Water and Wastewater Treatment in AfricaCurrent Practices and ChallengesSustainable access to safe drinking water and basic sanitation is an important part of the millennium development goals (MDGs). For most African countries, an extensive effort is needed for the last three remaining years for the achievement of the MDGs, especially in Sub-Saharan Africa. Current practices for water and wastewater treatment in Africa are insufficient to ensure safe water and basic sanitation. To address this challenge, joint efforts are needed, including transforming to green economy, innovating technologies, improving operation and maintenance, harvesting energy, improving governance and management, promoting public participation, and establishing water quality standards. IntroductionAfrica is often characterized by its clean water and abundant biodiversity [1]. It is no doubt that water quantity and quality is of vital importance for the ecosystem [2,3]. Unfortunately, as the world's second-driest continent after Australia, Africa has only 9% of global renewable water resources to support 15% of the global population [1]. The lack of water in Africa is further aggravated by insufficient treatment of water and wastewater, particularly with rapid population growth and urbanization [2].At present, however, the efforts to improve drinking water quality and wastewater treatment are not keeping pace with population growth and urbanization [4,5]. The growing population and rising economy has resulted in increasing consumption of water and discharge of wastewater, which cause heavy pollution [6]. Water pollution not only reduces available freshwater, but also affects human health and ecosystem [3,7,8]. According to the millennium development goals (MDGs), the proportion of people without sustainable access to safe drinking water and basic sanitation should be reduced in half by 2015 [9,10]. In fact, water and wastewater treatment is significant for the realization of the MDGs [11,12]. For example, goal 1 (to eradicate extreme poverty and hunger) is related to water treatment because the access to safe drinking water can save the time and cost to collect daily water, thus people may have more time to work and to get food [1]. Goal 2 is to achieve universal primary education. Some kids cannot go to school due to the fact that they have to collect drinking water, or they have to quit schools due to water-borne diseases [1]. Goal 3 (to promote gender equality and empowering women) is related to water treatment because the burden of water collection in Africa falls disproportionately on girls and women [1]. Goal 4 (to reduce child mortality rates) is related to water treatment because improving water quality can reduce child mortality [1]. Goal 5 (to improve maternal health) is closely related to water treatment [13]. Goal 6 is to combat HIV/AIDS, malaria, and other diseases. It was shown that some diseases including malaria are related with water treatment [14,15]. Goal 7 is to ensure environmental sustainability. One essential part (t...

T here is a significant lack of proper wastewater treatment in most African countries, especially in sub-Saharan Africa. Untreated sewage effluent is one of the most common types of pollution found around urban rivers and in groundwater sources in many African cities. By 2020, 75−250 million people in Africa may be exposed to increased water stress due to climate change and pollution will only exacerbate the situation. 1 In Kenya, for example, most municipal wastewater treatment plants (WWTPs) discharge partially treated or untreated wastewater containing high levels of organic matter with mean effluent TSS, COD cr , and BOD 5 being 246 mg/L, 253 mg/L and 98 mg/L, respectively, (as of 2004) against a discharge requirement of 30, 50, and 30 mg/L, respectively. This situation replicates itself across most cities in the developing world. Dar es Salaam, Accra, Khartoum, Harare, Maputo, and Kampala, to name but a few, discharge treated and untreated sewage into their water bodies. In 2004, only about 14% of sewage was collected and treated in Dakar, and the rest was discharged into the sea without treatment. 2 The story is the same in Latin America, where less than 15% of the wastewaters collected in sewered cities and towns is treated prior to discharge. 3 The inadequacy in treatment stems from a number of reasons that include poor operation and maintenance of existing systems or complete breakdown of the same, overloading, and lack of tertiary systems for extended

A ccess to safe water and sanitation is an important component of the Millennium Development Goals (MDGs). It was expected that 86% of the developing world would have gained access to safe drinking water by 2015. 1

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Organic waste in Nairobi City County accounts for 58-63% of the municipal solid waste generated. Food waste is at the center of urban waste management in the city as it accounts for 64% of the recoverable material. The city is estimated to have a food waste generation per capita of 6.1 kilogram per year, which accumulates to 29.4 thousand tons yearly. It transpires that upstream activities of the food supply chain, mainly production, postharvest loss, processing and distribution are the major food waste hotspots, accounting for 95% of the food waste in developing countries. Additionally, downstream activities of the food supply chain show that hotels, restaurants and super markets are the most important food waste hotspots. Such food waste hotspots should become the primary targets for resource recovery in a circular economy. Currently, the exploitation of food waste for animal feed and composting is growing in Nairobi City County, which signifies that food waste is becoming a valuable urban resource that can be traded, thus creating employment. However, the application of food waste for energy recovery through anaerobic digestion is limited in the city due to lack of source separation of municipal solid waste. On average, food waste has a biomethane potential of 508.45 ml CH 4 /g VS. This implies that 29.4 thousand tons of food waste generated in Nairobi City County has the potential to yield 10.5 million m 3 of methane, and will demand a digestion volume of 4,299 m 3 . Using global case studies of electricity generation from biogas, it is estimated that food waste in the city potentially yields 1.38 MW of electricity. In addition, about 26.1 thousand tons of bioslurry can be recovered from the digestion of food waste, which can be used for urban agriculture. Regardless of the liquefied petroleum gas enjoying a tax exemption, biogas at 32.78 USD per gigajoule of delivered energy demonstrates to be more economical, and this can be enhanced by upgrading it. The removal of liquefied petroleum gas from tax-exempt goods through the Finance Act 2020, and an addition of 16% value added tax on the fuel by Kenya Revenue Authority that became effective on 1 st July, 2021 favors biofuels such as methane. However, long term realization of methane generation potential in NCC demands the adoption and implementation of more friendly biofuels policies and regulatory frameworks in the country.

Mbumbuni community water scheme is served by surface runoff and ephemeral streams which is harnessed in an earth dam. The dam has been in existence for decades, and was facing a big problem of reservoir sedimentation from the heavily loaded runoff water. De-silting the reservoir or increasing the dam height would not be long-term solutions without a proper system in place to protect the dam by reducing future siltation through conservation works in the catchment area. An urgent need for protection of the catchment area of the dam arose, not only for conserving or improving the water source and the storage capacity, but also to enhance agriculture and the livelihood of the inhabitants. The conservation plan was develop using project approach method. This article describes a proposed conservation plan for the study area. Implementation of the conservation plan will improve water supply and increase the Dam lifespan through reduction in siltation.

Mbumbuni community water scheme is served by surface runoff and ephemeral streams which is harnessed in an earth dam. The dam has been in existence for decades, and was facing a big problem of reservoir sedimentation from the heavily loaded runoff water. De-silting the reservoir or increasing the dam height would not be long-term solutions without a proper system in place to protect the dam by reducing future siltation through conservation works in the catchment area. An urgent need for protection of the catchment area of the dam arose, not only for conserving or improving the water source and the storage capacity, but also to enhance agriculture and the livelihood of the inhabitants. The conservation plan was develop using project approach method. This article describes a proposed conservation plan for the study area. Implementation of the conservation plan will improve water supply and increase the Dam lifespan through reduction in siltation.

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