Environment and health2.pptx community health nursing

CHN

1. Environment and health Presented by Deepa Manandhar Lecturer Community Health Nursing

2. Environmental Sanitation It is defined by WHO as “The control of all those factors in man’s physical environment which exercise or may exercise a deleterious effect on his physical development

3. Components of environment

4. water Water for consumption should be safe and wholesome i.e. Free from pathogen agent Free from harmful chemicals Pleasant to taste (no color and odour ) Usable for domestic purposes.

5. mcq Purest water in nature is: River water Rain water Deep well Impounding reserviour ANS: b

6. Sources of water

7. Rain water Purest water in nature Physically clear, bright chemically soft Impure as it passes through atmosphere

8. Surface water Surface water originates from rain water. It is the main source of water supply in many areas. Surface water is prone to contamination from human and animal sources. Examples of surface water include rivers, tanks, lakes, man-made reservoirs and sea water.

9. Ground water Rain water percolating into ground constitutes ground water. Ground water is safer than surface water because the ground itself acts as a successful filtering medium. Calcium & magnesium may be high resulting chemical hardness of water Sources of ground water are wells, tube wells, springs

10. Sources of ground water The sources of ground water are: Wells (Deep well and Shallow well) Tube well Springs (Deep and shallow)

11. wells Shallow wells: water above the first impervious layer in the ground and more liable to pollution Deep wells: form of ground water, water below first impervious layer in the ground ,machine dug, several hundred meters deep that furnish safest water; also become health hazard if it is open.

12. Wells… The water is much harder and contains pure water. This well provides a source of constant supply. Shallow well is the water that taps water from above the first impervious layer. This is often grossly contaminated and moderately hard.

13. Sanitary well A sanitary well is one which is well constructed properly, located and protected against contamination, thus supplying safe water. Location: 50ft or 15m away from sources of contamination (toilet) It should have covering on top with a hand pump (open wells are not sanitary wells)

14. springs Ground water comes to the surface & flows freely under natural pressure Two types shallow spring dry up quickly & deep spring usually do not dry

15. Purification of water Purification on large scale Purification on small scale

16. Purification on large scale Storage Filtration (Slow sand & rapid sand) Disinfection (chlorination, chemical agent)

17. storage Water is drawn out from the source and impounded in natural or artificial reservoirs. Storage provides a reserve of water from which further pollution is excluded. As a result of storage, a very considerable amount of purification takes place.

18. storage This is natural purification, and we may look at it from three points of view: Physical Chemical Biological

19. physical About 90 per cent of the suspended impurities settle down in 24 hours by gravity. The water becomes clearer.

20. chemical Certain chemical changes also takes place. The aerobic bacteria oxidize the organic matter present in the water with the aid of dissolved oxygen. As a result, the content of free ammonia is reduced and a rise in nitrates occurs.

21. biological A tremendous drop takes place in bacterial count during storage. The pathogenic organisms gradually die out. It is found that when river water is stored the total bacterial count drops by as much as 90 per cent in the first 5-7 days.

22. filtration Filtration is the second stage in the purification of water, and quite an important stage. Two types of filters are in use, the " biological " or " slow sand " filters and the " rapid sand " or " mechanical " filters.

23. Slow sand filter Elements of a slow sand filter are: Supernatant (raw) water A bed of graded sand An under-drainage system A system of filter control valves .

24. Slow sand filter

25. rapid sand filtration Flow diagram of rapid sand filter

26. rapid sand filtration the steps involved are: Coagulation Mixing Flocculation Sedimentation Filtration

27. rapid sand filtration Coagulation : raw water is first treated with a chemical coagulant such as alum or aluminium sulphate 5 to 40 mg/liter depending on turbidity. Mixing: The treated water is then subjected to violent agitation in a "mixing chamber" for a few minutes. This allows a quick and thorough dissemination of alum throughout the bulk of the water, which is very necessary.

28. rapid sand filtration Flocculation : the gentle and slow stirring of the treated water in a “flocculator chamber” for about 30 minutes . This slow and gentle stirring results in the formation of a thick, copious, white flocculant precipitate of aluminium hydroxide. The thicker the precipitate or flock diameter, the greater the settling velocity.

29. rapid sand filtration Sedimentation : Following this, the coagulated water is led into sedimentation tanks for a period of 2-6 hours. At this time, the precipitate along with other impurities including bacteria gets settled down in the tank. At least 95 per cent of the flocculant precipitate needs to be removed before the water is admitted into the rapid sand filters.

