Sanitation: Controlling problems at source:
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What are the barriers to control at source?
Why does 40% of the world's population still have no basic sanitation? Many people do not realize the health benefits to the individual, the community and to society from improving sanitation. The high cost of improving sanitation is often cited as a barrier to implementing sanitation projects. However, to decrease the proportion of people lacking basic sanitation and water supply by 50% worldwide by the year 2015, it is estimated that US$ 23 billion per year would be needed - about US$ 7 billion a year more than is currently spent (WHO, 2000; WHO, 2001b). On a global basis this is truly a small sum of money. Improving sanitation is often low on the list of priorities. There are so many other pressing needs for the attention of governments: food supply, education, medical treatment and dealing with war and conflict. Most people are aware that poor sanitation has a health impact, but there is a lack of awareness of the extent of ill-health that it causes.
There needs to be a political will for - and in investment in - sanitation, and those in need of such services need to exert sufficient pressure to bring about change. WHO's strategy for improving access to sanitation focuses on targeting the highest risk communities. Success depends on:
- identification of the communities at highest risk from diseases related to insanitary conditions;
- giving higher priority to sanitation in national planning for health and investment in infrastructure;
- community involvement in planning, implementing and maintaining the services;
- the development of sanitation technologies suitable for difficult geographical and residential conditions;
- taking into account cultural beliefs and habits;
- sanitation should be integrated with other aspects of development, e.g., hygiene promotion, child survival, maternal and child health, essential drugs, and agricultural development;
- allowing for long-term ecological and financial sustainability.
The question of who pays for improvements often arises. The set up costs have to be considered: but public investment would lead to substantial returns in the form of better health for these communities, and the associated economic benefits for the community and nation as a whole. To offset costs and ensure greater sustainability of sanitation systems, considerable community involvement and self-help are needed (WHO, 1997).
The cultural factor: throwaway societies versus ‘waste-not-want-not’ societies
People have evolved different ways of thinking and behaving about waste: this affects behavior and also affects the way messages about health effects or sensible re-use will be received. Human society has developed very different sociocultural responses to the use of untreated excreta. This ranges from deep disgust to practical preference. While determined partly by survival economics, these cultural differences apply to many water poor countries, as well as to water rich areas of the north. For example, in Africa, the Americas and Europe, excreta use is generally regarded as culturally unacceptable, or at best with indifference. This results from the strongly held view that human excreta, especially faeces, are repugnant substances best kept away from the senses of sight and smell. Products fertilized with raw excreta are regarded as tainted or defiled in some way. These views are less rigid in the case of using excreta in compost and sludge for agriculture, but still pose a barrier to use of waste.
In contrast, both human and animal wastes have been used as fertilizers in agriculture and aquaculture in, for example, China, Japan, and Indonesia for thousands of years. Some countries such as China, India and Japan have used wastewater and excreta for irrigation for over 100 years. In China over 1.3 million hectares are irrigated with wastewater. This practice reflects the high social importance of frugality: a waste not, want not approach. It also relates to a deep ecological, as well as economic, appreciation of the way soil fertility and enrichment with waste are related. In such societies intensive cultivation practices have evolved in response to the need to feed a large number of people with only limited land available. All resources have to be carefully conserved, included excreta. This does not mean that the excreta are always used safely. There can be strong cultural barriers in changing practices to make them safer. For example, excreta are safer if stored long enough for worm (helminth) eggs to be inactivated. Introducing the use of stored rather than fresh excreta is likely to be culturally acceptable: but persuading people not to eat raw fish from contaminated waters is much more difficult. In some cultures, consumption of raw fish is a major element of the diet and it may be hard to persuade them that raw fish pose an increasing hazard, because of rising pollution of marine and freshwaters (Mara and Cairncross, 1989).
Waste as a resource
Reducing the adverse health effects associated with inadequate management of wastewater, sludge and excreta is possible but takes sustained effort at the individual, community and national levels. Additionally more emphasis must be placed on finding sustainable approaches for reducing health hazards associated with wastewater, sludge and excreta, and at the same time, closing the nutrient cycle from waste to agriculture and aquaculture and protecting limited fresh water sources and the environment.
If waste is to be used safely then:
- Wastewater and excreta need to be treated in such a way as to reduce pathogen concentrations and facilitate the use of nutrients;
- application of wastes should be done safely;
- exposed workers should wear protective clothing;
- wastewater and excreta application to crops should be restricted based on the degree of treatment it receives and the type of crop to be grown (e.g., food eaten raw, food normally cooked or industrial crops);
- industrial wastes need to be treated separately to avoid contamination of drinking water sources and the environment by toxic chemicals.
Wastewater - and human excreta - is used in many countries and in some places this dates back thousands of years, for example in the cultivation of fish. In urban communities, use of wastewater may supplement an otherwise insufficient water supply (Table 1).
Setting for wastewater use
Type of use
Coastal/ river banks
Aquaculture (fish cultivation), aquifer recharge to prevent saline intrusion.
Car washes, toilet flushing, irrigation of recreational areas, and street cleaning
Use of wastewater and excreta
The goal of safe wastewater and excreta use is to ensure that wastewater, sludge, and excreta are managed, treated and used so that the adverse health effects are controlled and the water and nutrients can be reclaimed for beneficial use.
