Environmental Health Lectures PDF

07/06/2024 Lectures on Environmental Health Delivered to Masters degree students of the Department of Preventive and Social Medicine University of Port Harcourt...

07/06/2024 Lectures on Environmental Health Delivered to Masters degree students of the Department of Preventive and Social Medicine University of Port Harcourt by Prof. Best Ordinioha Professor of Community Medicine and Public Health Lecture ONE Introduction/Definition of concepts Environmental hazards Environmental Sanitation Sustainable Development  07/06/2024 Definitions, concepts and history The environment contains elements essential for life, and the maintenance of good health, The environment also contains potential hazards, things capable of causing harm and ill health Air, flora and fauna are in the environment, for the sustenance of man, as well as viruses, bacteria, disease vectors and insanitary conditions that pose a serious threat to the health, wellbeing and longevity of man. Definitions, concepts and history Most of the deleterious environmental conditions are caused by human activity. As the first country to industrialize, Britain was the first country to be confronted by the grim effects of the deteriorating environment on health. The slums that accommodated the working class in nineteen century Britain were noted for their narrow alleys and tenement housing, the total inadequacy of the water supplies and sewerage systems, and the squalor and violence of the streets. The noxious air and vapours generated by the filth in these slums were said to have made the slums fever dens, while the inhabitants were feared as agents of infection.  07/06/2024 Edwin Chadwick In 1842, the ubiquitous Victorian civil servant and lawyer, Edwin Chadwick published his investigation on “the sanitary condition of the labouring poor” facilitated by his job as the secretary to the first British Board of Health. In this report, he emphasized the crucial link between dirt due to unsanitary conditions and overcrowding, and disease; and stressed the need for a central administrative structure to oversee health issues. Municipal housekeeping The recommendations in “the sanitary condition of the labouring poor” Triggered the government into action, leading to the enactment of the Public Health Act and the establishment of local boards of health It also elicited the response of reformers including middle- and upper-class women who wanted to escape the narrow bounds of domestic responsibilities. These women saw sanitary reform activity as “municipal housekeeping” a natural extension of women’s training and experience as the “housekeepers of the world”.  07/06/2024 Medical Officers for Health Medical Officers for Health were appointed in Britain to oversee public health activities in the local councils. The main duties of the Medical Officers of Health (MOsH) were two fold, involving: first the duties of sanitary inspection and improvement (which were to earn the MOsH the derogatory title of “drain doctors”) and second, disease control, emphasizing primarily isolation and removal to hospital of infected persons, and the tracing of the foci of infection during epidemic. History of Environmental Health in Nigeria An inspector of nuisances was appointed for the Lagos colony as early as 1887. The pioneer public health staff helped draw up ordinances and rules for: the meat markets, slaughterhouses, hospitals, sanitaria, and housing. Approval of building plans Registration of businesses providing sanitary services; and Mandatory notification of smallpox, and similar diseases  07/06/2024 Dr. Isaac Ladipo Oluwole Dr. Isaac Ladipo Oluwole became the first African Medical Officer for Health in Nigeria when he was appointed first, as Assistant Medical Officer for Health in 1925, and then Medical Officer for Health in 1935. He reclaimed swampy islands in Lagos to aid malaria control, He instituted control measures for smallpox, rabies and plague. He was given an OBE in 1940 for his efforts, and recognized as the father of public health in Nigeria. Medical Officers of Health The Medical Officers of Health were mainly concerned with environmental sanitation. Environment sanitation is defined as the control of factors in the environment that exercises, or may exercise a deleterious effect on the physical development, health and survival of humans. It includes the following: Provision of a safe and adequate water supply Proper disposal of solid waste Proper sewage disposal, and treatment Safe guarding of food. Provision of good housing Control of atmospheric pollution (air hygiene) Control of insect vectors, and other pests Control of animal reservoir of infection. Disinfection Elimination of other hazards e.g. noise, radiation etc.  07/06/2024 The aids of the MOH Environmental sanitation was very important at the inception of the work of the Medical Officer of Health, because all diseases were then considered to be from filth (miasmic concept of disease) To effectively perform his responsibilities, The MOH had sanitary inspectors as foot soldiers, to move around and identify hazards in the environment Engaged the services of public health engineers, to provide engineering solutions to the environmental hazards. Environmental hazards Filth cause illnesses that are acute and often easily treated The hazards posed by filth have largely been controlled in the developed countries, where the current problem is with hazards that are produced by technology The hazards produced by technology cause mostly chronic and difficult to treat diseases like cancer, Hence the great efforts made to keep them within the regulatory limit  07/06/2024 Environmental hazards 2 The modern environmental hazards threaten the ability of earth to continue to sustain life This forced the United Nations (UN) to promote the concept of sustainable development. Sustainable development is defined as development that meets the needs of the present generation, without compromising the ability of the future generation to meet their own needs. Environmental hazards 3 The traditional environmental hazards are handled by the Health ministry, using health workers such as: MOH Environmental Health Officers The new environmental hazards are however handled by the Ministry of Environment, and its agencies such as NESRA Ministry of Environment employ people who are not traditionally classified as health workers, more commonly: Ecologists and Scientists able to measure and institute control measures for the modern hazards  07/06/2024 National Policy on the Environment Activities of the MOE are geared towards achieving sustainable development, Sustainable development is achieved in Nigeria through the National Policy on the Environment, which was first formulated in 1989, The National policy on the environment recommended: The establishment of adequate environmental standards, monitoring and evaluation of changes in the environment, and the conduct of an Environmental Impact Assessment of any proposed activities that may affect the environment, or the use of a natural resource. Environmental Impact Assessment Environmental Impact Assessment according to the International Association for Impact Assessment (IAIA) is the process of identifying, predicting, evaluating, and mitigating the biophysical, social, and other relevant effects of development proposals, prior to major decisions being taken and commitments being made.  07/06/2024 Lecture Two: Water Supply Introduction Water-related diseases Introduction Water is one of the fundamental requirements for human life This makes an essential human need that government should ensure that everyone has access to it The Romans more than two thousand years ago, recognized this and believed that a place is not civilized unless it has a water supply system with house connections, public fountains and public baths  07/06/2024 The water situation in Nigerian communities The steps involved in ascertaining the water situation of a community include: The identification of the sources of drinking water Quantity of water available to members of the community; and Quality of the drinking water Sources of drinking water The sources of drinking water supply of members of a community include: Rain water Surface water, including rivers, ponds, lakes and sea; and Ground water, including wells, bore holes and springs These sources give a clue to the water situation in the community  07/06/2024 Rainwater Several communities in Nigeria rely on rainwater as their main source of drinking water. The communities include: Communities that are far from surface water sources. For example, several communities in northern Nigeria Communities with very low groundwater level, as found in the hilly communities of the South-East and other parts of Nigeria; and Communities with very salty groundwater, as found in the mangrove forest ecological zone of the Niger delta region Communities dependent on rainwater Communities that rely on rainwater for their drinking water supply are able to meet their drinking water needs during the rainy season, but barely have enough during the dry season. Members of the communities therefore face water shortages during the dry season. To solve this problem, members of the communities have over the years developed rainwater harvesting systems that store the excess water in rainy season for future use during the dry season.  07/06/2024 Communities dependent on surface water Communities whose main water supply is surface water do not have problem with quantity of water, but are faced with the problem of quality. This is because surface water sources like rivers, ponds and lakes are the most polluted sources of drinking water. polluted not only from natural sources, but also from several human-related sources such as crude oil spills, sacrificial items, and faecal contamination, arising from the use of pier toilets. Members of these communities are therefore exposed to several water-related diseases, arising from the different sources of contamination. Communities dependent on groundwater The water situation in communities that depend on groundwater for their drinking water supply is influenced by: the depth from which the water is harvested, and the geological features of the soil. Water harvested from above the first impervious layer is scanty and barely enough to meet the water needs of members of the communities that depend on them. The water sources are also often contaminated by surface contaminants such as pit latrines, soakaway and chemical spills. This is because soil is a good filter, and the soil depth in the shallow wells are usually not enough to filter out many of the surface contaminants.  