We all produce a rich resource in our homes and then spend millions of
dollars to throw it away. A new movement says there are smarter ways to
think about waste.
The Boston Globe, Sunday, July 13, 2008
"IN A WORLD of rapidly diminishing resources, there's one we tend to
overlook. It's easy to produce and extremely abundant. But instead of
viewing it as an embarrassment of riches, we're more likely to see it as
just an embarrassment.
This neglected treasure is human waste. Urine is rich in nitrogen,
potassium, and phosphorus, the three main ingredients in artificial
fertilizer. Feces contains these nutrients, too, in smaller doses, and
the methane it produces can be harnessed as biogas, a green energy source.
But now a growing global movement aims to make sanitation more
sustainable by changing how both rich and poor countries think about
human waste - recasting it as a valuable resource that is most costly
when thrown away. Following a philosophy known as ecological sanitation,
or "ecosan," and fueled by a convergence of factors - the rising prices
of energy and artificial fertilizer, increasing worries about food
security, and concern for the environment - the push to reform
sanitation has gained currency around the world, driving innovations
from toilet design to farming practices.
In Europe, recent years have seen the advent of "urine diversion"
toilets, which separate the two kinds of waste in order to treat it more
efficiently, among other benefits. Locally, a private school in Weston
has installed flushless compost toilets manufactured by Clivus Multrum,
a company based in Lawrence. And several European pilot projects have
begun to experiment with vacuum-biogas toilets, which require very
little water and turn waste into energy.
Not everyone shares the enthusiasm for these sanitation technologies.
Skeptics point to the cost, health concerns, and challenge of changing
deeply ingrained habits and beliefs. Depending on the particular kind of
system, the changes could entail a different experience of the toilet,
or a different attitude toward the waste, or both.
The idea of recycling our feces and urine may seem surprising, and
perhaps disgusting, but the concept is hardly new. China and Japan have
long traditions of re-using human waste as fertilizer. Even in England,
as recently as the 19th century, "nightmen" would take human waste from
backyards to sell to farmers.
The flush toilet and its infrastructure have since become standard
throughout the developed world. Excreta flow out of sight to a sewer
system, and then to a waste treatment plant. In more remote areas, the
sewage goes to nearby septic tanks that must be periodically emptied.
The system's benefits are obvious, but it also has downsides that are
growing increasingly apparent.
Annually, each of us produces about 13 gallons of feces and 130 gallons
of urine, which is instantly diluted into the 4,000 gallons we use to
flush it. This large quantity of contaminated liquid further mixes with
"greywater," the water from the laundry, shower, and sink, tripling or
quadrupling the amount of water that must be treated as sewage in
energy-intensive plants. In effect, the system takes a relatively small
amount of pathogenic material - primarily the feces - and taints
enormous amounts of water with it. Especially in regions struggling with
freshwater scarcity, many observers have come to see this system as
In this model, it's not only water that's wasted, critics say - it's
also the valuable nutrients in the feces and urine, notably phosphorous.
Global fertilizer prices have tripled in the last year, partly due to a
shortage of phosphorus, which some see as a looming crisis. Against this
background, some argue that it would be folly not to capitalize on the
plentiful phosphorus in human waste. In the same vein, the methane it
generates has the potential to provide cheap, renewable energy.
Over the past couple of decades, some measures have already begun to
exploit the value of waste and improve the system's efficiency. It has
become common for treatment plants to convert some of the methane
generated by sludge into biogas to partially power their own plants.
Low-flush toilets and waterless urinals are small steps to conserve
water. And the practice of using treated sludge - renamed "biosolids" -
as chemical fertilizer has become customary in parts of the developed
world. In the United States, according to the Environmental Protection
Agency, about 50 percent of all biosolids are being recycled to land.
The Massachusetts Water Resources Authority turns all of its sludge into
fertilizer, some of which it sells commercially through a contractor and
some of which it gives to communities.
Although the EPA has issued treatment regulations, and the MWRA defends
the safety of its fertilizer, there are concerns about the impact of
sludge-derived products on soil and human health.
The most radical visionaries of this movement would apply the same
principles to sanitation that we have begun to apply to other garbage in
The benefits of taking urine out of the waste stream are clear: Urine
makes up less than 1 percent of all waste water in developed countries,
but contains a huge proportion of the nitrogen and phosphorus. Those
nutrients are essential to agriculture but harmful in water bodies, and
removing them is the most energy-intensive part of treating waste water.
And since urine is almost sterile, it can be used as fertilizer with
little to no treatment.
There are, however, obstacles to widespread implementation of unorthodox
toilets. Space limitations make compost toilets infeasible in most urban
areas. Vacuum toilets require a different plumbing system. And there may
be psychological barriers to changing habits in the bathroom.
Partly due to the lack of infrastructure, it's in the developing world
where the biggest changes have so far taken place. The problems there
are quite different. Due to the lack of proper sanitation facilities,
diseases caused by ingested fecal matter are rampant; diarrhea, for
example, kills more children than AIDS. But the advantages of the ecosan
approach are similar, because a well-designed system allows people to
harvest the benefits of waste. And given the poverty and food
insecurity, these benefits are often more acutely felt.
A popular kind of toilet is called the fossa alterna, in which two
3-meter-deep pit latrines are dug side by side. Once one is filled,
after about a year, it is sealed off, and the other one is used.
Eventually, the waste in the first pit will be ready to be retrieved -
after time, the pathogens die off - and used or sold as fertilizer for
A more sophisticated system, used most often in urban areas, allows
groups of families, as well as schools, to produce their own biogas. To
create biogas, vegetable scraps and grass and human excreta are
collected in a pit. They produce methane, which is captured in a tube
and channeled to a kitchen stove or shower. The UN is involved in such
projects in India and Senegal, among other places.
One of the most successful efforts has unfolded in Ethiopia. Starting in
2005, Catholic Relief Services introduced a toilet called the arborloo
to extremely poor Ethiopian farmers.
The arborloo is a shallow pit latrine that costs only $5. When it's
filled, the farmer plants a fruit tree seedling. The farmers are given
two seedlings, one to plant in the arborloo, and another as a control.
The comparison enables them to observe that the one in the arborloo
grows much faster and produces more fruit. The farmers can eat the fruit
and sell it on the market. Today more than 26,000 farmers are using
these toilets, with strong support from the Ethiopian government.
This simple device has brought about the kind of change in thinking that
reformers hope will eventually take root in the developed world.
"Some of our farmers say, 'We used to think poop was dirty, but now it's
our gold,'" says Mayling Simpson-Hebert, a technical adviser with
Catholic Relief Services in East Africa. "They won't let their children
defecate in the open. They say, 'Go put your gold in the toilet.'" "
Dr. Ann C. Wilkie Tel: (352)392-8699
Soil and Water Science Department Fax: (352)392-7008
University of Florida-IFAS
P.O. Box 110960 E-mail: [log in to unmask]
Gainesville, FL 32611-0960
Campus location: Environmental Microbiology Laboratory (Bldg. 246).
BioEnergy and Sustainable Technology Society