Coconut Shell Charcoal Filter
What are activated carbon filters?
Interestingly, activated carbon filters (aka activated charcoal filters) aren’t like traditional water filters. Instead, they consist of small, black beads or a solid black porous sponge that has undergone some additional processing to make it better at selectively trapping impurities. First, it is injected with heat, steam, or chemicals, which creates millions of small pores in the carbon, vastly increasing the size of the surface area. This activation process creates more pores for the carbon to trap and absorb a broader range of contaminants, making the carbon far more effective as a filter medium.
Each particle of carbon has a large surface area that gives the contaminants the maximum possible exposure to the active sites within the filter media so that more of the pollutants can be absorbed/removed. One pound (450g) of activated carbon contains a surface area of approximately 100 acres, which is almost three times the size of The Pentagon!
This and other remarkable properties of activated carbon make it a useful medium to eliminate impurities from water through adsorption. It’s also used to make respiratory masks and used in air conditioning units and exhaust fans to rid the air of unwanted odours like smoke fumes, and animal odour.
How does activated carbon filters treat water?
Activated carbon filters treat water by using a process called adsorption. As the water passes through the activated carbon, the carbon acts like a sponge with a large surface area and absorbs the contaminants in the water. Simply, the activated carbon exerts a magnetic-like pull on the specific impurities and attracts and traps them in the pores of its surface area.
The dissolved impurities migrate from the liquid to areas in the pore channels with the most potent attractive forces. The contaminants are absorbed because the attraction of the carbon surface is much stronger than the attractive forces that keep them dissolved in the fluid. Following that, the filtered water flows to the next stage of filtration, if any.
As for chlorine and other chemicals that do not adhere to carbon, activated carbon filters use a chemical reaction to eliminate such pollutants. Activated catalytic carbon, which is more reactive than regular carbon, chemically alters the chlorine molecules, converting them into a chloride.
Are all activated carbon filters the same?
Activated carbon filters remove significantly higher concentrations of pollutants than regular carbon, but some of them have some slight differences. Some filters contain more or less activated carbon than others, which can impact their filtering capacity, the speed at which they absorb, etc. Besides, high levels of activated carbon extend the lifespan of a filter. Consequently, it will require fewer replacements and keep producing filtered water for longer.
Types of activated carbon filters
Activated carbon filters usually come in two main types: granular activated carbon (GAC) filters and carbon block filters.
GAC filters contain loose millimetre-sized granules of activated carbon that can detect and filter contaminants that would often go undetected in some other types of filters. The filter media used in these filters are usually coconut shell, coal, wood, and a few others, with coconut shell carbon being the most renewable.
GAC filters are perfect for water purification because:
They’re porous, inexpensive, and readily available for use as absorbents
They have more useful surface area per gram than any other material available for physical adsorption
They aren’t as restrictive as carbon block filters, thus allowing water to flow through the carbon at a faster rate
They last longer
The activated carbon can be re-activated, unlike the single-use powdered granules in carbon block filters
Despite all those excellent benefits, a significant issue with GAC filters is that the water can sometimes cut a path through the carbon and allow contaminants to pass through.
On the other hand, carbon block filters are made of finely powdered granules (usually 1 micron or less in size) and a binding agent that holds the granules together, so they don’t move about each other. The combination of the pellets and the binding agent is then heated and formed into blocks. Inside a carbon filter are three main types of filter media: bituminous coal, wood-based media, and coconut-shell media.
Carbon block filters provide 7 to 10 times more surface area than GAC filters and prevent channelling. However, the compact structure of the granules is likely to result in a lower flow rate, which may be an issue for some people.
What water contaminants do activated carbon remove or reduce?
Activated carbon filters do an excellent job of removing and reducing many different contaminants from water, including chemicals, gases, and physical impurities. Several studies cited by the Environmental Protection Agency in the United States (EPA) and NSF International claim that activated carbon filters eliminate between 60 and 80 chemicals from water, effectively reduce another 30, and moderately reduce an additional 22. Of course, the capacity of the system to remove or reduce those contaminants depends on two things:
- The type of activated carbon used (whether GAC or carbon block)
- The quality of the activated carbon
With that in mind, you must ensure that the filter you choose removes the problem-causing pollutants in your tap water. It might help to know that the EPA recommends activated carbon filtration technology as the only water treatment technology that eliminates almost all common and identified herbicides, pesticides, and inorganic contaminants in water.