07/06/2024 Communities dependent on groundwater 2 Communities that get their drinking water from shallow wells include: Communities in the Barrier Island ecological zone of the Niger delta region that are forced to rely on shallow well for drinking water, because wells of greater depth yield salty water; and Communities that reside close to seasonal rivers in northern Nigeria that are able to get drinking water by digging holes in dry river beds. Members of these communities are at risk of water-chemical diseases and other water-related diseases, arising from the different surface contaminants. Communities dependent on groundwater 3 Geological features also affect the quality of groundwater, often contaminating the water with iron, arsenic and other chemicals that are derived from the soil. For instance, the groundwater of most of the communities in the freshwater swamp ecological zone of the Niger delta have a very high iron content that is derived from the soil.  07/06/2024 Communities dependent on groundwater 4 In recent years, there is a growing saline intrusion into the ground water of communities in the transition zone between the mangrove forest and the freshwater swamp ecological zones of the Niger delta region. This has been attributed to factors including the dredging of water channels, and the over-abstraction of the groundwater. Saline intrusion significantly increases the cost of providing potable water to communities in the transition zone, as the boreholes of moderate depth that once provided them with good quality water now yield water of increasing salinity, resulting in their abandonment. This has worsened the access to drinking water in the communities. The quantity of water available to each member of the community. This is assessed by estimating the volume of water collected by a household in a day, for the domestic and sanitation needs of its members. It does not however include water used for gardening, or used in watering animals. The WHO recommends that each individual in a community should have 20 – 40 liters of water for his/her domestic and sanitation needs, and at least two liters for his/her drinking water needs (per capita water requirement).  07/06/2024 Per capita water requirement An indirect method that makes use of the distance to the water source is often used to calculate the per capita water use This is based on the fact that the closer the water source is to the household, the greater the water use. Based on this, the WHO recommends that households in urban centers should have a public stand pipe within 200 meters of their residence; The WHO also recommends that the to and fro journey to fetch water should not exceed 30 minutes. The quality of water The desire is to make potable water available to all members of the community, at all time. Potable water is defined as water that is safe and acceptable for drinking This means that the water should not be harmful, and should be acceptable for drinking. For the water to be harmless, its constituents must be within the drinking water quality guideline values. These values represent the concentration of constituents that do not result in any significant health risk to the consumer over a lifetime of consumption, including the different sensitivities that may occur in the various stages of life.  07/06/2024 The quality of water 2 The standard for drinking water quality is assessed by considering the: physical, chemical, microbiological and radiological qualities of the water. The physical/aesthetic quality of water The physical quality of water often determines the acceptability of the water to the people The determinants include: turbidity, (cloudiness, or haziness of water caused by particles) colour, taste and odour of the water  07/06/2024 The chemical quality of water The chemical quality of water considers the chemical content of the water. It often takes a massive chemical contamination of water to cause an acute health problem. Experiences have shown that such excessive contamination often renders the water undrinkable, owing to its unacceptable taste, odour and appearance. The chemical quality of water 2 The main public health fear of chemicals in drinking water is the long-term drinking of water contaminated with certain chemicals like arsenic and fluorides that are easily found in ground water sources like borehole. In recent times, there is increasing concern over the salt content of drinking water, due to the possible health effects of the widespread intrusion of salt water from the sea into the freshwater sources that are often used for drinking purposes in the Niger delta. Drinking of water with high salt content has been associated with increased risk of hypertension.  07/06/2024 The radiological quality of water The radiological quality of water considers the radioactivity of the drinking water. Water can gain radioactivity from natural sources, as well as wastes from establishments that use nuclear energy. It has to be noted that nuclear energy is commonly used in hospitals and in the oil industry. The radiological quality of water 2 Formation water that is one of the waste products of oil exploitation has been found to contain Naturally Occurring Radioactive Materials (NORMs), which were to be removed before the formation water is discharged into a water body. Studies indicate that oil companies in Nigeria often do not, thus contaminating many water bodies with NORMs, which significantly increases the level of radioactivity of the water bodies.  07/06/2024 The radiological quality of water 3 Avwiri GO, Ononugbo CP and others of the department of Physics of the University of Port Harcourt recorded high levels of background radiation in several Niger delta communities, as a result of the NORM produced by the oil companies. Exposure to the levels of radiation recorded in these studies can increase cancer rates in the communities. The microbiological quality of water This tests the water for the presence of micro- organisms, especially those that are known to cause disease. Where funds are limited, the microbiological quality is about the only consideration given to drinking water. Ideally, drinking water should not contain any microorganism known to be a pathogen, but the WHO advocates that all drinking water should at least be tested for E.coli, whose presence is indicative of definite faecal pollution.  07/06/2024 The microbiological quality of water 2 It is expected that drinking water should not contain any E.coli, NAFDAC guideline requires that bottled water and sachet water should be completely free of E.coli. This high standard is however very difficult to achieve in hand-dug well and other sources of public water supply, such that the limit for the water sources is set at less than 10 E.coli per deciliter of water. Water associated diseases The water situation in the community can reflect in the pattern of diseases seen in the health center. These diseases are called water-associated diseases Water-associated diseases are broadly classified as: water-borne, water-shortage, water-impounding, water-arthropod and water-chemical diseases.  07/06/2024 Water borne infections These are infections acquired through the drinking of water contaminated with micro-organisms. The source of such contaminations is often human faeces, which explains why water supply is often paired with the provision of adequate toilet facilities in most health programmes. They include: viral infections like poliomyelitis and infective hepatitis; potentially epidemic causing diseases like typhoid fever and cholera, and parasitic diseases like amoebic dysentery. Water shortage diseases These are diseases that arise due to poor availability of water, such that little water is available for bathing and other sanitation purposes. Examples of such diseases include: Trachoma and skin infections.  07/06/2024 Trachoma Trachoma is a disease of the eye caused by infection with the bacterium Chlamydia trachomatis. It is a public health problem in 44 countries, and is responsible for the blindness or visual impairment of about 1.9 million people. Infection spreads through personal contact (via hands, clothes or bedding) and by flies that have been in contact with discharge from the eyes or nose of an infected person. The transmission of the infection is aided by inadequate hygiene, crowded households, inadequate access to water, inadequate access to and use of sanitation. Water impounding diseases These are diseases contracted through repeated contact with impounded water sources such as ponds, wells and flooded areas of irrigation schemes. The infections are mostly parasitic worms that breed in impounded water sources, especially the water sources with rich organic contents, such as human faeces. Examples of such diseases include schistosomiasis and guinea worm.  07/06/2024 Guinea worm Guinea worm also called dracunculiasis is contracted by drinking water containing cyclops that is infected with the guinea worm larvae. Initially there are no symptoms, but after about one year later, the female worm forms a painful blister in the skin, usually on a lower limb, and begins to expel its eggs, which go on to infect other cyclops, when the leg is dipped into a water body Schistosomiasis Schistosomiasis, also known as snail fever and bilharzia is a disease caused by parasitic flatworms called schistosomes. It is spread by contact with impounded water bodies in which infected freshwater snails breed. The disease is especially common among children, as they are more likely to play in contaminated water. Other high-risk groups include farmers, fishermen, and people using unclean water during daily living. The disease affects the urinary tract and the intestines, and manifests often as abdominal pain, diarrhea, bloody stool, or blood in the urine.  07/06/2024 Water – arthropod diseases These are diseases caused by arthropods that breed in water. Examples include such mosquito-borne diseases such malaria, yellow fever and filariasis, and the simulimum (black fly) that transmits onchocerciasis (River Blindness). The diseases are very common in the Niger delta region, where the massive water bodies provide the arthropods with ample breeding sites. Mosquito activities Mosquito activities are particularly significant in Niger delta communities, as various species of mosquitoes take turn to cause nuisance and diseases in the communities, round the clock and throughout the year. A visit to the mangrove forest exposes the person to the attack of Anopheles melas, recreational activities at dusk are made almost impossible by the attacks of culicine species of mosquitoes; even as the residents of the communities are constantly denied sleep by the mosquitoes.  