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Desalination by pervaporation for sub- surface irrigation in arid regions Dr Michael Templeton Department of Civil and Environmental Engineering Imperial.

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Presentation on theme: "Desalination by pervaporation for sub- surface irrigation in arid regions Dr Michael Templeton Department of Civil and Environmental Engineering Imperial."— Presentation transcript:

1 Desalination by pervaporation for sub- surface irrigation in arid regions Dr Michael Templeton Department of Civil and Environmental Engineering Imperial College London

2 What is the problem?  Clean fresh water is an increasingly scarce resource  Groundwater supplies are being abstracted faster than they are being replenished and are becoming salted  Agricultural land is being polluted by irrigation water itself and by agri- chemicals  There is an increasing demand for food crops to support growing populations  There is an increasing demand for non-food crops (e.g. biofuel crops)

3 What is pervaporation?  Specially constructed material – non-porous hydrophilic polymer  Water permeates across the surface and condenses on the opposite side as moisture  Virtually all non-water constituents are rejected (e.g. salts, microbes, organics)  When partial pressures are balanced, water transfer stops  The new idea - to construct irrigation piping out of this material  Partnership with Design Technology & Irrigation Ltd (DTI Group), based in Brighton

4 How does it work?

5 What does a pervaporative material look like?

6 Does it work?

7

8  Tested in the UK (Eden project), Middle East, USA, and South America  Trial crops have included peppers, tomatoes, strawberries, radishes, beans, lettuce, potatoes, grass, vines, sunflowers, and various types of trees (cherry, banana, Acacia)  Major trial in Abu Dhabi currently – 200 Prosopis trees growing in 45 ºC watered with highly saline untreated groundwater (140,000 ppm!)  Possibly better crop uniformity and yield - i.e. one trial yielded higher radish biomass

9 What are the advantages?  Allows the use of otherwise unusable water resources (e.g. brackish water, seawater)  By definition, it is an efficient water delivery process – impossible to over-water; potential for significant reduction in water use  Easy to operate and manage  No requirement for high pressure input (unlike other membrane filtration processes)

10 What are the challenges?  It is not possible to provide nutrients to the plants through this system  Some plants have shown better aptitude for this method than others  Currently more expensive than drip irrigation (but it is more efficient and allows the use of water resources that would be otherwise unusable)  Disposal of the reject water must be considered

11 What are some research questions?  What are the limits of water quality that are feasible?  How do different soil characteristics influence water transfer rate?  How can fouling and salt accumulation best be managed?  What are the limits of pipe diameter and thickness?  When is this technology more favourable/appropriate compared to drip irrigation or other irrigation techniques?  What is the pattern/rate of crop growth when a new irrigation project is started with this technology?  Do water-stressed plant roots develop differently and have different requirements than plants under un-stressed conditions?  Are plants grown in this way as healthy / productive as those grown by alternative irrigation methods?

12 Interested in collaborating?  Dr Michael Templeton, Imperial College London Tel: +44 (0) Web:


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