Practical experience of evaporation beds used to evaporate urine?

  • DominikR
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Practical experience of evaporation beds used to evaporate urine?

Dear all,

I am a student from Austria comparing currently used (and promoted)a sanitation systems with UDDTs in rural, coastal areas of Vanuatu (a small island state in the South Pacific) in regard of their appropriateness under the prevalent conditions (high groundwater table, flood prone, no piped water supply, rising sea level, cyclones ). The main part of this comparison is about the identification of potential exposure routes along the 'functional groups' of the system (Tilley et al., 2014) and measures to mitigate the risks.

The concept of UD was not tried in Vanuatu so far, but people seem to be very interested (the majority of people depend on home consumption, i.e. subsistence agriculture).
Concerning UDDT, I thought about Dehydration vaults with a combination of storing the urine in jerry cans, and evaporation (or combined evaporation & infiltration) of urine (collection, treatment and application of urine on household level only).
Such a combination would allow maximum flexibility for the user (motivation, size of garden, monetary resources (e.g. even jerry cans are costly, everything has to be imported and transport costs from main islands to outer islands are considerable) , potentially preventing overapplication, etc.).

Unfortunately, I hardly find any sources reporting practical experiences and recommendations of evaporation beds used to evaporate urine.

Hence my question: Are there any (long-term) experiences regarding odours from ammonia volatilization, salt accumulation, clogging, proper dimensioning, O&M, common problems etc. when urine is evaporated by means of evaporation beds?


Any help or hints are appreciated,

regards,
Dominik

a Single Pit System (Bush toilet, Single-Pit Dry Latrine, Single-Pit Ventilated Improved Pit Dry Latrine, Single-Pit Pour-Flush Latrine), 'Composting toilet' (= Double vaults (VIP) above ground operated like Fossa Alterna; promoted by NGOs)
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  • bowenarrow
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Re: Practical experience of evaporation beds used to evaporate urine?

Morning Dominik.
I cannot give you any references to academic papers on this subject however I can give you anecdotal information as a manufacturer of Urine Diverting toilet pedestals based on my 35 years experience of distributing these pedestal across Australia, both in single sales and bulk sales to the Composting Toilet industry. In the 1980's we sent many pedestals to the Pacific area and am quite aware of water table and flooding issues that exist.
Prior to the uptake of Urine Diverting pedestals industry relied on pedestals that collected all the waste, urine included into one chamber with a leachate drain taking fluids to a "French drain" being a trench backfilled with layered gravel. This method is deficient in that the urine being mixed with faeces just carries pathogens to another place.
With the use of Urine Diverting pedestals the urine is carried away separately to a layered gravel trench and plants such as Bananas and citrus trees did very well from the rich potassium delivered. We are always mindful that not all sites will be suitable however in warmer climates reports we have from users are that there is no evidence of problems at least at a domestic level. The added advantage of UD pedestals is that the collected mass is greatly reduced and breakdown occurs much quicker.
The biggest problem with UD's is cultural and behavioural.
I would not go as far to say that larger group systems rather than domestic individual systems would act in the same manner, but my experience (anecdotal as it is ) and the take up of these UD's over the last 30 years is that they are becoming more and more popular, giving a solution in a "dry" country such as Australia to the larger problem of flushing toilets.
Ross
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  • muench
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Re: Practical experience of evaporation beds used to evaporate urine?

Hi Dominik,

You asked about:

"Are there any (long-term) experiences regarding odours from ammonia volatilization, salt accumulation, clogging, proper dimensioning, O&M, common problems etc. when urine is evaporated by means of evaporation beds?"

I am wondering if you did a search on the forum using the keyword "urine evaporation"? I did and found this thread, I am wondering if you've seen this already?:
A Novel Urine Evaporation and Collection System (via a solar oven and chimney) - research from Calgary, Canada
forum.susana.org/forum/categories/34-uri...-from-calgary-canada

Does that help?

Please tell us more about your research, sounds interesting! And Vanuatu is a nice place to do your field experiments at - just a bit far from Austria? ;)

Regards,
Elisabeth

Dr. Elisabeth von Muench
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  • DominikR
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Re: Practical experience of evaporation beds used to evaporate urine?

Dear Ross, dear Elisabeth,

thanks to both of you for your constructive responses, sry for the somewhat delayed response on my part.

I am looking for experiences with infiltration or better evapo-transpiration beds to infiltrate/evaporate urine of UDDTs or leachate from 'composting toilets'. Since these should be applicable in areas with high water tables as well as areas which have already deterioated ground water quality, evapo-transpiration beds would may be a better choice. Hence I wanted to know if there are any experiences regarding accumulation of precipitates of urine in the bed may causing it inoperable after some time; and long-term experience concerning the effectiveness of evapo-transpiration beds, especially during raining season etc. (combination of infiltration - evapo-transpiration beds to prevent overflows?); as well as practical experience when leachate is drained off via a infiltration bed, and if it is potentially possible to implement this technology to evaporate leachate also.

It's a bit problematic, because I hardly find experience about these rather simple measures in regard of long-term operation and it would be nice to draw from the experience others already made to come up with something that may be operable for a prolonged time.

kind regards,
Dominik
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  • DominikR
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Re: Practical experience of evaporation beds used to evaporate urine?

@Elisabeth: indeed, Vanuatu is not around the corner :)

The research is split in two parts, my colleague covers the technical planning, economical comparison and utilization of materials available on-site to minimize the costs and potentially increase the acceptance.
May part comprises of the identification of potential exposure points and measures to mitigate the risk along the system, similar to SSPs. Further a rather small part on awareness raising is included.

The idea of my colleague and me was to come up with something which is not only taking a look on a specific problem, but rather take the most important factors into account.

UDDTs would be very interesting to be implemented in the region since the greater part of the population (partly) rely on subsistence farming. At least to give it a try :)

kind regards,
Dominik
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