Water Treatment Plant ,water purification method.pptx

Water Treatment Plant

1. Water Treatment Plant Presented by: Executive, Quality Control, AFBL Welcome to

2. Water Source

3. Impurities Coarse Impurities: Plastic, Packets….. Suspending Impurities: Clay, Sand, Organic Compounds… Colloidal Impurities: Silica, , , Organic wastage, Humic Acid, Colours, Complex compounds…… Dissolved Impurities: Cation: , , , , , , ………….. Anion: , , , , …….. Gas: , , , , , ………………  

4. Drinking Water Quality Standard Parameter Bangladesh Standard (BDS) pH Value 6.4 to 7.4 Total Dissolved Solid (TDS), mg/L 500 (maximum) Total Hardness as CaCO3, mg/L 300 (maximum) Total Alkalinity as CaCO3, mg/L 50 (maximum) Chloride, mg/L 250(maximum) Iron, mg/L 0.3 (maximum)

5. Purpose of Treatment The  purpose of drinking water treatment  is to produce  water  that is physically, chemically & biologically safe for drinking. Increasing Self Life to preserve long time. Increasing taste Beverage Production For boiler feed water, chiller feed water and so on

6. Purpose of Alkalinity Reduction Alkalinity: Alkalinity is buffering capacity or capacity of neutralizing acid of water. It is expressed as calcium carbonate in ppm or mg/L unit. Alkalinity: 2 types. P-Alkalinity: with respect to phenolphthalein indicator. Main responsible is hydroxyl and carbonate ion M-Alkalinity: with respect to Methyl red indicator . Main responsible is bicarbonate, carbonate and hydroxyl ion. Impact on Beverage: a lot of acid (Citric Acid) need for decreasing pH as well as on taste also. Around 370 mg/L or 3.7 kg/10000L citric acid need. Impact on health: a lot of gastric acid need to adjust stomach pH

7. Steps of Water Treatment Pretreatment: Chlorination Chemical Treatment Coagulation Physical Treatment: Sand Filter Carbon Filter Polisher Ozone UV-Light

8. Flow chart of Treated Water Deep Underground Water Tank Coagulation Tank Buffer Tank Sand Filter Reserve Tank AC Filter Treated Water Reserve Tank polisher Beverage Production Drinking water Production pH adjustment

9. Pretreatment Definition: A  pretreatment  is something which is applied to a feed in order to make a process or stage more effective. Pretreatment Process: Screening for removal of coarse impurities. Chlorination for oxidation & growth inhibition and killing of microorganism so that microorganism and algae can not grow in storage tank and so on…… 0.2-0.5 ppm dosing applied in ground water tank due to inhibition of microbial growth. If the raw  water  is clean, less  treatment  steps are needed. Ground Water Tank Capacity: 100000 Ltr Cleaning: Yearly cleaning with vim & 100 ppm  

10. Chemical Treatment Coagulation: Coagulation is a chemical process that involves neutralization of charge by adding desired chemical with appropriate dosing. Lime, Ferrous Sulfate( FeSO 4 ) , Alum ( Al 2 ( SO 4 ) 3 .18 H 2 O ), PAC (Poly Aluminium Chloride), Ferric Chloride etc. are most common Coagulating agent. Coagulation and flocculation are often the first steps in water treatment. Chemicals with a positive charge are added to the water. The positive charge of chemicals neutralizes the negative charge of dirt and other dissolved particles in the water . This process is called coagulation. The chemicals which are used for coagulation process called coagulants. When this occurs, the particles bind with the chemicals and form larger particles, called floc. This process is called flocculation.

11. Chemical Selection & Dosing Chemical Selection: Chemical selection is depend on the source water and parameter to be controlled and condition of the reaction environment. For AFBL: Targeted parameter is alkalinity. Jar Test: The dose of the coagulant to be used can be determined via the jar test . The jar test involves exposing same volume samples of the water to be treated to different doses of the coagulant and then simultaneously mixing the samples at a constant rapid mixing time. The micro floc formed after coagulation further undergoes flocculation and is allowed to settle. Then the turbidity of the samples is measured and the dose with the lowest turbidity can be said to be optimum.

