It's everyone's favorite topic to skirt, that topic that's discussed only when talking about cleaning up after the dog, or kitten, or baby. What is it? Poop! While there are a variety of names for it in many languages--feces, kaka, crap, etc.-- it's something that's rarely ever talked about. I mean, how often do you think about where your last lunch went after you flushed it down the drain? Probably never. And what's the worst-case scenario for you when you really have to go? Someone forgetting to put the seat up or down?
Well, what IS the worst-case scenario for the rest of the world? Probably a lack of a toilet in the first place. No, not a lack of a flushing toilet, but literally people doing their business wherever they please because no structure, hole, or anything else is available. An estimated one-third of the world's 2010 population lacked access to a toilet according to the Joint Monitoring Program of the World Health Organization, United Nations, and UNICEF. Numbers for some of the poorest areas of the world, including sub-Saharan Africa and South Asia, get as high as 70% lacking access to suitable toilet facilities. This becomes a problem when talking about stopping the spread of disease-causing microbes in the environment.
Onto a lesser thought-of question...
Where does that stuff go after I flush it?
For those in the United States, most of our solid waste (poop) is sent in water to a wastewater treatment plant, where it is treated to kill microbes present, then released. While we may think we have the resources (read: clean water) to deal with our crap, we do have to worry about where our waste goes and the resources used to process it and make it safe. It isn't a reality for us or the rest of the world to expect new, clean water to continuously be available for our sanitary systems. Additionally, a lot of nutrients and minerals that are consumed by animals have been shown to be limited in quantity throughout the world. We simple don't have an unlimited source of certain materials that we both use and consume.
How does this relate to your own poop? Well, our bodies, while amazing at many things, are far from 100% efficient at using the nutrients in the food that we consume. Thus, our stool contains nutrients and minerals that comes from plants and animals that we eat--that is, nutrients that came from our environment and could possibly be returned to that environment. The recycling of these nutrients back into agriculture or the environment is the idea of Ecological Sanitation or "EcoSan."
Gross! I want to use a toilet, I'm not just going to do 'it' on the ground! That's unclean!
EcoSan uses toilets. The idea is that you have a Port-o-Potty of sorts, except instead of the poop just sitting there, it is covered with husk or other plant material in a barrel under you. This allows the fresh stool to start to compost--that is, chemically and biologically break down to generate usable nutrients for fertilizer. Once the barrel is full, it's replaced. Generally, the full barrels are collected regularly and brought to a composting site where they can be dumped into bins, introducing oxygen into the composting process and allowing the piles to heat up.
 |
| "Fresh" compost pile in Port-au-Prince, Haiti |
Do I urinate into this as well?
Nope! Urine is generally diverted (like a small urinal inside the toilet) to be collected in a separate jug (see below). It provides a valuable source of nitrogen for the future fertilizer!
 |
| Urine collected in jugs to be added to compost piles |
Is it safe?
Yes, when done correctly, EcoSan produces a safe final compost product that is essentially fertilizer for future farming. There are a variety of ways to kill off the nasty bacteria, viruses, and parasites that you might worry about in there. When the poop/husk/plant material combination is assembled into piles off-site, it heats up due to the decaying process. This temperature can get over 160 degrees, high enough to kill even the hardiest microbe if sustained long enough. Other ways? Well scientists have determined that adding ash or lime (the powdered kind, not the citrus!) can speed the death of the microbes. Drying is another process unfriendly to microbes that live in feces. After several months of composting, all microbes are generally dead and the fertilizer is ready, though these methods can speed up microbe die-off to requiring only days.
What's the catch?
There are 3 catches: compost quality, the size of the operation, and its acceptability. While drying compost and/or adding lime or ash may hasten the death of the microbes, it can also affect the overall quality of the final compost product. Think about it, would you want fertilizer that's really dry? No! Would you want fertilizer with low nutrient quality? No! Ash and lime can also take away some the nutrients in the compost that would make it good as a fertilizer. Thus, use of these methods must be balanced with the need to ensure a final product of good quality, which requires trial and error, since every situation is different. The quality of the final fertilizer will affect its growth and acceptability by the local community, discussed more below.
Also, most EcoSan operations worldwide, of which there are many, have been in small contexts: on the order of small villages, not cities or even large villages. Assuring the quality of the process and final product when operations are scaled up is a challenge that has not yet been encountered in the EcoSan community, but one that will have to be addressed in the near future.
Finally, there are obvious stigmas surrounding the re-use of our waste for agriculture or other processes that eventually produce crops, etc. that we consume. To many, this seems unclean, wrong, or otherwise unsafe. If done correctly, EcoSan can be effective and safe, but important conversations must take place between the community and those promoting EcoSan to make sure that everyone's on the same page. This is another challenge to the scaling up of operations discussed above as well.
What's the takeaway?
For now, EcoSan provides an effective way to recycle some of the limited nutrients, like nitrogen and phosphorus, that would otherwise be wasted in a landfill. It does have its limitations, which at this point include the quality of the compost as a fertilizer, its ability to be used on a large scale, and the general acceptability of the whole process. Through careful development and cooperation, EcoSan can grow into a successful operation on a local scale. Whether it grows to succeed on a larger scale remains to be seen.
David Berendes is a first-year PhD student in the Environmental Health Sciences Department at Emory University's Rollins School of Public Health. His research interests include sanitation and environmental pathogen transmission.
