371754892-Group-1-Chapter-4-the-Sewage-Disposal.pptx



from the viewer, the smaller is the size of the object. Relative size is supported by the concept of linear perspective. Parallel lines that meet at the horizon give the illusion of distance. Objects, therefore, become smaller the nearer they are to the point in the horizon where the two lines converge.
Atmospheric Perspective. This is also known as aerial perspective. The illusion of depth is created by techniques known as gradient (a gradual change). This may be a gradient in texture, brightness, color intensity, and combination of warm and cool colors. To understand gradient better, the picture plane is divided into three parts: the lower part is the foreground, which is nearest to the viewer, the second is the middle ground, and the upper part of the picture plane is the background. In applying gradient to give the illusion of depth, objects in the foreground would be bigger, detailed, and brighter. As the eye moves to the middle ground, the objects' appearance would gradually change. In the middle ground objects would be smaller compared with those in the foreground. There would be less detail, and colors are not so bright. When the viewer looks at the background, objects will be smaller, they will have very little detail, and the colors are hazy giving the illusion of distance.

1. The Sewage Disposal System By: Abcede, Enrico Agbing, John Ayuson, Erielle Benitez, Theresa

2. 4-1. The Sewage and its Disposal Critical problems of environmental health Dysentery, typhoid, diarrhea, etc. Waterflow, air transmission, and vermin served as vectors for disease Daily average human waste/excreta per capita is at 80g of fecal matter and 950g of urine Diluted, results to 30 to 100 gallons of sewage. Of the solid waste, half of which is organic and subjected to rotting

3. Types of Sewage Disposal System Cesspool Privy Septic Tank Public Sewer Line

4. The Cesspool A hole in the ground curbed with stones, bricks, concrete hollow block, or other materials laid in such a manner as to allow raw contaminates sewage to leech in to the soil. Organic wastes accumulate and finally disposed of by disintegration process

5. The Privy A concrete sealed vault with a wooden shelter constructed for the collection of raw sewage. Disintegration of waste is the same with a cesspool Objectionable due to the dangers of contaminating the local water supply

6. The Septic Tank A device or receptacle used expedite (hasten) the decomposition of elements in raw sewage waste Raw sewage- water, settleable solids such as organic material that can be precipitated in a septic tank in a short amount of time.

7. The Public Sewer Line Public Sewage System Owned and operated, and maintained by the government Consists of a sewage treatment plant that draws waste from buildings and houses to a disposal system

8. Of the four types of sewage disposal, the cesspool and the privy are obsolete. Prevailing sewage disposal systems recommended by authorities are the Public Sewer Line and the Septic Tank

9. 4-2. Public Sewer Line Classified into three types according to the kind of waste it disposes The Combination Public Sewer The Sanitary Sewer The Storm Drain

10. The Combination Public Sewer Oldest type of public sewer. Conveys both storm water and sanitary wastes. Obselete and no longer deemed sanitary by authorities

11. The Sanitary Sewer A public sewer facility that carries regular sanitary wastes only. Terminates modern sewage dispersal plant No rainwater permitted to enter into this type of public sewer Classified into two types: The intercepting or Trunk Line Sewer The Tributary or Contributing Sewer

12. The Intercepting Sewer Conveys sanitary waste to a dispersal plant Commonly made of concrete pipes that varies in sizes from 0.60 to 3.00 meters in diameter, laid underground to a minimum depth of 3 meters

13. The Tributary Sewer Classified as an intercepting sewer branch Pipes are made of vitrified clay or concrete pipe laid in an open trench Generally smaller in diameter Not installed more than 3 meters below the surface

14. The Storm Drain Another kind of public sewer line that carries storm water Terminates in a natural drain such as canals, lakes or rivers

15. The Manhole Classified as a device of the main and storm sewer. Serves as man’s access for inspection, cleaning and repair. Made of bricks, stone, adobe or concrete at an interval distance of 75m to 150m with a diameter of 0.9 to 1.2 meters provided with iron rungs to serve as ladder for the maintenance crew to reach the bottom

16. Sewage Ejector A pump that will discharge waste in the sump and transfer it to the house drain installed overhead. Necessary when public sewer lines are 2-4 meters below street level

