Water Treatment Plants


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Water Treatment Plants

  1. 1. Water Treatment Plants
  2. 2. Thought Of The Day Water Treatment Plants 2
  3. 3. Water Flow Water Treatment Plants 3
  4. 4. Water ConsumptionWater provided for human consumption requirestreatment in order to make it• safe (potable)• pleasant to taste (palatable)Modern technology offers remarkable capabilitiesto accomplish these goals• introduction of new and different pollutants• cost of treating to required levels is a challenge for the water supply industry Water Treatment Plants 4
  5. 5. Water Demand• Municipal water supplies are treated to be both palatable and potable, regardless of their intended use• If each person uses about 100 litres of water per day• Commercial and industrial users may increase that demand by more than 5 times Water Treatment Plants 5
  6. 6. Drinking Water - Quality Each source presents its ownOur water supply comes problemsfrom two sources • Surface water has elevated• surface waters i.e. levels of soil particles and algae, rivers, lakes and making the water turbid • may contain pathogens reservoirs• groundwater, which is • Groundwater has higher levels of dissolved organic matter stored below the (yellow color) and minerals such as iron earths surface • Both sources may have high levels of calcium and magnesium (hardness) • both can be contaminated by toxic chemicals Water Treatment Plants 6
  7. 7. Water Treatment Process Water Treatment Plants 7
  8. 8. Drinking Water Plant Water Treatment Plants 8
  9. 9. Untreated to Treated Water Water Treatment Plants 9
  10. 10. Conventional Surface Water Treatment Raw water Screening Filtration sludge sludge Alum Coagulation Cl2 DisinfectionPolymers Flocculation Storage Sedimentation Distribution sludge Water Treatment Plants 10
  11. 11. Screening• Removes large solids logs branches rags fish• Simple process may incorporate a mechanized trash removal system• Protects pumps and pipes in Water Treatment Plants Water Treatment Plants 11
  12. 12. Coagulation• Small particles are not • In coagulation removed efficiently by • we add a chemical such sedimentation because they as alum which produces settle too slowly positive charges to• they may also pass through neutralize the negative filters charges on the particles• easier to remove if they are • particles can stick together clumped together • forming larger particles• Coagulated to form larger • more easily removed particles, but they dont • process involves addition of because they have a negative chemical (e.g. alum) charge• repel each other (like two • rapid mixing to dissolve the north poles of a magnet) chemical • distribute it evenly throughout water Water Treatment Plants 12
  13. 13. Coagulants• Aluminum Sulfate Factors for choosing a Al2(SO4)3 coagulant?• Ferrous Sulfate FeSO4 1. Easily available in all• Ferric Sulfate dry and liquid forms Fe2(SO4)3 2. Economical• Ferric Chloride FeCl3 3. Effective over wide• Lime Ca(OH)2 range of pH 4. Produces less sludgesAluminum salts are 5. Less harmful forcheaper but iron salts are environmentmore effective over wider 6. FastpH range Water Treatment Plants 13
  14. 14. Flocculation• Now the particles have a neutral charge• can stick together• The water flows into a tank with paddles that provide slow mixing• bring the small particles together to form larger particles called flocs• Mixing is done quite slowly and gently in the flocculation step• If the mixing is too fast, the flocs will break apart into small particles that are difficult to remove by sedimentation or filtration. Water Treatment Plants 14
  15. 15. Sedimentation• water flows to a tank called a sedimentation basin• gravity causes the flocs to settle to the bottom• Large particles settle more rapidly than small particles• It would take a very long time for all particles to settle out and that would mean we would need a very large sedimentation basin.• So the clarified water, with most of the particles removed, moves on to the filtration step where the finer particles are removed Water Treatment Plants 15
  16. 16. Filtration• The filtration apparatus is a concrete box which contains sand (which does the filtering), gravel (which keeps the sand from getting out) and underdrain (where the filtered water exits)• After the filter is operated for a while, the sand becomes clogged with particles and must be backwashed• Flow through the filter is reversed and the sand and particles are suspended• The particles are lighter than the sand, so they rise up and are flushed from the system. When backwashing is complete, the sand settles down onto the gravel, flow is reversed and the process begins again Water Treatment Plants 16
  17. 17. Sedimentation Tank AerationFlocculation Coagulation Raw water Water Treatment Plants 17
  18. 18. Water Treatment Plants 18