12. Coagulation Tank Volume: 60000 L Number of Tank: 4 Production rate: 15000 L/h (for each tank or line) Retention time: 4 hrs. Total Production per hour: 60000 L/h Controlling parameter: Alkalinity, 2p-M= +2 +7 should be maintain all-time. Test: Alkalinity (p-alkalinity and total alkalinity or M-alkalinity). Chlorine test: Range of chlorine (6 8) ppm. Floc release: Every 2 hrs. for 2 3 minutes. Cleaning: Every four month with vim and 100 ppm chlorine solution.   Volume of chemical dosing tank: Lime dosing tank: 2000L Ferrous Sulfate dosing tank: 600 L Chlorine dosing tank: 400 L Chemical dosing: Lime (5% solution): 3200 ml/minutes. Ferrous sulfate (8.33% solution): 1600 ml/minutes. Bleaching powder (1.5% solution): 1600 ml/minutes

13. Clarification Clarification: Clarification  consists in removing all kind of particles, sediments, oil, natural organic matter and colour from the  water  to make it clear. On the other word it is a separation process of all insoluble matter from water based on specific gravity .

14. Clarifier (AFBL Coagulation Tank)

15. Dosing of Lime and Its Reaction CaO+H 2 O= Ca(OH) 2 + = + Ca(OH) 2 + Ca(HCO 3 ) 2 =2CaCO 3 ↓ + H 2 O Mg(HCO3)2 + 2Ca(OH)2 → 2CaCO3↓ + Mg(OH)2↓ +2H2O According to carbonate and bicarbonate equilibrium pH- pC diagram above pH 10.3 bicarbonates converted to the carbonate. That’s why lime is so necessary for dosing that pH will be above 10.3 to convert maximum bicarbonate to carbonate. AFBL: 5% lime ( 40 kg lime in 800 Ltr . water) which is actually around 3.3% and it is converted to Ca(OH) 2 solution which is used in coagulation tank. Q: Why it is necessary to convert bicarbonate into carbonate? Ans : Solubility Product of CaCO3 is very low, Ksp = 4.7x That means when Ca and Carbonate ion meet together then only 0.0000686 mol /L calcium carbonate can remain in the solution and carbonate ion removed from water, means buffering capacity of water or alkalinity decreased.  

16. pH- pC diagram Source: Handbook for the operation of water treatment works (Water research commission of South Africa)

17. Reaction of Ferrous Sulfate & Bleaching Powder 6FeSO 4 + 3Cl 2 = 2Fe 2 (SO 4 ) 3 + 2FeCl 3 2Fe 2 (SO 4 ) 3 +12H 2 O= 4Fe (OH) 3 ↓+ 6H 2 SO 4 2FeCl 3 + 6H 2 O = 2Fe (OH) 3 ↓+ 6HCl H 2 SO 4 = H + + HCl = H + + Alkalinity reduction reaction. 2H + + C = CO 2 + H 2 O 4FeSO 4 + 2Cl 2 + 3Ca(OH) 2 + 3Ca(HCO 3 ) 2 = 4Fe (OH) 3 ↓+ CaSO 4 + 2CaCl 2 + 6 CO 2 8.33 % Ferrous Sulfate solution used in AFBL coagulation tank. 1.5 % Bleaching Powder solution used in AFBL coagulation tank.  

18. Sand Filter The clear water from top of reaction tank pass through the buffer tank to control flow and then it pass through the sand filter. In sand filter suspended silts, parasites, residual floc etc. are removed.

19. Sand Filter (AFBL) For Line-1+2: Gravel 1 inch : 2000 kg Gravel 3/4 inch : 1000 kg Gravel 1/2 inch : 1500 kg Sand : 95 cft For Line-03 & 04: Gravel 1 inch : 1000 kg Gravel 3/4 inch : 1000 kg Gravel 1/2 inch : 1000 kg Sand : 75 cft Gravel Washing: Yearly cleaning with 32% HCl until dust/dirt would be cleaned properly. But new gravel is preferred.