07/06/2024 Onchocerciasis Onchocerciasis – or “river blindness” – is an eye and skin disease caused by the filarial worm Onchocerca volvulus transmitted by repeated bites of infected blackflies (Simulium spp.). These blackflies breed along fast-flowing rivers and streams, close to remote villages located near fertile land where people rely on agriculture. In Nigeria, onchocerciasis has been reported in almost all the States of the federation, but with very few cases in Lagos, Katsina, Rivers and Bayelsa States. Onchocerciasis 2 In the human body, the adult worms produce embryonic larvae (microfilariae) that migrate to the skin, eyes and other organs. When a female blackfly bites an infected person during a blood meal, it also ingests microfilariae which develop further in the blackfly and are then transmitted to the next human host during subsequent bites  07/06/2024 Water chemical diseases These are diseases that arise as a result of excess or lack of certain chemicals in water. Examples include: Methaemoglobinaemia in bottle-fed infants whose infant formula is constituted with water containing high concentration of nitrates Water chemical diseases 2 Examples include: Tooth decay that result from drinking water that is low in fluoride; and the skeletal fluorosis that result from drinking water that is high in fluoride.  07/06/2024 Water chemical diseases 3 Examples include: The hypertension that can result from drinking water that is high in salt Water chemical diseases 4 Water-chemical diseases are not widely recognized as significant causes of morbidity and mortality in Nigeria and Ghana; but there are indications to the contrary, considering the geology of the area and the activities of the oil and gas industry. The groundwater of several communities in the core Niger delta States are known to have water that is “hard” and high in iron. A study found that the concentration of iron can be as high as 6.2mg/l (1). This is considered a problem; hence the elaborate purification methods that are often deployed in the community water projects, constructed to serve these communities.  07/06/2024 Water chemical diseases 5 Drinking water high in calcium has also been found to be healthy, even as the water is not too good when used for bathing and other cleaning purposes. Several studies have demonstrated the inverse relationship between the drinking of hard water and mortality from cardiovascular diseases like ischaemic heart disease Chemical contamination of drinking water Common sources of such contaminations include: Crude oil spills, resulting in the contamination of drinking water with hydrocarbons. Hydrocarbons such as benzene and poly- aromatic hydrocarbons (PAH) are known carcinogens naphthalene and hexane are known to cause haemolytic anaemia, ototoxicity, and physical symptoms like tiredness, itchy nose, sore- throat and headache5.  07/06/2024 Chemical contamination of drinking water 2 Crude oil exploitation activities such as the contamination of drinking water with formation water, a waste of oil exploitation that has been linked with the contamination of the environment with the carcinogenic Naturally Occurring Radioactive Materials (NORMs)6 among other contaminants. A study found that the level of the NORMs in a Niger delta community can be several times the level found to be detrimental to human health7. Chemical contamination of drinking water 3 The use of discarded drums of drilling and other industrial chemicals as water storage containers, with little knowledge of the possible health risks. The use of these drums is widespread in the communities of the Niger delta because many households are without piped water supply, and at best fetch water from the nearest public water tap.  07/06/2024 Chemical contamination of drinking water 4 The improper disposal of solid waste could contaminate the water with toxic metals. For example, fluorescent bulbs, a common household waste contain mercury in a form that can easily contaminate the receiving water. Even a small amount of mercury from the bulbs can bio-accumulate in fish, especially the big, carnivorous fish like shark, that are preferred by members of the Niger delta communities8. Chemical contamination of drinking water 5 Mercury is a neuro-toxin, but damages have also been reported in the kidney, skin and the cardiovascular system. The neurological damages often present as Minamata disease, a disease that was first reported in the Minamata Bay, Japan, and followed the long-term consumption of fish with high concentration of mercury. It presents mostly with neurological symptoms that include paraesthesia; impaired peripheral vision, hearing, taste, and smell  07/06/2024 Lecture Three: Interventions for safe water supply Introduction The prevention of water related diseases requires the provision of at least 20 liters of potable water, from easily accessed sources in the community. This requires identifying sources of large quantity of water in the community, tapping them to make the water available, and then ensuring that possible sources of contamination of the water source are identified and purified.  07/06/2024 Introduction 2 Sources of water supply of members of the community include: Rain water Groundwater Surface water Water from these three sources are tapped, to meet the water needs of the community Rainwater Rainwater is often of good quality except that it can pick up impurities from the atmosphere, roofs, roof gutterings and the storage tank. When these sources of contamination are taken care of, rainwater can be a source of good quality drinking water for the household, at least during the rainy season. A rainwater harvesting system can be put in place to divert the rainwater from the roof of the house to a storage tank  07/06/2024 WELL Well for water supply are of two types: Hand-dug well and Water borehole. The hand-dug well is dug with hand, and is of small depth and therefore it gets its water from the soil at a depth that is below the first impervious layer. The water is therefore of poor quality, because of the ease with which it is contaminated by nearby latrines and septic tanks. WELL 2 Water borehole is dug to greater depth, especially as it is dug with a type of machine, It therefore gets it water supply from a depth that is deeper than the first impervious layer.  07/06/2024 Hand-dug well Hand-dug well is an important source of drinking water especially in communities like Bonny, where drinkable water can only be found at lower depth. Purification methods for hand-dug well Hand-dug well is easily contaminated, hence efforts must be made to protect it from contamination. The following measures are usually taken: Putting a distance of least 30 meters between the well and possible sources of contamination such as the latrine/septic tank.  07/06/2024 Purification methods for hand-dug well 2 The construction of a concrete lining and parapet. These involve: the plastering the upper part of the well with cement, down to the dry season water level; creating a two feet high parapet, and the construction of at least, a two-meter concrete floor around the well head, to keep out the often- contaminated surface water. These ensure that spilled water do not enter the well directly, but have to be filtered through the soil. Purification methods for hand-dug well 3 The use of a windlass and a single bucket, in lifting water from the well. A better improvement is fitting the well with a hand pump and then covering the top of the well with a concrete stab.  07/06/2024 Purification methods for hand-dug well 4 Pot chlorination can be used to further improve the quality of the water in the well, especially if it is found to have high level of faecal contamination. Water from a borehole Water from deep boreholes is normally free from microbiological contamination, Because sand is a very good filter Water from deep boreholes therefore may not require further treatment to make them potable. because the water is from a source below the first impervious layer of the soil  07/06/2024 Water from a borehole 2 However, certain structural precautions are essential when the well and the associated pumps are installed. The pump casing should extend approximately 30cm above ground, and down wards to the parent rock. Other precautions observed with the shallow wells should also be observed. Water from a borehole 3 Although, water from a borehole often has good microbiological qualities, it might however contain certain chemicals, arising from the intervening rocks and sediments. Water from boreholes in the Niger delta are often high in sodium (due to saline intrusion from the sea), iron, manganese and arsenic. These have to be removed using technologies that include Reverse Osmosis that draws out the contaminants from the water.  07/06/2024 Spring water Spring water is derived from a source below the first imperious layer of the soil, but has tracked its way to the surface. It is often of very good quality, except that it can be contaminated by the various sources of pollution located adjacent to it. Purification of spring water The quality of spring water can be preserved with the following: Preventing rain runoffs from contaminating the spring water The construction of a fence to prevent livestock from contaminating the water; and The construction of a spring encasement, to collect, store and distribute the water from the spring. Water from a protected spring may be supplied to small community either directly or via a distribution system.  