Discussion
“Conventional wisdom” or fecophobia (the irrational fear of feces) may
lead people to have the following doubts about this system:
Couldn’t the fecal pathogens get out through
the woven cloth of the sack?
Aside from hookworm larvae, fecal pathogens do not actively move
anywhere and just wait passively to get washed into someone’s drinking water,
brushed onto someone’s unwashed hands before they eat, or carried by flies to
someone else’s food. These are the risks of open defecation, with fecal
pathogens set loose in the environment. Liquids do not flow out of these sacks,
given the dry cover material we add after each use, the separation of the
urine, and the protection against the rain. The permeability of the woven cloth
is actually a positive thing, since this allows humidity to evaporate out and
oxygen to filter in (without smell or flies coming or going), so the feces can
decompose normally, with the pathogens dying off at an exponential rate. See an
example of letting feces decompose in these woven sacks in this video.
As shown in this graph from the Humanure Handbook by
Joseph Jenkins, fecal coliform bacteria die in the soil at an exponential rate.
Getting back to the hookworm larvae, they only travel through moist sandy
or loamy soil (not clay), so some sticks or stones may be placed under the sack
when it is placed under that bridge, and wood ash (which is alkaline) may also
be placed on, around, and under the sacks. Furthermore, hookworms are not
usually life-threatening, nor are they terribly common, with “only” up to
some 740 million persons infected
in the world, mostly in Africa and Southeast Asia. It is reasonably easy to
check if people have them (using a microscope) and to wipe them out with
chemicals or with natural alternatives, such as papaya seeds. Plus we should
always remember that hookworm larvae can only be in the feces if the users have
these worms. Pathogens cannot come out of nowhere, and, in the case of
hookworms, the biggest factor is dogs practicing open defecation and the larvae
crawling into people’s feet. (If you do not know what hookworms look like, see
this article in the Examiner.
Hookworms do not just eat people’s food, but instead their blood. They were
clearly the inspiration for the creature in the movie Alien.)
Can we be absolutely sure that all the
pathogens will die and that no one could possibly ever get sick via this
system?
No. Someone could come along and open the sack before it is time,
without reading the tag, but any system can go wrong if not used right. What we
can be sure about is that all the fecal pathogens are still alive and kicking
in people’s fresh feces that might otherwise go straight into the environment.
We also know that these pathogens die off at an exponential rate as feces
decompose. The important thing is to keep these nasties jailed up while this is
happening and every day of containment is a victory in the war against disease.
Essentially all of these pathogens are anaerobes adapted to live in the absence
of oxygen, in the aqueous habitat inside our guts, and there is only a certain
amount of time they can hang on in a dry, oxygenated substrate before infecting
the next person. Given this situation, the most persistent fecal pathogens have
evolved desiccation-resistant packaging, like the amoebic cyst and the shell of
the Ascaris egg, but even these can only protect them for a certain amount of
time.
A key factor is the rambunctious and relentless nature of the microbes
in rich organic soil, eating everything that does not eat them first. Most
pathogenic microbes would be easy prey to soil organisms and it has been shown
that fecal bacteria die-off faster in species-rich
soil, as I recommend using here, optimally with the reuse of finished
compost as cover material, with exactly the microbes that broke down the feces
of the previous cycle, and which are not human pathogens.
Schönning and Stenström (2004)
recommend storing the feces, with an ample amount of wood ash or mineral lime
for over 2 years in the Temperate Zone and 1 year in the Tropics. Personally, I
think this is overcautious, especially in the biodiverse, warm Tropics, but
these detention times can easily be applied if there is enough space and it
makes people feel more comfortable. These times refer to the most persistent
fecal pathogens, which are the eggs of the Ascaris Giant Roundworm, and all the
really dangerous microbial pathogens are wiped out in less than three months. We have
done trials to look for Ascaris eggs in our fecal compost, here in Amazonian
Ecuador, and have yet to find any beyond four months of decomposition. More
trials need to be done and a simpler, more conclusive protocol that mostly only
requires a microscope needs to be developed. And even I store the feces for
over a year, for more peace of mind of all the users.
No one wants to go on record recommending a detention time that may
potentially allow someone to get sick, and this is especially the case with
governmental and international organizations. I am nonetheless willing to go
out on this limb, given that the worst alternative is to continue with the
currently abundant cases of open defecation, raw sewage going straight into so
many rivers and bays, and 2.6 billion people in the world that do not have any
sort of decent toilet. And, if over time, we find that we should modify these
suggested detention times (longer or shorter), we can do so.
Aren’t we supposed to store urine for a
number of months to sanitize it before applying it on the soil?
This concern is due to the possibility that feces may have contaminated
the urine through people using the UDDTs improperly or having accidents … and
this is very unlikely with this “bare bones UDDT”, in which the user holds the
urinal right where it needs to be. If an accident were to happen, the user
could dump the urine in a hole in the ground and cover it up, instead of
spreading it on the surface of the soil. In places where there is the Bilharzia
parasite, Schistosoma haematobium, urine should be spread on the
soil far from lakes and rivers, so that this parasite cannot get to the
freshwater snails it needs to infect in order to continue its life cycle.
Won’t some animal, like a dog or a rat, tear
open the sack and spread this dangerous material around?
Experience has shown that they do not, especially if we are using soil
as a cover material, in particular that special recycled soil. There have been
a couple of cases of mischievous dogs, but only when pure sawdust was being
used as the cover material. Soil and finished compost are also among the best
filters for odors.