  19. 19. Disinfection• With particles removed, it only remains to provide disinfection, so that no pathogens remain in the water• Protozoan pathogens are large in size and have been removed with other particles• Bacteria and viruses are now destroyed by addition of a disinfectantChlorination• Enough chlorine is added so that some remains to go out in the water distribution system, protecting the public once the water leaves the plant Water Treatment Plants 19
  20. 20. Softening• Areas where water comes into contact with limestone, there may be high levels of calcium and magnesium present• these chemicals make the water "hard"• Hardness is removed by a process called softening• Two chemicals (lime, CaO and soda ash, Na2CO3 ) are added to water• causing the calcium and magnesium to form precipitates• solid substance is then removed with the other particles by sedimentation and filtration Water Treatment Plants 20
  21. 21. Synthetic Organic Chemicals• Water supplies can be contaminated with synthetic organic chemicals (SOCs) from agricultural runoff or commercial and industrial sources• such as the leaking underground storage tank• These chemicals are not efficiently removed by the simple water treatment process• These chemicals can be removed by passing the water through a layer of activated carbon in a column• The carbon granules strongly attract organic chemicals removing them from the water by a process called adsorption• When the carbon is full and cant hold any more chemical, it is removed from the column, heated to burn off contaminants and can then be re-used. Water Treatment Plants 21
  22. 22. Distribution• Pumping of the clean water produced at the treatment plant to the community is called distribution• This can be done directly or by first pumping the water to reservoirs or water storage tanks Water Treatment Plants 22
  23. 23. Onsite Treatment Color, Taste and Odor• The activated carbon technology used in municipal drinking water treatment can be applied in homes as well• the carbon is contained in a "household-sized" column• water passes through the carbon removing organic matter (which can cause a yellow color) and also compounds which cause unpleasant taste and odor Water Treatment Plants 23
  24. 24. Onsite Treatment At The Tap• Home water treatment systems may also be installed at the tap• Although the technologies vary somewhat among products, they typically include pre-filtration• hardness and metals removal by ion exchange• organic matter removal with activated carbon• post-filtration Water Treatment Plants 24
  25. 25. US Bottled Water Sales Water Treatment Plants 25
  26. 26. Decrease in Tap Water Consumption Water Treatment Plants 26
  27. 27. Bottled Water vs Filtration System Water Treatment Plants 27
  28. 28. The Plastic Planet Water Treatment Plants 28
  29. 29. Implement A ProjectLow Cost• Water Conservation• Water Treatment• Wastewater Treatment• Safe Drinking Water for Flood Effected People• Rainwater HarvestingOr• Any Smart Idea related to Public Health Engineering Water Treatment Plants 29
  30. 30. Water Treatment Plants 30
  31. 31. Rawal LakeWater Treatment Plant
  32. 32. Water Supply• Water supply in Potohar region• Groundwater- major source• Groundwater is supplemented with treated surface water• Disinfectants Water Treatment Plants 32
  33. 33. Sources of Drinking Water in RawalpindiTwo main sources of water in Rawalpindi. Groundwater • Groundwater with Tube wells • located throughout the city • 290 tube wells in WASA controlled area • supplying approximately 28 MGD water to the residents of Rawalpindi. Surface water in the form of lakes • Surface water is supplied from Khanpur Dam (14.6 MGD) through Sangjani Water Treatment Plant • Rawal Lake through Rawal Lake Water Filtration Plant (23 MGD). Water Treatment Plants 33
  34. 34. Ground- vs. Surface Water Groundwater Surface water• constant composition • variable composition• high mineral content • low mineral content• low turbidity • high turbidity• low color • colored• low or no D.O. • D.O. present• high hardness • low hardness• high Fe, Mn • taste and odor Water Treatment Plants 34
  35. 35. HistoryInitial Construction 1962-63 Capacity 14 MGD Executing Agency WAPDA Contractor WABAG, GermanyFirst Extension (7 MGD) 1975-79 Extended Capacity. 21 MGD Executing Agency PHED, Govt. of Punjab Contractor M/S Federal Const. Corp. Lahore.Second Extension (7 MGD) 2000-2002 Extended Capacity. 28 MGD Executing Agency PMU, WASA/RDA Contractor VA TECH. WABAG GmbH, Austria. Water Treatment Plants 35
  36. 36. Main Components• Screening• Coagulation• Aeration• Flocculation• Sedimentation• Filtration• Disinfection or Chlorination• Lime Dosing Water Treatment Plants 36
  37. 37. ComponentsScreening• 3 Bar Screens.• large pieces• form of branches of trees• leaves• clothes• plastic bags• dead animalAeration• 2 Blowers. Air flow @ 6 m3/min.• remove taste and odor problems from incoming raw water• Dissolved Oxygen (DO) level of water is enhanced by this processCoagulation• 2 geared drives• shaft mounted mixers for alum mixing• coagulant delivery pipes• alum is added and rapidly mixed with water• remove suspended particles in the form of turbidity Water Treatment Plants 37
