Health risks in connections with using UDDTs - example of eThekwini in South Africa

  • christoph
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Health risks in connections with using UDDTs - example of eThekwini in South Africa

The following 14 posts used to be in this thread about composting toilets:
forum.susana.org/forum/categories/70-com...omposting-in-general

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Joe,

But surely we want good solutions not just any old solution?

For me (sufficiently, minimum) good is: a double UDDT bench system with a drying period of 1 year were the feces are buried in the garden and the urine is infiltrated, acompained by a control (kind of the former eThekwini situation). If possible I always would have a real service model by a service utility (which could be just burying in the garden as minimum solution).

I understand that this is not sufficiently good in your view. Right?
Christoph
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  • joeturner
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Re: What do we know about odorous gases from composting toilets (or from composting in general)?

I understand that after consideration the authorities in eThekwini have decided that is not good enough and are emptying and collecting the faeces in the UDDTs for central treatment.
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  • muench
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Re: What do we know about odorous gases from composting toilets (or from composting in general)?

(I think we need to tidy up this thread and break is off into a separate thread as the heading doesn't match with the content of the last few posts)

I am with Christoph on this one: pragmatic solutions are needed which are good enough ( meeting minimum standards, yes), rather than theorizing about a miracle technically perfect solution - which is actually affordable).

Yes at eThekwini municipality they are now also emptying the content of UDDTs free of charge (see two related threads on this forum, one about LaDePa and one about their new business model with black soldier fly larvae
forum.susana.org/forum/categories/53-fae...it=12&start=24#12590
forum.susana.org/forum/categories/147-pr...ipality-south-africa ).

But I understood that the main reason for this move is NOT because anyone has fallen sick from emptying a UDDT or burying the material (there is no reuse there). The main reason is rather to make it fair for everyone, as those people owning VIP latrines also get those emptied free of charge. EThekwini municipality is quite unique in Africa with their free emptying services...


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Related comment by Chris Canaday (which has now been moved to another thread ):

(Joe, that eThekwini Municipality mentions health risks from extracting biosolids from properly used UDDTs is apparently due to psychology and social norms, not documented cases of people getting sick. So many people, including you, have the mindset that ''once feces, always feces, thus the world human population is gradually converting all of the non-feces in the biosphere into feces.'' The biosolids that come out of a properly used UDDT are not feces any more, based on microbiology or any other variable you choose. They had been feces for a while and before that they were other things, including soil if we turn the clock back far enough. There may be some Ascaris eggs, but we can fine tune things to control them also, as I have done here in Ecuador.)


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  • joeturner
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Re: What do we know about odorous gases from composting toilets (or from composting in general)?

According to a paper at the FSM3 conference:

Since 2002, eThekwini Municipality has installed over 80,000 Urine Diversion (UD) double vault toilets at the household level in rural areas. This technology was selected to replace Ventilated Improved Pit Latrines (VIPs) as the Municipality’s basic onsite sanitation option as it was expected that the UD systems would produce a degraded sludge which could be safely removed and buried on site by the resident. This approach eliminated the challenges and costs encountered when servicing VIP systems, which included access to pits and sites, removal of sludge containing solid waste, and transport and disposal of sludge.

However, a number of concerns have since arisen over the removal of faecal sludge from UD toilets. These include health risks to residents who handle the potentially pathogenic sludge and dissatisfaction amongst household owners over the expectation that they will remove the sludge from their systems themselves while other recipients of basic sanitation receive a free service from the Municipality. The Municipality therefore needs to identify other safe and economically feasible faecal sludge removal options which can be provided to the 80,000 (and increasing) homes.


It appears from that that the health risks of emptying the UDDTs was a concern leading to the need to provide removal options to the homes.
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  • joeturner
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Re: What do we know about odorous gases from composting toilets (or from composting in general)?

Health assessments of UDDT and VIP systems in eThekwini Municipality:

The hygienic evaluation showed that both UD toilets and VIP latrines pose medium to high risk to the users. Helminth ova were found to be present in both UD and VIP faecal material. Increased concentration levels (ova/g ww) of Ascaris lumbricoides ova were found in VIP sludge. However, the viability of Ascaris between UD and VIP sludge at the time of sampling was similar.

The content of the UD toilet has a lower contamination/concentration level than the sludge of the VIP latrines, but emptying is done more frequently by householders, who are not well trained and equipped. The sludge accumulating in VIP latrines has a higher contamination, but emptying is done every 5 - 9 years by trained contractors. Flush toilets pose the lowest risk to the users as they do not get in contact with wastewater or side products.