07/06/2024 Surface water Surface water sources are often very contaminated. It is therefore better to supply the water needs of small communities with a ground water source, that require little or no treatment, than to bring the highly contaminated surface water to the required standard. The use of surface water for community water supply is only cost effective for urban centers, with high water requirement. Purification of surface water The purification process of surface water for the use of the community includes: Abstraction and storage Plain sedimentation (primary sedimentation Slow sand filtration Coagulation, flocculation and secondary sedimentation. Rapid sand filtration Aeration Disinfection  07/06/2024 Abstraction and storage This is the first stage in purifying surface water for use as drinking water. It involves pumping the water from a restricted part of the river to a storage facility. The time the water spends in the storage facility is often long enough to kill most of the disease pathogens. Plain sedimentation (primary sedimentation) Water from the preliminary storage facility is passed slowly through a sedimentation tank, to allow time for the settling of suspended solids  07/06/2024 Slow sand filtration This improves the physical, chemical and microbiological quality of the water. It consists of an upper sand bed, and a lower bed of gravel. A thin, slimy mat known as the schmutzdecke or filter skin forms at the upper surface of the filter. This is said to be rich in organic matter, and has the ability to trap and destroy microorganisms, with up to 99% efficiency. Coagulation, flocculation and secondary sedimentation Slow sand filtration is able to remove all, but the smallest of solids; These solids are however taken care of in this stage of purification. First, coagulants are added to react with the suspended solids to form settleable flocs, in the process called flocculation. These flocs aggregate into bigger macroflocs, as more time is spent in the secondary sedimentation tank, and then eventually filtered out  07/06/2024 Rapid sand filtration Rapid sand filtration involves the passage of water under pressure through a sand filter. Aeration Aeration is used to reduce taste and odour, and to alter the concentrations of dissolved gases in the water. It involves passing a thin film of water over surfaces, to maximize the transfer of oxygen into the water from the surrounding air.  07/06/2024 Disinfection Disinfection serves as a backup for slow sand filtration, for the removal of micro-organisms in water. Disinfection methods may be physical or chemical. Physical methods include ultraviolet (UV) irradiation; while chemical methods include the addition of ozone, or most commonly chlorine, or its derivatives. Chlorine is preferred because it is not only capable of killing most pathogens within the contact time, but also has residual effect, to deal with small possible recontamination Household water treatment Because most community water supply in Nigeria is intermittent, water is often stored in the home, to ensure that enough is available when it is needed. Water supplied at the well or public stand post may be microbiologically safe, but can become grossly contaminated with faecal material before consumption, in the course of its transportation and storage at home. Most recontamination is the result of behavioural patterns that can be changed through hygiene education, especially for women and children, who are mostly involved in water collection and storage.  07/06/2024 Household water purification methods Contaminated water can be purified to the required standard through: Boiling Filtration Chemical disinfection Cloth filtration (to prevent dracunculiasis Boiling water for purification Boiling is a simple way of killing all the microorganisms in the water. For it to be effective, the water needs to be brought to a “rolling boil” for one minute. Rolling boil occurs when large bubbles come continuously to the surface of the boiling water.  07/06/2024 Boiling water for purification 2 Boiling as a household purification method is not highly recommended, because of the following reasons: The cost of buying fuel to bring the water to a rolling boil might be too much for the poor. Boiling can add an unpleasant taste to the water Very hot water is a source of accident in the home; Boiled water can become recontaminated once it has cooled. Filtration Filtration uses a filter to remove solids, silt and large microorganisms like ova, cysts and bacteria from the drinking water. The pores in the filters are however too large to filter out viruses, and are therefore incapable of preventing water-borne viral diseases like polio and hepatitis A virus. Filters are of various types and sophistication, but the ones that are available for household use include: cloth filter, candle filter and stone and sand filters.  07/06/2024 Cloth filter This involves using cloth to filter water for drinking. The cloth is usually folded to make four or eight layers and then placed over a wide-mouthed container used to collect the filtered water. Cloth filters are mostly capable of filtering out large pathogens like the cyclops that causes guinea worm, but incapable of filtering out bacteria. Studies however indicate that cloth filters are able to reduce the bacterial count in the water by as much as 90%, because most of the bacteria like cholera are attached to particles and plankton that are filtered out by the cloth filter Candle filters Candle filters are often commercially produced and involve filtering contaminated water slowly, through a porous ceramic material. The filtered microorganisms are left on the outer layer of the filter material, and therefore had to be periodically cleaned, by gently scrubbing the filter under clean, running water. The candle filter is often designed to minimize the risk of recontamination of water after the filtration. Most consist of two inter locking containers; the upper container has the candle(s) and receives the raw water, while the lower container receives the filtered water.  07/06/2024 Sand filters Sand filters can be locally made, and consist of fine sand at the top and gravels at the base. The household sand filter is capable of removing ova, larva, cysts and cyclops, but incapable of removing most bacteria and viruses. Therefore, disinfection might be required to bring the quality of sand filtered water to the required standard. Chemical disinfection Disinfection is ideally carried out with clear water. When carried out on turbid or cloudy water, the disinfectant is largely consumed by the suspended particles in the water. These particulates also provide protection for microorganisms against the actions of the disinfectant. Therefore turbid water should be allowed to settle, or should have coagulants like alum added, before disinfectants are added to them. The most common disinfectant for household use is chlorine, in the form of bleach and chlorine tablets Water-guard, a mixture of chlorine and coagulants is being socially marketed in Nigeria. It is the ideal disinfectant for use in most communities in Nigeria.  07/06/2024 Household storage of drinking water Households without piped supply often fetch and store water at home. Experiences show that potable water fetched and stored in storage containers often become contaminated in the course of storage and use, hence the need for storage containers that have the capacity to reduce the contamination. Water storage container Studies indicate that drinking water is best stored in plastic, ceramic, or metal containers with the following characteristics that provide physical barriers to recontamination: A small opening with a lid or cover that discourages users from placing potentially contaminated items such as hands, cups, or ladles into the stored water; A spigot or small opening to allow easy and safe access to the water without requiring the insertion of hands or objects into the container  07/06/2024 Household storage of drinking water 2 Jerry-cans have been found to be the most hygienic way of storing water, because they prevent recontamination since contaminated cups cannot be dipped into them The use of jerry can for the storage #of the household’s drinking water can reduce the risk of diarrheal disease in the household by up to 75%. Water storage container 2 Commercially produced safe water storage containers are available. They include: The Oxfam Bucket, a 14-liter bucket with lid and tap The CDC SWS Container, 20-liter modified jerry can, designed by the CDC; and Modified Clay Pots that have installed tap, from which water is collected.  07/06/2024 Lecture Four: Sewage Disposal Introduction Excreta-related diseases Introduction The WHO defines sanitation as facilities and services for the safe disposal of human urine and faeces. In 2007, readers of the British Medical Journal voted the introduction of clean water and sewerage system in Victorian Britain as the most important medical milestone, above anaesthesia, antibiotics, or vaccines. This is because of the dramatic reduction in morbidity and mortality associated with faecal-oral infections, such as typhoid fever and cholera that resulted from the introduction.  07/06/2024 Introduction 2 Safe disposal of excreta is the less glamorous cousin of safe water supply; while many people hail water as the fountain of water, only very few are willing to be associated with excreta disposal. Yet, the two must work together to achieve most of the envisaged health goals. Improvements in water supply alone is able to reduce the prevalence of diarrhoeal diseases by just 17%; A combination of water and sanitation projects reduces the prevalence by up to 30%. Introduction 3 The synergy between water and sanitation stems from the fact that both work together to reduce the pathogen load in the ambient environment, and in the interruption of the transmission of the pathogens. The WHO estimates that: 5.5% of the global disease burden is due to inadequate water and sanitation, including 88% of the four billion diarrhoeal cases, and the 1.8 million deaths that result from the diarrhoeal diseases in the world annually.  07/06/2024 Introduction 4 The importance of safe water and improved sanitation is further reflected in the global quest to ensure their universal accessibility as reflected in the following global programmes: The International Drinking Water Supply and Sanitation Decade, declared in 1980 by the United Nations General Assembly, Target 10, goal 7 of the Millennium Development Goal that set a 2015 target of halving the proportion of people without access to safe water supply; and The Sustainable Development Goals (SDGs) target of ensuring that everyone has access to safe drinking water by 2030. Access to sanitation facility The WHO recommends that each household should have a sanitation facility within 50 meters of their residence. It also recommends that the number of households that share a sanitation facility should not exceed five, to ensure that facility is not overwhelmed, and unable to effectively prevent excreta-related diseases.  