  38. 38. Components• Flocculation• Clarifier # 1 to 3 • 3 Mechanical Flocculation mounted on a central rotating full bridge with sludge scraper rotating bridge • Clarifier Area = 475 m2 • Up flow velocity = 2.55 m/hr. • Total flow = 336 L/s• Clarifier # 4 • 4 flat bottom clarifiers Hydraulic flocculators (Vertical baffles) 16 sludge concentrator Cones • Clarifier Area = 4 x 190 = 760 m2 • Up flow velocity = 2.2 m/hr. • Total flow = 475 L/ s • Coagulant is mixed through vertical baffling arrangements Water Treatment Plants 38
  39. 39. ComponentsSedimentation • large flocs are removed by gravity settling • clear water is collected from the surface • settled material (sludge) removed from sedimentation tank • rotating vipers and sludge valvesFiltration • removal of suspended non settleable solids from the drinking water • supernatant water after sedimentation • passed through a 1.4 meter column of silica sand • effective size of 0.95mm ( 10 %) • filtration rate of 5.4 m/hr. (average)-6.5 m/hr (Max)(110-130 glns/ft2. /hr.)Filter Backwashing • Conventional backwashing system includes • Compressed air • Air and Water • Water • Approximate time 12 to 20 minutes Water Treatment Plants 39
  40. 40. Filter Backwash• Sand is backwashed when • It becomes clogged • Turbidity of filtered water gets too high• During backwash, water is pumped upwards through the sand bed• Sand becomes “fluidized”, and particles are flushed from the sand• Dirty backwash water is pumped into a settling pond and either • Recycled back into plant or • Disposed• Backwashing can consume 1% to 5% of a plant’s production Water Treatment Plants 40
  41. 41. Sedimentation Tank AerationFlocculation Coagulation Raw water Water Treatment Plants 41
  42. 42. Water Treatment Plants 42
  43. 43. ComponentsDisinfection or Chlorination • Liquid chlorine is used for this purpose • dosage rate varies from 1.5 to 2.0 mg chlorine per liter of water • depending upon the level of contamination, pH, and temperature • ensuring the residual chlorine upto 0.3-0.5 mg/l.Lime Dosing • last unit process applied at Rawal Lake water filtration plant • lime is used to adjust the pH of water Water Treatment Plants 43
  44. 44. Disadvantages of Chlorination Chlorine is a dangerous chemical because 1. it irritates the respiratory system 2. it irritates the eyes 3. can form Trihalomethanes, THMs, which are possible carcinogensOther disinfectant chemicals Ozone gas (O3) Ultraviolet light (UV)Not as desirable because More expensive than chlorine Can’t maintain a residual concentration Water Treatment Plants 44
  45. 45. Water Quality Monitoring Program• Water quality analysis laboratory• regularly monitor and analyze the quality of water supplied through plant• equipped with latest instruments and chemicals• to test all the basic physico-chemical and biological parameters• recommended by the World Health Organization• Urban Water Supply & Sanitation Project Phase I Water Treatment Plants 45
  46. 46. Serial No. Water Quality Parameter PHYSICAL PARAMETERS 1 Appearance 2 Color 3 Odor 4 Taste 5 Temperature 6 Turbidity CHEMICAL PARAMETERS 7 pH 8 Alkalinity 9 Hardness as CaCO3 10 Electrical Conductivity 11 Sulphate 12 Calcium 13 Magnesium 14 Total Dissolved Solids 15 Chlorides 16 Residual Chlorine 17 Nitrate as NO3- 18 Nitrite as NO2- BACTERIOLOGICAL PARAMETERS 19 Total Coliform Count 20 Fecal Coliform Count TOXIC SUBSTANCES 21 +3/+5 Water Treatment Plants As Arsenic as 46 22 Cyanide as CN-
  47. 47. Treated Water Quality• Turbidity. 1-3 NTU• Color. Colorless• Odor Unobjectionable• pH 7.5 to 9.5• Residual Chlorine. 0.3 to 0.5 mg/L (at WW 1 and Topi WW)• Coliform Bacteria Nil/100 ml Water Treatment Plants 47
  48. 48. Rawal Lake Catchment Area Poultry Waste from Noor Pur Shahan MurreeBari Imam Q.A. Malpur Chatter Park University Village Diplomatic Enclave Kurrang River Bani Gala Village Lakhwal Village Filtration Plant WASA Water Treatment Plants 48
  49. 49. Upstream Water Treatment Plants 49
  50. 50. Shahdra Kass Water Treatment Plants 50
  51. 51. Bari Imam Water Treatment Plants 51
  52. 52. Bari Imam Water Treatment Plants 52
  53. 53. Bari Imam Water Treatment Plants 53
  54. 54. Bari Imam Water Treatment Plants 54
  55. 55. Human Activities at Korang River Water Treatment Plants 55
  56. 56. Quaid-e-Azam University Water Treatment Plants 56
  57. 57. Pictorial View - Filtration PlantRAWAL LAKE FILTRATION PLANT Water Treatment Plants 57
  58. 58. Intake Structure WASA WASA Water Treatment Plants 58
  59. 59. Main Building WASA Water Treatment Plants 59
  60. 60. Main Electrical Control Panel WASA Water Treatment Plants 60
  61. 61. Circular and Rectangular Clarifiers Rectangular Circular Clarifier Clarifier Filtration Media WASA Water Treatment Plants 61
  62. 62. Filtration System WASA WASA Water Treatment Plants 62
  63. 63. Filtered Water Collection System WASA Water Treatment Plants 63
  64. 64. Lime Dosing System WASA Water Treatment Plants 64
  65. 65. Safe Drinking WaterHow can you ensurethat your drinkingwater is safe?a) Boilingb) Storing it safelyc) Drinking water fromsafe sourcesd) All of above Water Treatment Plants 65
  66. 66. Thank You