Topic Tuesday #10 2012/09/25 "Water World - Part 2"
We need quite a bit of water to survive on. It needs to be clean...Last week I discussed the requirements of how much water we need to survive. Today, how do we make it safe?
- I am going to quickly give some ways to clean up water so you don't die.
- There are 4 categories; Separation, Chemical, Filtration, Oxidation.
- SEDIMENTATION gravitationally settles heavy suspended material.
- BOILING WATER for 15 to 20 minutes kills 99.9% of all living things and vaporizes most chemicals. Minerals, metals, solids and the contamination from the cooking container become more concentrated.
- DISTILLATION boils and re-condenses the water, but many chemicals vaporize and recondense in concentration in the output water. It is also expensive to boil & cool water.
- ULTRAVIOLET LIGHT is a good bactericide, but has no residual kill, and works only in clearly filtered water. Still in its infancy stage is a new technology involving super white light.
- CHLORINE is common, cheap, but extremely toxic. It does not decrease physical or chemical contamination, it does increase colesterol formations, is a carcinogen, amd causes heart disease.
- IODINE is not practical, and is mostly used by campers.
- HYDROGEN PEROXIDE kills bacteria with oxygen, is chemically made and is very toxic. It is used in emergencies.
- COAGULATION-FLOCCULATION adds chemicals which lump together suspended particles for filtration or separation.
- ION EXCHANGE exchanges sodium from salt for calcium or magnesium, using either glauconite (greensand), precipitated synthetic organic resins, or gel zeolite, thus softening the water. Minerals, metals, chemicals or odors are not affected, and the water is salty to drink.
- SLOW SAND of 1 cubic meter passes about 2 liters/min, and does a limited bacteria removal.
- HIGH PRESSURE/RAPID SAND of 1 cubic meter passes about 40gpm and must be backwashed daily.
- DIATOMACEOUS EARTH removes small suspended particles at high flow rates, must be back-washed daily and is expensive.
- PAPER or CLOTH filters are disposable and filter to one micron, but do not have much capacity.
- CHARCOAL:
- -COMPRESSED CHARCOAL/CARBON BLOCK is the best type of charcoal filter, can remove chemicals and lead, but is easily clogged, so should be used with a sediment prefilter.
- -GRANULAR CHARCOAL is cheaper, but water can flow around the granules without being treated.
- -POWDERED CHARCOAL is a very fine dust useful for spot cleaning larger bodies of water, but is messy and can pass through some filters and be consumed.
- REVERSE OSMOSIS uses a membrane with microscopic holes that require 4 to 8 times the volume of water processed to wash it in order to remove minerals and salt, but not necessarily chemicals and bacteria.
- AERATION sprays water into the air to raise the oxygen content, to break down odors, and to balance the dissolved gases. However, it takes space, is expensive, and picks up contaminants from the air.
- OZONE is a very good bactericide, using highly charged oxygen molecules to kill microorganisms on contact, and to flocculate iron and manganese for post filtration and backwashing.
- ELECTRONIC PURIFICATION and DISSOLVED OXYGEN GENERATION creates super oxygenated water in a dissolved state that lowers the surface tension of the water and effectively treats all three types of contamination: physical, chemical and biological.
The easiest for you and me to go through is likely to be the separation method. An issue to remember here, and one that has caught entire villages with a bad case of the runs, is proper storage of the water once you have sterilized it. There are many methods to do that, but that will be another topic. Look for "Food Safety" later on.
Now for your consideration:
- What are your plans on keeping a supply of available, CLEAN, water on hand?
- What would be the best method for scaling up for family clusters, to villages, to towns, etc?
- Are you going to try any of these methods?