Activated Carbon Filters

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Activated carbon filters

Activated carbon filters retains organic contaminants, including those that give taste, odor and color to purify drinking water, process water, production water, beverage, purification, surface water from wells and rivers, tertiary wastewater treatment.

Among the main groups of contaminants are pesticides, detergents, hydrocarbons, dissolved fats and oils. In addition, these filters eliminate free chlorine.

The purpose of an industrial activated carbon filter is to remove chlorine, taste, odor and colors of organic origin, either with activated carbon of bituminous mineral origin or coconut shell carbon.

The recommended grain size or mesh size for this application is as follows: 12×40 and 8×30.

For an activated carbon industrial water system, it is necessary to know the water quality through an analysis.

When dealing with municipal mains or reliable well water, we can expect a low amount of contaminants and can use a coconut shell activated carbon.

In case the water has high turbidity, high total organic compounds or comes from surface water from rivers or lakes, the type of activated carbon must be of bituminous mineral origin.

What does the activated carbon filter remove from the water?

Activated carbon is very effective in removing or reducing substances, contaminants and organic chemicals. In the United States the agencies that have done studies are EPA and NSF, which mention that they remove from the water between 60 and 80 chemical elements and an effective reduction of another 30 and some 22 moderate removal.

This range of effectiveness depends on the quality of the activated carbon used and the amount of pollutants in the water, the higher the concentration the life time decreases in proportion.

According to EPA (Environmental Protection Agency in the United States) studies, activated carbon is recommended for removal from water:

Identified organic contaminants, including THMs (chlorine by-products).
Listed pesticides (this includes nitrates and pesticides such as glyphosate, also known as Roundup).
Common herbicides.

Chlorine (Cl)

Municipal or state water supply agencies use chlorine to eliminate microorganisms so that it is protected until it reaches the cisterns or water tanks. However, sometimes chlorine can affect other treatments or equipment, or simply when it is used for drinking water. Activated carbon filters are ideal to eliminate free chlorine, its bad taste and odor.

For more information you can read the article related to

Declorination with activated carbon.

Chlorine by-products

One concern with chlorine is its by-products (VOCs), such as THMs, which are identified as potentially carcinogenic. Activated carbon is the most effective technology for removing these byproducts. According to the EPA, it removes the 32 most common chlorine byproducts.

Chloride Cl-

A very common mineral in water is chloride, which in a certain amount can be beneficial to health. However, an excess of chloride in water gives a salty taste and can cause heart problems. Activated carbon usually reduces chloride by 50 to 60%.

Pesticides

Pesticides are products used to control pests, including some weeds. These pesticides end up in groundwater, rivers, lakes, oceans and in our home or process water. Activated carbon can remove most of the pesticides used, including chlordane, chlordecone (CLD/Kepone), glyphosate (Round-up), heptachlor and lindane. It also includes Nitrate (see below).

Herbicides

Herbicides are substances used to control unwanted plants or weeds. Activated carbon has been tested to remove 12 of the most commonly used herbicides, including 2.4-D and Atrazine.
Nitrate (NO32-)
Nitrate is a compound essential for plant growth. Nitrate has no known harmful effect on humans, unless in very excessive amounts. However, an excess of nitrate in water can cause methemoglobinemia, or “blue baby” disease (lack of oxygen). Activated carbon usually reduces nitrate by 50 to 70%.

Perfluorooctanesulfonic acid PFOS

PFOS is a synthetic chemical that is used, for example, in fire-fighting powders, metal coatings and stain repellents. And it eventually ends up in the environment and in drinking water. According to a 2002 study by the OECD Environment Directorate, “PFOS are persistent, bioaccumulative and toxic to mammalian species.” Activated carbon has been found to effectively remove PFOS, including PFASs, PFOAs and PFNAs.

Fosfate PO43-

Phosphate, like nitrate, is essential for plants to grow. It is also a corrosion inhibitor. A high concentration of phosphate has not shown any health risk to humans. Municipal water agencies (PWS) often add phosphates to drinking water to prevent leaching of lead and copper from pipes. But in may be undesirable in industrial process waters or meet standards.

Lithium Li+

Lithium is naturally present in drinking water. Although it exists in a very low proportion, lithium is actually an antidepressant component. It has not been shown to have any harmful effects on the human body. Lithium can be found in brackish well water, geothermal water and brine from oil and gas fields. Vegetable activated carbon filters can reduce between 70 and 90% of this element.

Pharmaceuticals

The use and disposal of pharmaceuticals has resulted in them reaching wastewater. Current observations indicate that pharmaceuticals in drinking water do not cause significant adverse risks to human health, as the concentrations of pharmaceuticals detected in drinking water are well below the minimum therapeutic dose. Pharmaceuticals can reach water sources through effluents from industrial waste and poorly controlled manufacturing or production, mainly those associated with generic drugs. High quality activated carbon cartridge filters remove 95% of pharmaceuticals in water.

Microplastics

Microplastics are the result of plastic waste entering bodies of water. The exact effect of microplastics on human health is difficult to determine for a variety of reasons. There are many different types of plastics, as well as different chemical additives that may or may not be present. When plastic waste enters waterways, it does not degrade like natural materials. Instead, exposure to sunlight, reaction to oxygen and degradation by physical elements such as waves, or river currents, cause plastic waste to break down into tiny pieces. The smallest micro-plastic identified in public reports is 2.6 microns. A 1-micron carbon block can retain microplastics larger than 2 microns.

Special activated carbon filters

In addition to normal activated carbon, some filters use carbon impregnated with silver, which gives the activated carbon bacteriostatic properties, preventing bacteria from forming on the carbon.
By adding other treatment methods such as ion exchange, ultrafiltration, reverse osmosis it is possible to remove more elements, including calcium and pathogens (bacteria, coliforms and viruses).

What activated carbon does NOT remove

Despite the more than 70 pollutants that activated carbon purifies, there are also some elements that it does not remove.

Non-harmful minerals such as magnesium, potassium, sodium and calcium. Dissolved solids including minerals, salts or metals such as iron.
Microorganisms, including coliforms, viruses and bacteria.
Inorganic contaminants such as arsenic and asbestos.

An activated carbon water filter does not retain minerals or TDS (Total Dissolved Solids) which is a parameter that is widely used in water treatment. Read our learning center to learn more about TDS (Meaning of Total Dissolved Solids in Water).

Activated carbon filters do not filter/remove coronavirus that can cause COVID-19. But don’t worry, they have never been found in water, but even if they did, you can use elements such as ultraviolet light and reverse osmosis for that purpose.

Arsenic

Common in some places where ground water has been contaminated. Activated carbon removes 30 to 60% of the arsenic, but it is not sufficient in places where there is a level that exceeds the standards.

If the water contains one or more of these substances, you should use other treatments such as ion exchange or reverse osmosis.

Conclusion

Activated carbon is a widely used material and technology for water treatment and solves most, but not all, contaminant problems.
Make sure you understand the limitations of activated carbon and choose a filter that you will require for your type of water.

High quality activated carbon filters, such as the ones we use, improve filtration efficiency, including lead, other heavy metals, microplastics and some bacteria.

Activated carbon or charcoal filters are also used as one of the stages in most reverse osmosis (RO) filters, household purifiers, germicides such as UV and other technologies.

Sources:

Activated Carbon Filters