WATER PURIFICATION by Mah Noor Tahir.pptx

This topic is about how we can save water by the treatment of waste water from city areas.Different steps are applied to get 99% pure water for reuse and added to natural resources .

1. WATER PURIFICATION METHOD Presented by :                         MAHNOOR TAHIR

2. Steps of purification Preliminary method Primary method Secondary or biological method Tertiary or advanced method This Photo by Unknown author is licensed under CC BY-NC .

3. Preliminary treatment of sewage  Main objective is to remove solids from waste water Some important techniques are: ( i ) screening (ii)grit removal (iii)skimming This Photo by Unknown author is licensed under CC BY-SA .

4. (1): Screening Used to remove solid waste like plastics,cloths,or dead animals from waste water Water is passed through a screener. Screener may be coarse,fine or medium depending on the size of the oppenings . This Photo by Unknown author is licensed under CC BY .

5. (2) Grit removal Small ,non-biodegradable particles which are heavier than suspended organic matters The heavy inorganic materials like sand and ash others can be removed by grit chambers (3):skimming​ ​ Process of removal of fatty and oily material from sewage​ In this method, sewage water is placed in skimming tank.​

6. (2):Primary treatment Primary treatment  remove fine suspended organic solids that can not be removed in the preliminary treatment  Some techniques are:  Sedimentation,mechanical   flocculation,chemical flocculation

7. 1.sedimentation The solid particle of the sewage tend to settle down due to gravity. It is done in sedimentation tank. This Photo by Unknown author is licensed under CC BY-SA .

8. 2 . Mechanical Flocculation  In this method sewage is placed in a flocculation tank . The sewage is rotated at a speed of 0.43m/sec with the help of rotating paddles. 3. Chemical Flocculation In this method sewage is placed in coagulation tank and then some precipitating agents  such as alum is added. Alum forms precipitate of ALUMINIUM HYDROXIDE[Al(OH) 3 ]

9. (I)Trickling Filter Aerobic water treatment A bed of crushed rocks or other coarse media roughly 2 meters deep and up to 60 meters in diameter . Trickling filters remove up to 85 percent  of organic pollutant from sewage. (II)Activated sludge system The activated sludge process is a type of biological wastewater treatment process for treating sewage  Industrial wastewater using aeration and a biological floc composed  of bacteria and protozoa.

10. (III)oxidation ditch Removes biodegradable organics Oxidation ditch is ma de of a circular or oval shaped channel complete with mechanical aerators installed into the system. It is essentially a modification of a completely mixed activated sludge system used to treat wastewater from small communities.

11. 4.Tertiary or advanced treatment  Tertiary treatment of water is the final stage of the multi-stage water cleaning process. This stage removes inorganic compounds bacteria,viruses and paracites . Removing these harmful substances make the treated water safe to reuse ,recycle or release into the environment. It is proceed by: Disinfectionation Dechlorination .

12. Disinfection Water at this stage is cleaned but microorganisms are still present that are removed by these of the following method: Physical method  Boiling for 15 –20 minutes Ultraviolet rays (Gama rays may also be used sometimes) Chemical method Chlorination process is addition of chlorine to water to make it safe for use.It is most benificial  as it removes taste and odour,and also prevents water born illness.                    Ozone is swiftly gaining popularity as a cleaning agent.It  bonds to and breaks down viruses,bacteria , and other harmful pathogens. Excess Lime treatment Potassium permanganate Bromine and Iodine

13. Dechlorination It is the process of removal  of residual chlorine from disinfected waste water to prior to discharge into the environment. Sulphur dioxide is most commonly used for dechlorinaion . other compounds used for this process are sodium bisulphate , sodium suiphite , sodium thiosulphate and activated carbon. 

14. Thank you   Any question?