Here are several classes of water contaminants that activated carbon filters work to remove and reduce:
Perfluorooctanesulfonic acid, or PFOS for short, is a water and stain-resistant synthetic compound that is widely used to make carpets, fire-fighting foams, furniture, paper packaging for food, clothing fabric, and other materials that are resistant to water, grease, or stains. PFOS chemicals are difficult to break down, so they can continue to exist in the environment and drinking water sources for decades. Exposure to PFOS over certain levels can result in adverse health effects, including congenital disabilities, cancers, liver effects, and more. Activated carbon filters are designed to effectively remove PFAS, including PFAS, PFOS, and PFNA.
High-quality activated carbon filters can remove pharmaceutical residue in drinking water. The World Health Organization (WHO) defines pharmaceuticals as “synthetic or natural chemicals that can be found in prescription medicines, over-the-counter therapeutic drugs, and veterinary drugs.” These compounds can get into water sources through human waste from persons who have used the chemicals, uncontrolled and improper disposal of drugs (e.g., flushing drugs into sinks or toilets), and from agricultural runoff comprising livestock manure. When accumulated in the environment, pharmaceutical residues can significantly impact aquatic life. What’s even worse is that they can also leach into well water.
Phosphate in drinking water comes from a range of sources, including runoff, human and pet sewage, chemical manufacturing, and others. Phosphate is crucial for healthy plant growth, but excess phosphate in water can result in a massive increase of algae, causing the water to become cloudy due to algal bloom. Premium charcoal filters usually remove up to 90% of phosphates in water.
Chlorine is a popular water disinfectant in America. Almost every U.S. public water provider uses some form of chlorination to treat their water before distributing it to customers. Chlorine is added to destroy bacteria and other pathogens that make water smell and taste bad. But despite its remarkable disinfecting capacity, reports show that the risk for people who ingest chlorinated water is up to 93% higher than for those whose water does not contain the chemical. Thankfully, some activated carbon filters are excellent are eliminating chlorine and the unpleasant taste and smell that accompany it. Impressively, premium activated carbon filters can remove 95% or more of the free chlorine in some water sources.
· Chorine byproducts
Harmful chlorine byproducts, including THMs, VOCs, haloacetic acids, and others, can form when chlorine used to treat water reacts with the naturally present compounds in the water. Long-term exposure to some of these toxic byproducts has been linked to an increased risk of cancer, infant birth delivery problems, and other unwanted diseases and ailments. Activated carbon filtration is possibly the most effective technique used to eliminate chlorine byproducts from water. The EPA states that the technology removes the 32 most known chlorine byproducts, including the most common byproduct recorded in tap water reports: total THMs (TTHMs).
Chloride plays a significant role in chlorinating drinking water. But according to WHO, “Chloride concentrations above about 250 mg/liter can give rise to detectable [salty] taste in water…” On top of that, high levels of chloride can have adverse effects on human health, especially for people on low-sodium diets or those with certain health complications.
Activated carbon filters are designed and tested to remove the 14 most common pesticides potentially found in water. These pesticides include Chlordecone (CLD/Kepone), Chlordane, Heptachlor, Lindane, and Glyphosate (Round-up). The National Institute of Environmental Health Sciences (NIH) defines pesticides as “any substance[s] used to kill, repel, or control certain forms of plant or animal life that are considered to be pests.” These substances include herbicides, insecticides, fungicides, and others. Because of the widespread use of these agricultural chemicals, they can easily reach water-bearing aquifers below ground. Pesticides can cause short-term adverse health effects, as well as chronic long-term health effects that can occur months or years after exposure.
The use of herbicides has been a common practice in global agriculture for centuries, mainly to control unwanted weeds and increase agricultural production. However, when these chemicals are used in an uncontrolled manner, they sometimes end up in water sources and impact non-target aquatic organisms and even humans. Some herbicides can potentially cause cancers in humans, among other illnesses and ailments. Fortunately, activated carbon is tested and proven to remove 12 of the most common herbicides, including atrazine and 2,4-D weed killer.
Lithium is a naturally-occurring trace metal typically found in soil and other mineral formations, as well as in drinking water. Lithium in tap water is said to be a stress reliever and an antidepressant. Until more observational studies are done, we must consider the potentially harmful effects of the metal on human health. Charcoal filters reduce up to 90% of lithium in drinking water.
What activated carbon won’t filter
Activated carbon is most commonly used to filter water. It improves water quality, eliminates unpleasant odors, and removes chlorine and other pollutants. However, it’s not sufficient for eliminating certain toxic organic compounds, significant levels of metals, fluoride, or pathogens.