Monteverde, in northwest
Costa Rica, has been described as being home to one of Central America's
'jewels in the crown'-the world famous Monteverde Cloudforest Reserve.
And to say Monteverde has boomed in the last 15 years would be to
put it mildly-the number of visitors to the Cloudforest Reserve alone
has jumped from some 300-odd biologists and intrepid travelers in
the early 1980s to over 60,000 in 2003. The total number of visitors
to the larger Monteverde area is estimated at more than 200,000 annually.
And the impact? While ecotourists get to see and experience the area's
pristine flora and fauna, it is the locals in the ever-expanding
nearby town of Santa Elena who are subjected to a burgeoning wastewater
problem. Rural has turned urban too quickly, and unfortunately the
price is the common sight and smell of greywater and septic overflow
running down the roadside drains and nearby creeks. This situation
is not uncommon throughout Latin America where it is estimated that
less than 15% of all wastewater receives any form of treatment.
Stewart Dallas with a rather large Costa Rican
creepy-crawlie!
I arrived in Monteverde
in March 2000 for a three-month research affiliate position based
at the Monteverde Institute at a time when the Institute, in conjunction
with Smith College, Massachusetts, had just commenced a river water
quality monitoring program of the entire Monteverde watershed. The
contrast between the state of upstream and downstream water quality
in any one river was dramatic. Coming from Murdoch University's Environmental
Technology Centre (ETC) I was aware that biological systems such
as composting toilets and reedbeds (mini constructed wetlands) for
wastewater treatment should work well in the tropics and subsequently
spent the next three months designing and building one of each. Three
years later I am still here with my wife focusing my doctoral research
on the use of reedbeds for greywater treatment. An interesting cultural
trait in rural areas throughout most of Latin America is to separate
greywater (all the household wastewater such as from the shower,
laundry, kitchen etc) from the toilet wastewater or 'blackwater'.
This 'separation at the source' is recognized as being desirable
in waste management, as it is in the new field of ecological sanitation.
While the blackwater goes to a septic system (of dubious quality
in itself) all the greywater is generally piped straight onto the
ground, street or nearest creek. In Monteverde, greywater makes up
around 70% of the total wastewater produced by a typical home, which
equates to about 600 litres of greywater per day per household. With
over 650 homes now in the area, this equates to some 390,000 litres
per day of raw greywater entering the environment.
Children playing
in greywater in a street drain
(taken by Ing. Dagoberto Araya Villalobos
engineer with the Costa Rican Water & Sewage Authority).
So in a case such
as Monteverde, what are the options? Developed world conventional
sewage treatment
systems (deep sewerage and activated sludge treatment) have been
described as "prohibitively expensive" and "unsustainable
in developed countries, not just developing countries". And
yet conventional sewage treatment is still perceived as the panacea
to all problems in all countries. And when might this so-called panacea
arrive, and at what cost? Until then rivers will continue to be used
as open sewers, waterborne diseases will continue to maintain high
levels of morbidity and mortality, particularly amongst children,
and beaches will remain unfit to swim in with massive eutrophication
of lakes, rivers and oceans.
Reedbed treating
greywater from four homes
in Santa Elena near Monteverde.
Constructed
wetlands for the treatment of wastewater have been described as 'having
enormous
potential in developing countries", particularly tropical
ones. Since the bulk of the wastewater problem was greywater
(less hazardous
than blackwater) I concentrated on trialing reedbeds to treat
this fraction. Briefly, reedbeds are a trench at ground level
which is
lined with either plastic or clay, filled with gravel and planted
with reeds-a simple hydroponic system. Very early on I decided
that submerged-flow (or sub-surface flow [SSF]) reedbeds would
be the
only viable type. With an SSF type reedbed the water level is
always at least 10cm below the gravel surface which means that
you never
see the greywater, there are no odours, children and dogs can't
come into contact with the greywater and most importantly mosquitoes
cannot
access the water to breed. Dengue in particular is rife in Costa
Rica. I also had to find a species of reed that was non-invasive,
native if possible and would survive in greywater. Many constructed
wetlands in Europe and Australia use the common reed phragmites
australis which, apart from being uncommon in Costa Rica, is
also considered
a noxious weed. I finally found a species locally known as 'Job's
Tears' or Lagrimas de San Pedro in Spanish (Coix lacryma-jobi)
which is doing the job, as well as providing a seed which is
widely used
in local handicrafts. While not native to Costa Rica, Job's Tears
is considered to be a 'naturalised' species by local botanists
and is non-invasive.
The community
response to my work has been very encouraging and I have now installed
over five
reedbeds in the area ranging from single households, to a cafÇ,
a system treating the greywater from four homes and also one treating
septic effluent. I monitor all of these systems for water quality
parameters such as nitrates, phosphates and fecal coliform as part
of my case studies research. I am also intensively monitoring 12
mini-reedbed cells I have established in order to develop a model
for predicting performance. With the four household system I developed
an environmental services contract whereby the users pay a nominal
fee to have their greywater treated privately; the first of its kind
in Costa Rica.
As with the introduction
of any new technology there needs to be consideration of the cultural,
economic and environmental impacts amongst others, particularly if
it is to be sustainable. Sustainability and improved health outcomes
are key to my research although quantifying these two parameters
is much easier said than done.
I hope to conclude my field
work here this year and hopefully continue working on ecological
sanitation initiatives for developing countries in the future.
