WATER TREATMENT METHODS

WATER TREATMENT

The  water treatment involves treatment for portable or drinking purpose, taste, odor, hardness, contamination. Removes many volatile organic chemicals, some pesticides, radon gas, hydrogen suphide, and mercury. It also reduces  odor, color, and taste problems (such as residual chlorine). Water is filtered through carbon granules that traps filters and result in higher  concentrations of contaminations and can serve as a breeding ground for bacteria.

Distillation removes radium, odour, off tastes, heavy metals, some pesticides, nitrates, fluoride, and salt. Units with gas vents can remove some volatile organic chemicals as well with distillation; water is evaporated, leaving impurities behind. The steam is then cooled and becomes distilled water. But the distillation process is slow and consumes a lot of energy, making it expensive. It also consumes large amount of water if the coolant used in the distilled water can corrode materials such as iron and copper in plumbing systems.

                   Reserve osmosis removes inorganic minerals such as radium, sulfate, calcium, magnesium, potassium, nitrates, fluorides, boron, and phosphorous, it also helps to remove salts, certain detergents,ntr volatile organic contaminants, some membrane that has passage smaller than the contaminant molecules. Under-the skin installations are costly and take up a lot of space. In addition, reverse osmosis is slow and wasteful of water, and filter replacement is costly. Some micro organisms may be small enough to pass through the reverse osmosis membrane  and colorize the holding tank.

Cation or anion exchange (water softening ) removes barium, radium, and radium, and taste, coluor, and odor- producing  chemicals, it will remove dissolved iron and manganese when they are present in low concentrations. Also, anion exchange units will remove nitrate and fluoride, but cation exchange units will not. The water softening process works by passing hard water through resins beads. Magnesium and calcium ions in the water exchange place with sodium ions on the beads softening the water. People with hypertension or high blood pressure should consult their doctor about personal health risk associated with drinking softened water. Because of the added sodium  mechanical filtration removes dirt, sediment, loose scale, and insoluble iron and manganese (flakes that have not dissolved) the water is cleared by sand, filter paper, compressed glass wool, or other straining material mechanical filtration does not do much to remove harmful dissolved chemicals. Chlorination removes bacteria : other microbiological contaminants, and some taste- odour and color –producing chemicals, also t removes hydrogen  sulfide and dissolved iron and manganese when followed by mechanical filtration or an activated carbon filter. During chlorination, a pump feeds chlorine into the water. Chlorine has a residual effect which means it works for a while after being added to the water. But if the system is not operated  properly, it is expensive and possibly toxic also,  chlorination by products may be harmful.

Ultraviolet radiation removes bacteria and other microbiological contaminants. Water passes a special light bulb where ultraviolet radiation kills contaminants. However, this system may not work effectively in cloudy water or when the water flow is too fast. Also unless the unit is equipped with a special meter, it is hard to know whether the system is doing the job.

Domestic water treatment methods

1, filtration methods

2, oxidation methods

3, ion- exchange

4, ultra- violet irradiation

5, aeration

6, pH neutralization

1, filtration methods simply stated removes suspended matter from water by mechanical “screening” (sometimes the word “filtration” is used (incorrectly) to refer to all types of water treatment) basic filters usually are porous beds of insoluble material. Other examples include cast forms, plates of sheets materials, synthetic membranes, finely perforated  plastic or specially sized beds or inert particles ion –exchange: water softening is based on the ion – exchange process and employs a tank containing a bed of insoluble materials. This material ( a resin ) has a negative charged sodium ions attached to it . with most water supplies the resin has a stronger affinity for calcium and magnesium ions than for sodium ions. Thus, when water containing calcium and magnesium. Passes through the resin, the hardness ions are attracted to the resin and released in an equivalent quantity to the water supply.

3, oxidation methods:

Chlorination is used primarily for disinfection. It is probably the most popular oxidizing technique that changes taste and odor-causing substances into innocuous forms because chlorine controls the growth of algae and microorganisms, it is able to reduce the quantity of the taste and odor-causing organisms in a water- system. Chlorine also has residual germicidal action that provides continuing antibacterial protection.

4, ultraviolet irradiation

Ultraviolet light provides bacterial killing action much the same way sunlight helps kill bacteria. The ultraviolet unit consists of one or more ultraviolet lamps usually enclosed in a quartz-sleeve, around which the water flows. The lamps are similar to fluorescent lamps while the quartz sleeve surrounding each lamp protects the lamp from the cooling action of water. The killing effect of the lamp is reduced when the lamp temperature is lowered.

5, Aeration

This process treats water through intimate contact with air. Aeration may be accomplished through several methods including spraying. Cascading, aspiring or bubbling the water supply to bring it in direct contact with air. Either pressure (closed system ) or gravity (open system) aerators may be used. Pressure systems are used primarily for oxidation while gravity systems are commonly  used for degassing (e.g removing dissolved radon, carbon dioxide, hydrogen sulfide or methane).

6, pH neutralization:

             In order to increase the overall efficiency of a water conditioning system, acidic water may be pre-treated by passing it through a tank containing a bed of granular lime, calcium carbonate or marble before entering the remainder of the treatment process. Similarly, alkaline  water may be treated with an acid drip or injection process to neutralize the water.