Water filter concepts

The idea of water filtration continues the  project of water harvesting. Physical filtration of water should not be a problem, the trick comes in treating the water to rid it of biological contaminants or chemical residues.

Several alternatives are ideal:

1.  Fractional Distillation of water, whereby the water is boiled and condensed. This rids the water of micro-organisms which die due to heat exposure, as well as chemical residues, which mostly have boiling points different from that of water. The only drawback of this approach is the energy input requirement, since distillation until condensation is a long process. It would be more economical if done on a large scale. But its general simplification makes it the best alternative since no chemical additives have to be included in the treatment process.

(see: http://en.wikipedia.org/wiki/Fractional_distillation)


2. UV lamps used to treat the water. The process lasts for a few minutes, and renders microorganisms incapable of reproduction. Germicidal UV lamps should be kept away from contact with skin as it can cause cancer, as well as damage to the retina if looked at directly. Finally, once the water has been treated with UV lamps, it has to be kept in a dark location away from light, (e.g. sunlight) as this exposure will reverse the DNA mutation and enable the bacteria to reproduce. The water must also be clear, since suspended dirt particles may shield or absorb some of the UV radiation.

(see: http://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Potential_dangers)



3. Chlorine. Chlorine tablets can be used to kill germs in the water, The undesired result is the after-taste of chlorinated water. Chlorination alone cannot rid the water of chemical residues in the water, nor physical materials that make filtration necessary. That means that chlorination must be accompanied by a physical filtration process.

(see: http://en.wikipedia.org/wiki/Chlorine#Purification_and_disinfection)


4. Activated Carbon.  Activated carbon is carbon that has been treated to give it a massive surface area. e.g. one gram of activated carbon has a surface area of 500 square metres. Activated carbon is an excellent medium for absorbing chemical contaminants, though it cannot rid the water of any microorganisms. Activated carbon can for instance be made by roasting coconut husks in a furnace at 500 degrees celsius for 4 hours and then chemically treating it.

(see: http://en.wikipedia.org/wiki/Activated_carbon)

(images courtesy of google)



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