detritus and abrasive sands/glass etc.

The belt life is 3- 5 years, balance is pulleys and bearings.

Power can be through a Genset and/or network. In future probably direct gas to MIR as well.

I trust I have answered most questions.

Particle Separation Systems Holding (Pty) Ltd]]>
Faecal sludge management Wed, 13 May 2015 11:30:13 +0000
Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on? - by: RadfordJT
Coming back to the original topic (and as you know) Mott MacDonald and Cambridge Uni have been working together on R&D, to date mostly focused on pump benchmarking and providing technical support to Water for People's sanihubs. Much of this is indirectly linked to BMGF funding in some way. Can't claim to have commercial R&D/prototyping facilities, but the uni does have capacity for making 1-offs - eg the original ball penetrometer we made there for testing the physical strength (i.e. ("mechanical"/undrained shear strength/"pumpability") of FS. Main benefit is being able to plug MM's WASH network (drawn from a few 1000 water-sector professionals around the world) into university R&D projects at minimal cost, the drawback is being limited to the academic project cycle in terms of programme.]]>
Faecal sludge management Wed, 13 May 2015 06:10:37 +0000
Sanivation sharing lessons learned on live youtube stream Thurs 5/14, 11am-12pm EDT - by: AFoote
1. Sanitation as service and how we got here
2. Household toilets (suprising tid bit, people want one)
3. Poop and it's ingredients
4. The opportunities we see for social businesses in sanitation

We hope you'll join us and ask some tough questions.

Register via this link

See you on the web,
Faecal sludge management Tue, 12 May 2015 04:55:55 +0000
Sanitation option in low water contexts - in the northern Kenya town of Wajir - by: jamesoriga I am a WATSAN engineer in Kenya actively practicing with an INGO in the northern Kenya town on Wajir.
Wajir has had a perenial sanitation problem which is yet to be solved.The situation is that the water table is quite high,almost every household has dug their own shallow well in the compound.The government does not allow residents to dig pit latrines owing to that high water table.
The British colonialist introduced bucket latrines in the 1950s to provide a sanitation option but the management of such systems is just horrible and had terrible failed.
A couple of NGOs have tried the UDDT but that has also fialed mostly because of the socio-cultural aspects involved with sanitation.The are is 100% muslim residents so a possible sanitation solution should factor in the socio-cultural aspects.
We currently have the opportunity to access a social ventures fund for sanitation.

My discussions point/question is what are the possible sanitation options for such a context where purchasing power is also very low and had basically been a drought disaster transition zone for the last 50 years.
Again what are some possible sanitation business models that could work in such a context.

Eng.James Origa,
Nairobi Kenya
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Faecal sludge management Mon, 11 May 2015 11:05:47 +0000
Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on? - by: pkjha
I hope reply of Elizabeth is clear to you.
As per the Manual of septic tank by the CPHEEO, Ministry of Urban Development, Government of India, cleaning intervals of septic tank should be 1-2 years only.
A major concern in India is that most of the households construct septic tanks not as per the approved design of the CPHEEO. People construct two chambers of any capacity/ size with a baffle wall and name it septic tank. Size of the tanks depends on affordability of the households, not on the design. People feel more comfortable with larger size of tanks.
Secondly,it is never a felt need of quality of effluent coming out of the tank. Only after the tanks are completely filled with sludge and there is back flow, household realizes that the septic tank is not working and needs to be cleaned.In most of the cases function and mechanism of septic tank is completely misunderstood.I have seen several such septic tanks (connected with public toilets) with visible human excreta in effluent coming out of the tank, connected to a drain. But for the persons in charge of the public toilet,it was not a problem.
Faecal sludge management Mon, 11 May 2015 07:38:36 +0000
Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on? - by: muench Just about your septic tank question: Septic tanks seem to be generally little understood by those who own them even though they are so commonly used.

If a septic tank seems to not require fecal sludge removal for 10 years or more then it could have the following reasons:
  1. It was designed very large for the amount of wastewater load (or the wastewater load much lower than expected).
  2. The wastewater has very few solids in it.
  3. The septic tank is not sealed at the bottom and sludge is somehow getting out (not so common (?)).
  4. The septic tank should get emptied, and the effluent quality is deteriorating but nobody is noticing because solids are leaving with the effluent which is perhaps being infiltrated in a way that the solids "disappear" into the ground (?).

Have I got all the possible reasons together? I don't think aerobic degradation can be suspected as a reason as there is no aeration with a septic tank.

I think you might also enjoy this previous forum discussion on sludge quantities from septic tanks:
Quantities of faecal sludge from pits, tanks etc

And this one about septic tank emptying frequency in India:
Appropriate Septic tank Cleaning (emptying) Frequency

There is also a Wikipedia article about septic tanks by the way:

It is not yet great; I have done some basic improvements on it (like added the schematic from the Sandec compendium, and added a link to the newly created Wikipedia page on groundwater pollution). But it would greatly benefit from more editing work if someone has the energy to do so.


P.S. Christoph: I think I should perhaps split off all the posts relating to Dale's design ideas into a new thread, wich a new precise title, right?]]>
Faecal sludge management Sun, 10 May 2015 21:14:21 +0000
Information about septic tanks, emptying frequency, and Wikipedia article - by: vishwanathdalvi Note by moderator: this post was initially in this thread:


I do apologise for misrepresenting you!

And I am learning a lot, so thanks for that.

We have septic tanks in India that don't need to be cleaned for decades. How does that square with the impossibility of aeration? I am just asking. I really don't know ...]]>
Faecal sludge management Sun, 10 May 2015 16:41:18 +0000