The Water Quality Association :
Tools and Resources :
Technical Briefs :
Treating the Water We Drink, When & Where We Drink It
This article is an overview of common Point-of-Use and Point-of-Entry water treatments, including Activated Alumina; Activated Carbon; Anion and Cation Exchange; Disinfection Technologies including Chlorination, Microfiltration, Ozone, and Ultratviolet Light; Distillation, and Reverse Osmosis.
It's ironic that many areas of the world face critical shortages of drinking water on a planet whose surface is 3/4 covered with water. Most of the water, of course, is seawater, which is far too saline for human consumption. And of the little "fresh" water that remains, most is trapped in polar ice caps where it is difficult to harness for use by the world's population. Much of the natural supply of potable water that is accessible faces stress from a growing world population, which increases the basic demand for this natural resource, while reducing the supply further through biological and industrial contamination.
Major population centers in developing nations without established waste treatment or water treatment infrastructures often suffer from epidemics of waterborne disease. In these areas, raw sewage often directly contaminates the rivers and streams used for drinking, washing, and cooking. In other cases, unchecked industrialization leads to water contamination through improperly disposed-of chemical and nuclear wastes.
Some good news about this problem is that individuals can take control of their own water quality, and treat their water for nearly all biological and chemical contaminants that may be encountered. These technologies also treat for "aesthetic" contaminants that cause potable water to have unpleasant tastes, colors, and odors.
Point of Use (POU) and Point of Entry (POE) water treatment equipment can effectively treat the water used by a small community, home, or business.
POU equipment treats the water that is used at a single tap, while the rest of the water in the building remains untreated. POU equipment is primarily used to treat health contaminants like lead, and aesthetic contaminants like sulfur. These contaminants are a concern in water used for drinking and cooking.
POE equipment treats most or all of the water before it is distributed, either throughout a small community or at a single building. POE equipment treats for health contaminants like volatile organic compounds (VOCs) that can be absorbed through the skin, or contaminants like radon which exist as a harmful vapor suspended in the water that can be inhaled during showering. POE is also used to describe water softening, which inhibits scale formation in plumbing while increasing the efficiency and longevity of water-related appliances like water heaters.
There are many effective technologies used to provide POU/POE treatment solutions, and no single technology is effective for treating all of the possible contaminants. A specific technology or combination of technologies is usually applied to treat the specific problem at hand.
It should be noted that different levels of performance can be found between products using each technology. If a product is to be used to treat a health contaminant, it is important that the specific product be tested successfully for the reduction of that contaminant. Offered below is a brief description of the main technologies, and what they are typically used to treat.
Activated Alumina
Activated alumina is a filter media made by treating aluminum ore so that it becomes porous and highly adsorptive. Activated alumina will remove a variety of contaminants, including excessive fluoride, arsenic, and selenium. The medium requires periodic cleaning with an appropriate regenerant such as alum or acid in order to remain effective.
Activated Carbon (Granular and Solid Block)
Granular activated carbon is a well-established technology for the reduction of a wide range o
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Sat, Jul 31, 2010
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Copyright 2010 by the Water Quality Association – All rights reserved.
Water Quality Association
International Headquarters & Laboratory
4151 Naperville Road
Lisle, IL 60532-3696
USA
630 505 0160, Fax 630 505 9637
info@wqa.org, www.wqa.org
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