Water purification methods

Water purification is the transition of dirty harmful (Contaminated) water into clean safe water.

Water purification generally means freeing water from any kind of impurity it contains, such as contaminants or micro organisms.

Water is of major importance to all living things.

We purify water to get rid of contaminants that can be detrimental to our health.

Up to 60 percent of the human body is Water.

Therefore the quality of Water we drink is very important.

The Drinking Water should be totally clean, pure and free of any disease causing MICROBES, and that’s why it should be properly Treated and DISINFECTED before using it for drinking purpose.

Purification on Large scale Purification on Medium Scale Purification on Small Scale(Domestic

Methods)

When sources of water are Rivers, Streams, Lakes etc. then water is Purified by Coagulation Sedimentation Filtration Disinfection Storage

When sources of water are wells, Springs, Tanks etc.Then water is purified by the addition ofBleaching powder/Chlorinated Lime as it is Cheep Easy to use Reliable and safe

BOILING: for 5-10 minutes kills almost all organisms & removes temporary Hardness.

DISTILLATION: not commonly used due to higher cost, used in Labs. etc.

ADDITION OF CHEMICALSBleaching Powder: 5% solution is used Dose: 3-6 drops/L contact

time of ½ hour. Chlorine Tablets/Halazone Tablets. one tablet/litre.

Iodine Solution: 02 drops of 2% Soln./litreKMnO4: an amount that gives just pink coloration to the Water.Alum: used for turbid water in a dose of 0.1-0.4 grains/5 litres of

Water.

surface waters (Rivers, Streams, Lakes and Reservoirs)

groundwater (wells).

Where does the water come from?

Water Treatment

COAGULATION:

WATER TOWARDS

SEDIMENTATION

Coagulation removes dirt and other particles suspended in water. alum and other chemicals are added to water to form tiny sticky particles called “floc” which attract the dirt particles. The combinedweight of the dirt and the alums (floc) becomes heavy enough to sinkto the bottom during sedimentation.

Water TreatmentWATER

FROM COAGULATION

WATER TOWARDS FILTRATION

Coagulated particles fall, by gravity, through water ina settling tank and accumulate at the bottom of thetank, clearing the water of much of the solid debrisand clear water moves to filtration.

SEDIMENTATION:

Water TreatmentFILTRATION, DISINFECTION & STORAGE:

FILTRATION: The water passes through filters, some made of layers of sand, and charcoal that help remove smaller particles.

DISINFECTION: A small amount of chlorine is added or some other disinfection method is used to kill microorganisms that may be in the water.

STORAGE: Water is placed in a closed tank or reservoir for disinfection to take pace. The water then flows through pipes to home and business in the community

WATER FROM

SEDIMENTATION

Water DisinfectionPurpose of disinfection: To make Drinking water free of any disease causing

bacteria and microbes.

Methods of disinfection:

There are 3 mainly used disinfection methods at large scale.

CHLORINATIONOZONATIONULTRAVIOLET RADIATION

CHLORINATIONChlorine is the most common cost-effective means of disinfecting water in the U.S.

The addition of a small amount of chlorine is highly effective against most bacteria, viruses, and protozoa.

But cysts (durable seed-like stages) formed by parasitic protozoa such as Cryptosporidium and Giardia can survive chlorine.

Chlorine is applied to water in one of three forms: elemental chlorine (chlorine gas), hypochlorite solution (bleach), or dry calcium hypochlorite. All three forms produce free chlorine in water

OZONATIONOZONE is Strongest oxidant/disinfectant available.

More effective against microbes than chlorination.

But, costly and difficult to monitor and control under different condition.

Ozonation process:

Ozone (o3) is generated on-site at water treatment facilities by passing dry oxygen or air through a system of high voltage electrodes.

ULTRAVIOLET RADIATIONWhen UV radiation penetrates the cell wall of an organism, it damages genetic material, and prevents the cell from reproducing.

Now a days emerging technology made UV radiation to find a place in both household and large scale drinking water disinfection.

How is UV light generated?

Ultraviolet light is most typically generated from a low pressure or a medium pressure lamp generating UV light.

ULTRAVIOLET RADIATION

COAGULATION

SEDIMENTATION

FILTRATIONDISINFECTION

STORAGE

COMPLETE CYCLE OF WATER TREATMENT: