1.On-site sanitation_Final Lecture material for University Students at Aksum University_2.pptx

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1. Outline Review of sanitation options Sanitation, hygiene and health Types of sanitation Design of selected sanitation facilities Ecological sanitation Technologies Sustainable sanitation concept Sanitation business

2. Learning Objective To understand the traditional and ecological sanitation options available, and the technical, cultural, social and economic factors influencing the choice of options To understand design principles of on-site sanitation systems To understand the resource recovery system for urine and faecal material To have knowhow on sanitation business

3. Sanitation Overview

4. Definition of Sanitation Why focus on sanitation ? Sanitation coverage on global scale Sanitation and Public health Diseases related to poor sanitation How does sanitation prevent disease? What is the economic costs of sanitation ? How does sanitation affect the environment ? Conditions to be satisfied by sanitation system Chapter Outline

5. What do we mean by "sanitation"? With respect to defining sanitation most professionals would agree that "sanitation" as a whole is a “ big idea ” which covers:

6. cont’d… The challenge is to decide what aspects are the most important. In other words, what aspect of the problem is going to be dealt with as a priority . Countries or communities may try different solution to solve sanitation problems. The key issue here is that each community, region or country needs to workout what is the most sensible and cost effective way of thinking about sanitation in the short and long term and then act accordingly. The   World Health Organization  states that: Sanitation generally refers to the provision of facilities and services for the safe disposal of human urine and faeces . 

7. Why focus on sanitation? Progress in sanitation and improved hygiene has greatly improved health, but many people still have no adequate means of disposing of their waste . This is a growing nuisance for heavily populated areas , carrying the risk of infectious disease, particularly to vulnerable groups such as the very young, the elderly. Poorly controlled waste also means daily exposure to an unpleasant environment . The build up of faecal contamination in rivers and other waters is not just a human risk: other species are affected, threatening the ecological balance of the environment.

8. Cont’d… The discharge of untreated wastewater and excreta into the environment affects human health by several routes : By polluting drinking water; Entry into the food chain, for example via fruits, vegetables or fish ; Bathing , recreational and other contact with contaminated waters; By providing breeding sites for flies and insects that spread diseases;

9. What is the size of the problem? In 2004, only 59% of the world population had access to any type of improved sanitation facility. In other words , 4 out of 10 people around the world have no access to improved sanitation. They are obliged to defecate in the open or use unsanitary facilities, with a serious risk of exposure to sanitation-related diseases . While sanitation coverage has increased from 49 % in 1990, a huge effort needs to be made quickly to expand coverage to the MDG target level of 75%.

10. Source: WHO / UNICEF

11. Sanitation and public health The importance of the isolation of waste lies in an effort to prevent diseases which can be transmitted through human waste, which affect both developed countries as well as developing countries to differing degrees. It is estimated that up to 5 million people die each year from preventable water-borne diseases , as a result of inadequate sanitation and hygiene practices .

12. Sanitation and public health Sanitation is a necessity for a healthy life. The results of studies published in Public Sanitation show that better sanitation produces an enhanced feeling of wellbeing. Disease of our interest here include: Waterborne diseases, which can contaminate drinking water Diseases transmitted by the faecal -oral route Hookworm, where eggs can survive in the soil There continues to be many countries that are struggling with diseases due to unhealthy living conditions all in the name of poor sanitation .

13. What diseases are associated with poor sanitation? Human excreta have been implicated in the transmission of many infectious diseases including cholera, typhoid , infectious hepatitis, polio, cryptosporidiosis, and ascariasis . WHO (2004) estimates that about 1.8 million people die annually from diarrhoeal diseases where 90% are children under five, mostly in developing countries . Poor sanitation results: many infections the ideal opportunity to spread plenty of waste and excreta for the flies to breed on, and unsafe water to drink, wash with or swim in

14. What diseases are associated with poor sanitation? Trachoma is closely linked to poor sanitation and is one of the best examples of an infection readily preventable through basic hygiene . Infectious agents are not the only health concerns associated with wastewater and excreta. Heavy metals, toxic organic and inorganic substances also can pose serious threats to human health and the environment particularly when industrial wastes are added to the waste stream .

