Water filters reduce impurities in drinking water and help extend appliance life. They use a variety of methods to filter out sediment, taste and odour, hardness and chemical contaminants.
Filtering methods range from simple mechanical ones such as a screen filter, to more advanced chemical or biological processes. Distillation is one of the oldest ways to purify water, involving boiling and condensing steam.
Chemical compatibility
The chemical compatibility of a water filter is a significant aspect that needs to be taken into consideration during the process of filtration. This is because the filter’s material may intermingle undesirably with the dissolved substances in the fluid that is being filtered. This will reduce the efficacy of the filter and cause it to fail in the process.
A water filtration system is a convenient way to ensure that your home’s water is free from toxins. In addition to reducing the risk of health issues, it can also prolong the life of your appliances by preventing them from reacting with the chemicals in your water. Besides, it is less expensive than buying bottled water and provides the same level of purity.
However, water filtration systems have several disadvantages. For one, they are not suitable for drinking water that has been contaminated by organic matter or microscopic bacteria and viruses. In addition, filtered water is too pure and lacks small quantity elements that are important to human anatomy like sodium and magnesium.
For example, if your water contains arsenic, you need a special filter to remove it. Some filters can only remove trivalent arsenic while others require a pre-oxidation step to convert it to the more toxic pentavalent form. Nonetheless, most home water filtration systems can effectively remove arsenic through distillation.
Sequestration
The quality of your water can have a significant impact on your health and well-being. The contaminants in your water can make it taste unpleasant or cause a variety of health problems, including diarrhea, headaches, nausea, and even death. Fortunately, there are ways to ensure that you drink safe water. One way is to use a water filter.
A water filter can remove harmful bacteria, minerals, and other particles that may be present in your drinking water. Moreover, it can also remove toxins and other impurities that affect the quality of your food. It is important to choose a quality filter that will suit your needs.
Some types of filters rely on a chemical process to isolate certain substances. For example, some filters use a compound known as polyphosphate to sequester calcium and magnesium minerals that cause limescale. However, this technique only inhibits scale, rather than eradicating it completely. Therefore, it is not as popular as other methods of water filtration.
Other types of water filters rely on a physical barrier to remove particles from your water. These filters can include everything from simple mesh filters to ceramics that have complex pore structures for filtration of fine pathogens. These filters are typically rated based on the size of the particle they can capture, in microns. Moreover, they can be expensive.
Ion exchange
The ion exchange process is a tried-and-true method for water filtration. It uses a charged resin bed to attract specific ions in the water and trap them. The resulting pure water passes through the system, while the unwanted ions are removed by a regenerating solution. The ion exchange process is also the basis of water softening and for taking out regulated contaminants like lead and copper. The resin is comprised of insoluble polymer beads that have functional groups on them with an electric charge. The resin can be set up to target cations (positively charged ions that contribute to hardness) or anions (negatively charged ions like arsenic and nitrate).
The desirable cations stick to the resin, while the undesirable anions are flushed away and replaced with a new supply of desired ions. The desirable ions are released into the water as they bind, so the resin must be regularly rinsed to keep its effectiveness. Most home ion exchange systems use backwashing techniques, making the maintenance more hands-off than other methods.
Anion exchange is also used for removing heavy metals like lead, mercury, and cadmium that can seep into the water supply through industrial processing or from runoff. Most home anion exchange systems require periodic monitoring for nitrate and sulfate levels, as these are often a sign that the resin has exhausted its capacity. In addition, it’s important to periodically regenerate the resin with a brine solution to remove any remaining nitrate and sulfate.
Reverse osmosis
Water filtration systems that use reverse osmosis are among the most efficient available. The process works by using a semi-permeable membrane that allows water molecules through but rejects larger ones, such as contaminants, organic materials and salt. The system also uses pre- and post-filters that trap contaminants to reduce the amount of waste water produced.
Reverse osmosis is often used to desalinate seawater or reduce high chemical contaminants in industrial applications, but it can be used on a smaller scale for homes. Homeowners who are concerned about their water quality or want to make sure they are drinking the recommended amount of ounces per day should consider this type of system.
To understand how reverse osmosis works, it’s best to start with an easy experiment. Place some fresh water and a concentrated aqueous solution on opposite sides of a semi-permeable membrane. Apply pressure on the side of the membrane with the concentrated solution and watch as water molecules move from the concentrated solution to the pure freshwater side.
The process is accelerated by the fact that dissolved ions have different charges. The charged water molecules are more likely to pass through the membrane than those without a charge, which causes a concentration gradient across the membrane. This is the same principle that drives osmosis in nature. The difference is that the force of pressure applied needs to be greater than the osmotic pressure for the process to work.