07/06/2024 Public toilets Public toilets are often constructed as a way of ensuring universal access to sanitation facility Studies however indicate that: public toilets are rarely used, They only showcase toilet facilities that can be copied by members of the community, to meet their individual sanitation needs. Public toilets are used as last resort because they are often misused, or not used at all. An unhygienic toilet does not have much health benefits, Public toilets are often not used, because defecation is considered a private matter that should be carried out without the knowledge of others. Excreta-related diseases Poor access and unhygienic use of toilet facilities results in certain diseases described as excreta-related. These diseases are classified as follows: Faecal – Oral infections Soil transmitted helminths Beef and pork tapeworms Water based helminths Excreta –related insect vectors  07/06/2024 Faecal – Oral infections Faecal – Oral infections are same as the water-borne infections discussed under water-related diseases. They basically involve the ingestion of minute quantity of faecal matter through fluid, fingers, flies, food, and the foot, as illustrated in the F-diagram. They are of several types, and include: bacterial infections such as cholera that require large infective doses for their transmission, and viral infections like polio and hepatitis A that have very small infective doses. Faecal – Oral infections The most effective ways of reducing the transmission of the faeco-oral diseases is to erect “primary” barriers, to prevent the seeding of the pathogens from faeces into food, fluids, flies and fingers. This is achieved through the provision of sanitation facility that ensures safe disposal of faeces; and Good hand washing behaviour.  07/06/2024 Soil transmitted helminths These include ascaris (roundworm), trichuriasis (whipworm), and hookworm. They are parasitic worms whose eggs are passed in human faeces, but require some time in favourable conditions, usually moist soil, to mature and become infective. Soil transmitted helminths 2 Soil transmitted helminths are very common in communities with poor toilet facilities, especially those where open defecation is common, as is in several rural and peri-urban communities in Nigeria. The soil transmitted helminths are so linked with open defecation that their prevalence amongst children is often used as proxy measure of the state of the toilet facilities in the community.  07/06/2024 Beef and pork tapeworms These infections are common where pigs and cattle eat untreated excreta, or graze on soil contaminated with fresh sewage or sludge. This scenario is more likely to occur if members of the community defecate openly, or use poorly maintained latrines that pigs can easily gain access to Beef and pork tapeworms 2 The ova of these tapeworms are passed in human faeces, but require a period in the body of the animal before they could reinfect man. The control of beef and pork tapeworms therefore requires that the animals are denied access to toilet facilities, and the stoppage of open defecation.  07/06/2024 Water based helminths This group is equivalent to the diseases classified as water impounding infections. They are parasitic worms that are acquired through repeated contact with faecal contaminated surface water. They include guinea worm and schistosomiasis, which is ranked second behind malaria in terms of parasitic diseases of socioeconomic and public health importance in the tropics. Excreta –related insect vectors These are insect vectors that breed in excreta, septic tanks or flooded latrines. They include the Culex mosquito, houseflies and cockroaches. They are very common in communities with significant open defecation, or where poorly maintained pit latrines are commonly used.  07/06/2024 Excreta –related insect vectors 2 Excreta-related are also a problem in communities with deficient sewerage system, as has been noted in several big hospitals in Nigeria, where the spillage of sewage from broken sewage pipes was found to provide good breeding sites for the excreta-related vectors. The control of these excreta-related vectors is best achieved with better sewage management, instead of the use of insecticides that tend to kill in millions, whereas the vectors often breed in billions. Faeco-oral diseases and hand washing practices Studies have shown that the provision of toilet facilities alone is not enough to halt the transmission of excreta related diseases in a community. Hand washing with soap and water after defecation was found to reduce the transmission of dysentery within a household, by as at least 40%. Appropriate hand washing behaviour has two dimensions to it: Washing at critical times, and The use of the right-hand washing technique  07/06/2024 Critical times for hand washing Critical times are times the hands are most likely to be contaminated or capable of causing an infection. The critical time include: After defecation After cleaning babies bottoms Before food preparation Before eating; and Before feeding children Good hand washing techniques Good hand washing techniques include The use of water for hand washing The use of soap or ash Washing of both hands, rubbing hands together at least three times Drying the hands hygienically by air, or using a clean cloth.  07/06/2024 Hand washing Use of running water is essential for proper handwashing The usual practice of washing into a bowl contaminates the water in bowl with faeces, which then lingers after the handwashing. A study carried out in Accra, Ghana isolated eight different bacteria, two different parasites, and a fungus in a communal bowl used for handwashing in a school Device for running water Running water is often not available in the toilet, but can be made available through devices such as the tippy tap. Tippy tap, a handwashing device designed by Dr. Jim Watt of the Salvation Army. The Tippy Tap is a hands-free device for hand washing that consists of a water container with a small hole, which can be tipped to produce a running water by foot lever that is basically a stick tied to the bottom of the water container with a rope.  07/06/2024 Lecture Five Interventions for safe sewage disposal Introduction The term sanitation facility is often used interchangeably with toilet facility. They are facilities for the treatment of sewage, enough to achieve an interruption in the transmission of excreta-related infections.  07/06/2024 Introduction 2 There are many types of toilets, but the choice of the most appropriate one for a particular community, in a particular circumstance, is guided by: The technical details of the facility that enables it to interrupt the transmission of excreta related diseases, The felt needs of members of the community, and The cost of the facility. Technical considerations for the appropriate toilet facility Technical features are materials and designs incorporated into a product or service to achieve a certain objective. A sanitation facility is basically a sewage treatment facility, so the main technical consideration of a toilet facility is the ability to treat sewage to the extent that there is an interruption in the transmission of the common excreta related diseases in the community.  07/06/2024 Technical considerations for the appropriate toilet facility The technical features to be possessed by a toilet that enable it to interrupt the transmission of excreta related diseases include: The sanitation facility should not involve the handling of fresh stool, Should prevent the contamination of the soil surface or surface water or groundwater The quantity of water used in the sanitation facility should be such that the users can comfortably cope with. The facility should be such that fresh stool is not accessible to animals. Technical consideration: No handling of fresh stool The sanitation facility should not involve the handling of fresh stool, to discourage the transmission of faeco-oral infections, as illustrated in the F-diagram. Fresh stool contains millions of viable microbes, which can contaminate hands and the environment, once it is handled In contrast, excreta kept for up to two years, as is common in pit latrines are almost free of pathogenic organisms, and are often not a source of any of the excreta-related infections.  07/06/2024 Technical consideration: Don’t contaminate soil surface This feature of a good toilet prevents the transmission of soil-transmitted helminths These worms are common in communities with high prevalence of open defecation, especially when the soil is moist, which is a good environment for the maturation of the helminths into their infective stages. Technical consideration: Don’t contaminate soil surface 2 A good toilet must also have an impermeable toilet floor, to prevent the transmission of soil-transmitted helminths This is because hookworm larvae do not move sideways, but climb upwards along the walls of a pit latrine, to reach the floor of the toilet, where they lie in wait for a person with bare feet.  07/06/2024 Technical consideration: Water requirement The quantity of water used in the sanitation facility should be such that the users can comfortably cope with. The standard water-flush toilet consumes ten liters of water per flush, and often requires more than one flush, to completely dislodge the faeces. This makes it unsuitable for households without piped water supply, especially in some rural communities where householders walk great distances to fetch water Technical consideration: Don’t not contaminate ground water Pit latrines are not suitable for communities, such as riverine communities that have high groundwater level. This is because the depth of the latrine easily contaminates the groundwater, The pit latrine is also often flooded by the groundwater, creating ideal breeding site for excreta- related vectors like Culex mosquitoes. In other communities with lower groundwater level, pit latrines and soak-away should be at least 30meters from any water borehole  07/06/2024 Technical considerations: Toilet should be affordable The toilet facility should be affordable to operate and maintain, using expertise that can easily be sourced in the community. In the rural areas, the concept of Village Level Operation and Maintenance Management (VLOM) was adopted during the International Water and Sanitation decade. The VLOM approach restricts technology choices to those that can be operated and maintained within the community for which the intervention is intended. Felt needs of members of the community Needs are things that are considered so important that one cannot do without. It is called felt need, when the need has not been shared with another person; It is called an expressed need, when the need has been brought to the attention of others. The use of the toilet is a very private matter in many cultures, therefore most of the features that will encourage the use of any particular toilet are felt needs that are not easily shared with others, but nevertheless has to be ascertained and incorporated into the sanitation programme, to ensure the judicious use of the sanitary facility.  