Disinfecting Urine and Being “Claire Twa”

Hello! My name is Claire or, as I was known around the office, “Claire Twa” (meaning Claire Three), since there were two other women named Claire working there at the time. I am a Master of Public Health student in Environmental Health at Emory University, and I worked with SOIL this summer to study various inexpensive and easy ways to disinfect urine before disposal. I tested the addition of different levels of ashes, vinegar, and Clorox since these three materials are accessible and inexpensive.


A typical container used for urine collection in toilets.

SOIL’s style of Ecological Sanitation (the safe re-use of the nutrients in human waste) utilizes a urine diversion toilet which separates the urine into a front container to be dumped by the user, and the feces into a bucket to be covered and collected by SOIL for treatment. SOIL diverts urine due to the high cost of transporting liquid to the waste treatment site. This leads to the difficulty of figuring out what to do with the urine that is diverted within the toilets. Currently, users simply dump the urine container out when it becomes full. While the vast majority of diseases are contained within the feces, some diseases can be transmitted through urine, and urine is often cross contaminated with fecal matter. The only WHO approved way for the disinfection of urine is to store it for 6 months. While effective, this is not something users can do easily in their homes.

For most of the summer, I worked in Atlanta, completing background research and planning the project. However, for 2 weeks in late June to early July, I was in Cap-Haitien completing my data collection.

While I did not have the ability to test directly for pathogens within the lab, I used pH and ammonia levels as a proxy for disinfection power. Urine is disinfected naturally by the ammonia it contains and raising the pH releases more of this ammonia and increases the disinfection rate. I tested this idea by adding different amounts of vinegar, Clorox, and ash to small samples of urine in the lab and adding ash directly to the toilets in the office to see how they would affect the pH of the urine.

The lab at the office, where I spent much of my time testing urine.

The lab at the office, where I spent much of my time testing urine.

Since vinegar is an acid, it lowered the pH of the urine. In order to lower the pH to a level effective enough to reduce pathogens, I discovered I needed a 1:1 mixture of urine and vinegar, which is not feasible for users. Vinegar did not turn out to be a feasible disinfection additive.

Clorox did not alter the pH of the urine at amounts likely needed to disinfect (20-100 ppm chlorine). At 1000 ppm chlorine, it significantly lowered the pH of the urine by approximately 0.2. While it did not show an increase in pH, according to the literature, these levels of Clorox likely disinfected the urine, I just did not have the ability to test for it.

Finally, adding ash to the urine raised the pH significantly in all of our trials in the laboratory. When I treated the toilets in the office, on the 2 days I added 500 ml of ashes to the 1 gallon bucket of urine, the pH was significantly higher by between 0.5-2.5. However, on the one day when I only added 200 ml of ashes, the pH of the urine from the treatment toilet was lower than that of the control toilet. These results show that adding ash to toilets or urine could potentially increase the disinfection rate, however more tests quantifying the change in disinfection rate and the amount of ashes needed will need to be done. We are hoping that this project will help guide future research to develop an easy way for users of urine diverting toilets to dispose of their urine safely.



While I was working hard collecting data for most of my time in Haiti, I was able to play tourist during my one full weekend there. On Saturday, we went to Paradis, which is a beautiful beach you can only reach by boat. We first took a moto to Labadee, which is where the cruise ships dock and then from there took a boat to the beach. It was amazing to how different the area where the cruise ships dock is from Cap-Haitien. It made me wonder if the tourists who dock there think this is what “normal” Haitian life is like and especially grateful for my experience with SOIL living in Cap-Haitien and meeting and working alongside Haitians daily.

On Sunday, I took a taptap out to Milot and hiked up to the Citadel. The hike was a lot longer than I anticipated, however we did stop often along the way and even bought coconuts to drink. The Citadel was breathtaking. It rivaled the forts I’ve visited San Juan, Puerto Rico in both size and beauty. There were also beautiful views of the Haitian mountains, and you could see all the way to Cap-Haitien on the coast. It was without a doubt one of the most impressive places I have ever been.


The view from the citadel.

Living in Haiti for two weeks was a constant adventure and learning experience. I loved the adventure of taking a moto, a ti bus (a 12 seater van), and a taptap to and from work every day, even if they were sometimes extremely uncomfortable rides. I loved walking around Cap-Haitien, even when I couldn’t understand 95% of what people were saying around me. I met so many wonderful people in Haiti, and I cannot thank SOIL enough for being wonderful hosts and helping me constantly throughout this project!

