In this presentation you will:

1. Purification In this presentation you will: • explore some purification techniques • examine the process of water purification Next >

2. Introduction Purification is a process used in many industries as a means of obtaining pure or purer substances. Different purification techniques can be used to take advantage of the properties or performance that purer substances provide. In this presentation, you are going to see what purification is, some purification techniques, and the most relevant purification stages applied in the water treatment process. Next >

3. Purification Purification is the process of separating a substance of interest from foreign or contaminating elements to obtain a pure or purer substance. Purification A pure substance is a type of matter in which all samples have the same molecular composition and the same properties. Pure substance Contaminant Next >

4. Purification Purification can involve one or several different techniques, for example: • Filtration • Distillation • Refining • Crystallization • Precipitation and Decantation Next >

5. Question 1 Which of the following is a purification technique? A) Filtration B) Distillation C) Crystallization D) All of them Next >

6. Question 1 Which of the following is a purification technique? A) Filtration B) Distillation C) Crystallization D) All of them Next >

7. Mixture Filter Separatedsubstances Filtration This is the process of using a filter to mechanically separate a fluid (gas or liquid) mixture. Many methods can be used in filtration, but they all intend to separate two or more substances. Next >

8. Filtration The separation of two or more substances through filtration is achieved with a mechanical interaction between a porous medium and the substance or solid to be removed. For example, relying upon the size difference between the fluid particles and the solid particles in a solution, a liquid can be sieved through a filter. Solid particles The filter traps the solid,while the fluid passes through. Filter particles Fluid particles Next >

9. Question 2 What is filtration? A) The separation of two or more substances through filtration is achieved with a mechanical interaction between a porous medium and the substance or solid to be removed. B) Any mechanical separation of two or more substances. C) Any single process that separates a substance from foreign or contaminating elements to obtain a pure substance. D) All the processes that can be used to separate a substance from contaminating elements to obtain a pure substance. Next >

10. Question 2 What is filtration? A) The separation of two or more substances through filtration is achieved with a mechanical interaction between a porous medium and the substance or solid to be removed. B) Any mechanical separation of two or more substances. C) Any single process that separates a substance from foreign or contaminating elements to obtain a pure substance. D) All the processes that can be used to separate a substance from contaminating elements to obtain a pure substance. Next >

11. Condensation Vaporization Distillation Some liquids can be purified using a method called distillation. Distillation uses the vaporization and condensation of liquids to separate a mixture. Next >

12. Condensation Vaporization Distillation In simple distillation, the mixture can be heated to force the more volatile components, or the components with lower boiling points, to vaporize and turn into the gaseous state. The gas is then cooled and condensed back into liquid form and collected to obtain a purified component. Next >

13. Refining Refining is any of the various techniques of purification that a crude substance undergoes in order to remove its impurities. Refining includes the finer processes of metallurgy, the fractional distillation of petroleum, and the production of sugar from raw cane, beet, and maple sap. Next >

14. Refinery gas Gasoline Naptha Kerosene Diesel oil Heatedcrudeoil Fuel oil Hot (350°C) Residue Refining In the petroleum industry, refining primarily involves distillation, whereby crude oil is heated and separated into stages according to the condensation points of the various elements. Next >

15. Question 3 Which refining technique is primarily used in the petroleum industry? A) Filtration B) Evaporation C) Distillation D) Crystallization Next >

16. Question 3 Which refining technique is primarily used in the petroleum industry? A) Filtration B) Evaporation C) Distillation D) Crystallization Next >

17. Precipitation and Decantation Precipitation is the formation of an insoluble solid in a solution which may occur, for example, as a result of a chemical reaction or during saturation in a solution. In this example, two colorless liquids are added together and a yellow colored solid instantly appears, suspended in the liquid. Next >

18. Precipitation and Decantation Precipitation is a purification technique used to separate a solid from a solution. The solid can precipitate (settle out) as a sediment (deposition) or it can be collected by either filtration or centrifugation. In a suspension, such as sand in water, the solid spontaneously precipitates on standing. Solid and solution mixture Solid settles at the bottom Next >

