In part 1(1) of this article I explored a little into why humanure is beneficial to the planet, including the need to replenish our aquifers and for people to have access to safe drinking water, the high phosphorous content of human poo compared to the finite and dwindling supply of phosphate rock as an agricultural product, and the reconnection of the ‘human nutrient cycle’ (2). In this part I will look more deeply into the different ways you can safely use humanure, and make some practical suggestions for beginning the process of redressing the human nutrient balance, even while we live within an unbalanced system.
Ways to deal with our crap
In ‘The Humanure Handbook’ (2) , Joseph Jenkins points out that we as a species have four different ways to deal with human excrement:
- To treat it as a waste product and dispose of it – this includes all water-based sanitation techniques such as flush toilets. As mentioned in part 1, this method ends up contaminating water even if the sewage is later treated, exacerbates the spread of water-borne diseases, and ignores the principle of ‘Produce No Waste’.
- To use it unprocessed in agriculture – at the time of the Handbook’s publication (1999) this was apparently still a common practice in parts of Asia (2). As you may guess, spreading unprocessed human waste on fields can be quite a large health risk because of the pathogens which are present in fresh humanure. This practice, euphemistically known as ‘night soil collection’ (3) , has apparently now been banned in many countries although there are some reports of people continuing to use fresh human waste, or ‘faecal sludge’ on their crops, for example in India (4) .
- To slowly compost the poo over a period of months – this is how most compost toilets work. As long as you leave the composting excrement for long enough using this method, the resulting humanure should be generally safe to use on your food crops.
- To cultivate heat-loving microorganisms as part of the compost process – this method, known as ‘thermophilic composting’, creates a high-temperature environment to ensure the destruction of all disease-causing organisms.
Some like it hot…
Slow composting “eliminates most disease organisms in a matter of months, and should eliminate all human pathogens eventually” (2); however, thermophilic composting is “the only composting method that can kill all human pathogens and parasites that can exist in human excrement” (5). So if you slow compost your poo it will generally work and the risk of pathogens in your compost may be low. It seems its up to each of us to make our own decision about whether or not it is worth taking that risk. If you are going to begin composting your poo, thermophilic composting can be seen as the safest (or some might say, the only safe) method of doing so.
‘Thermophilic’ is a complicated word and may be putting some readers off. However, you will probably be pleased to know that heat-treated compost toilets can be made on a home-scale, using natural resources, such as the greatest source of heat available to those on our planet; the sun.
Utilising passive solar energy can be seen as a very efficient way to add heat to your compost toilet. There are many home solar toilet designs out there, most of which are based on the simple process of collecting the sun’s heat using a flat, dark-coloured surface or mass of some kind, and encouraging air flow via a ‘chimney’ or ‘exhaust’ (5). There are also a few ‘do-it-yourself’ guides available online though as with all DIY guides, it is advisable to look with a slightly critical eye at the designs to check if they are really what you want to do. One example is the solar composting toilet design from ‘Solar Homesteading’, which uses a concrete tank sunk into the floor with windows on top to capture the sun’s heat (6). Though the heat-capturing of this design can be seen as energy-efficient, the lack of access to the humanure itself seems inefficient. A much more useful-seeming design comes from Dunton Farms, in Oregon, USA (7).They have a very detailed description of their solar composting toilet design and build process on their website (8).
There also appear to be a few companies offering ready-built solar composting toilets or for you to pay in order to purchase instructions for how to build them. I have not tried out any of these companies so I cannot comment on them, but if you want a solar compost toilet but don’t have the time or skills to build it yourself, it could be worth investing in.
If you can build a solar or other thermophilic compost toilet in your garden, you may be content to stop reading now. However, many of us may wish to start regenerating soil and replenishing aquifers by recycling our excrement, yet for whatever reason, cannot create our own compost toilet right now. This could apply to those who live in an apartment, don’t own their own property, live with people who are opposed to the idea, or are nomadic. In situations such as these it may still be possible to begin composting your poo, but it will probably involve a lot more of the social permaculture aspect in order to get it to happen.
Encouraging others to poo consciously
One idea for enabling the safe composting of at least some of your excrement could be to try to persuade a community centre in your area to input compost toilets. In order to do this you would also need to gain the support of the community; but if this was achieved the toilet could theoretically be built more swiftly and easily than if it was in a private home, since you would have access to more manual and financial resources from the expanded network of conscious composters. If you have a community centre in your area which is already designed for regenerative practices this could be a relatively easy process. I plan to look into some examples of successful community compost toilet implementation in part 3 of this article.
Do what’s right for you
In conclusion, it seems that although changing human excrement into safe and utilisable compost is a relatively simple process, without adequate high temperatures there is a health risk, and so if you are not certain that your compost toilet design is pathogen-free, it may be better for you to wait until you can make sure that it is. However, there are many examples out there of slow-composting toilets which can still be seen as effective. I have visited and lived in a number of places all over the world which use slow-composting toilets, though I do not necessarily recommend them. As with everything, what you decide to do is your choice.
- Ashwanden, C, 2018. ‘Humanure part 1: Why should we give a crap?’ Permaculture News, 23/11/18. https://permaculturenews.org/2018/11/23/humanure-part-1-why-should-we-give-a-crap/
- Jenkins, J, 1999. the Humanure Handbook. Joseph Jenkins: Grove City, USA
- Tilley, E.; Ulrich, L.; Lüthi, C.; Reymond, Ph.; Zurbrügg, C, 2014. Compendium of Sanitation Systems and Technologies (PDF) (2nd Revised ed.).Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland.
- Maier Vidorno, 2018. ‘Water and Sanitation in India’.http://www.maiervidorno.com/water-sanitation-india/
- Roper, LD, 2016. ‘Composting Toilets for a Sustainable Living’. http://www.roperld.com/science/compostingtoilets/compostingtoilets.htm
- Solar Cabin, (?). ‘Solar Assisted Composting Toilet’. https://www.instructables.com/id/Solar-Assisted-Composting-Toilet/
- Dunton Farms, 2018. ‘About Us’. http://www.duntonfarms.com/about_us.html
- Dunton Farms, 2006. ‘Constructing Our Solar Composting Toilet Building 33’. http://www.duntonfarms.com/projects/2006_toilet.htm