Filter Purifier Part 1 | Waternet
Terms Used in Water Filtration & Purification
CERAMIC FILTER ELEMENT
At the core of the ceramic filter element is the most basic of elements.
EARTH
This is the same substance which artisans, first in Asia and then in Europe, refined into the exquisite porcelain and pottery of the Shoguns and Kings. This material is Diatomaceous Earth (D.E.), a fossil substance, made up of tiny silicon shells left by trillions of microscopic, one celled algae called diatoms that have inhabited the waters of the earth for the last 150 million years.
DIATOMS
Diatoms have one property that sets them apart from other algae. They weave for themselves microscopic shells, or frustules, are covered with a pattern of tiny holes so regular that even the slightest change in their design usually signifies a different species.
As the diatoms died, their shells survived, slowly piling up in deposits at the bottom of geological lakes and lagoons. When these dried up, what remained were huge deposits of "diatomaceous earth". The Egyptians as well as earlier cultures used D.E. to protect stored grains.
It has been speculated that the reason birds take dust baths and other animals roll in the dust is to rid themselves of ticks and fleas.
DIATOMACEOUS EARTH
Today there are over 1500 uses for Diatomaceous Earth, from abrasives for toothpastes, filtering agents in alcoholic brewing processes, heat insulators for kilns, polishing agents for water and milk, fireproofing material, process material in making pigments, fillers for blotting papers, substitute for talc in printing processes, absorbents and dilatants for compositions to prevent growth of fungi, fumigants, insecticides, fillers in welding rods, to inert packaging materials for dangerous goods and many, many more.
The latest ceramic filter elements incorporate silver components into a porous ceramic outer shell that can trap bacteria down to as low as .22 of a micron in particle size - (a micron is 1/1OOth the width of a human hair or about 1/25,000th of an inch). Porous ceramics act as "depth filters" as they can retain particles finer than their maximum pore sizes.
For example the ceramic filter element used by Diamond Spring Water Technologies has over 80,000 pores, many of which are below 1 micron in diameter. Bacteriological laboratories consider 0.01 micron to 0.45 micron to be 'bacteriologically sterile' and 0.45 micron to 1.00 micron to be 'bacteriologically safe'.
The silver prevents any regrowth of bacteria that becomes trapped either outside or in the ceramic material. As the water comes into contact with the silver impregnated ceramic material, the bacteria is neutralized and destroyed as the Oligodynamic silver releases small quantities of positively charged metal ions which are taken into the enzyme system of the bacteria's cells. The flow rate of the ceramic filter can be easily renewed simply by brushing its surface. As the old layer of contaminants is brushed off and flushed away, a new layer becomes available. This process can be repeated a number of times before the ceramic material is exhausted.
The ceramic filter element is certified/approved by the World Health Organisation, Department of Health, Toronto, Ontario; Counties Public Health Laboratories, London, England; Japan Food Research Laboratories and is currently sold and used in over 100 countries throughout the World.
Granular Activated Carbon
Carbon, in the form of ashes, has been used to treat drinking water since Biblical times. "Activated" carbon is formed by exposing a carbon-containing material (usually charcoal) to high temperatures and steam in the absence of oxygen. The carbon used in the manufacturing of the filter is bituminous coal, a soft coal. The resulting material is honeycombed with miniscule channels that branch and twist within. These channels greatly increase the surface area and thereby account for activated carbon's impressive adsorptive powers. As the water passes over the positively charged microscopic labyrinth, the negative ions of the contaminants stick to the walls of the channels.
This process is known as ABSORPTION.
Granular Activated Carbon (GAC) filters are widely used to clean up water's bad taste and odours. One thing carbon cannot do, is filter bacteria from the water. As a general rule, absorption ability of granular activated carbon depends largely on a number of factors.
They are as follows:
1. TURBIDITY
How clean is the water from fine particulate matter. The cleaner the incoming water, the greater is the ability to absorb. This filter media should not have to contend with any sediment or particulates in the water as they should be filtered out by a dirt/sediment filter element first.
2. FLOW RATE
Gushing water is not filtered as well as water flowing at slower speeds. Purifiers usually slow the flow rate, thereby ensuring sufficient contact time.
3. CONTACT TIME
The water must be in contact with GAC for a certain period of time to allow the GAC the necessary time needed to absorb the contaminants from the water supply.
4. DEPTH OF THE BED
There must be a sufficient amount of granular activated carbon in any filter cartridge to ensure that the GAC is able to reduce the contaminant levels in the water. There is a standard formula used to determine how much carbon is required to filter a known quantity of water.
That formula is as follows:
1 cubic foot of granulated activated carbon will process about 36,000 gallons of water.
12 ounces of granular activated carbon in a filter is sufficient to process 540 gallons before it becomes fully saturated. If used longer the activated carbon may start to UNLOAD the contaminants it has absorbed and release them back into the water.
5. MESH SIZE
GAC that is too large or too small in size will not be very effective in removing all the contaminants from the product water. Some carbon cartridges use either solid carbon blocks or powdered activated carbon embedded in a felt-like pad through which the water flows.
Carbonblock cartridges are not as effective as GAC because of the problems of channelling inside the block of carbon. As water, which will try to find the path of least resistance, flows through the channels it does not have sufficient contact time with the carbon.
The powdered activated carbon felt pads are probably the least effective in removing contaminants from the water in larger quantities as they become clogged with the finer particulate matter found in most water supplies and therefore will have to be replaced more frequently.