Dear Cecile,

thanks a lot for your thoughts and sorry for this very, very late reply. As I also mentioned in the other post I was asking this questions since there was a competition on this topic and I wanted to know what the SuSanA community thinks about it.
You find the competition here: www.gcsm.eu/gcsm_award.html
Because I had so much work I had to stop thinking about this model, unfortunately. But you can find the contributions of the other groups on the same webpage: www.gcsm.eu/gcsm_award.html

You are definitely right that the software part is at least as important as the hardware! Thanks for your insights on that aswell. Nowadays I completely understand that it is not possible to have a general model, since the solution is always so case-dependent.

I am now finalizing my master thesis where I look at the diffusion of composting toilets in community gardens in Berlin and which parameters and variables affect the decision to adopt a composting toilet. I also look at the adoption potential of a specific technology that I call TPPS (Terra Preta Pasteurization Sanitation), where faeces are sanitized through a pasteurization process. Let me know if you are interested in it, I can send it to you after submission (also to other people, if someone else is reading this eventually...just send me pm).

Best,
Georg

Dear Georg,

Could you please give us a little bit more on your background ? Are you working for a university ? And also, what is the purpose of your research ?

I understand your project is reasearch and modelling, but I can't help thinking about the concrete, more "down to earth" aspects of such a project.
In all sanitation projects the solutions are not only issued from technical constraints but also from the software component.
As Ralf mentionned both technologies work and as you mentionned, both have their pros and cons.
If you are trying to use a "suitable (...) system for a community" it is as important to consider the technical suitability and the suitability for the users as importantly. The personal hygiene habits and culture of the users (washers / wipers, pros / against separation) density, types of building, climate, will influence the technology, as much as the technology itself. Are the users more likely to have UD type toilets like in Sweden or non separation toilets like in France.
How many participants can you reasonnably get ?
The financial sustainability is important, as door to door collection systems rely on human resources, which depending on the country you are modelling your system can be quite heavy.
I am basing these thoughts on a couple of initiatives in France, where this idea of door to door collection and external treatment of dry toilets residues are popular among dry toilet users. There were several attempts to set up door to door collection systems and undertaking composting or co composting on platforms. For these initiatives the technical issues were not as important as the behavioural, legal, financial and participatory aspects. I think if you consider these aspects it will narrow the starting parameters of your research.
Kind regards,
Cecile

Dear Ralph,

thanks a lot for your comment.

I also think that no-diversion can make sense in densely populated areas where people do not use urine for their own garden plots.

In this case more cover material is necessary to soak up urine, right?
What sort of material could possibly be used and how does this affect the fermentation?
Is it then still necessary to add sugars/fruit waste to keep the Lactic Acid Fermentation running?

Let´s imagine an urban area where excreta collection in a container without diversion and transportation to a municipal composting site is feasible, where the fermentation and vermicomposting can take place.
Isn´t it better in this scenario to simply collect excreta at household level without fermentation, therefore no need to distribute inoculum, add sugar material and especially keep the lid air tight? The fermentation can be done afterwards at the composting site.

Dear Georg,

Such question is slightly too general... Choice of systems is highly dependent of density, type of houses (multi storey?), socio-economics and availeability of reliable service providers, users of compost e.g. for reforestation in the region and so on.

UD is a great solution for single houses with some land in more sparsely populated situations and where people use urine themselves. Lactic acid fermentation of feaces is always good, ideally with fruit waste. This will solve the severe problem of the remaining repelling smells in UDDT, even well maintained ones. Will still function where too little cover is supplied.

Excreta collection unter lactic acid fermentation in container toilets of different kinds seem feasible for this scale. This requires a local service provider and a nearby composting station with soil conditioner demand and supplies of dry woody waste. Mulity Storey is feasible. Costs can be very low. Simple Container-Toilets of different types are availeable and the WTO design award winner (see professional 4 ' animation on
)
can be produced for such a scale at costs of around 100 Euros or leasing.
Charcoal should be produced with woodgas stoves ideally fed with briquets from woody waste materials. This can be combining very well with santitation and make it more feasible together. However, composting can so without charcoal, the fine dry woody material is crucial to balance C/N ratios and make huge amountsof soil conditioner.

I do have very much involvement in practical also larger projects. It must be a simple as possibe, so for the more densely populated areas we should avoid UD. It can still make sense from case to case, there is no absolute Yes or No...

Regards

Ralf

Dear Sanitation Experts,

my name is Georg and I am very interested in Terra Preta Sanitation (TPS). A good overview about the system can be found here .

I am trying to model a suitable, exemplary TPS system for a community (urban area) of 20000 inhabitants, which means a municipal collection and treatment of excreta should be possible.

While most researchers agree that charcoal is necessary for the formation of Terra Preta, still many open questions remain in my mind and I would like to share them with you. I hope the SUSANA community will be able to shed light on this issue.

Question 1 can be discussed here. For discussion of questions 2 and 3 please follow the links below.

1. URINE DIVERSION OR NO DIVERSION?
2. LACTIC ACID FERMENTATION (LAF) OR SIMPLE COLLECTION (SC)?
3. VERMICOMPOSTING (VC) OR THERMOPHILIC COMPOSTING (TC)?

1. URINE DIVERSION OR NO DIVERSION?

	most proponents of TPS proposed: Diversion [ SPUHLER & GENSCH 2010 ; FACTURA ET. AL 2010 ]; (Pieplow; Reckin; triaterra.de)	others recently proposed : No diversion [ OTTERPOHL n.y. ]
pro	[SPUHLER & GENSCH 2010] - no odour - no need to ferment and compost urine - different usages of urine possible (direct application, composting..)	- no odour if enough cover material is used [JENKINS 2005] - one container needed -> easier handling
contra	- not necessary, since composting of urine is better than direct application [OTTERPOHL n.y.] - 2 collecting containers needed -> more complex - proper separation is often complicated in practice	- more cover material is necessary to soak up liquids [JENKINS 2005] - more storage room needed

What do you think is the most suitable TPS system for a 20.000 people urban community?