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Types of Water Treatment

Ningthoujam Sandhyarani Oct 28, 2018
The treatment of water involves the removal of contaminants present in the raw or partly treated water. Let's see some of the methods used for water purification.
Water obtained from the natural sources like streams, rivers, and lakes are unfit for specific purposes. The major causes of water pollution are microbes, dissolved chemicals, and other particulate matter, which have originated either naturally or through man-made sources.
Hence, it becomes necessary to treat water before using it for drinking, irrigation, or other purposes. The objective of all water treatment procedures is to remove the contaminants or at least reduce their presence in raw water.

Methods of Treatment

Some of the common water purification methods are sedimentation or settling, boiling, chemical disinfection, and filtration. There are several methods of purifying water as mentioned here:

Ultraviolet Treatment

In this technique, the water to be purified is passed through germicidal ultraviolet (UV) light configured inside a low-pressure lamp. As the water passes the ultraviolet purifier, the biological contaminants are exposed to UV light. This damages the genetic components of the microbes, thereby killing them.
A major drawback of ultraviolet treatment is that it is ineffective in the removal of dissolved chemicals and other particulate matter.

Ozone Treatment

Ozone, a colorless and unstable gas, is effective for killing the biological contaminants than that of chemical disinfection method like chlorination. Other than this, it also reduces odor problems and concentrations of iron, sulfur, manganese, and other dissolved chemicals.
In this procedure, an ozonation system is used to generate ozone gas, which is then dissolved in raw water for purification purpose. The disadvantages of this technique are mild carcinogenic by-products and high cost of operation.

Membrane Treatment

Membrane technology is indeed an innovative method in which a semipermeable membrane is used for the removal of water impurities. There are two types of membrane water treatment methods, namely, pressure-driven (e.g. reverse osmosis) and electrically driven.
In the pressure-driven method, hydraulic pressure is used to drive the raw water across the membrane, whereas in the electrically driven method, electric current is used to allow the movement of water through the membrane. Though this procedure removes organic and biological contaminants, it is costly to maintain.

Reverse Osmosis Treatment

Reverse osmosis (RO) is one of the most effective methods. It is usually used for treating home water in order to remove chemical toxins, organic contaminants, pesticides, and microbes. In reverse osmosis, the raw water is forced (with pressure) through a dense membrane filter that prevents passing of impurities.
The advantages of reverse osmosis are no alteration in the taste and smell of water, and effective removal of microbes and toxins. However, a major disadvantage is that the purified water obtained after reverse osmosis is devoid of useful minerals. The membrane may become clogged after prolonged use, and therefore it needs to be replaced periodically.
Not all the aforementioned methods are practiced for drinking water purification. The effectiveness of the treatment method depends on the type of contaminants and/or water quality. For the effective removal of contaminants or pollutants, a combination of methods can be used at a time.
Disclaimer: This is for informative purposes only and does not in any way attempt to replace the advice offered by an expert on the subject.