30. rapid sand filtration Filtration: The partly clarified water is now subjected to rapid sand filtration. As filtration proceeds, the “alum-floc” not removed by sedimentation are held back on the sand bed. It absorbs bacteria from the water and effects purification.

31. rapid sand filtration Filtration: As filtration proceeds suspended impurities & bacteria clog the filters. Filters become dirty and begin to lose their efficiency. Filtration is stopped and filters are subjected to a washing process known as “backwashing’.

32. disinfection Disinfection is synonymous with chlorination. It is supplement, not a substitute to sand filtration. It kills pathogenic bacteria but no effect on spores & certain virus Bleaching powder is commonly used; whose chemical name is calcium chlorohypochlorite .

33. chlorination Minimum recommended concentration of free chlorine = 0.5mg/liter constitute correct dose of chlorine Break point chlorination: The point at which the chlorine demand for water is met is called the ‘break point’.

34. Purification in small Scale Household purification Boiling Chemical disinfection Filtration UV radiation Disinfection of wells (bleaching )

35. Disinfection of well M ost common, cheapest and effective method of disinfecting wells is by bleaching powder Calculate volume of water in well Volume liters (V) =(π (3.14)*d2*h)/4*1000 Find the amount of bleaching powder required for disinfection: Roughly 2.5 gm of good quality bleaching powder would be required to disinfect 1000 liters of water

36. Disinfection of well Dissolve the bleaching powder in water in bucket and pour into well and leave for 1 hour. Test for residual chlorine at the end of one hour ( orthotolidine - arsenite test) : This is done to test for residual chlorine at the end of one hour contact. If the free residual chlorine is less than 0.5 mg/ liter , the chlorination procedure should be repeated.

37. Hardness of water Hardness is defined as the soap destroying power of water. Type of hardness Underlying causes Temporary hardness (Carbonate hardness) Calcium & Magnesium salts of Bicarbonate Permanent hardness (Non-carbonate hardness) Calcium & Magnesium salts of sulphates Calcium & Magnesium salts of Chlorides Calcium & Magnesium salts of Nitrates

38. Bacteriological indicators of water quality Coliform organisms: Primary and most reliable bacterial indicator for water quality. E.coli is most important coliform indicator. Fecal streptococci: indicate recent contamination of water Clostridium perfringens: indicate remote contamination of water.

39. Public health classification of water borne diseases

40. mcq Which is not a feature of deep well? Water from below the first impervious layer Mostly contaminated water Provides a source of constant supply Much harder water ANS: b

41. MCQ Temporary hardness of water is primarily due to: Calcium and magnesium sulphates Calcium and magnesium chlorides Calcium and magnesium bicarbonates Calcium and magnesium nitrates ANS: c

42. mcq Scabies, an infection of the skin is an example of: Water borne disease Water based disease Water related disease Water washed disease ANS: d

43. Air pollution Air pollution refers to any physical, chemical & biological change in air. More than 100 substances which pollute air have been identified. The two type of pollutants that cause air pollution; primary & secondary pollutants Primary pollutants involves directly cause air pollution; lead, fly ash, metalic oxides and nano particles Secondary pollutants formed by reaction of primary pollutants like gases carbon monoxide, co2 , chloroflorocarbons

44. Air pollution Sulphur dioxide: best indicator of air pollution. Best biological indicator of air pollution: Lichens.

45. Air pollution Air pollution causes various types of respiratory diseases Air quality index is a tool that measure air quality status Pollutants may be in form of solids, liquids or gases. The combination of smoke and fog is “smog.” Carbon Monoxide (CO) is one of the most common air pollutants. Produce from automobiles, industrial, heating facilities and incinerators. Largest source of Co is vehicle emissions.

46. noise Wrong sound in wrong place at the wrong time Sources of noise Automobiles, factories, TV, radio, industries, aircraft etc

47. Noise level Whisper: 20-30dB Normal conversation: 60-70 dB Daily maximum tolerable sound level to human ear: 85dB Auditory fatigue: 90 dB Repeated or continuous exposure to noise around 100 decibels may result in a permanent hearing loss Exposure to noise above 160 dB may rupture the tympanic membrane and cause permanent loss of hearing.

48. MCQ Whispering produces a sound of: 20-30 dB 30-40 dB 40-50 dB 50-60 dB ANS: a

49. MCQ The ‘acceptable’ noise level is: 85 dB 90 dB 95 dB 100 dB ANS: a

50. MCQ Continuous exposure to noise above 100 dB leads to: Temporary hearing loss Permanent hearing loss Auditory fatigue Rupture of tympanic membrabe ANS: b

51. Waste disposal

52. MCQ Waste water without human excreta is called: Sewage Humus Sullage Effluent ANS: c

53. Types of waste Refuse: solid waste Sewage: liquid waste containing excreta Sullage: liquid waste without excreta

54. Method of refuse disposal Dumping Control tipping or sanitary landfills Incineration or Burning Composting Burial Manure Pit

55. dumping Refuse is dumped in low lying area partly as a method of renovation of land. An easy method of dry refuse disposal.