20. Sand Filter Volume: For line 1+2: 10000 L For line-03: 5000 L or line-04: 5000 L Number of Tank: 3 Flow rate: 30000 L/h for line 1+2 and 1500 L/h for line-03 & line-04. Target: Removal of suspended solids, parasites, residual floc etc. Test: P-alkalinity and M-alkalinity. 2p-M should be in between (+2 +7) ppm Chlorine test: Range of chlorine (6 8) ppm. Cleaning: Back wash: Every day (24 hrs.) with treated water. Chlorine wash: Every week with 100 ppm chlorine solution. Sand is changed per year.  

21. Advantage of Sand Filter Very effective in removing large particles. It removes floc produced in coagulation tank during reaction. Reduces Turbidity by removal of particles. High Filter Rate: 4000L to 12000 L per hour per square meter surface area. Easy Cleaning Process: Backwash interval 24 hrs (AFBL).

22. Reserve Tank Volume: For line 1+2: 20,000 L+ 20,000 L = 40,000 L For line-03: 20,000 L+ 20,000 L = 40,000 L or line-04: 20,000 L+ 20,000 L = 40,000 L Number of Tank: 6 Flow rate: 30,000 L/h for line 1+2 and 15,000 L/h for line-03 & line-04. Target: Maintaining flow rate consistently Cleaning: Every four month with vim and 100 ppm chlorine solution.

23. Activated Carbon Activated Carbon Filter After sand filter water reserve in reserve tank. Then the water passes through the carbon tank where carbon adsorbed residual chlorine (mainly). Also color, odor and organic matter if presence. Activated Carbon: Granular Iodine Value above 950 mg/g AC Filter Contains ( Line1+2): Activated Carbon-1800 kg Sand-1500 kg Gravel ½ inch- 2500 kg Gravel ¾ inch- 1000 kg Gravel 1 inch: 1500 kg Water Quality after AC Filtration: water must be chlorine free

24. Role of AC Filter Removes Organic Compounds Removes Colour of water Removes Bad Test & smell of water Removes residual chlorine or free chlorine Effectivity of ac filter highly depends on iodine value of ac. Activity of AC filter based on Adsorption Technique.

25. Activated Carbon Filter Volume: For line 1+2: 15000 L+10000 L = 25000 L For line-03: 15000 L or line-04: 5000 L Number of Tank: 4 Flow rate: 30000 L/h for line 1+2 and 1500 L/h for line-03 & line-04. Target: Removal of bad taste, bad odor, colour, organic compounds, chlorine etc. Test: Chlorine should be 0 ppm. Cleaning: Back wash: Every day (24 hrs.) with treated water. Steam wash: Every week. Activated carbon is changed per year.

26. Polisher or Micron Filter or cartridge Filter treated water pass through 5.0 µm and 1.0 µm filter to remove particles getter then 5.0 n1.0 µm. For drinking water 0.2 µm filter also used for remove all micro organism and particles getter then 0.2 µm. Water Quality: pH>8.5 TDS<250 Hardness<250 Chloride<250 Cleaning: Weakly by hot water(85 ° c) & citric acid. 4 hrs. contact time

27. Advantage of Alkalinity Reduction & pH Adjustment for drinking water. Advantage of Alkalinity Reduction: Buffering capacity of water with respect to acid is proportionally reduced with decreasing alkalinity. So that low amount of acid need to maintain pH for beverage production . pH Adjustment for drinking water: Usually sulfuric acid/ phosphoric is used for adjustment of pH for drinking water. But sulfuric acid is more suitable. pH controlled according to Bangladesh standard (BDS) in between 6.4 to 7.4.

28. Ozone Treatment & UV Light During filling of drinking water it is need to sterilize. Ozone, UV light etc. are commonly used for sterilization. After ozone treatment, 48 hrs. should wait for drinking that filled water. Mode of action: Ozone oxidize protein so that microbes are killed. UV denature protein that’s why microbes are killed.