15. How does proper sanitation prevent disease? For a sanitation system to provide the greatest health protection to the individual, the community, and society at large; it must: Isolate the user from their own excreta ; Prevent nuisance organisms (e.g. flies) from contacting the excreta and subsequently transmitting disease to humans; and Inactivate the pathogens before they enter the environment or prevent the excreta from entering the environment

16. What are the options for controlling excreta? For practical purposes sanitation can be divided into on-site and off-site technologies. On-site systems ( e.g. latrines), store and/or treat excreta at the point of generation. Off-site systems (e.g. sewerage) excreta is transported to another location for treatment, disposal or use . Some on-site systems , particularly in densely populated regions or with permanent structures, will have off-site treatment components as well.

17. What is the economic costs of sanitation? The health impact of inadequate sanitation leads to a number of financial and economic costs including: direct medical costs associated with treating sanitation-related illnesses lost income through reduced or lost productivity and the government costs of providing health services Additionally , sanitation also leads to time and effort losses due to: inadequate sanitation facilities, lower product quality resulting from poor water quality, reduced income from tourism (due to high risk of contamination and disease ) and clean up costs.

18. How does sanitation affect the environment? In regions where a large proportion of the population is not served with adequate water supply & sanitation : sewage flows directly into streams, rivers, lakes and wetlands, affecting coastal and marine ecosystems , fouling the environment and exposing millions of children to disease Particularly in the context of urbanization : domestic wastewater, sewage and solid waste improperly discharged presents a variety of concerns: providing breeding grounds for communicable disease vectors and contributing to air , water and soil pollution

19. Cont’d… The results of poor waste management also contribute to a loss of valuable biodiversity . Improved sanitation: reduces environmental burdens, increases sustainability of environmental resources and allows for a healthier , more secure future for the population

20. What conditions must be fulfilled by a sanitation system ? A sanitation system must: Protect and promote health it should keep disease-carrying waste and insects away from people . Protect the environment avoid air, soil , water pollution, return nutrients/resources to the soil, and conserve water and energy. Be simple the system must be operational with locally available resources (human and material ). Where technical skills are limited, simple technologies should be favored.

21. Cont’d… Be affordable total costs (including capital, operational, maintenance costs) must be within the users’ ability to pay. Be culturally acceptable it should be adapted to local customs, beliefs and desires. Work for everyone it should address the health needs of children, adults, men, and women.

22. End of introductory section!!

23. On-site sanitation facilities Shallow pit Simple pit latrine Ventilated improve pit latrine (VIP) Pour-flush latrines ECOSAN latrines Urine diverting dry toilet (UDDT) Composting toilet Septic tank Aqua-privies Vault and cesspit Imhoff tank

24. The concept of on-site sanitation On-site sanitation is the whole of actions related to the treatment and disposal of domestic wastewater that cannot be carried away by an off-site sanitation system because of low density of population . On-site sanitation systems aim to contain human excreta at the point of generation (the household level). On-site sanitation systems are being promoted widely as they can play a key role in increasing access to improved sanitation .

25. The concept of on-site sanitation On-site sanitation can be substantially cheaper and easier to promote than sewerage networks particularly in rural and peri -urban areas Because space availability and population density are not constraining factors on its adoption On-site sanitation can be classified into two main categories: ‘ wet ’ which require water for flushing ‘ dry ’ which do not require any water for flushing

26. On-site sanitation technical options Various sanitation systems are introduced based on their: suitability for particular situations, the constraints on their use, their disadvantages Each community must choose the most feasible and convenient option to provide necessary health protection. Selecting the most appropriate option requires a thorough analysis of all factors including: cost , cultural acceptability, simplicity of design and construction, operation and maintenance, local availability of materials and skills

27. Cont’d… Open defecation

28. Cont’d… Shallow pit ( Arborloo ) People working on farms may dig a small hole each time they defecate and then cover the faeces with soil. Pits about 300mm deep may be used for several weeks. Excavated soil is heaped beside the pit and some is put over the faeces after each use. In shallow pits: Decomposition is rapid because of the large bacterial population in the topsoil , Flies breed in large numbers and Hookworm larvae spread around the holes Hookworm larvae can migrate upwards from excrete buried less than 1m deep, to penetrate the soles of the feet of subsequent users.

29. Cont’d… Shallow pit

30. Cont’d… Advantages No cost Benefit to farmers as fertilizer Disadvantages Considerable fly nuisance Spread of hookworm larvae Shallow pit

31. Cont’d… Simple pit latrine or traditional latrine It is a simple wooden or concrete slab installed over a pit of 2m or more in depth. This support should stand on a sufficiently waterproof edge of the pit to avoid surface water (runoff and grey water) entering and destroying the facility. The pit should be lined in case of unstable soil where there is a risk of walls collapsing. However , in the case of lining, openings have to be provided in the walls to allow infiltration of liquid in the soil. Excreta fall directly into the pit through a drop hole or a seat. A superstructure is necessary to provide privacy and protection .

