Removal of Solid Contaminants
Making drinking water safe involves physically removing solid contaminants such as rust and dirt with the proper sediment filtration, removing inorganic and organic dissolved sub-stances with separation processes (ion exchange and adsorption), and killing biological microbial pathogens with high intensity UV light, much like the sun.
1. Solid Material, Sediments
Filtration is used to remove solids and particulate matter from water. Sediments down to 5 microns are removed by MF (Micro Filtration). Anything smaller is not solid and is removed by separation.
UF (Ultra Filtration) or RO (Nano Filtration) are not an option for particulate matter removal.
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Types of Sediment Filtration Methods
Filtration systems typically comprise of 2 filters, one for solids and one for dissolved contaminants. The first filter housing contains a sediment filter that removes solid substances by direct interception down to 5 microns, where the particles run into a physical barrier and are captured in the filter. This mechanical retention is called sieving.
Principles of Sediment / Particulate Matter Filtration
The sediment filter cartridge removes any solids by direct interception, where the particles run into a physical barrier and are captured in the filter. The 5-micron sediment filters are the perfect size to remove most debris and solids from the water without clogging up quickly. It is also the required size for the UV process so that particles in the water can not be used by organisms to shade against the killing rays of the UV lamp.
Removal of Dissolved Chemicals and Organics
Retention filters can not physically remove dissolved substances, instead, ion exchange and a chemical reaction based on adsorptive retention are used. It is when molecules attach to the filter surface and change their molecular structure by losing ions to the media.
2.1 Harmless Dissolved Chemicals, Minerals and Heavy MetalsHardness is not a contaminant but an aesthetic problem. Iron and Manganese can be aesthetic problems and are removed by the activated carbon in the second filter of a typical filter set to some degree. Carbon filters can also remove Hydrogen Sulfate (H2S - rotten eggs) and other odour. |
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2.2 Harmful Dissolved Chemicals, Minerals and Heavy MetalsArsenic and Lead, Fluoride and Contaminants of emerging concern”, when occurring in the drinking water, need to be reduced or removed as much as possible. Average levels of these contaminants can be reduced by the carbon filtration in the water treatment system.
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3.1 and 3.2 Harmless and Harmful Dissolved Organics3.1. Not harmful organic contaminants - Tannins and Lignins The cation-ion exchange treatment method used in softening systems is effective at removing tannins to a certain degree. If no softener is installed, the activated carbon in the carbon block filter cartridge can reduce these to some degree.Elevated levels can be removed with extra treatment. 3.2 Toxic organic substances (humic acid particles and coagulants, VOCs, disinfection byproducts), are removed by the sediment and carbon filtration to a high degree. |
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Removal of Pathogens
The two most common methods for the removal and destruction of disease-causing pathogens in drinking water are
- Chemical-based solutions (adding chlorine and chloramine to the water)
- UV disinfection, employing ultra-violet light
4. Removal of Pathogens and Biological Contaminants in the Water
While chemical-based solutions have been employed for a very long time, UV disinfection (without using any chemical) has quickly become the favoured method of water disinfection due to its inherent safety, ease of use and the extremely low cost per liter of treated water.
Other methods for at least partial reduction and removal of pathogens include UF and RO systems however they can be expensive and quite wasteful of water due to their design and function.
How Does UV Disinfection Work?
A UV disinfection system, also called sterilizer or purifier, is designed to expose the water running through the unit to a specific wavelength of UV light at 254 nanometers. To achieve this, a translucent UV emitting light source (UV lamp) is placed inside a stainless steel reaction chamber. The UV light is penetrating the water thoroughly while it flows by and the wavelength of the UV rays are effectively disrupting the DNA or RNA of pathogens, such as bacteria, viruses, and protozoa, rendering them unable to reproduce or cause infections.
Conclusion
The vast majority of households will benefit greatly using a basic, low-cost, whole home water treatment system made up of a dual filtration system (sediment and carbon block filters) and a properly sized UV disinfection system. This will serve to process all the water in the home, all the time to ensure a high-quality of drinking and wash-up water is always available, in unlimited quantities.
Households with specific issues whether related to water hardness, clarity, chemical or radiological contaminants, may contact us for additional information and guidance.