Starkl, M., et al. "Evaluation of community and household based sanitation systems in Ethekwini Municipality, South Africa: lessons learned and recommendations." Water Practice & Technology 5.4 (2010).

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  • muench
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Re: Pathogen removal in UDDTs

I would like to come back to the discussion about the situation in eThekwini where they have recently decided to have the UDDTs emptied free of charge by the municipality.

The publications that you, Joe, mentioned above don't fully convince me. They are at the end of the day only theoretical risk assessments. Are there any studies that have shown more disease in UDDT users than in VIP users or even open defecators? This is something that I would find interesting, and alarming, but I don't think such research exists.

In fact, I remember one research from 2007 which showed the opposite (which is also what I would expect), i.e. less diarrhoea in areas of eThekwini which had UDDTs compared to the control area without UDDTs.

It is this one:

Lutchminarayan, R. D. (2007). Sanitation, water and hygiene in eThekwini Municipality, Durban, South Africa - Baseline cross-sectional study.
www.susana.org/en/resources/library/details/1169

From the abstract:

An observational analytic cross sectional study design was undertaken. A
multi-stage sampling procedure was followed and six study areas were randomly selected. Three Intervention Areas (urine diversion toilets) were matched with three Control Areas (no urine diversion toilets). A total of 1337 households, comprising of 7219 individuals, were included in the study. A Household Questionnaire and an Observational Protocol was administered by fieldworkers.
[...]
Households in the Control area are at a greater risk of developing diarrhoeal and other related diseases. The provision of safe water, urine diversion toilets and hygiene education in the Intervention area has proved to be successful.


I really wonder why not more of this kind of research is available by now? This one was done nearly 10 years ago now. Perhaps such research is available on the internet but I have missed it so far?
Or perhaps it's too expensive to do and therefore people rather do the desktop type studies looking at possible risks?

My point is this: I think it's really great if eThekwini has the money and resources to offer free UDDT emptying to all their clients, and to then proceed with value adding processing of the faecal material, like what they are trying now with the black soldier flie larvae. This centralised collection, management and treatment of UDDT products is most likely a very safe way of going about it. But it should not lead us to the knee-jerk reaction of saying that all municipalities shall do it like that, and that emptying of UDDTs by the toilet owners themselves is not acceptable and always too risky.

I think in the case of eThekwini the real reason for going towards the free emptying is actually a political reason. If VIP latrines are emptied free of charge then why should the UDDTs not also be emptied free of charge, too? And the "free of charge emptying thing" has something to do with the legacy of apartheid - why should one part of the population have a "sub standard" sanitation system than the other one... i.e. those outside of the sewered area compared to those inside of the sewered area of Durban.

Pointing to possible health risks with emptying of UDDTs is a theoretical reason but probably not the main reason for doing this.

From Nick Alcocks's presentation, the problem statement was (see his presentation www.susana.org/_resources/documents/defa...73-22-1424430016.pdf or check it out in this post: forum.susana.org/forum/categories/147-pr...ipality-south-africa )
  • Faecal degradation and pathogens die off not as effective as envisaged
  • High risks to households and environment
  • Service level inconsistencies
Personally, I suspect the third point (which I called the "political aspects" above) might have been much more important in this decision than the first two. But I might be wrong and it will be interesting to see how this all pans out in the longer term.

Regards,
Elisabeth

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  • neilmacleod
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Re: How aerobic are composting toilets really? How much pathogen kill? Clivus Multrum? And comparison with UDDTs

As the person responsible for this decision, perhaps I should comment. EWS is a customer driven organisation and so when market surveys showed an 80+% usage rate and a 35% acceptance rate, we realised that something had to be done. Customer feedback also showed that UDDT users did not like having to empty their own toilets.

As for the politics, political candidates have always pushed for flushing toilets for everyone at election time. My last estimate was that the cost to sewer the rural areas in Durban would be $6 billion, so piped water borne sanitation for all remains a dream. I will leave my personal views on the flushing toilet as a sustainable solution aside! It must also be remembered that our constitutional obligation is to provide BASIC services. If families want a higher level of service, they are not prevented from installing it themselves. A septic tank and soak away system costs about $2000 to construct and requires 400 square metres of undeveloped ground for evapotranspiration and that puts it out of the reach of poor families.