56. dumping As a result of bacterial action, volume of refuse decreases considerably and is converted gradually into humus (paste). some drawbacks like breeding of flies, bad odour , scattered by wind and pollute water sources Most unsanitary method that creates public health hazard (WHO Expert Committee)

57. Control tipping/sanitary landfills the most satisfactory methods of refuse disposal, where suitable land is available. It differs from ordinary dumping where the materials is placed in a trench or other prepared area, adequately compacted and covered with land at the end of the working day. Three methods are used: trench, ramp & area

58. Trench method Trench method usually chosen where ground level available Long trench dug out 6-10 ft deep 12-36 ft wide Compacted refuse is placed in the fill to a depth of 2m (6ft) Refuse compacted and covered with earth Estimated that one acre land per year will be required for 10,000 population.

59. Trench method

60. Ramp method Ramp method suited where land is moderately sloping

61. Area method This method is used for filling land depressions, disused quarries and clay pits. The refuse is deposited, packed and consolidated in uniform layers up to 2-2.5m deep. Each layer is sealed on its exposed surface with a mud cover at least 30 cm thick.

62. Incineration Disposed of hygienically by burning or incineration. Method of choice where suitable land unavailable Dangerous refuse is best disposed

63. Composting Combined disposal of refuse and nightsoil Natural process where organic matter breaks down under bacterial action Heat produced during composting about 60 deg C or higher Nitrates & Phosphates are major plant nutrient which produced as a end product compost.

64. Methods of composting

65. Anaerobic method

66. Anaerobic method

67. Anaerobic method Within 7 days as a result of bacterial action considerable heat is generated in the compost mass. This intense heat which persists over 2 or 3 weeks, serves to decompose the refuse and nightsoil and to destroy all pathogenic and parasitic organisms.

68. Anaerobic method At the end of 4-6 months, decomposition is complete and the resulting manure is a well decomposed, odourless, harmless material of high manorial value ready for application to the land.

69. Aerobic method In this method, compost is literally manufactures in a large scale by processing raw materials and turning out a finished product. The refuse is first cleared of salvageable materials such as rags, bones, metal, glass and items which are likely to interfere with the grinding operation.

70. Aerobic method It is then crushed in pulverizing equipment in order to reduce the size of particles to less than 2 inches. The pulverized refuse is then mixed with sewage, sludge or nightsoil in a rotating machine and incubated. The entire process of composting is complete in 4-6 weeks.

71. burial This method is suitable for small camps. A trench 1.5 m wide and 2m deep in excavated and at the end of each day the refuse is covered with 20-30 cm of earth. When trench is 40cm from ground level, trench is filled with earth & compacted & new trench is dug out. At 4-6 months contents taken out & used in fields.

72. Manure pit Manure pits are dug by the individual householders. The garbage, cattle dung, straw and leaves should be dumped into the manure pit and covered with earth after each day’s dumping. Two such pits will be needed, when one is closed the other will be in use 4-6 feet deep and 3-4 feet wide pit is dug.

73. Manure pit In 5-6 month of time the refuse is converted into manure which can be returned to the field. The method of refuse disposal is effective and relatively simple in rural communities.

74. MCQ Most satisfactory method of refuse disposal is: Dumping Control tipping Incineration Manure pit ANS: b

75. sewage Waste water from a community containing solid & liquid excreta. It contains 99.9% of water and 0.1% are partly organic partly inorganic particles. Sullage: waste water which does not contain human excreta. Sludge: thick black mass and consist of 95% of waste and 5% of other organic materials.

76. sewage Sewage purification: Inadequately treated sewage should not be discharged into rivers, sea because oxygen in water supply used by aerobic bacteria found in sewage. Depletion of O2 lead to death of animal life in water. The aim of sewage treatment is to stabilize the organic matter so that it can be disposed off safely and convert sewage water into effluent of an acceptable standard of purity which can be disposed off into land, rivers or sea.

