TWENTY-FIVE METHODS TO PURIFY WATER
There are twenty-five methods to purify water, divided into four categories: separation, filtration, chemicals, oxydation.
There are five types of contaminants that are found in water: particulates, bacteria, minerals, chemicals, and pharmaceuticals. Methods to remove these elements range from simple and inexpensive to elaborate and costly. Often to achieve purely potable water, several technologies must be combined in a particular sequence. Listed here are general brief descriptions of the twenty-five methods to purify water.
CHEMICALS
CHLORINE is common, cheap, but extremely
toxic. It does not decrease physical or chemical contamination, it
does increase colesterol formations, is a carcinogen,
and causes heart disease.
BROMINE, used in pools and spas, doesn't
smell or taste as bad and doesn't kill bacteria very well.
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.
SILVER is an effective bactericide
but a cumulative poison which concentrates and doesn't evaporate.
NONTOXIC ORGANIC ACIDS should be used
with caution in large water plants only.
LIME AND MILD ALKALINE AGENTS should
also be used with caution only by large water plants, or only for laundry.
NEUTRALIZING CHEMICALS react with the
unwanted chemicals and produce outgases and a sediment, but levels of need
vary.
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.
FILTRATION
SLOW SAND of 1 cubic meter passes about 2 liters/min, and does a
limited bacteria removal.
PRESSURE 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 daily backwashed and is expensive.
POROUS STONE/CERAMIC filters are small but expensive, and do
not effect chemicals, bacteria or odors.
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.
ENZYMES &BACTERIA combined can remove contaminants, reduce sludge, and even digest oil. See recent article on enzymes & bacteria.
PLANTS There are numerous plants, animals and organisms that are quite effective in filtering water.
OXYDATION
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 ozidize and flocculate iron,
manganese and other dissolved minerals 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.