32. Simple Pit Latrine 6 5 4 8 9 1 3 7 2 Effective volume of pit (up to 0.5 m from hole) Defecation hole Slab Cover Superstructure Roof Slab seating Drainage channel Water table (pit 1.5m above) When the pit is 50 cm from the surface: move superstructure and slab to a neighbouring place and fill the pit with soil. Do not dig this place again for at least two years .

33. Cont’d… Simple pit latrine

34. 34 Pit latrine problem Pit latrine Shallow drinking water well

35. Cont’d… Advantages Relatively cheap Can be constructed by the user (particularly in rural areas) Does not need water to function Easy to maintain Disadvantages Considerable nuisance because of flies, insects (mosquitoes if pit is wet) Bad smell Simple pit latrine High potential for groundwater pollution

36. Cont’d… Ventilated improved pit latrines (VIP ) The principle is to cancel or to reduce harmful side-effects (smells and flies) related to traditional latrines by providing a vent pipe higher than the superstructure. This vent-pipe is fitted at the end by a mesh that stops flies from entering. Wind that blows at the top of the pipe creates: an ascending air current between the pit and the outside atmosphere, and a descending air current between the superstructure and the pit through a drop hole Smells are evacuated through the vent pipe . Venting the pit dries the waste which assists natural decomposition and destruction of potential pathogens , ultimately rendering a safe humus-like waste product.

37. VIP single-pit latrine Eliminating the primary  vector (flies) greatly reduces possibility of transmission of potential public health risks.

38. 38 VIP double-pit latrine User interface Receiving unit (in this case underground) Urine into the ground

39. Cont’d… Advantages Relatively cheap Can be constructed by the user Does not need water to function Easy to maintain No smell and no flies It can take different sorts of cleansing materials (solid and liquid ) Disadvantages Darkness is obligatory within the superstructure to fight off flies Only functions properly when conveniently oriented towards the wind No surrounding obstacle (trees and buildings) should be higher than the vent pipe Ventilated improved pit latrines (VIP) High potential for groundwater pollution

40.   Pour-flush latrines or toilets A pour-flush latrine is composed of a pan with a water-seal installed in a superstructure. The water-seal is connected to a pit by a pipe. The water-seal flushes out excreta with just enough water: to drain off the solids and to restore the water level in the water-seal Cont’d…

41.   Pour-flush latrines or toilets Cont’d… The pit can be dug far from the superstructure and connected with a pipe or covered drains. The pan is laid down on the floor on top of the water-seal for urine reception, under minimal hygienic conditions.

42.   Advantages Relatively cheap No smells, no flies and mosquitoes Agreeable to use Can be improved by a connection to a sewer network at the right moment Low water consumption 2 – 3 liters of water for each flush Latrine can be in house Disadvantages A source of water is needed The use of solid cleansing material is not advisable (except paper) Skilled labor (mason) is required Cont’d… Pour-flush latrines or toilets

43. Cont’d…   ECOSAN latrines (ecological sanitation ) Ecosan latrines are latrines that ensure the recovery of waste by separating urine and faeces in view of their reuse in the fertilization of soil for agricultural purposes . The variety of available eco-sanitation systems helps to choose a system that is culturally acceptable . The issue of cost is relative, some systems are complicated and expensive, others are simple and cheap. There is always a compromise to be made between cost and functionality : Cheap solutions imply more handling and maintenance of sanitation systems. In the case of more expensive systems, there could be less handling and maintenance.

44. Cont’d…   ECOSAN latrines (ecological sanitation ) These latrines have been set up in order to: preserve the environment and recover waste products Pits are completely lined and the bottom is waterproof in order to avoid infiltration into the soil. An eco-latrine is composed of a pit constructed above ground. The pit is covered by a slab on which a superstructure is built . The pit is ventilated like the VIP latrines but its volume is less important, because the filling time calculated is less than a year. The storage of ash inside the superstructure (in a bowl) is advisable so that it can be mixed with the excreta, after every use, in order to control the moisture content . A tank installed outside the superstructure is used for the storage of the urine .