07/06/2024 Felt needs of members of the community 2 The technical features of the toilet ensure that the toilet is able to interrupt the transmission of excreta-related diseases, An understanding the felt needs of members of the community is however necessary in ensuring the judicious use of the toilet facility. Felt needs for a toilet The following felt needs are very important in encouraging the use of the sanitation facility. Preferred method of anal cleaning Posture for defecation Degree of privacy preferred The preferred location of the facility in relation to the house. Preference for bathing in the sanitation facility after defecation Traditional use of human excreta as fertilizer. Is the design convenient for users, particularly women and children?  07/06/2024 Preferred method of anal cleaning This determines the type of toilet that would be ideal for members of the community. Water flush toilets are more suitable for communities that use water for anal cleaning, Dry toilets like pit latrines are more ideal for communities whose members use solid materials for anal cleaning. Posture for defecation Most communities in Nigeria adopt the squatting position during defecation, hence will prefer sanitation facilities that allow the use of the squatting position, such as pit latrine and the various types of squat water-flush toilets. The use of the standard water-flush toilets, especially in public toilets has been problematic, as several injuries have resulted from mounting on top of the toilet bowl, to assume the preferred squat position.  07/06/2024 Degree of privacy preferred The use of sanitation facility is seen as a private matter in most communities in Nigeria, therefore the location of the toilet should be hidden from plain view, to encourage use. The preferred location Excreta is considered unclean in Muslim societies, therefore toilet facilities should not be located at the east end of the house, the direction of Mecca, where Moslems face towards in their prayers.  07/06/2024 Preference for bathing after defecation In communities where water is used for anal cleaning, where bathing is recommended after defecation, it is important to incorporate a bathroom into the toilet facility, to make it easier for users. Traditional use of human excreta as fertilizer If members of the community use human excreta as fertilizer, as is the case in Chinese communities, the most appropriate toilet for the community is a toilet that allows access to the pooled stool. The pooled stool should however be collected with all the necessary precautions, to avoid contaminating the environment with fresh stool, which negates the main objectives of the sanitation programme.  07/06/2024 Convenient design Is the design convenient for users, particularly women and children? Many facilities are designed with only the technical consideration in mind. Simple things such as the spacing of footrests on a latrine slab can discourage certain users. For example, children might find it difficult to use the latrine if the footrests are widely spaced. Types of toilet facilities Toilet facilities are of various types and design, and several options exist in meeting every sanitation need of a community. The sanitation facilities can be broadly classified into two categories: on-site and off-site systems. Based on the location of their sewage treatment facility.  07/06/2024 Types of toilet facilities On-site toilet facilities are able to treat the sewage at the location of the facility, Off-site facilities have their sewage treatment facilities located far from the location of the toilet, as is the case with the sewerage system that serve most modern cities. Off-site facilities are often regarded as the ideal technology, particularly for high density residential areas, but they are very expensive to manage, and involves the use of massive quantities of water, which exerts a lot of pressure on scarce water resources. On-site toilet facilities On-site facilities can further be sub- divided into: flush-and-discharge systems; and drop-and-store systems The flush-and-discharge toilet systems, also called wet toilets use water to flush the faeces into a container. Examples include the pour-flush toilet and the standard water closet toilet.  07/06/2024 The drop-and-store toilet systems The drop-and-store toilet systems on are designed to have the faeces dropped directly into a container that also serves as the sewage treatment facility. This explains why they are sometimes called dry toilets. Examples of drop-and-store toilet systems include: Simple pit latrines Ventilated Improved Pit (VIP) latrines Borehole latrine Aqua privy The pit latrines Pit latrine is the most appropriate and affordable technology for excreta disposal in rural communities Because it can be constructed by householders with little external assistance The principle of all types of pit latrine is that wastes such as excreta, anal cleaning materials and sometimes refuse are deposited inside a hole in the ground. The liquids percolate into the surrounding soil, The organic component decomposes into gases, liquids and a consolidated residue that might be used as a natural fertilizer for agriculture.  07/06/2024 The pit latrines 2 Pit latrines are of various types, including: Simple pit latrine Ventilated Improved Pit (VIP) latrine. At its best, the health benefits and the convenience afforded by the pit latrine are comparable to other more sophisticated methods. Drawback of pit latrine Poorly designed, poorly constructed pit latrine Produces unpleasant smell, Serves as breeding ground for insect vectors Liable to collapse; and A source of chemical and biological contamination of ground water These drawbacks are often corrected in the various improved designs, including the VIP latrine.  07/06/2024 Ventilated Improved Pit (VIP) Latrine The VIP latrine is a pit latrine with a vertical vent, with a fly screen at the top It is so designed to reduce the smell and flies that are usually associated with the simple pit latrine Ventilated Improved Pit (VIP) Latrine 2 The vertical vent of the VIP latrine drives the odour produced by the decomposition of the excreta out of the toilet, instead of letting the smell remain in the superstructure as in the simple pit latrine. This is accomplished with the current of air passing through the latrine door, into the squat hole, and out through the vent pipe  07/06/2024 Ventilated Improved Pit (VIP) Latrine 3 The fly screen at the top of the vent pipe assists in controlling flies. Flies are attracted to the pit by the odour coming from the vent pipe, but are unable to enter because of the screen. Ventilated Double Pit Latrine A VIP latrine with double pit (Ventilated Double Pit Latrine) is especially recommended for urban centers Where there is shortage of land and the toilet cannot be moved to a new site. It requires the construction of two pits, lying side by side, and lined with bricks or blocks. Each of the pits has its own squat hole and vent pipe, but only one of the holes is available for use at any time.  07/06/2024 Borehole latrine This is not routinely used by households, but designed to be used for a short time, in large displaced person’ camps. It is tackles the problem of smell and flies with its small cross- sectional area, and great depth which might be up to 10m. However, the sides of the hole near its top are often soiled during use, making fly infestation possible. The capacity of borehole latrine to pollute groundwater is very high, hence it is not where groundwater is the main source of drinking water Aqua Privy An aqua-privy is a small, single-compartment septic tank directly under or slightly offset from the toilet opening (squat hole). The excreta drop directly into the tank through a chute, which extends 100 mm to 150 mm below the surface of the water in the tank. This provides a water seal that prevents odour and keep insects away. The tank must be completely watertight, to help retain the water-seal; it may therefore be practical to use a prefabricated tank  07/06/2024 Pour-Flush toilet This is another toilet facility that can controls the problem of flies and smell with a water-seal Faeces is deposited in a pan with a water seal, which is dislodged into a septic tank by pouring (or better, throwing) a few liters of water into the pan. The use of little water in flushing has the added advantage of reducing the risk of groundwater pollution Sanitation facilities with septic tank These are commonly used by individual households in urban centers The common water closet toilet consumes about 10 liters of water per flush, required to flush the faeces out of the toilet bowl and down into the septic tank. This quantity of water is required to propel the faeces into the septic tank, preventing the faeces from remaining in the sewage pipe, caking and blocking the pipe.  07/06/2024 Septic tank The septic tank is a sealed watertight tank that provides an ideal environment for the anaerobic decomposition of faeces. Septic tank receives the faeces flushed from the toilet, which then separate into three components: a lower solid sludge that settles at the bottom of the tank, a middle liquid component that passes into the soak-away pit, and an upper greasy layer of scum. The organic matter in the sludge and scum layers are broken down by anaerobic bacteria into water and gases, leaving a black non-offensive reside that can be evacuated and used as soil conditioner Soakaway tank The soak away pit is lined with block in a honeycomb construction or open joints. It serves as a receptacle for the liquid effluent of the septic tank, which is held just enough to allow the liquid seep into the surrounding soil. Discharge vents connected to a stormwater drain or leach field are sometimes added to the soakaway to aid their discharge capacity  07/06/2024 The Sewerage System A sewerage system is a series of underground pipes collecting and transporting sewage and household sullage from the various houses in the community, to a central point where the effluents are treated. It is ideal for communities with high groundwater level, because it removes the need for each household to have its own septic/soak-away tanks. The Final Disposal of Sludge Sludge from the septic tank/Soakaway have high Biological Oxygen Demand, and so should not be disposed untreated into a water body, as is often the case in Nigeria. This is to ensure the waste does not consume the oxygen in the water enough to asphyxiate aquatic animals Biological Oxygen Demand (BOD) is the amount of dissolved oxygen that is consumed by the waste. It is technically defined as the amount of oxygen needed by aerobic organisms to decompose a given quantity of the waste, in five days, and at a temperature of 20 degree Celsius.  