17. Materials estimation on public sewer lines On the plan of the public sewer line, obtain net distance between manholes to be laid with concrete pipes. Net distance = total distance – space are occupied by manhole The net distance found divided by the length of one pipe at 1.00 meter long regardless of diameter # of pipes = net distance / 1m per pipe Decrease by 3-4% from the obtained number of pipes to get exact number required # of pipes * 0.97 or 0.96 = exact number of pipes

18. Comments. To estimate the amount of pipes, the total net length of piping between two stations is divided by the length of one pipe. Then an addition of 3%-5% to make room for contingencies

19. Comments. 3%-5% addition is allotted for small gaps when joining the pipes, especially during deep excavation to make well fitted joints. This may be corrected by means of cement grout or plaster

20. 4-3. The Septic Tank It is a vault used to collect organic waste discharged from the sewer. It is an underground tank where waste matters are made harmless using bacteria.

21. Sewage discharged into the tank is retained. 60%-70% of suspended solid of the sewage is removed mostly by sedimentation. Sludge – a semi-liquid substance formed be sedimentation Scum – a layer of dirt or froth on the surface of a liquid.

22. Digestion – the process which the sludge and scum are being separated from the wastewater by anaerobic bacteria and transforming it into liquid and gases. The septic tank combines two processes: - Sedimentation (for the upper portion of the tank) - Anaerobic Decomposition (for the sludge)

23. Decomposition of organic matter is a bacteriological process caused by: -Aerobic Bacteria (aerobes) -Anaerobic Bacteria (anaerobes) -Facultative Bacteria These bacteria have no relation to diseases. They thrive naturally in sewage, and will function when conditions are favorable in terms of: -Food Supply -Temperature -Moisture

24. The process of decomposition is regarded as stabilization. Putrefaction – decomposition caused by anaerobic bacteria is accompanied by unpleasant odors On the other hand, aerobic decomposition does not carry unpleasant odors. It is accomplished with no specific time. Septic – a sewage that turns dark and smell unpleasant due to anaerobic decomposition

25. Gases that are Produced Inside the Septic Tank Methane Gas (CH 4 ) Carbon Dioxide (CO 2) Carbon Monoxide (CO) Hydrogen (H 2 ) Hydrogen Sulfide (H 2 S) Sulfur Dioxide (HO 2 )

26. 4-4. Construction of the Septic Tank Materials commonly used: - Reinforced Concrete - Plastered Concrete Hollow Blocks

27. - Prefabricated Asbestos - Thin Metal and Plastic

28. General Conditions in Constructing a Septic Tank The concrete or masonry septic tank is usually constructed in a rectangular form. 90 cm x 150 cm – minimum inside dimension A 120-centimeter depth of the liquid content is necessary. The inlet and outlet inverts of the septic tank shall be long turn sanitary tee. The invert is extended down the liquid of the tank not more than 30 centimeters.

29. 6. The bottom of the digestion chamber should be sloped to one low point. The septic tank should be provided with a manhole extended a few centimeters above the surface of the solid to overcome infiltration of the surface water. Septic tank (large plumbing installation) are provided with suspended compartment attached to the ceiling slab of the tank. Septic tank should be constructed near the surface of the ground, because the correction of the waste depends upon the extent of oxidation and the existence of anaerobic bacteria.

30. 4-5. Size of the Septic Tank Principles in determining the size of the Septic Tank For a family of 6 persons, the minimum tank capacity should be approximately 1.3 cubic meters with a minimum size of 90 cm wide by 150 cm long and 120 cm depth 2. A very large tank is not advisable, because the bacterial activities would be retarded. The size of the tank is proportionally based on the number of persons expected to be served. In other words, the volume of the tank has a rational proportion with the volume of incoming waste for bacterial activities to be in favorable condition.

31. 3. For residential installation, the practice is to allow 5 to 6 cubic feet of tank volume per person. Thus, a septic tank that will serve a family of 12 persons must have a liquid capacity of 6 * 12 = 72 cubic feet or 538 gallons ( 1 cubic foot = 748 gallons )

32. Technical Data in Determining Volume of Septic Tank Minimum width 90 cm Minimum length 150 cm Minimum depth 120 cm For residential buildings to serve large number of people, allocate of liquid per person ……………………….. 0.14 to 0.17 cu.m . For small residential house to serve up to 12 persons, the chamber should have a liquid content of not more than ………. 2.0 cu.m . For school, commercial, and industrial establishments, the volume of the tank should not be less than ……………. .057 cu. m. nor more than ………………………………………………………………....... .086 cu. m./person