19. Precipitate remains at the bottom Precipitation and Decantation A precipitated solution can be decanted, where it is carefully poured from a container leaving the precipitate at the bottom of the container. When decanting, care must be taken to prevent the precipitate from flowing out of the container with the solution; so, usually, a small amount of solution is left in the container with the precipitate. Next >

20. Question 4 Which of the following can be considered as precipitation? A) The formation of solid particles from a solution. B) The sediment formation in a soil and water mixture. C) The crystallization of sugar in a solution of sugar when is cooled. D) The coagulation of milk by addition of citric acid. E) All of the previous Next >

21. Question 4 Which of the following can be considered as precipitation? A) The formation of solid particles from a solution. B) The sediment formation in a soil and water mixture. C) The crystallization of sugar in a solution of sugar when is cooled. D) The coagulation of milk by addition of citric acid. E) All of the previous Next >

22. Crystallization Crystallization is a technique with important applications in chemistry. It consists of a purifying procedure for a compound contaminated by a small amount of a substance whose solubility differs substantially from that of the compound. Next >

23. Crystallization A contaminated compound is added to a warm solvent to make a saturated solution. For most compounds, the solubility decreases with decreasing temperature, so its temperature is then lowered. Next >

24. Crystallization Solution at normal temperature Ice to reduce temperature Crystallization If the compound is not soluble in the solvent at lower temperatures, but the contaminating substance is, then the compound will crystallize as the temperature decreases; the contaminating substance stays in solution. The crystallized precipitate now has a much higher purity than the original mixture. The cost of this purification method is the loss of some of the compound that stays in solution. Next >

25. Question 5 "Crystallization relies on the difference in solubility, in a cold solvent, between a compound and its contaminating substance." Is this statement true or false? Answer True or False. Next >

26. Question 5 "Crystallization relies on the difference in solubility, in a cold solvent, between a compound and its contaminating substance." Is this statement true or false? Answer True or False. True Next >

27. Salt crystals Evaporation Evaporation can be used as a method to purify solutions, removing the volatile substance and obtaining the non-volatile ones. A solution of salt may be concentrated by evaporation until the salt crystallizes. Next >

28. Water Purification Water purification is the process of removing contaminants from water to make it safe and satisfactory for human consumption. Normally, the main purifying stages of the water purification process are: • Screening • Natural purification • Flocculation • Rapid Sand Filtering • Slow Sand Filtering • Disinfection Next >

29. Mesh panel Solids Waterfiltered Screening This is the mechanical process of sieving out large objects, such as trash and leaves, by filtering the water through a mesh. Next >

30. Natural Purification This process may include the natural oxygenation of swamps and ponds. This involves the intake of nutrients by riverbank flora and water plants, and the detoxifying abilities of micro-organisms and mollusks. Next >

31. Question 6 "Filtering the water through a mesh in the screening stage of water purification will remove all its impurities, contaminating particles and bacteria." Is this statement true or false? Answer True or False. Next >

32. Question 6 "Filtering the water through a mesh in the screening stage of water purification will remove all its impurities, contaminating particles and bacteria." Is this statement true or false? Answer True or False. False Next >

33. Flocculation The water is treated with small volumes of appropriate chemicals. Colloidal particles,with a negative charge, are heldapart by mutualrepulsion This treatment forms a chemical floc precipitate that entraps particles. Ions neutralize thenegative chargesand allow theparticles to flocculateand then settle Next >

34. Flocculation The most common flocculent chemicals are metal salts, such as aluminum sulfate, ferric sulfate, or ferric chloride, and polymers (polyelectrolytes). Colloidal particles,with a negative charge are heldapart by mutualrepulsion Ions neutralize thenegative chargesand allow theparticles to flocculateand then settle Flocculation can be enhanced by adjusting the pH (alkalinity or acidity) with acid, lime, and/or carbon dioxide. Next >

