Examples of the contagious clinical waste include laboratory cultures, wound dressings, blood and other body fluids, and needles. Although most of the hospitals have waste treatment facilities, some of the clinical waste finds its way into the nearby streams that are tributaries (EPA 2005).
INDICATIONS OF POLLUTION
While the quality of the water being distributed by the Addis Ababa Water and Sewerage Authority is monitored and generally safe for drinking, Alemayehu and others (2005) noted high concentrations of trace elements such as chromium in surface water. Chromium levels were observed to increase downstream of rivers. In the northern elevated non-industrialized area of Intoto Ridge, the chromium and manganese levels were found to be low, but increased to 14 µg/l and 6 531 µg/l, respectively, as the streams reached the southern part of the city. Manganese concentration higher than 0.1 mg/l is considered unsafe for industrial and domestic use (WHO 1984). The chemical pollution is blamed on industrial activity, including tanneries. Nitrate concentrations of as high as 728 mg/l were also found in some spring water (Alemayehu and others 2005). This is probably attributed to leaking septic tanks and the pit latrine system used in highly populated areas. According to the World Health Organization (1984), safe drinking water should not have nitrates exceeding 10 mg/l.
IMPACTS OF POLLUTION
The high levels of pollution in the water sources of Addis Ababa have impacts on human and animal health, as well as on the urban ecosystem.
HUMAN HEALTH Pathogens transmitted through polluted water cause intestinal infections, and common water-borne diseases in Addis Ababa include typhoid, dysentery and cholera. According to EPA (2005) all of the people using the Akaki River water are affected by these pathogens. In addition, the people are also exposed to heavy metal toxicity in the vegetables that are grown using the Akaki wastewater (Itanna 2002). Although most levels of metals have been found to be tolerable, it is feared that metals such as arsenic will build up in Swiss chard, and chromium will build up in lettuce. Fears of food poisoning from wastewater are worsened by the fact that 60 per cent of the city’s food consumption is supplied by urban farmers, who irrigate their crops using wastewater (Weldesilassie 2008).
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ECOSYSTEM HEALTH One of the environmental effects of the pollution of the water sources of Addis Ababa is eutrophication. Caused by excessive use of phosphorous and nitrogen in agriculture, and effluents from sewerage and pit latrines and municipal wastes, eutrophication causes growth of algae and weeds, which deplete the oxygen level of the water bodies, and in turn affect aquatic fauna and flora.
According to the Addis Ababa Environmental Protection Authority (AAEPA 2002), the pollution of the Akaki River is blamed for the emergence of water hyacinth weed in the Aba Samuel Lake. By the year 2000, the weed had covered almost 50 per cent of the lake.
RESPONSES
The City of Addis Ababa has stepped up its efforts to address water pollution by implementing a range of activities. These include the decentralization of Solid Waste Management services to the lower administration levels for more effective administration; the establishment of efficient and equitable service charge collection systems; community participation in sanitation activities; and planning the establishment of new sanitary landfills. Through its environmental arm, the Addis Ababa Environmental Protection Authority also initiated plans to green parts of the city. One example of such greening efforts is the allocation of 1 300 hectares of land for productive forest plantation to the Ethiopian Heritage Trust for the restoration of native flora and fauna (Gullele Botanic Garden 2011). In addition, the Addis Ababa Sewerage and Sanitation Authority initiated a plan to rehabilitate the Akaki River (Gullele Botanic Garden 2011).
LESSONS LEARNED
• It is imperative to improve municipal waste management, and for Addis Ababa, this can be done by constructing more on- site sanitation facilities; increasing the capacity of wastewater treatment plants; increasing the number of connections to the sewers systems; extending reticulated sewerage system to planned settlement areas; and discouraging the use of pit latrines.
• Industry and domestic users of water need to exercise responsible behavior, and ensure that their activities do not pollute water and the environment. Where such pollution takes place, punitive measures must be meted on the responsible.
• As some of Addis Ababa’s water bodies are already polluted, it is important that they are reclaimed.
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