77. mcq The biological oxygen demand(BOD) indicates: Organic matter Bacterial content Anaerobic bacteria Chemicals ANS: a

78. sewage A standard of test which is an indicator of the organic content of sewage is biochemical oxygen demand (BOD)

79. sewage The “strength” of sewage is expressed in terms of Biochemical oxygen demand(BOD): Important test done on sewage. BOD defined as amount of oxygen absorbed by a sample of sewage during a specific period of time (generally 5 days), at a specified temperature (generally 20d Celsius) BOD value range from about 1mg per litre for natural waters to about 300mg/L for untreated domestic sewage. • If the BOD is 300mg /L and the above , sewage is said to be strong, if it is 100mg/L, it is said to be weak.

80. sewage b. Chemical oxygen demand: measures amount of oxygen required to chemically oxidize the organic material and inorganic nutrients, such as ammonia or nitrate present in water. c. Suspended solid: Amount of this vary from 100 to 500 mg/lit Strong sewage has suspended solid amount >500mg/ litre . Weak sewage has suspended solids amount <100mg/ litre .

81. MCQ Strength of sewage is expressed in terms of all except: E.coli count Suspended particles Chemical oxygen demand Biological oxygen demand ANS: a

82. Method of excreta disposal Latrine should be located 50 fts (15m)away from a source of water supply.

83. Method of excreta disposal Unsewered areas 1. Service type latrines (conservancy system) 2. Non-service type (Sanitary latrine) Bore-hole latrine Dug well or pit latrine Water seal latrine Septic tank Aqua privy Trench latrine

84. 1. Service type latrines (conservancy system) The collection and removal of nightsoil from bucket or pail latrines by human agency is called the service type or conservancy system , and The latrines are called service latrines .

85. Sanitary latrine Criteria of sanitary latrine: Not contaminate the ground or surface water Not pollute the soil Not accessible to flies, rodents & other vehicles of transmission Not create a nuisance due to odour

86. Non Service types of latrine Bore hole Latrine Dug well latrine Water Seal latrine Septic tank Aqua privy

87. Bore hole Consists circular hole 30-40cm (12-16 inch) diameter Dug vertically into the ground to a depth of 4-8 meter (13-26 ft) A concrete squatting plate with central opening and foot rest is placed over the hole. Used for 5-6 people of a family for a year When fecal matter fill up to 50cm, squatting plate removed and hole is closed with earth. Then new hole dug.

88. Dug hole latrine Circular pit 75cm (30 inch) in diameter and 3-3.5m (10-12 ft) deep is dug into the ground. A concrete squatting plate is placed on the top of pit. When pit filled up a new pit is constructed Action of this latrine is same as bore hole; anaerobic digestion

89. Dug hole latrine It is an improvement over the above bore hole latrine. Pit will last for about 5 years for a family of 4-5 people .

90. Water seal latrine A further improvement in the designing of sanitary latrines for rural families in the hand-flushed is “water seal” type of latrine. The squatting plate is fitted with a water seal which prevents breeding of flies due to a trap, a small water container in a bent pipe, and escapes of odours and foul gases.

91. Water seal latrine Once the latrine is flushed, nightsoil is no longer visible. So this type of latrine is more popular to rural people than the bore hole or pit latrine. When the pit fills up, a second pit is dug nearby and the direction of the connecting pipe is changed into the second pit.

92. Septic tank This is water tight masonry (concrete) tank into which household’s sewage is admitted for treatment. It is a satisfactory means of disposing excreta and liquid wastes from individual resistance, small group of houses and institution which have adequate water supplies but do not have access to public sewage drainage system.

93. Septic tank Most satisfactory means of disposing excreta and liquid waste Capacity of tank depend upon the number of user Capacity of 20-30 gallons or 2.5-5 c.ft per person is recommended for household tanks Minimum capacity at least 500 gallons Depth; 1.5-2 meter (5-7 ft)

94. Septic tank Solid waste settle down in tank to form “sludge” which undergoes anaerobic digestion Lighter solids including grease and fat rise to surface and form scum. Effluent liquid which passes out of the outlet pipe and percolates into surrounding soil and undergoes aerobic digestion.

95. Septic tank the aerobic bacteria present in the upper layer of the soil attack the organic matter present in the effluent. As a result, the organic matter is oxidized into stable end products i.e. nitrate, carbon dioxide and water.

96. Aqua privy Latrine with septic tank for the public purpose Small septic tank below the toilet seats A water tight-chamber filled with water and a short length of a drop pipe from the latrine floor dips into water. an aqua privy is very similar to a septic tank, the latrine is located directly over the tank, which means less water is needed for flushing.