29. Water Softening Purpose of water softening: Avoid scale formation in boiler mainly. Avoid hardening with respect to detergent and soap in RMG of Textile Factory for washing.

30. Flow chart of Soft Water Treatment Soft Water Reserve Tank Raw Water Multimedia Filter (DMI) Carbon Filter Resin Tank Resin Tank (DMI) Multimedia Filter

31. Multimedia/DMI Filter Multimedia Filter Contain: Sand, Carbon and Manganese Dioxide (MnO2) Role of Multimedia Filter: MMF mainly used to remove iron, manganese and hydrogen disulfide. How it works: MnO2 have catalytic effect on oxidation of iron ( to ) and Manganese ( to ) those are insoluble in water. That’s why those insoluble compound trapped in filter bed and finally removed. Those trapped substance are removed finally from filter bed during backwash.  

32. Ion Exchange Mode of action: Mainly calcium ion and Magnesium ion are exchange with sodium ion of sodium zeolite. 2NaZ+ = Ca + 2 Resin Regeneration: When hardness of soft water would be >5 resin regeneration is necessary. 10% NaCl solution is used for resin regeneration. Contact time of NaCl with resin is 30 minutes. Resin are kept sinking in salt solution. Ca + 2 ( NaCl ) = 2NaZ+ Regeneration need when hardness of soft water would be >5 Generally every 10-20 hrs. interval regeneration necessary. Regeneration time depends on resin quality and quantity. Soft Water should be free from Iron & Manganese. Hardness should be below 5 ppm.  

33. Reverse Osmosis Osmosis: Process in which dilute solution goes to concentrate solution through a semipermeable membrane. Reverse Osmosis: Reverse means reverse process of osmosis by applying pressure . Quality of RO Water : Hardness: ≈0 Total Dissolved Solid (TDS): below 10 ppm

34. Flow chart of Reverse Osmosis RO line-01: RO line-03: Soft Water DMI Filter AC Filter Membrane Filter Taco Filter RO Water Raw Water AC Filter DMI Filter Membrane Filter RO Water Taco Filter Taco Filter Buffer Tank

35. Role of Multimedia & DMI Filter Multimedia Filter Contain: Sand, Carbon and Manganese Dioxide (MnO2) Role of Multimedia Filter: MMF mainly used to remove iron, manganese and hydrogen disulfide. How it works: MnO2 have catalytic effect on oxidation of iron ( to ) and Manganese ( to ) those are insoluble in water. That’s why those insoluble compound trapped in filter bed and removed. Those trapped substance are removed finally from filter bed during backwash.  

36. Role of AC Filter Removes Organic Compounds Importance of removal of organic compound: Organic compounds are generally long chain polymer and would block the membrane filter, so that filtration can not be possible .

37. Role of Anti-Scaling Agent If Raw water is directly use for RO treatment, than anti scaling agent is necessary for inhibition of scale formation which is caused by mainly calcium and magnesium. Anti-scaling agent react with calcium and magnesium and capture or bonded together to stop deposition of those metals. That’s why no blockage occurred by above two metal compound and membrane remain smooth. Generally poly carboxylic acid are used for this type of treatment.

38. Role of Anti-Chlorine Agent If AC filter is not use in any plant then anti chlorine agent is necessary for removal of chlorine. Generally Sodium metabisulfate is used as anti-chlorine agent. Na2S2O5 + 3H2O + 2Cl2 ------ NaHSO4 + 2HCl Disadvantage of absence of AC filter: Organic compounds can not be removed so that membrane filter blocked soon.

39. Role of Taco Filter Pore size of Taco filter is 1 micron. Role of Taco Filter: Removes Particles greater than 1 micron. Reduce particle load on membrane filter. Make easy reverse osmosis process.

40. Membrane Filter Osmotic Pressure: Pressure need to reverse osmosis process. Membrane Type: Semipermeable Membrane pore size: 0.0001 micron Around 2 third water passes through membrane which is known as RO water or permeated water. One third water can not pass through membrane due to dissolved particles, greater size organic compound and silica. THANK YOU