If conventional water treatment processes cannot effectively clean the water, then additional Filtration (Micro-, Ultra-, Nano- or RO Filtration) would be advisable.
However:
MembraneFiltration, especially UF, NF and RO cause increased pressure drops and reduced throughputs and are usually applied as industrial systems. Small UF, NF and RO filter units are suitable to install under the sink, but cannot supply all household appliances. Therefore the compatitive priced NanoCeram cartridge (a NASA nanofilter product) has been selected to filter the drinking water in the main water supply of households, small businesses and special applications, because of it`s low pressure drop and small throughput reduction. The NanoCeram achieves the same filter results as a comparable membrane filter.
The MembraneFiltration units MF-UF-NF-RO
Specifications and comparison (1mm=1000µm=1000000nm)
Please note that the suppliers specifications of their MF, UF, NF, RO filters vary up to 500-fold with regard to the "standard" pore size specifications.
Example: "Ultrafiltration has a pore size of approximately 0.002 to 0.1 microns"
MICROFILTRATION - Pore size up to approx. 0,1 micron.
Recommended: When water undergoes microfiltration, many microorganisms are removed, but viruses remain in the water. No significant pH change.
- Microfiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia);
- Microfiltration has a moderate effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli);
- Microfiltration is not effective in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus);
- Microfiltration is not effective in removing chemicals.
ULTRAFILTRATION - Pore size up to approx. 0,01 micron.
Recommended: Ultrafiltration would remove larger particles and may remove some viruses. Neither microfiltration nor ultrafiltration can remove dissolved substances unless they are first adsorbed. No significant pH change.
- Molecular Weight Cut Off (MWCO) of 13,000 to 200,000 Daltons). Ultrafiltration filters remove particles based on size, weight, and charge;
- Ultrafiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia);
- Ultrafiltration has a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli);
- Ultrafiltration has a moderate effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus);
- Ultrafiltration has a low effectiveness in removing chemicals.
NANOFILTRATION - Pore size up to approx. 0,001 micron.
Recommended: Nanofiltration removes most organic molecules, nearly all viruses, most of the natural organic matter and a range of salts. Nanofiltration removes divalent ions, which make water hard, so nanofiltration is often used to soften hard water. Needs pH adjustment.
- A nanofiltration filter has a pore size of approximately 0.001 micron.
Molecular Weight Cut Off (MWCO) of 200 to 2000 Daltons); Nanofiltration filters remove particles based on size, weight, and charge; - Nanofiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia);
- Nanofiltration has a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli);
- Nanofiltration has a very high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus);
- Nanofiltration has a moderate effectiveness in removing chemicals.
REVERSE OSMOSIS (RO) - Pore size up to approx. 0,0001 micron.
A reverse osmosis filter has a pore size of approximately 0.0001 micron.
After water passes through an RO 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. Only CO2 comes thru. pH decreases and requires additional pH adjustment.
- Reverse Osmosis Systems use a process that reverses the flow of water in a natural process of osmosis so that water passes from a more concentrated solution to a more dilute solution through a semi-permeable membrane. Pre- and post-filters are often incorporated along with the reverse osmosis membrane itself.
- Reverse Osmosis Systems have a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia);
- Reverse Osmosis Systems have a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli);
- Reverse Osmosis Systems have a very high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus);
- Reverse Osmosis Systems will remove common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead; may reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous.
Pros & Cons
Common NanoFiltration and RO need an extra booster pump; RO needs an extra upstream Chlorfilter to ensure it`s proper working.
pH needs to be adjusted. This is positive, because any natural selected components can be added.
https://www.safewater.org/fact-sheets-1/2017/1/23/ultrafiltrationnanoandro
https://www.cdc.gov/healthywater/drinking/home-water-treatment/household_water_treatment.html#