Regards

Neil Macleod

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  • joeturner
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Re: How aerobic are composting toilets really? How much pathogen kill? Clivus Multrum? And comparison with UDDTs

QMRA is the accepted scientific method to assess risks from sanitation systems. I guess we would have to ask Chris Buckley, whose team conducted the work (I think) how this risk assessment corresponds to rates of infection measured in those communities. Personally, I find the microbiological risk assessment rigorous and compelling.
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  • DaveBates
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Re: How aerobic are composting toilets really? How much pathogen kill? Clivus Multrum? And comparison with UDDTs

On the pathogen kill aspect, remember for those of us working in developmental settings where the standards are pit latrines leaching into groundwaters, sewage systems discharging raw sewerage to streams, and villagers defecating in the field or backyard, expecting 100% pathogen kill does not really make sense. The end product from most UDDT's that are just moderately well maintained far exceeds the options mentioned above.
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  • joeturner
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Re: How aerobic are composting toilets really? How much pathogen kill? Clivus Multrum? And comparison with UDDTs

Again, I am not talking about 100% pathogen kill - which would be impossible - but purely about the risk of infection. Those who have studied it in eThekwini state that the risk to a homeowner of infection from emptying a UDDT is substantial.
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  • KaiMikkel
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Re: How aerobic are composting toilets really? How much pathogen kill? Clivus Multrum? And comparison with UDDTs

I recently utilized the video that showcases the exclusive interview of Ian Macleod as captured by Idube Media for prerecorded video testimony that I created and presented to the House Committee on Fish, Wildlife and Water Resources of the Vermont (USA) legislature as part of my testimony on behalf of H.375, a bill that seeks to expand and incentivize the use of ecological toilets (UDDTs and composting toilets) and onsite greywater systems. Because I couldn't be certain of the acoustics of the room where the presentation will be shown or the quality of people's hearing who will see it, I added English subtitles to the portions of the film where he speaks in English. I wanted to make sure that everyone who watches the presentation understands every word that he says. I also edited the video for length.

Thereafter, and for purely educational purposes, I uploaded the edited and English subtitled version to YouTube. Here is the link to that version:



I made sure to provide as much information as I could as to the provenance of the film. And since I am only interested in promoting what Mr. Macleod said in the interview (which I think is crucial for people to hear) I hope that the information I provided in the notes section quells any concern over copyright.

Enjoy! :)

Kai Mikkel Førlie

Founding Member of Water-Wise Vermont (formerly Vermonters Against Toxic Sludge)
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  • muench
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Re: How aerobic are composting toilets really? How much pathogen kill? Clivus Multrum? And comparison with UDDTs

Dear Kai,

Thanks a lot for posting Neil's interview from October 2012 into this thread, that's great. Adding the English subtitles is a good idea as it helps particularly non native English speakers or those unfamiliar with the South African accent (hah! I see that even you struggled. ;-) Neil said "sewage works" but you understood "sewage books/plant", perhaps you can still correct that? I also saw an "its" instead of "it's" towards the beginning).

For those who cannot view Youtube, I have written down the main parts from Neil's message here:

[...] We are saying that we cannot carry on using flushing toilets. Nobody can. Not even the rich people.
And so it's trying to move away from this idea that a flushing toilet is something to aspire to.
And also to deal with this perception that a flushing toielt is what the wealthy people have and a dry toilet is what you give to poor people.
And rather try and move that debate to saying that everybody needs to change their toilet: the toilet that was invented in 1860 is no longer relevant in the 21st century.
And so we've made basically no technology advances in those 160 years and we need to do something new. So, the work that we're doing is trying to find ways to replace the old fachioned toilet with something that doesn't need water.

And we could have a decentralized system, process the effluent, recover the nutrients - which is another big concern, we're running out of nutrients for agriculture. Then what goes to the sewage works will be clean, the sewage works will be a lot simpler, we won't pollute the environment, the solution will be a lot more affordable to our customers and to ourselves.
So, there's a win-win all the way around. [...]


Kind regards,

Elisabeth

P.S. Kai, could you please still add the link to the original Youtube location (SuSanA Youtube channel) to the video description in Youtube and also add the date of the interview which was October 2012. In fact, perhaps you could add this link for people to find out more about this conference:
www.susana.org/en/resources/conference-m...-africa-october-2012
Thanks a lot.

And could you please tell us more in the other thread how things worked out with your proposed bill?
forum.susana.org/forum/categories/142-go...stems-in-vermont-usa

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