Drinking water treatment process/Drinking water treatment/Potable water treatment

This video describes the drinking water treatment or portable water treatment. This video describes the various sources of water. The various steps involved in the water treatment plant. The steps include screening, sedimentation, coagulation, flocculation, filtration and disinfection. The different types of disinfection methods are also described. Chlorination,, UV treatment and ozone treatment. The drawbacks of chlorination and UV treatment. is also described. The major advantages of UV treatment is also mentioned. Some optional treatment steps such as fluoridation, is also discussed. In screening process, floating impurities such as paper, cloth etc. In sedimentation process, the suspended particles are removed by keeping the water undisturbed for few hours in a deep tank. In filtration process the Colloidal particles are removed. In three disinfection process, three microorganisms are removed. we get our drinking water. Drinking water treatment/Potable water treatment You will be able to enumerate the sources of water and contaminants present in water. list out the requirements of drinking water. elaborate the process of drinking water treatment. explain the need of each step in this process. brief the various disinfection methods. Requirements of Drinking Water Should be free from odour, colour and taste Should be free from dissolved objectionable gases Should be slightly alkaline (pH about 8.0) TDS should be less than 500ppm. Should be free from pathogens such as bacteria, virus, protozoa etc. Should be free from toxic impurities. Should not be turbid. Contaminants in Surface Waters Floating matter –paper, cloth, twigs, logs, leaves, fish, plastic waste etc. Suspended particles –sand, silt etc. Colloidal particles –fine particles, clay etc. Microorganisms –bacteria, virus, protozoa etc. Screening To remove the floating matter like paper, plastics, twigs, logs, cloth, fish, plants and trash etc. Sedimentation To remove the insoluble suspended particles like sand, silt, dirt etc. Particles denser than water settle down at the bottom. Coagulation - Coagulation is done using chemicals called as coagulants (alum, sodium aluminate, FeCl3, FeSO4 etc). Rapid mixing uniformly disperses the coagulant. The colloidal particles like clay etc. are destabilized. Flocculation Slow mixing brings the dispersed the coagulant particles together to form a floc. The fine colloidal particles (negatively charged) adheres to the floc (positively charged), which grows bigger in size and becomes heavier. Sedimentation The heavy flocs descend down due to gravity and settle at the bottom Filtration It removes the left out particles, residual turbidity and few microorganisms. If activated carbon is used, it removes taste and odour. Disinfection - Destroys the pathogens (disease causing microorganisms) Methods of disinfection Chlorination – bleaching powder, chloramines or liquid chlorine Ozone treatment – Ultraviolet (UV) light – 254 nm UV light damages the RNA and DNA of the microorganisms. Destroys chemical contaminants also. Optional steps Aeration – to remove iron and manganese Pre-chlorination – helps to remove fats, oil, and grease. Also removes iron and manganese. Fluoridation – to strengthen the tooth and prevent tooth decay.