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As water resources continue to be depleted, access to clean water and sanitation in developing countries remains a high priority. Scientists and nanotechnologists are rising to the challenge of making water remediation more efficient and cost effective. But is science enough? Will the poor receive the benefit of the technologies that have the capabilities of changing their world?
July 31st, 2008
Water for Poor
The New York Times published an article recently that describes the scarcity of water in the Middle East and Northern Africa. In those areas, the costs of drilling and pumping from aquifers, desalination of sea water or diverting river waters are cost prohibitive, making it more practical to import food than to produce it. According to the World Water Assessment Program of the UNESCO, more than 6000 people die each day due to water-related diseases, including diarrhea, worm infections, and infectious diseases.
The availability of drinking quality water is fast becoming a major socio-economic issue across the globe, especially in the developing world.
As world water resources continue to be depleted, access to clean water and sanitation in developing countries remains a high development priority. Scientists and nanotechnologists are rising to the challenges associated with making water potable. To date, this may be the biggest single application of nanoscience. Not only can nanotechnology can be used to make water remediation more efficient, but ultimately more economically viable.
There is an array of established water-treatment technologies including filtration, ultraviolet radiation, chemical treatment and desalination, but proponents suggest that nanotechnology-based materials could lead to cheaper, more durable, and more efficient water treatment technologies that will meet the needs of developing countries. Several water treatment methods and devices that incorporate nanoscale materials are already commercially available, and others are being developed.
Carbon nanotube membranes and nanomesh are two very viable options for water purification.
Membranes are key to reverse osmosis desalination, but energy requirements for this technology are high. A typical seawater reverse-osmosis plant requires 1.5 to 2.5 kilowatt-hours of electricity to produce 1 cubic meter of fresh water. The use of carbon nanotubes membranes allow for much faster flow rates of water which could enable a sharp reduction of energy required to purify water.
Vermont-based Seldon Laboratories has developed a "nanomesh" that allows water to pass through it but catches cysts, parasites, fungi, microorganisms, viruses, and many mineral toxins. The filter is composed of carbon nanotubes that are bound together and placed on a flexible, porous substrate which can be placed on a flat substrate to form a paper-like filter or on a rolled substrate that can be wrapped around a conventional cylindrical filter or other support structure. Sheldon's goal is a filter that can quickly purify water from any source -- a river, ground well or even a mud puddle.
Additional emerging technologies for water purification include:
Nanofibrous alumina filters
Nanofiltration membranes and devices
Nanoporous ceramic biomedia filtration
Nanoscale titanium dioxide photocatalysts
Nanoscale zero-valent iron
Nanostructured iron oxide adsorbent
Self-assembled monolayers on mesoporous supports (SAMMS)
Titanium oxide nanoparticle adsorbent
With the largest cost in water treatment being energy, Dr. Zvi Yaniv, CEO of Applied Nanotech, Inc., predicts that there will be a tremendous synergy between obtaining cheap energy and obtaining clean water. He believes we will soon see a combination of both functions - energy and water - in the same materials.
Emerging technologies will continue to push for safe, readily available water on a global scale. Nanotechnology is beginning to tilt the economic balance of many existing water related technologies in favor of large scale use, including improved filtration techniques, new absorbing active materials (nanoparticles and composites), high efficiency UV catalytic materials and processes, improved activated resins for deionization, embedded networks for nanosensors for contaminants testing and treatment change and new efficient and low cost methods for desalinization.
There are very real opportunities of significance to developing countries for creating potable water. The Meridian Institute's Global Dialogue on Nanotechnology and the Poor: Opportunities and Risks (GDNP) has published a publicly available paper that compares conventional and
nanotechnology-based water treatment devices.
In spite of these disruptive technologies, poor and developing countries may still not have access to clean water.
Tearfund, a UK relief and development charity, reports that aid for water and sanitation from the EU and its members has been falling for five years, despite the fact that each day thousands of children continue to lose their lives as a result of poor water and sanitation. More aid money is going to middle-income rather than low-income countries.
In 2006, some of the world's largest companies pulled out of developing countries, mainly due to political resistance and privatization. Some left voluntarily; some were forced out. Many governments have absolved themselves of the obligation to extend water connections to the poor.
Is water for the poor a surmountable obstacle?
As the Washington Times so eloquently reported: "…where water is concerned, poor people need results -- not rhetoric."