What is Microfiltration?
Microfiltration is a filtration process which removes contaminants from a fluid by passage through a microporous membrane. A typical microfiltration membrane pore size range is 0.1 to 10 micros. Microfiltration is fundamentally different from Reverse Osmosis and Nanofiltration because those systems use pressure as a means of forcing water to go from concentrated solution to a weaker solution.
What is Ultrafiltration?
An Ultrafiltration filter has a pore size around 0.01 micron. A Microfiltration filter has a pore size of 0.1 micron, so when water undergoes Microfiltration, many microorganisms are removed, but viruses remain in the water. Ultrafiltration would remove these larger particles and may remove some viruses. Neither Microfiltration not Ultrafiltration can remove dissolved substances unless they are first absorbed (with activated carbon) or coagulated (with Alum or Iron salts).
What is Nanofiltration?
A Nanofiltration filter has a pore size around 0.001 micron. Nanofiltration removes most organic molecules, nearly all viruses, most of the natural organic matter and range of salts. Nanofiltration removes divalent ions, which make water hard, so Nanofiltration is often used to soften hard water.
What is Reverse Osmosis?
Reverse Osmosis filters have a pore size around 0.0001 micron. After water passes through a Reverse Osmosis filter, it is essentially pure water. In addition to removing all organic molecules and viruses, Reverse Osmosis also removes most minerals that are present in the water. Reverse Osmosis removes monovalent ions, which means that it desalinates the water.
WHAT DO THESE FOUR PROCESSES REMOVE?
- Microfiltration removes only suspended solids and possibly bacteria.
- Ultrafiltration removes bacteria, protozoa and some viruses.
- Nanofiltration removes these microbes, as well as most natural organic matter and some natural minerals, especially divalent ions which cause hard water. Nanofiltration, however, does not remove dissolve compounds.
- Reverse Osmosis removes turbidity, including microbes and virtually all dissolve substances. However, while Reverse Osmosis removes many harmful mineral, such as salt and lead, it also removes Calcium and Magnesium. This is why water that is treated by Reverse Osmosis requires a small reintroduction of Magnesium and Calcium to the treated water. This addition of Calcium and Magnesium will increase the pH and decrease the corrosive potential of the water. Corrosive water may leach Lead and Copper from distribution systems and household water pipes.
Selecting the RIGHT Membrane Filtration Technology.
Rule #1: Know where you need to go!
What will the finished water quality need to be make this a successful application for the needs of the end user!
Rule # 2: What do you have to work with?
- Water Source – Surface, Well or Municipal
- Water Quality –Good, Bad or Ugly
- Water Quantity – Limited or Unlimited
- Installation Requirements / Limitations
- Special Customer Requirements
- Suspended Solids Dirt, clay, colloidal materials, silt, dust, insoluble metal oxides and hydroxides.
- Dissolved Organics Trihalomethanes, syntethic organic chemicals, humic acids, fulvic acids.
- Dissolved Ionics (Salts) Heavy metals, silica, arsenic, nitrate, clhorides, sulfates.
- Microorganisms Bacteria, viruses, protozoan cysts, fungi, algae, molds, yeast cells.
- Gases Hydrogen sulfide, methane, radon, carbon dioxide.
Click Image Below For Larger View