Readers of this blog probably don’t have to be told that the
proliferation of synthetic chemicals over the past century has hugely impacted
drinking water sources around the world. But you might be shocked to learn that
these toxic contaminants are completely ignored by international, governmental
and non-governmental agencies concerned with expanding the provision of safe
drinking water in developing communities.
This is because, from a WASH
(water-sanitation-hygiene) perspective, microbial pathogens typically represent
the most immediate threat to health. However, although they receive no
attention for the international WASH development establishment, a huge variety
of synthetic organic contaminants (SOCs) such as pesticides, pharmaceutical
residues, fuel compounds, and industrial wastes heavily impact the safety of
surface waters collected for drinking in communities around the globe.
Hundreds of millions of tons of SOCs,
including several million tons of pesticides, are produced annually, impairing
water quality on a global scale. Consequently, for example, “pesticide
pollution” appears twice in the top ten of The World’s Worst
Toxic Pollution Problems Report (2011) by the Blacksmith Institute. Long-term
chronic exposure to trace quantities of SOCs such as pesticides can lead to
cancer, diseases of the endocrine and reproductive systems, and damage to the
liver, kidneys, or central nervous system, and a variety of other toxic
effects.
In the rural hill country of SE
Asia where my colleagues and I work these problems are acute. Few scientific
studies have been undertaken among the impoverished hill tribe villagers here,
but the data we do have indicate, for example, detection of a wide array of
biocides in mothers’ milk samples. One study found that infants’ exposure to DDT
and several other organochlorine compounds exceeded by up to 20 times the
acceptable daily intakes as recommended by UN-FAO and WHO. Along with residues
in food and occupational exposure, drinking water is a major pathway for
harmful agrichemical residues to enter into our bodies.
Using charcoal for water treatment
is a technique that is at least 4,000 years old – there are references to
ritualistic purification of water using charcoal in ancient Hindu and Egyptian religious
texts. My colleagues and I have hypothesized that charcoals produced by
traditional methods could be effective for removing modern organic contaminants,
as charcoal has properties similar to activated carbon (AC) – a highly
micro-porous structure, and a large internal surface area with a plenitude of
adsorption sites for removing toxicants from water.
But unfortunately, traditional charcoal
production can cause substantial environmental damage through deforestation and
atmospheric emissions. Moreover, traditional charcoaling systems are geared
towards the production of charcoal-for-fuel, not an optimal adsorbent for water
treatment.
Thus part of our work at Aqueous
Solutions has been to develop low-cost, “low-tech,” environmentally friendly
systems for production of optimal water filter char. Using scrapyard tin and
steel, surplus 55-gal oil drums, and simple hand tools, we’ve made chars from
waste agricultural and forestry residues that rival the performance of
commercial ACs for uptake of herbicide and a range of other trace SOCs from
surface water.
Here I am
on a typical day of field research in northern Thailand – collecting temperature
data on a 55-gallon drum pyrolyzer used for making adsorbent biochar. (Photo
credit Lyse Kong.)
If you want to learn more about our
work please visit aqsolutions.org, where you
can download open-access handbooks and watch instructional videos for making your
own biochar adsorbent and using it in decentralized water treatment.
Also, feel free to follow me on
Facebook (https://www.facebook.com/joshua.kearns.399), view
more pictures from our field projects, and “Like” Aqueous Solutions (https://www.facebook.com/AqueousSolutions)!
