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Biomimicry in Practice - Purifying water natures way

 

Nature has an unparalleled processes of water purification (P1)

Bottled water is the most accessible form of water today, but due to its plastic packaging this industry is not often thought of as sustainable.

Besides the packaging it is common for the water itself to be purified using Chlorine (Cl2) and other chemicals. Below, we are going to look into a few methods of purification that mimic nature, currently utilized by top players in the industry. First though, what are the requirements for drinking water?

 

 
A glass of water being filled

Good drinking water is essential for health (P2)

Requirements for drinking water?

  1. Healthy pH (Neutral except for alkaline water)
  2. Good minerals
  3. Low contaminants of;
    1. Heavy metals from factory waste
    2. Pesticides from agricultural activities
    3. Choliform and E.coli bacteria from feces of warm blooded animals (1)
  4. Low or Negative Oxidation Reduction potential (ORP)
    1. This prevents the water from removing electrons from the molecules in your body, creating free radicals (2)

 

 
Illustrated diagram of a rapid sand filter

The sand and gravel act as a physical filter trapping impurities in the water (P3)

Rapid sand filtering

Rapid sand filtration utilises a high pressure to push water through a dense block of sand and rock particles. Physical impurities in the water are trapped in this filter as the water flows through. As this process is purely a mechanical filtration method, it is used in conjunction with other technologies that get rid of chemical and biological impurities the water may have.

 

 
Waterfall

A waterfall mixes air into the water which allows oxygen to decontaminate it (P4)

Aeration

An aerator attempts to mimic the effect a waterfall has on the water falling. By spraying water upwards onto a dome through tiny nozzles, it mixes air in with water. While this process may seem inconsequential, it has a significant impact on the quality and taste of the water. This process primarily does 3 things;

  1. Removes carbon dioxide (CO2), in a process called decarbonation
  2. Oxidises Iron and Manganese compounds, in a process called oxidation
  3. Reduces the level of ammonia (NH3) and hydrogen sulfide (H2S), commonly found in decaying organic matter, in a process called stripping.

These processes neutralise the pH of the water, and reduce its oxygen reduction potential (ORP). This breaks down any contaminants present. The taste is improved by removing metallic and chemical contaminants.

 

 
Image of a stream of water

UV Rays in Sunlight inactivate microorganisms in the water by altering their DNA (P5)

Ultraviolet-C Rays

Industrial Ultra Violet (UV) Bulbs are utilized to simulate the natural downstream flow of water under daylight. UV light penetrate microorganisms, also known as pathogens, in the water and are absorbed into their DNA. The DNA is altered in such a way that the pathogen cannot reproduce and is essentially killed and cannot cause infection. This process of DNA modification is called inactivation and unlike chemical disinfection these microorganisms are unable to develop any immunity to it. (3)

   
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