07/06/2024 The Final Disposal of Sludge Sewage are treated using the following methods, to reduce their BOD: A conventional sewage treatment plant; or A waste stabilization ponds (or lagoon). Waste stabilization ponds are a series of ponds that provide ideal environment for the anaerobic and aerobic decomposition of faeces, just like in the septic tanks/soakaway Waste stabilization ponds Waste stabilization ponds were commonly used during the colonial period They are low capital, provide a good level of treatment and have a low operating and management cost. The major disadvantage however, is that significant area of land is needed for its effective operation.  07/06/2024 Sewage treatment Despite the difference in sophistry, the conventional sewage treatment plant and the stabilization pond operate with the same principles of: sedimentation, filtration and biological decomposition of the waste. The processes are achieved in waste stabilization ponds using natural processes, while they are accomplished in the conventional sewage treatment plants using different types of machinery. Processes of sewage treatment Sewage treatment is carried out in a two-stage process of sedimentation: Primary and secondary sedimentation of the sewage that respectively create ideal conditions for the anaerobic and aerobic decomposition of the sewage Primary sedimentation is the first stage of the sewage treatment process where the solid components of the raw sludge are allowed to settle, creating an ideal environment for the anaerobic decomposition of the faeces into inert materials (sludge), and gases like methane that can be exploited as an energy source.  07/06/2024 Secondary sedimentation The second stage of sedimentation (called secondary sedimentation) occurs in another tank or pond, containing the watery effluents of the first tank, that has the ideal environment for the aerobic decomposition of the remaining organic content of the sewage The product of the second stabilization pond is a clearer fluid that can be safely discharged into the river, or used for irrigation. The quality of the effluent of the second sedimentation tank is further improved in a modern sewage treatment plant through some filtration processes such as that provided by the trickling filter method. Lecture Six: Solid Waste Disposal Introduction Health problems of improper solid waste disposal  07/06/2024 Introduction Solid waste or refuse is defined as useless, unwanted or discarded materials that arise from man’s activities, and are not free-flowing. Free flowing wastes are called sewage. Solid wastes vary, but can generally be put in two main categories: Fermentable organic wastes or garbage that decompose rapidly, and Non-fermentable wastes or rubbish, that resist decomposition, or decompose very slowly. Garbage Garbage are generated primarily from the preparation of food for human consumption. They are closely linked with the food consumption pattern, and vary with social custom, and living standards. In the developed countries where most of the foods consumed are processed, the amount of garbage produced at household level is very much reduced, The amount of garbage generated by households in developing countries are significantly higher, because of most of the food items are processed at household level  07/06/2024 Rubbish Non-fermentable waste are also called rubbish They range from those generated in homes, to industrial and agricultural wastes, and can include such products as disused refrigerators, empty containers, packaging and nonfunctioning machinery. The disposal of non-fermentable waste (rubbish) is usually not as urgent as garbage, because they decompose slowly and are often less offensive. History of waste disposal The need to deal with waste materials has been recognized for millennia, as indicated by the Biblical waste burial specifications in Deuteronomy 23:12 – 13; However, the idea of organized collection and disposal of waste only started in the mid-19th century, with the recognition of the role played by indiscriminate waste disposal in the epidemics that swept through countries and continents in that period.  07/06/2024 History of waste disposal 2 At present, solid waste management refers to the collection, transfer, treatment, recycling, resource recovery and disposal of solid waste. These processes are carried out within existing legal, social, and environmental guidelines that protect the public health and the environment, and are aesthetically and economically acceptable Hazards of improper solid waste disposal Improper disposal of solid waste can lead to: The proliferation of vectors and pests; and The contamination of the environment Vectors and pests that proliferate as a result of indiscriminate dumping of solid waste include: rats and insect vectors such as mosquitoes, housefly and cockroaches,  07/06/2024 Mosquitoes that breed in refuse The mosquito species that breed in solid waste are: Culex mosquitoes and aedes mosquitoes. Culex mosquitoes cause severe nuisance as they have a painful bite, and bite from dusk to dawn, when people are still awake. Culex mosquitoes also transmit filaria worms, and thus cause lymphatic filariasis and its complications like hydrocele and elephantiasis. Mosquitoes that breed in refuse 2 Aedes mosquitoes, especially Aedes Aeypti breed in artificial containers that collect water, such as discarded car tires and empty cans. Aedes mosquitoes have whitish stripes and are also biting nuisance. They transmit yellow fever, Zika fever and dengue fever. Anopheles mosquito that transmits malaria breeds in clean water in natural setting. Therefore, the incidence of malaria might not increase in a community with improper refuse disposal.  07/06/2024 Housefly Houseflies are also called filth flies, because they breed in garbage and other filth. They are called mechanical vectors, because they transmit diseases by picking up germs from filth and transferring them to food. Houseflies are able to transmit infection in this way through: The carriage of the pathogens on their hairy limbs The regurgitation of the contents of their stomach onto solid food, as a means of liquefying the food (vomit drop); and Defecating on the food. The faeces often contain surviving pathogenic organisms picked up from the refuse. Housefly 2 Houseflies have been implicated in the following diseases Dysentery and diarrhoeal diseases Eye infections (such as trachoma and epidemic conjunctivitis) Poliomyelitis; and Skin infections (such as yaws, cutaneous diphtheria)  07/06/2024 Cockroach Cockroach is another mechanical vector that proliferates in refuse dumps. They are not usually the most important cause of a disease, but like houseflies, they may play a supplementary role in the spread of dysentery, diarrhoeal diseases, plague, and even leprosy. In addition, cockroaches may carry the eggs of parasitic worms, and may cause allergic reactions. Rats Domestic rats, as well as peri-domestic rat species such as those that transmit Lassa fever proliferate in refuse dumps, and can result in increase in the incidence of the diseases they transmit. Diseases transmitted by rats include: Plague, a disease caused by gram-negative bacterium, yersinia pestis and transmitted by the bites of rat flea Leptospirosis, a disease caused by bacteria, Leptospira interrogans that is transmitted through contact with water, food or soil contaminated with the urine of infected animals, especially rodents  07/06/2024 Diseases transmitted by rats Lassa fever, an acute viral haemorrhagic fever, caused by a single- stranded RNA virus that is transmitted by inhaling or ingesting dust, water or food contaminated with the urine or faeces of the peri- domestic multi-mammate rat. Rat bite fever, a severe disease caused by the bacteria Streptobacillus moniliformis that is transmitted either by rat bite or ingestion of contaminated products Contamination caused by the improper waste disposal The improper management of solid waste has been known to cause the following additional health problems: The generation of toxic fumes The chemical contamination of ground water The radiological contamination of ground water The generation of air-borne allergens and pathogens The generation of toxic fumes. The dumpsite is often a smouldering heap, caused by the decomposing garbage. Apart from the stench, heaps of refuse also emit particulate matter, So2, No2, various hydrocarbons, and other noxious gases, that have adverse health effects.  07/06/2024 The chemical contamination of ground water Dumpsites have a high capacity to pollute ground water, especially in communities with high groundwater level, like the Niger delta region. The radiological contamination of ground water Industrial solid wastes such as those produced by the oil companies, and medical x-ray studies can be radioactive. They can contaminate ground water sources if not properly disposed. The Koko toxic dump saga should keep everyone in Nigeria alert to this possibility.  07/06/2024 The generation of air-borne allergens and pathogens Dumpsite has the ability to release enormous amounts of allergens and pathogens into the ambient air. This is because they provide the right environment for the multiplication of various bacteria and fungi. Lecture Seven: Solid Waste Disposal Interventions for proper solid waste disposal  07/06/2024 Introduction The 3R strategies are the keys to the proper management of solid waste. The strategies are practiced in order of priority, called waste hierarchy, and include Reduction Recycling Prompt Removal Reduction is the first and the most preferable of the 3R strategy in the management of solid waste. It includes waste reduction and reuse. Introduction 2 Recycling of waste is the next best after the waste reduction strategies of reduce and reuse. It involves reprocessing the product, and then using it as raw material in the making of new product. Prompt removal is the least preferred of the 3R strategies, because it depends on the prompt removal of the waste, to ensure that the environment is not contaminated.  