45. Cont’d…   ECOSAN latrines (ecological sanitation )_ UDDT

46. Cont’d…   ECOSAN latrines (ecological sanitation )_ Fossa Alterna

47.   Advantages Recovery of urine and waste products No pollution of ground water Very hygienic Easy to maintain Does not need water to function Disadvantages Containers for urine storage are needed Water is not recommended for cleansing Addition of ash is required after every use Overhead pits require climbing stairs to access the facility Skilled labor (mason) is required Cont’d… ECOSAN latrines (ecological sanitation) Insignificant potential for groundwater pollution

48. Cont’d… UDDTs are simple, low-cost, on-site sanitation facilities that make use of desiccation ( dehydration ) processes for the hygienically safe on-site treatment of human excreta. UDDTs divert all liquids (i.e. urine and anal cleansing water, if applicable) in order to keep the faeces as dry as possible. Adding wood ash, lime, dry earth etc. after defecation helps in lowering the moisture content and to raise the pH , which enhances pathogen die-off during storage . Urine-diversion dehydration/dry toilets (UDDTs)

49. Cont’d… Urine is collected in containers for direct use , storage , further processing (desiccation, struvite production, etc.). Hygienised urine can be used at small or at large scale, or locally discharged by infiltration into the soil (e.g. evapotranspiration bed). Separately collected urine is rich in nutrients and low in pathogens and can be used as fertilizer . Faeces collected in UDDTs can either be dehydrated (storage and dehydration) or composted (co-composting small-scale or large scale) before they are used as soil amendment . There are two distinct types of UDDTs : double-vault UDDTs and single-vault UDDTs. Urine-diversion dehydration/dry toilets (UDDTs)

50. Urine-diversion dehydration/dry toilets (UDDTs) Exterior and interior view of Double-Vault

51. Double-Vault UDDTs Advantages: Suitable for: hard rock soil areas, high ground water levels and areas prone to flooding No contamination of groundwater sources (contained processing of human faeces ) They allow for an easy treatment and reuse of excreta Urine can be used directly as a fertilizer No need for water Simple in construction Disadvantages: Possibility of smell if too much liquid (urine, anal cleansing water, etc.) enters processing compartment Increased surface area for construction of toilet (compared to Single-Vault UDDTs) Careful operation is essential Cont’d…

52. Cont’d… Composting latrine Composting toilets are based on the philosophy of ecological sanitation , which looks at urine, faeces and water as resources in an ecological loop . The basic premise of this approach is: to protect public health, to prevent pollution and return valuable nutrients and humus to the soil In this latrine, excrete fall into a watertight tank to which ash or vegetable matter is added. If the moisture content and chemical balance are controlled, the mixture will decompose to form a good soil conditioner in about four months .

53. Cont’d…   Composting toilet_ Fossa Alterna Pathogens are killed in the dry alkaline compost , which can be removed for application to the land as a fertilizer.

54.   Advantages A valuable humus is produced Disadvantages Careful operation is essential Ash or vegetable matter must be added regularly Cont’d… Composting latrine Insignificant potential for groundwater pollution

55. Cont’d… Septic tank A septic tank is an underground watertight settling chamber into which raw sewage is delivered through a pipe from plumbing fixtures inside a house or other building. The sewage is partially treated in the tank by separation of solids to form sludge and scum. Effluent from the tank infiltrates into the ground through drains or a soak pit . The system works well where the soil is permeable and not liable to flooding or waterlogging The sludge is removed at appropriate intervals to ensure that it does not occupy larger proportion of the tank capacity.

56. Cont’d… Septic tank

57. Cont’d…

58. Liquid Solid separation chamber polishing chamber

59.   Advantages Gives the users the convenience of a WC They are best suited for isolated rural areas, and for isolated hospitals, buildings A proper functioning septic tank can considerably reduce solids and BOD from sewage Disadvantages High cost Reliable and ample piped water required Only suitable for low-density housing Regular desludging required and sludge needs careful handling Permeable soil is required Cont’d… Septic tank High potential for groundwater pollution

60. Disposal of effluent from the septic tank The effluent coming out from a septic tank is not better than the effluent of an ordinary sedimentation tank . It contains large amount of putrescible organic matter and its BOD is quite high. This effluent should therefore be disposed of carefully so as to cause minimum nuisance or risk to the health of the people. The following three methods of disposal of septic tank effluent are usually adopted: Soil absorption system (disposal of effluent on the land) Biological filters Upflow anaerobic filters

