hazards from urine collected from UDDTs - new research paper from eThekwini

  • kudert
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Re: hazards from urine collected from UDDTs - new research paper from eThekwini

I am not aware of any experiments using UV for urine treatment, but there is a study on using ozone. The purpose of the study was rather the removal of pharmaceutical residues:

Dodd, M.C., Zuleeg, S., Von Gunten, U. and Pronk, W. (2008) Ozonation of source-separated urine for resource recovery and waste minimization: Process modeling, reaction chemistry, and operational considerations. Environmental Science and Technology 42(24), 9329-9337.

pubs.acs.org/doi/abs/10.1021/es800560r

Swiss Federal Institute of Aquatic Science and Technology (Eawag)
Process Engineering
Dübendorf, Switzerland

Recover nutrients!
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On-site treatment going to extremes: www.bluediversiontoilet.com

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  • joeturner
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Re: hazards from urine collected from UDDTs - new research paper from eThekwini

Thanks Kai, that is interesting.

Do you have a feel for the way that the UDDTs you've studied are actually being used? Are they storing the urine for long enough to be safe enough for reuse without further treatment? Should be still not be focussing on the risks from untreated faeces rather than the (far lower) risks from urine?
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Re: hazards from urine collected from UDDTs - new research paper from eThekwini

Hi Joe,

As far as I know the "regular" users of UDDTs in the eThekwini area do not reuse urine at all, but the urine is simply infiltrated. Reason being that they don't do any gardening activities (apparently). So no risks with respect to urine reuse there.
I think during the VUNA project there might have been some treatment and reuse work but that was done in a research context where it is much easier to provide the "perfect" conditions with regards to safety (?). Kai, please correct me or clarify? Thanks.

See also here for a related thread about the UDDTs in the eThekwini area:
forum.susana.org/forum/categories/34-uri...wini-in-south-africa

Overall (for other cases than the eThekwini case where people are not looking for fertiliser), as Kai pointed out, we need to balance the risks of urine reuse regarding potential disease transmission and pharmaceutical residues entering the environment (which is - as we all know - much less significant than with reused faeces or faecal sludge or partially treated wastewater), versus the potential benefits regarding a potential increase of crop yield. Nevertheless, I do think the research that you (Kai) and others have done and are still doing on risks of urine reuse is very important so that we gain more clarity over the risks and how to manage them. So I think it's good to discuss it in this thread here.

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Elisabeth

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Re: hazards from urine collected from UDDTs - new research paper from eThekwini

muench wrote: Hi Joe,

As far as I know the "regular" users of UDDTs in the eThekwini area do not reuse urine at all, but the urine is simply infiltrated. Reason being that they don't do any gardening activities (apparently). So no risks with respect to urine reuse there.
I think during the VUNA project there might have been some treatment and reuse work but that was done in a research context where it is much easier to provide the "perfect" conditions with regards to safety (?). Kai, please correct me or clarify? Thanks.


That's how I understood the situation in eThekwini too, but I assume this means that fresh urine is being released regularly into the surface-soil environment, so I don't know whether this actually means that there are "no risks with respect to urine reuse".

We know the potential for problems with latrine leaks into groundwater, which then comes around again in potable drinking water, but I think many have assumed as you have above that there is "no risk with respect to reuse" from UDDT urine infiltration and I'm trying to understand if that is actually now considered to be the case. Presumably eThekwini think it is a potential problem or they'd have not commissioned the research.
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Re: hazards from urine collected from UDDTs - new research paper from eThekwini

Ah, OK, see what you mean, so you're referring more to the groundwater pollution aspect in this case? I thought you were referring to inexperienced (or careless) users/owners of UDDTs handling the urine from their UDDTs during reuse activities (which they are not in the case of eThekwini).

Groundwater pollution is a different matter but as far as I know this has also been researched in great detailed by South African researchers (see also this forum category here: forum.susana.org/forum/categories/193-gr...king-water-treatment ). No generalised statements can be made on this but for this specific case of eThekwini I think the conclusion was no signficant risk because a) the groundwater level is extremely deep and b) the groundwater from that area is not used for drinking water (i.e. no local wells). (how the groundwater might interact with surface water somewhere else in the hydrological cycle of that particular area - i.e. with regards to pharmaceutical residues - I don't know)

But I look forward to Kai's response on this.

Did eThekwini really comission this research? I thought they were a research partner but the funding came from the Bill & Melinda Gates Foundation for the VUNA project (more on VUNA see here:
www.susana.org/en/resources/projects?search=VUNA ) and it had also a rather fundamental research aspect, rather than perhaps responding to immediate questions from the municipality, let alone responding to situations of people falling sick from using UDDTs (?).

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Re: hazards from urine collected from UDDTs - new research paper from eThekwini

There are other potential pathways than groundwater contamination - for example sideways leaking onto foodcrops. Lateral/sideways flow is a common thing in topsoils (which might be different to the issue of plumes from a latrine if the latrine is much deeper into the ground than a UDDT).

Or the pathogens/viruses might persist in the surrounding soil where the urine has generally percolated and disperse, to be picked up by small children playing with the soil.

Maybe it really is no risk at all, hence why I was asking the question.
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  • kudert
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Re: hazards from urine collected from UDDTs - new research paper from eThekwini

Hi Joe and Elisabeth

Lots of questions and comments! I try to address them.

It is correct that the hygienic risk from feces is much higher than from urine. However, it should also kept in mind that there are some risks from urine as well. This does not only concern the direct use as fertilizer, but also the collection of urine including spilling urine in a larger tank, and the discharge of untreated urine to the ground. Our data hopefully help to make a proper risk assessment.

Uncontrolled discharges to the ground, i.e. directly at the toilet and not for agricultural purposes is also critical due to the high nutrient loads. For the drinking water quality, this might be at least as critical as the pharmaceutical residues.

In the VUNA study, the urine was collected by municipal staff from UDDTs in peri-urban eThekwini but also brought by toilet users to a central collection point. We tried to provide safe conditions during collection. These conditions will also be provided by EWS for further collection campaigns.

The VUNA study was financed by BMGF. It was a joint project of Eawag and EWS.

Swiss Federal Institute of Aquatic Science and Technology (Eawag)
Process Engineering
Dübendorf, Switzerland

Recover nutrients!
www.vuna.ch

On-site treatment going to extremes: www.bluediversiontoilet.com

On the bookshelf: Source Separation and Decentralization for Wastewater Management
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