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Most of the activated carbon filters are inexpensive to replace if needed, but are considered high quality filtration. Today, carbon filters can come in many sizes and designs, for example small filters can go onto faucet taps and large filters can go under sinks.
Johnson, R., & Scherer, T. (n.d.). Filtration: Sediment, Activated Carbon, and Mixed Media. Retrieved October 4, 2012, from http://www.ag.ndsu.edu/pubs/h2oqual/watsys/wq1029.pdf -
Wikipedia. (2012, August 10). Carbon filtering. Wikipedia. Retrieved October 4, 2012, from http://en.wikipedia.org/wiki/Carbon_filtering
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Historians have proof that activated carbon filters may have been used in old Egyptian cultures to sanitize the air and water in 2000 B.C. Activated carbon filters use the process of adsorption, a process of negatively charged contaminant ions being attracted to the positively charged activated carbon. Activated carbon filters removes and organics in the water that can affect the water’s taste, odor, and color. It also, reduces chlorine, radon gases and more.
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Another type of purifiers are distillers. Distillation is a process where water is boiled and then the condensing purified steam is collected into a clean container. The first clear evidence of distillation was in ca. 200 AD, the process being described by Alexander of Aphrodisiacs. This is a different type of purifier from activated carbon filters because it is a slow process.
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These distillers only make 3 liters of water per hour, must be kept in a ventilated area due to chlorine byproducts being released from the boiling water, and have to be regularly cleaned. Wikipedia. (2012, September 18). Distilled water. Wikipedia. Retrieved October 4, 2012, from http://en.wikipedia.org/wiki/Distilled_waterGoogle Images. (n.d.). Google. Google. Retrieved October 4, 2012, from https://www.google.com/search?hl=en
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These filters were created in 1903 as a new process for desalination. In ion exchangers, cations were removed from the water using other cations or sodium. Softening, or ion exchanging is the removal of hard water. Hard water is water which contains a high concentration of calcium and magnesium ions. Water is thought to be hard if it is 100 mg/L or more of calcium carbonate.
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Water passes through the filter containing resin granules and the calcium and magnesium in the water creating the hardness are exchanged for sodium from the resin granules. This is why this filter is called an ion exchanger.
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Enzler, S. (2011). History of water treatment. History of Water Treatment. Retrieved October 4, 2012, from http://www.lenntech.com/history-water-treatment.htmLesson 9: Softening. (n.d.). Overview of Softening. Retrieved October 4, 2012, from http://water.me.vccs.edu/courses/ENV115/lesson9.htmGoogle Images. (n.d.). Google. Google. Retrieved October 4, 2012, from https://www.google.com/search?hl=en
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In the mid-1950s fresh water was produced from seawater. About 15,200 desalination plants were in operation or in the planning stages worldwide by the end of 2001. Reverse osmosis is a process when two liquids of different concentrations are separated by a semi- permeable membrane, and water passes through the membrane, now pure. This style of water purifier is preferred over distillers because it allows oxygen to be passed through so, it does not taste as flat as distilled water.
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Ion Life. (2012). Types of water filters. Types of Water Filters. Retrieved October 4, 2012, from http://www.ionizers.org/filter_types.htmlWikipedia. (2012, July 10). Reverse osmosis. Wikipedia. Retrieved October 4, 2012, from http://en.wikipedia.org/wiki/Reverse_osmosis
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This filter is a common style of countertop or under-the-sink systems.
What is the healthiest water? (1998). Discount Juicers. Retrieved October 4, 2012, from http://www.discountjuicers.com/healthywater.htmlEnvironmental Working Group. (2012). Reduce your Exposure to Chemicals in your water: Get a Water filter. EWG Home. Retrieved October 4, 2012, from http://www.ewg.org/tap-water/getawaterfilter -
Potwora, R. (2010, October 13). A POU workhorse — the carbon block filter. Water Technology. Retrieved October 4, 2012, from http://www.watertechonline.com/articles/a-pou-workhorse-mdash-the-carbon-block-filter
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Carbon block filters were created beginning in the 1970s and work by having active carbon shaped into blocks under high pressure. Carbon block filters are used to remove the contaminants by adsorption. These filters are generally of better use than granulated activated carbon filters because they have a bigger surface area of activated carbon. Carbon block filters must be cleaned thoroughly for the purified water to flow through it effectively.
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What is the healthiest water? (1998). Discount Juicers. Retrieved October 4, 2012, from http://www.discountjuicers.com/healthywater.html
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These are used as an alternative to just tap and bottle water today. They are unfortunately, usually low quality and sold at a higher price rate. The average pitcher filter sells for around $25 and includes one 30 gallon filter cartridge. Because of the small size of these cartridges they have a very limited level of effectiveness and a low capacity. Some of brands of filters even require the buyer to go back to the store to get more cartridges. Some popular brands are Pur and Brita.