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4 Replies to "Disinfecting Urine and Being “Claire Twa”"

    September 29, 2016 (7:48 pm)

    Claire ”3″,
    Thank You very much for sharing the results of your research about Managing the Urine from the UDDT.
    Body uses urine as a balancing medium for liquids and salts. At excretion, the Urine pH is normaly around 6 but can vary between 4.5-8.2 (more or less the same worldwide).
    As you said, the main problem when using UDDT Technology is the Urine contamination by faeces. Normaly number of pathogens in Urine is very low. One Pathogen of concern is ”Schistosoma haematorium” (causing Bilharziasis) where eggs can be excreted in the Urine. So, if this pathogen is endemic in Areas where the Ekolakay Toilet is used, urine should not be dumped without treatment (storage).
    Pharmaceuticals that we consume are excreted with the urine, this is also a problem. It is considered better to dump urine to arable land than to flush the Pharmaceuticals into recipient Water because pharmaceuticals are degraded in natural environments with a diverse microbial activity.
    As it is suggested by the results of some reserach, it is possible to degrade pharmaceuticals residues by Ozonation.
    Once again, thank you Claire ”3” for sharing your experience in Haiti.
    Best Regards.

    • Monika Roy
      October 1, 2016 (7:25 pm)

      Hi Josue,
      Thanks so much for your insights! Yes, schistosoma is a concern when dealing with urine. To date, most reports about schistosoma originate from sub-Saharan Africa, although we hope there will be more research in the future on whether schistosoma is also an issue in Haiti. As for pharmaceuticals, while this is also a concern for urine management, at our compost site all of our wastewater undergoes a primary septic treatment, and then a secondary sub-surface wetland treatment which we expect greatly degrades pathogens and other contaminants in the effluent. Thanks again, and take care,

      -Monika and Claire “3”

  • Chris Canaday
    October 13, 2016 (10:16 am)

    Dear Claire,

    Thanks for sharing your research.

    The use of wood ash is a great idea, since it is presumably abundant and free, if people are cooking on wood fires. In addition, some recent studies have shown that urine + ash is an especially good fertilizer for plants. Do Haitians currently use wood ash for anything?

    I would highly discourage disinfecting urine with Chlorine, since it combines with urea to form Trichloramine, which is a poisonous gas. Chlorine can also combine with other organics to form chlorinated hydrocarbons and other toxic substances, including those called disinfection byproducts. In addition, chlorine is expensive and is dangerous to handle (and alternatives should be promoted for laundry purposes).

    Vinegar also is costly and its acidity goes against the natural tendency for the pH of urine to increase and thereby sanitize itself.

    Bilharzia (= Schistosomiasis) is only transmitted if infected urine goes into fresh water where certain snails live and people swim, so there is no risk if it is spread on the soil.

    My preferred method is to distribute the urine immediately and directly from the UDDT via a perforated hose buried in the ground among productive plants. This way, the urine disappears immediately and productively, without anyone having to deal with it. Also, the soil receives small doses daily, which is presumably much better for soil microbes and plants than big (potentially overwhelming) sporatic doses. So far, I install 12-meter-long hoses for a family UDDTs. G. Sridevi did her PhD on fertilization with urine in India and found that a banana plant does really well with 63 liters of urine in its one-year life cycle, so it would be great to link each person to about 6 banana plants via these hoses.

    Another thing is that no one can catch anything that they already have, so there is very little risk if a family spreads their urine on the soil of their own garden.

    Are the users encouraged to dilute their urine with 3 or more times as much water (preferably greywater, to not waste clean water, plus the chemicals get more treatment and there are more nutrients present)? This is especially important in the dry season. One interesting tidbit is that apparently we can put very large amounts of pure urine on bare soil over a week before planting, since there are no plants present to get overdosed and microbes will integrate the nitrogen in the course of that week.

    Pharmaceuticals get much more treatment in the soil, as compared to any water-based system, plus water can go straight to other people. I also think that these big organic molecules simply do not fit through the various doors in root hairs, so they cannot contaminate the food produced by plants. (Can someone please confirm this with a plant physiologist?)

    I would be glad to help advise on future research, plus researchers would be welcome at the Omaere Ethnobotanical Park that I coordinate in the Amazonian part of Ecuador. omaere.wordpress.com

    Best wishes,
    Chris Canaday, inodoroseco.blogspot.com

    • Claire Remington
      October 14, 2016 (3:06 pm)

      Hi Chris! Hello from Claire “1!” Thank you for the message and for sharing your best practices!

      The recommendations for both storage and dilution, as well as mixing in wood ash, are currently under consideration by the operational team. Thank you Claire “3” for the useful and immediately relevant research! The banana watering strategy is less feasible as the majority of our clients live in dense, urban areas without gardens.

      Regarding PPCPs and plant-uptake, here is a link to an interesting summary article: http://citeseerx.ist.psu.edu/viewdoc/download?doi= Plants can uptake (and sometimes even concentrate) PPCPs, and the rate of uptake, degradation, and other chemical characteristics vary by contaminant. It does sound like composting is more effective than other waste treatment technologies in degrading PPCPs.

      The conversation around chlorination is interesting as well. I’ve done only a little bit of reading around disinfection byproducts (including trichloramine) from chlorination in wastewater treatment plants in the U.S. I know that there are conversations ongoing around replacing chlorination with ozone- and peracetic acid-treatments, but I don’t know what the current state of practice and regulation is?

      Thank you for the offer of advice and research! We’ll be in touch!

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