Treated municipal sludge has long been used by individuals and communities as a fertiliser and soil amendment. In the United States of America, some wastewater treatment facilities sell treated sludge to farmers and home owners for use as a fertiliser. This activity helps defer some of the cost of wastewater treatment. However, it is important that sludge is treated to a high degree before it is used in this manner. Most of the pathogens and toxic chemicals are concentrated in the sludge. Therefore, sludge is often composted or dried at high temperatures to kill pathogens that might be present. Care also must be taken to reduce the amount of toxic substances that might initially appear in the wastewater. This can often be accomplished by treating industrial wastewater separately from municipal wastewater.
Aquaculture, the cultivation of fish, shellfish, and aquatic plants, has been practiced for thousands of years in many different regions. Fish and plants grown in wastewater and excreta fed ponds still account for a large percentage of the world's aquaculture production. In Calcutta India, for example, 10 - 20% of the region's fish is supplied by a network of wastewater fed fish ponds to the east of the city. In many areas, untreated wastewater and excreta are directly used for pond fertilisation. However, this practice can have adverse human health effects. The use of untreated wastewater or excreta to fertilize fish ponds has been associated with the transmission of many diseases - particularly those caused by trematodes or flukes. Wastewater and excreta should be properly treated before they are used in aquaculture and products grown in this manner should be thoroughly cooked before they are eaten.
In many areas of the world, particularly in water scarce regions, treated wastewater has been used for numerous activities in urban settings including: irrigation of golf courses and public parks, creation of recreational lakes, street cleaning, environmental restoration, car/train washing, fire protection, and for toilet flushing. In many urban areas non-potable uses require larger amounts of water than potable uses. Using properly treated wastewater for these purposes is one way of extending water supplies. This could allow communities to protect high quality water sources, reserving them exclusively as drinking water sources.
Aquifers that supply drinking water may be used faster than they recharge. Moreover, in coastal areas saline intrusion of aquifers occurs as water is withdrawn faster than it can be naturally replaced. Increasing salinity makes water unfit for drinking and other purposes such as irrigation. In several countries where arid conditions exist and advanced wastewater treatment techniques are available, treated wastewater is used to augment ground water, creating a barrier to saline intrusion.
When treated wastewater is used to replenish ground water sources that serve as drinking water sources, important safe guards must be put in place. For example, after conventional secondary treatment, chemicals may be added to the water to help remove particles, the water may be filtered through several different types of filters, it may be processed through a membrane, and may be disinfected at several different stages of the process. Additionally, it is important to monitor the health of the exposed population through epidemiological studies to ensure that no adverse health effects occur because of this wastewater reuse practice. Highly treated wastewater has been safely used to supplement drinking water supplies in Windhoek, Namibia since 1968 (Box 5). The State of California, USA also has safely used highly treated wastewater to augment water supplies in aquifers for nearly 30 years.
Box 5: Use of treated wastewater for drinking water in Namibia
Windhoek, Namibia is located in an arid region characterized by chronic freshwater shortages. In the late 1960's, all available freshwater sources were being used at the maximum rate to supply the city with drinking water. During prolonged droughts, the only alternative water supply the city could turn to was treated wastewater. In 1968, Windhoek became the first city in the world to directly augment its drinking water supplies with treated wastewater.
To ensure the safety of the water supply Windhoek has developed a comprehensive treatment process that relies on primary, secondary and tertiary treatments. It also includes extensive chemical, bacteriological, virological and epidemiological monitoring. Potentially toxic industrial wastewater is prevented from entering the municipal waste stream and is treated separately (Haarhoff and van der Merwe, 1995).
Since 1973, epidemiological studies of Windhoek residents have shown no adverse health effects associated with drinking reclaimed wastewater (National Research Council, 1998).
The Role of WHO
The use of waste and wastewater has to be carefully controlled to prevent risks to health. In 1989, following extensive collaborative activity with the World Bank and others, WHO with UNEP published Guidelines for the Safe Use of Wastewater and Excreta in Agriculture and Aquaculture. These guidelines outline the health basis for guideline derivation and describe the practices necessary to protect public health. Other WHO reports relevant to sanitation include the Technical Report Control of Foodborne Trematode Infections (1995) and the Technical Report Food Safety Issues Associated with Products from Aquaculture published in conjunction with the Food and Agriculture Organization of the United Nations and the Network of Aquaculture Centres in Asia - Pacific. WHO is supporting UNEPs “Global Plan of Action” for the protection of the marine environment against land-based sources of pollution through the coordination of the ”Sanitation Connection” web-based resource (Box 6) as a mechanism to increase access to information on sanitation in general and sewage in particular. The WHO has also made prevention of trachoma a priority, through its worldwide campaign to eliminate the causes of preventable blindness.
Box 6: Sanitation Connection
Sanitation Connection is an internet-based resource intended to facilitate access to information on sanitation. The site brings together a number of ongoing initiatives in sanitation information management, to ensure that the best information is widely available, and brings together important institutions working in sanitation into a single wide-reaching information initiative. Sanitation Connection functions as a virtual partnership with a range of sector players taking responsibility for the provision and maintenance of state-of-the-art information on selected issues. Sanitation Connection is administered by a core group of partners and coordinated by WHO.
The core Sanitation Connection Partners include, the Water and Sanitation Program for South Asia (World Bank), the International Water Association, the Global Programme of Action for the Protection of the Marine Environment from Land-based Activities (GPA) of the United Nations Environment Programme, the Water Supply and Sanitation Collaborative Council, and the World Health Organization.
For more information please visit Sanitation Connection at http://www.sanicon.net
Sanitation: Controlling problems at source:
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