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Water Purification with Filtration
For more than 30 years the need has grown for water purification by all categories of users – municipal, industrial,
institutional, medical, commercial and residential.
The increasingly broad
range of requirements for water quality has driven the water treatment
industry to refine existing techniques, combine methods and explore new water purification technologies.
"Science has found that there are no two water treatment problems exactly alike. There will always be slight differences with more than one technically -acceptable and scientifically-sound solution to any given water treatment problem. Beyond these two statements, there are no absolutes in water treatment." Pure Water Handbook by Osmonics
Water is one of the most aggressive solvents known.
Called the "universal solvent," water, will dissolve
virtually everything to which it is exposed. Like everything else in nature, water seems to achieve energy
equilibrium with its surroundings. It will dissolve the quantity of material available until the solution reaches saturation, the point at which no higher level of solids can be dissolved.
Contaminants found in water include atmospheric gases, minerals, organic materials (some naturally occurring, others man-made) plus any materials used to transport or store water.
Natural Purification of Water
The hydrologic cycle describes the process of contamination and natural purification.
Water Evaporates from the Ocean and Lakes into Clouds and
During the evaporation and transpiration of moisture, many contaminants are left behind. The evaporated water condenses in cooler air on crriers such as dust particles and return to the earth's surface as rain, snow, sleet or other precipitation. It dissolves gases uch as carbon dioxide, oxygen, and natural and industrial emission such as acids and oxides...resulting in a pH of 5 to 6.
Moisture from plants rise to Clouds by Transpiration
Precipitation Falls from the Clouds
Precipitation hits the surface and percolates into the water table
Ground water is stored in the water table and runs off into lakes, rivers and the ocean
As more of these acids are dissolved into the precipitation, it is called "acid" rain with a pH as low as 4.0.
As precipitation nears the grund it picks up additional airborne particulates, spores, bacteria and emissions from other sources.
Since most of the surface of the earth is covered by oceans, most of the precipitation falls into the ocean.
Groundwater's Natural Filtration
Precipitation and runoff surface water that percolates down through the porous upper crust of earth is substantially "filtered" by the layers of soil, roots and rock through which it passes. Most particulate matter is filtered, organic contamination is consumed by bacteria in the soil and a relatively clean, mildly acidic solution is contributed to the water in aquifers.
This acidic condition allows water to dissolve many minerals, especially limestone, which contributes calcium. Other minerals that are attracted to water include magnesium, iron, sulfates and chlorides.
Aquifers provide the supply for well water used by homes and water systems.
Surface waters such as rivers, lakes and reservoirs typically contain less mineral cotent because that water did not pass through the earth's soils. Surface waters hold higher levels of organics and undissolved particles because the water contacts vegetation and runoff picks up surface debris.
Bacterial Contamination of Water
Bacterial contamination and control of bacterial growth is another problem with purification of water.
Bacteria are "natural", but natural doesn't always mean healthy for humans or effective for industrial purposes! That is where specialized water filtration and purification comes into the picture.
SOURCE: Adapted from Osmonics "Pure Water Handbook".
Edited by Carolyn Allen