Fecophobia aside, other
important questions can arise:
Why should we protect the sacks from the sun?
Wouldn’t the solar rays help to kill the
pathogens?
Yes, they would, but the ultraviolet light also destroys the
polypropylene plastic strands of the sacks. Solar ovens that take this into
account would be a good idea (and we can be much more patient about baking feces
for sanitation than about baking lunch for our urgent hunger). According to the
following graph, we only need to achieve 65°C for an hour to kill all of the
fecal pathogens, and this is much easier than the 100°C required to boil water.
One time, a student and I made a simple solar oven from recycled materials, and
we apparently got to above 80° C, because the PET plastic Coke bottle got
deformed and the Ascaris eggs held within were also seen under the microscope
to be deformed and almost certainly dead.
A graph showing the time necessary for various human fecal pathogens to
die at different temperatures, from Feachem, R.G., Bradley, D.J., Garelick, H.
and Mara, D.D. 1983. Sanitation and Disease – Health aspects of excreta and
waste water management. John Wiley and Sons, Chichester, UK (as reproduced
in Schönning and Stenström 2004).
For example, all pathogens die within one hour at 65° C, or within a month at
45° C.
What if we aren’t quite so broke and want
something nicer?
You can do it. If your soil is fairly dry and absorbent and never gets
flooded, think about making an ArborLoo, which is a lightweight outhouse that gets placed on one and another
one-meter-deep holes where trees later get planted, like this one we made
from mostly recycled materials. Remember to add a cup of soil, dry leaves or ashes with each use. If
you do not have room to plant an infinite number of trees, you can plant
vegetables, like pumpkins, and dig a new hole in the same spot after at least
two years.
Also, check out the Simple UDDTs I published in Sustainable Sanitation Practice and various other models on my blog, some of which have beautiful ceramic floors set into thin ferrocement
that only needs a half a sack of cement. And set up a TippyTap to wash
your hands.
What
about all the billions of people in the world who wash their back sides with
water?
I have been thinking about all the billions of “washers” in the world,
who use water for anal cleansing, and how they could use this Free UDDT … and
have come up with the following solution. A second Ecological Urinal could be
made and marked “Anal and Hand Washwater”, which would be laid on the ground,
or propped nearly on the ground, to catch this water. (The lip on this urinal
can be bigger to prevent this dirty water from coming out, and two sticks in
the ground can prevent it from rolling.) A TippyTap could provide this water,
such that the user can step on its pedal to acquire water for washing, without
touching the vessel or contaminating its contents. After anal cleansing, the
user can stand the urinal up and continue washing his or her hands.
(A TippyTap is a plastic bottle hung on a pole, with another stick on a
string that one steps on to tip it and receive a stream of water through a hole
in the bottle that was made with a red-hot nail. Standard versions can be seen
at http://www.tippytap.org and a version that fills automatically with the rain can be seen at http://inodoroseco.blogspot.com/2012/04/aumentamos-un-tacho.html )
This little bit of blackwater could be poured into a narrow hole in the ground (a “soak pit”), like a post hole, which could be filled with stones, especially if there is a tendency for the walls to cave in. One could also put a plank as a lid to keep flies and smells from coming and going. If the site has really high groundwater or flooding, some kind of Constructed Wetland of plants would be called for to purify this wastewater.
And
if we want to sit …?
You
can build a bench, as can be seen on my blog,
but I do want to remind you that squatting is the most natural
position for defecation (which everyone used for millions of years)
therefore:
- there is less constipation,
- there are fewer hemorrhoids,
- it is more hygienic (since genitals do not touch anything),
- it is more accessible for small children, and
- the evacuation is more complete.
It
is also usually easier and more economical to build for squatting,
plus there is better separation of the urine.
Where
could this go?
By
using this minimalist do-it-yourself toilet, people can not only
resolve this sanitary problem themselves immediately, but they can
also demonstrate to governments, foundations, and others that they
understand and embrace the concept and practice of Urine-diverting
Dry Toilets. Many planners and decision-makers would discard this
option as a utopian dream that could never be feasible, but in
reality local citizens are often much more practical, proactive and
down-to-earth than their “leaders”. Once people demonstrate that
they can properly manage this bare-bones UDDT, governments and
foundations would be much more confident in building fancier,
permanent units for these same users. Too many UDDTs have been built
and given to the users, with everyone simply hoping that they will
use them correctly, and then they are abandoned or misused, because
the users were not adequately prepared and convinced of the system.
In
fact, this simple toilet could be used as a test for these users to
confirm their spot on the list of permanent and elegant UDDTs to be
built. After a week of use, someone could visit to see how they have
been used, and this would put pressure on them to actually understand
and use the toilet and to actually use it properly, since no one
would want to be crossed off the list for being messy or not being
able to follow instructions.
This
design can thus be considered a low but solid rung in the ladder of
increasingly user-friendly UDDTs. With it, those 2.6 billion could
quickly have a toilet, maybe with some creative redistribution of
these plastic “wastes”, especially considering that, since these
polypropylene sacks are protected from the damaging rays of the sun,
they can be used again and again, year after year. This toilet is
accessible to anyone in the world who can rescue a few selected
things out of the trash and has a clear decision to keep the
environment cleaner and more productive.
If you have any questions or suggestions about this simple toilet, please let me know. I also invite you to read more about the current problems of sanitation in this interview and more about Urine-diverting Dry Toilets in this interview.
Keep
water clean
by keeping sh*t dirty.
by keeping sh*t dirty.