35. Question 7 "Flocculation is a precipitation method used in water purification, where water is treated with small volumes of appropriate chemicals. This forms a chemical floc that entraps contaminating particles." Is this statement true or false? Answer True or False. Next >

36. Question 7 "Flocculation is a precipitation method used in water purification, where water is treated with small volumes of appropriate chemicals. This forms a chemical floc that entraps contaminating particles." Is this statement true or false? Answer True or False. True Next >

37. Outlet Activatedcarbon Sand Gravel Raw water inlet Rapid Sand Filtering This is the most common form of physical treatment of water. It consists of a column containing sand and gravel layers through which water is filtered. Next >

38. Outlet Tasteandodorremoved Activatedcarbon Sand Floc andparticlesstrainedout Gravel Raw water inlet Rapid Sand Filtering Passing flocculated water through a sand filter strains out the floc and the particles trapped within it. Where taste and odor may be a problem (organo-leptic impacts), the sand filter may include a layer of activated carbon to remove the taste and odor. Next >

39. Question 8 What different types of filtering layers are normally used in a rapid sand filter? A) Gravel B) Sand C) Activated carbon D) All of the previous Next >

40. Question 8 What different types of filtering layers are normally used in a rapid sand filter? A) Gravel B) Sand C) Activated carbon D) All of the previous Next >

41. Slow Sand Filtering Slow sand filters rely on biological treatment processes for their action rather than physical filtration. Gentle inlet They produce an excellent quality of water that physical methods of treatment rarely achieve. Biological layer Sand Slow sand filters are graded layers of sand with the coarsest at the base and the finest at the top. Gravel Outlet Next >

42. Gentle inlet Protozoa Biological layer(Schmutzdecke) Fungi Sand Gravel Algae Bacteria Outlet Slow Sand Filtering At the top of a slow sand filter, a complex biological film removes the impurities from the water. This layer is called the Schmutzdecke and is comprised of bacteria, protozoa, fungi, and algae that build up on the surface of the sand, providing the effective purification in potable water treatment. Next >

43. Gentle inlet Protozoa Biological layer(Schmutzdecke) Fungi Sand Gravel Algae Bacteria Outlet Slow Sand Filtering Drains at the base of the filter convey treated water away for disinfection. Next >

44. Question 9 What different types of filtering layers are normally used in a slow sand filter? A) Gravel and mesh. B) Gravel and sand. C) Gravel, sand and active carbon. D) Gravel, sand and a biological film known as the Schmutzdecke. Next >

45. Question 9 What different types of filtering layers are normally used in a slow sand filter? A) Gravel and mesh. B) Gravel and sand. C) Gravel, sand and active carbon. D) Gravel, sand and a biological film known as the Schmutzdecke. Next >

46. Sodiumhypo-chlorite Chlorinegas Chlorinedioxide Chloramine Ozone ClONa NH2Cl ClO2 O3 Cl Ultravioletlight(UVL) Disinfection The finished water is disinfected with either chlorine gas, chloramine, sodium hypochlorite, chlorine dioxide, ozone, or ultraviolet light before it is pumped into the distribution system and storage tanks. Next >

47. Disinfection Some water treatment plants also pre-chlorinate the raw water influent to reduce the incidence of biological films in the treatment cycle. This will also oxidize and precipitate out dissolved iron and manganese from the water. Next >

48. Question 10 In the last stage of the purification process of a water treatment plant, chemicals are added to the treated water to cause ... A) water flocculation. B) water crystallization. C) water disinfection. D) water precipitation. Next >

49. Question 10 In the last stage of the purification process of a water treatment plant, chemicals are added to the treated water to cause ... A) water flocculation. B) water crystallization. C) water disinfection. D) water precipitation. Next >

50. Water Purification Use Water purification technology is extensively used in developed countries, but it is still unavailable in many developing areas of the world. One of the most serious problems that some developing areas struggle to solve is how to make safe drinking water widely available. This is why water purification technology and research into purification techniques is so important. Next >