61. Soil absorption system may be of the following two types: Soak pit or seepage pit Dispersion trench, drain ditch A Soak Pit is a circular covered, porous-walled chamber/pit that allows water to slowly soak or absorbed into the surrounding soil. Pre-settled effluent from septic tank is discharged to the underground chamber from where it infiltrates into the surrounding soil. It may either be filled with stone aggregate or may be kept empty. The rocks and gravel will prevent the walls from collapsing, but will still provide adequate space for the wastewater . Disposal of effluent from the septic tank

62. The field requires periodic maintenance, diversion of the flow at distribution box and repacking of the rock fill, removal of plant roots etc. Absorption field treatment of septic tank effluent Absorption trench system Distribution box septic tank

63. Cont’d… Aqua-privy An aqua-privy has a watertight tank immediately under the latrine floor. An aqua-privy is simply a latrine constructed directly above a septic-tank. Excreta drop directly into the tank through a pipe. The bottom of the pipe is submerged in the liquid in the tank, forming a water seal to prevent escape of flies, mosquitos and smell. The tank functions like a septic tank . Effluent usually infiltrates into the ground through a soak pit . Accumulated solids (sludge) must be removed regularly.

64. Cont’d… Aqua-privy

65. Cont’d… Aqua-privy

66.   Advantages Does not need piped water on site Less expensive than a septic tank Disadvantages Water must be available nearby More expensive than VIP or pour-flush latrine Fly mosquito and smell nuisance if seal is lost because insufficient water is added Regular desludging required and sludge needs careful handling Permeable soil required to dispose of effluent On-site sanitation latrines Aqua-privy High potential for groundwater pollution

67. Cont’d… Vaults and cesspits In some areas, watertight tanks called vaults are built under or close to latrines to store excrete until they are removed by hand (using buckets or similar receptacles) or by vacuum tanker. Similarly , household sewage may be stored in larger tanks called cesspits , which are usually emptied by vacuum tankers. Vaults or cesspits may be emptied when they are nearly full or on a regular basis

68. Cont’d… cesspits

69.   Advantages Satisfactory for users where there is a reliable and safe collection service Disadvantages High construction and collection costs Removal by hand has even greater health risks than bucket latrines Irregular collection can lead to tanks overflowing Efficient infrastructure required Cont’d… Vaults and cesspits

70. Imhoff Tank The technology was developed in the Emscher District of Germany and patented in 1906 by Dr. Imhoff. An Imhoff tank, which works similar to a communal septic tank , is in fact a two storied tank , so they are sometimes also known as Two-story Digestion tank. An Imhoff tank will remove 30 to 40 % of BOD and 60 to 65% of solids. It is a compact and efficient system for pre-treatment of municipal wastewater . The pre-treated wastewater from the Imhoff tank requires a secondary treatment. e.g . leach field, soak pits, horizontal flow, vertical flow or free-surface constructed wetlands. Cont’d…

71. Imhoff Tank Construction Feature The Imhoff tank may be either rectangular or circular and is divided into three compartments: The upper section or sedimentation compartment The lower section or digestion compartment and The gas vent or scum section The settling of solids occurs in an upper chamber and digestion of the solids in the lower chamber . The two chambers are separated by a sloping partition that contains narrow slots through which the solids passes into the lower chamber. Cont’d…

72. Imhoff Tank Construction Feature Solids settle out in the upper sedimentation chamber and gradually flow into the lower digestion chamber. In the digestion chamber, solids accumulate and slowly digest. Digestion chamber is divided into a number of interconnected compartments . The bottom of each digestion compartment is made up in the form of an inverted cone or hopper with side sloping 1:1, so as to concentrate the sludge at the bottom of the hopper . Cont’d…

73. Imhoff Tank Construction Feature The digested sludge from the bottom of the hoppers is removed periodically (after 30 to 45 days, depending upon the temperature of sludge) through the cast-iron de- sludging pipes provided in each compartment. Gas vent or Scum chamber is provided above the digestion chamber and alongside the sedimentation chamber to take care of the gases escaping to the surface . In order to prevent the particles of the sludge or scum from entering into the sedimentation chamber from the digestion chamber, the scum and sludge must be maintained at least 45cm above and below the slot respectively. (neutral zone) Cont’d…

74. Imhoff Tank

75. Advantages It requires little space It is simple as it has no moving parts as mixers, collectors It requires little operator time as sludge removal is periodic At the time, it offered a better solution to solid handling and digestio n Disadvantage Very low treatment efficiency Requires de- sludging Additional treatment of effluent and sludge is needed Inefficient treatment option if not regularly de- sludged Odor occurs from escaping gases Less simple than septic tank Cont’d… Imhoff Tank

76. A ny Q uestion