33. Sample Problem 1 Determine the size of a septic tank to serve 200 persons in a commercial establishment. SOLUTION Find the volume of the septic tank using the Technical Data of Information. For the commercial establishment, use .057 cubic meters/person. 200 persons x .057 cubic meters/person = 11.4 cubic meters

34. 2. To find the width, you can assume any width that will meet the minimum size needed in the septic tank. For example, assume 1.2 meter width of the tank for 200 persons. Multiply. 200 x 1.2 meters = 2.40 meters width 3. The maximum depth of a septic tank liquid is 1.50 meters. Find the length of the septic tank VOLUME = Length x Width x Depth

35. L = L = L = 3.20 meters This value of L is just for the length of the digestion chamber.  

36. 4. In order to get the full length of the septic tank, divide the value of L by 2 to include the leaching well. + L = +3.20 Total Length = 4.80 meters THEREFORE, the size of the septic tank to serve 200 persons is 2.40 meters wide by 4.80 meters.  

37. Cross-sectional View of the Septic Tank

38. Sample Problem 2 A motel with toilet and bath, and kitchen facilities will serve a maximum of 100 persons. Determine the capacity and dimensions of the septic tank. SOLUTION Refer to the table 4-2 in book. Under hotel without private bath, the waste per person per day is 50 gallons. Multiplied by 100 is 5,000 gallons a day. Using the formula: V = 1.125 + 0.75Q where: V = Liquid volume of the tank in gallons Q = The daily sewage flow in gallons *1.125 and 0.75 are constants

39. 3. Substitute, V = 1.125 + (0.75 x 5,000 gallons) V = 3,751 gallons 4. NOTE: There are 264 gallons in one cubic meter. Find the volume of the septic tank in cubic meter. = 14.2 cubic meters capacity of the septic tank  

40. To find the dimensions of the septic tank if the maximum depths is 1.50 m and the width is assumed to be 3.00 meters, divide: L = = 3.50 meters  

41. 4-6. Location of Septic Tank Location of the septic tank shall observe the following considerations: The septic tank may be located closer to the building it will serve, providing a minimum distance of 2.00 meters from the outside wall. As much as possible, the septic tank should not be located closer to the doors or windows. Septic tank should be at least 15 meters away from any source of water supply. The farther the better.

42. Requirements for a Satisfactory Disposal of Human Waste There should be no contamination of ground surface that may enter into the spring or wells. There should be no contamination of surface water. The surface soil should not be contaminated. Excreta should not be accessible to animals, flies, cockroaches, vermin and the like. There should be no odor and unsightly conditions. The methods used should be simple and economical in terms of construction operation.

43. 4-7. Safety Precautions Before cleaning or repair, septic tanks must NOT Be poorly aerated or ventilated Lack free oxygen Contain harmful and dangerous gases Under these conditions, If one enters a septic tank for repairs or cleaning purposes, he or she may meet almost instant death To avoid such situation Remove the manhole cover few days in advance of the work, and Supply fresh air inside the tank while work is being done

44. Septic tanks may also contain INFLAMMABLE gases that might result to an explosion So as a precaution, when working in the dark provide An electric emergency light with properly insulated cord, or A flashlight powered by dry cell Do not ignite flames near the septic tank Be alert to shock and electrical wire hazards

45. 4-8. Sewage Treatment Even after removing the effluent in the septic tank, countless of harmful anaerobic bacteria still needs to be disposed. Effluent - liquid waste or sewage discharge Anaerobic bacteria - organism that does not require oxygen for growth Which is why there are several methods or processes used in sewage treatment.

46. Methods in Sewage Treatment Activated Sludge Process A type of wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa.

47. Trickling or Sprinkling Filter Processes It consists of a fixed bed of rocks, lava, coke, gravel, slag, foam, sphagnum peat moss, ceramic, or plastic media over which sewage or other wastewater flows downward and causes a layer of microbial slime (biofilm) to grow, covering the bed of media.

48. Design and Construction of a modern sewage disposal requires engineering training in all the phases of natural science like Civil works for the design and construction of the structure Mechanical for the construction of equipment Plus engineers must have an extended knowledge of chemistry, physics and bacteriology