07/06/2024 Reduction in refuse generation Reduction in waste generation includes efforts taken to reduce the quantity of unwanted waste generated. It also includes the various ways the little waste that couldn’t be avoided are reused at the level of the household, by converting the wastes into other uses, without the need of treatment. Waste reduction methods are seriously needed in Nigeria, because the refuse generating capacity of urban residents in Nigeria is beyond the capacity of the disposal authority. Reduction in refuse generation 2 The following refuse minimization methods are commonly advocated: Composting Turning organic waste into fuel Limiting the use of plastics and food wrappings; and The use of household incinerator The reuse of plastic bottles  07/06/2024 Composting Vegetable waste can breakdown to form a valuable soil conditioner and fertilizer (compost). They can be stored together with such other non- odorous household wastes such as ash, goat and chicken droppings, in a facility and used after a few months as fertilizer. This is a common practice in northern Nigeria that has helped in no small way in reducing the amount of money spent in the purchase of artificial fertilizer. Composting 2 Composting also generates bio-gas that can be collected and used for cooking. Several low-cost equipment have been designed for this purpose.  07/06/2024 Turning organic waste into fuel Vegetable waste and wastes from the carpenter’s shop and sawmills can be pressed into bails and used in place of firewood. A special stove has been designed for this, The Fulanis have perfected the use of dried cow dung as fuel for cooking. Limiting the use of plastics and food wrappings Food wrappings and plastics are non- biodegradable, and can remain intact many years after their final disposal, hence the need to reduce their use The use of the use of cloth bags and baskets for shopping should be encouraged. Plastic bags can be washed and reused, and finally burnt when they cannot be reused.  07/06/2024 Use of Household incinerator Each household should be encouraged to own a small incinerator for the burning of combustible waste like papers and plastics, if it cannot be sold on to recyclers. The incinerator can be built with mud, cement blocks or metal, and can be built such that the heat generated can be used for heating water for bathing Reuse of plastic bottles In Nigeria, single use plastic bottles are frequently collected, washed and used as containers for drinking water, beverages such as zobo and kunu, and even for traditional medicines.  07/06/2024 Recycling Recycling involves reprocessing the wastes to serve as raw material for the production of entirely new product. It is therefore different from reuse that makes use of the product without changing it. For example: single use plastic bottles used for beverages can be reused as container for traditional medicine, but can be recycled and made into prayer mat, bead or flipflops. Prompt Removal Prompt removal is the least preferred of the 3R strategies, unfortunately, it is the major strategy used in municipal waste management in Nigeria. It depends on the prompt removal of the waste, to ensure that the environment is not contaminated, which has been difficult in Nigeria  07/06/2024 Prompt Removal 2 Prompt removal involves the following: Proper storage of the waste at the point of generation Refuse collection, to transport the waste to dump sites Final disposal The storage of refuse Refuse should be hygienically stored in preferably covered container, before they are collected for final disposal. Containers for storing waste should be hygienic, economical and suited to the accepted mode of collection. It is recommended that: Households should have refuse bins of 0.03 - 0.09m2 capacity that can be lifted and emptied into a refuse van  07/06/2024 The storage of refuse 2 It is recommended that: Public refuse dump sites should have containers of 200 – 300 liters capacity, like the mammoth bins that can be rolled along for emptying into the special collection vehicle (compacting vehicle). The storage of refuse 3 It is recommended that: In markets and other public places where refuse generation is enormous, very large bins like the Chassis mounted 20-tonne Dino-bins can be used.  07/06/2024 The storage of refuse 4 The mammoth bins and Dino-bins are expensive and need special vehicles for the retrieval of the refuse contained in them. Less expensive options are the Refuse storage chamber (or ashpit) and the elevated refuse depot. They are products of masonry, constructed with wire mesh at the base to encourage the drainage of fluids out of the structures. The fluid from these structures should ideally be channelled into the drainage system to prevent the contamination of groundwater, or surface water sources. Refuse collection This involves collecting the refuse from households, and dumping them in neighbourhood refuse dump sites, to be picked up and transported to the municipal dump site. It is the costliest phase, and may account for up to 80% of the total cost of waste management. The mechanization of the process in the developed countries has solved the problem of refuse collection and disposal, This is however expensive and may not be affordable.  07/06/2024 Refuse collection 2 Door-to-door collection, using refuse collectors is cheaper, especially as the willingness to pay for such service has been demonstrated in several communities in Nigeria. This approach will facilitate waste segregation and recycling at household level, which can provide extra income for the households, and create employment for several waste collectors Final disposal Refuse transported to the final disposal site are managed as follows: Dumped into a dump site or sanitary land fill Sorted to recover products for reuse or recycle; or Incinerated, to reduce its volume, before disposal in a sanitary landfill.  07/06/2024 Dumping This is the most common method used in Nigeria, and includes burial and dumping in communal or municipal dump sites Final disposal of refuse generated in rural communities not served by government’s waste disposal services should be buried, instead of the current practice of open dumping in nearby household and communal dump sites. This requires digging a pit, like the pit latrine, with the same spacing away from the water borehole or hand-dug well. This spacing is required because toxic chemicals can leach out from the refuse pit to contaminate the well. Sanitary land fill This is the ideal method for the final disposal of solid waste. This is because it has features that prevent the breeding of pests and vectors, and the contamination of ground and surface water. These features include: Adequate hydro-geological surveys are carried out before they are sited, to ensure that ground and surface waters are not put at risk from leachate or run off from the land fill site. The site is also fenced and provided with screens to catch wind borne litter.  07/06/2024 Incineration Incineration is high temperature combustion that reduces the waste to ash, flue gas and heat, resulting in the drastic reduction of the size of the waste. The ash produced by incineration can be disposed in sanitary landfill, while the heat generated can be recovered and used for electric generation or for heating. The flue gases generated by the incinerator can be a source of air pollution, but are often recovered by installed filters. Lecture Eight: Indoor Air Pollution Sources Health problems of indoor air pollution  07/06/2024 Introduction Air is essential for life. In its pure form is made up of 78 % nitrogen, 20.9% oxygen, 1% argon, with small traces of carbon dioxide, neon, helium, methane, krypton and water vapour. The ambient air (prevailing local air) contains many others things, mostly due to man’s activities, hence air pollution can be said to be due to the indiscriminate disposal of gaseous refuse. Introduction 2 Air pollution was previously erroneously equated to smoke pollution, Air Pollution is now said to occur when the substances in the ambient air attain concentrations that can adversely affect human health, or capable of causing damage to property, plant and/or animal life.  07/06/2024 Introduction 3 Harmful substances accumulate in the ambient air when the prevailing environmental condition prevents their dispersion or dilution. The condition includes: Temperature inversion that prevents the ascent of hot contaminated air, and the descent of cold cleaner air Example, Esau’s sacrifice Introduction 4 No dispersal of harmful substances in the ambient air Poorly ventilated houses, that prevent the dispersal of the pollutants in the indoor environment; and  07/06/2024 Introduction 5 No dispersal of harmful substances in the ambient air Mountains and high-rise buildings that can block the circulation of air. Introduction Air pollution is a broad subject, but would be discussed under: Indoor air pollution; and Outdoor air pollution Indoor air pollution is the air pollution that occurs in the indoor environment. Outdoor air pollution is the accumulation of high levels of pollutants in the ambient air of the outdoor environment,  07/06/2024 Indoor air pollution It is a significant cause of ill health, because of the amount of time spent indoors, The commonest source of indoor air pollution is the burning of biomass fuel, for cooking or heating. Biomass fuel refers to any plant or animal- based material that is deliberately burnt by humans. They include firewood, crop residues, charcoal and cow dung, in the case of Fulani herdsmen. Biomass fuel Biomass fuel produce a lot of smoke, and with the poor ventilation that is common in most African huts, the concentration of pollutants produced by the fireplace often exceed the guideline values. For example, a study in Lagos tested the fumes arising from the burning of firewood to which children with bronchiolitis and bronchopneumonia have been exposed, and found that: All the children were exposed to an average concentration of 940 ppm of carbon monoxide, whereas the WHO guideline value for it was 50ppm 71. 7% of them were exposed to 85.6ppm of aromatic hydrocarbons, whereas the WHO guideline value for it was 25ppm.  07/06/2024 Indoor air pollution 2 A Kenyan study found that smoke from indoor fires can contain as much as six times the guideline value for 17-benzaminopyrene, believed to cause naso-pharygngeal cancer. Air pollution from the fireplace affects mainly the women who are traditionally responsible for food preparation and cooking, and infants/young children who are usually with their mothers near the cooking area. Health effects of indoor