97. Aqua privy

98. Modern sewage treatment Primary treatment Screen Grit chamber Primary sedimentation (sludge, scum) 2. Secondary treatment Trickling filter method or Activated sludge process Secondary sedimentation Sludge digestion Disposal of effluent

99. screening The collected sewage and sullage is first passed through a metal screen which strains large particles (pieces of wood, rags masses of garbage and dead animals)- prevents clogging In some plants, the screens are of the moving type and are removed from time to time either manually or mechanically

100. screening

101. Grit chamber Long narrow chamber through which sewage passes 10-20 meters length It allow the settlement of heavier solids while permitting the organic matter to pass through. Collects at the bottom disposed by plain dumping

102. Grit chamber

103. Primary sedimentation The sewage is now allowed to flow slowly with a velocity of 1-2 feet per minute in a primary sedimentation tank. In this tank, the sewage stays for 6-8 hours. Nearly 50-70% of the solids settle down under the influence of gravity.

104. Primary sedimentation The organic matter which settle down called ‘sludge’ and is removed by mechanically operated devices. A certain amount of fat and grease rise to the surface to form scum which is removed from time to time and disposed off. When the sewage contains organic trade wastes it is treated by chemicals as lime, aluminium sulphate and ferrous sulphate.

105. Primary sedimentation

106. Secondary treatment Effluent from sedimentation tank still contains a proportion of organic matter in solution or numerous living organisms It has a high demand for oxygen and can cause pollution of water or soil

107. Trickling filter So need further treatment, aerobic oxidation Trickling filter method; the effluent from primary sedimentation tank is sprinkled uniformly on the surface of bed by revolving device. This device consist pipes which rotates to make effluent a thin film on the surface of filter.

108. Trickling filter Over the surface and down the filter, a complex biological growth consist algae, fungi, bacteria, protozoa and many kinds. This is known as zoogleal layer. Get oxidized by bacterial flora in zoogleal layer The action of filter purely a biological one The oxidized sewage is now led into the secondary sedimentation tanks.

109. Trickling filter With the help of trickling filter and biological action the oxidized sewage is now led into the secondary sedimentation tank.

110. Activated sludge process The heart of the activated sludge process is the aeration tank.

111. Activated sludge process Effluent from primary sedimentation tank mixed with sludge drawn from final settling tank known as activated sludge This sludge is a rich culture of aerobic bacteria The mixture is subjected to aeration in aeration chamber for 6-8 hrs.

112. Activated sludge process Organic matter of sewage gets oxidized into CO2, nitrates & water with the help of aerobic bacteria in activated sludge. When air is added into water it encourage microbial growth. The microbes in water feed organic matter and form bacterial masses a mesh like structure then settle down.

113. Secondary sedimentation The oxidized sewage from the trickling filter or aeration chamber is led into the secondary sedimentation tank where it is detained for 2-3 hours. It is a valuable manure, if dehydrated.

114. Secondary sedimentation Part of the activated sludge is pumped back into the "aeration tanks" in the activated sludge process and the rest pumped into the sludge digestion tanks for treatment and disposal.

115. Sludge digestion Sludge is incubated under favorable condition of temperature and PH Undergoes anaerobic auto digestion in which solids are broken into water, ammonia, methane Takes 3-4 week for complete sludge digestion Methane gas is by product of sludge digestion

116. Other methods of sewage disposal Sea outfall River outfall Land treatment (sewage farming) Oxidation pond

117. Oxidation pond

118. Oxidation pond Called lagoon, waste stabilization pond, redox pond Open shallow pool 1 to 1.5m deep with inlet and outlet Presence of algae, bacteria and sunlight The organic matter contained in the sewage is oxidized by bacteria (hence oxidation pond) to simple chemical compounds such as carbon dioxide, ammonia and water.

119. Oxidation pond The algae, with the help of sunlight, utilize the carbon dioxide, water and inorganic minerals for their growth. Oxygen that is needed for oxidation is derived to a small extent from the atmosphere but mostly from the algae which liberates oxygen under the influence of sunlight.

120. Oxidation pond The ponds are predominantly aerobic during sunshine hours as well as some hours of the night. In the remaining hours, the bottom layers are generally anaerobic. Thus sewage purification is brought about by a combination of aerobic and anaerobic types of bacteria.

121. Oxidation pond The effluent may be used for growing vegetable crops (land irrigation) or may be discharged into a river or other water courses after appropriate treatment.

122. mcq The function of grit chamber in modern sewage plant is: Formation of sludge Removal of floating large objects Settlement of heavy objects Formation of zoogleal layer ANS: c

123. MCQ The heart of activated sludge process is: Aeration tank Primary sedimentation Digestion tank Secondary tank ANS: a

124. MCQ Sewage treatment in a oxidation pond is done by a. algal photosynthesis b. bacterial oxidation c. algal-bacterial symbiosis d. chemical oxidation ANS: c