PAR T III
Optimizing water reuse and efficiency
UNESCO Multisectoral Regional Office in Abuja | Simone Grego and Oladele Osibanjo
AFRICA
CHAPTER 9
85
A f r i c a
9.1 Water and wastewater in Sub-Saharan Africa
Africa is home to 15% of the world’s population, but has only 9% of global
renewable water resources, unevenly distributed across the region (Wang et al., 2014). The gap between water availability and water demand is growing fast, especially in cities, where the urban population is expected to nearly quadruple by 2037 (World Bank, 2012). The improvement of living standards and the change in consumption patterns are contributing to this growth in water demand. On the other hand, water availability is decreasing due to competing demands from agriculture, mining and industry, and deteriorating water quality. Large numbers of people are dependent on groundwater as their primary or alternate source of water, but pollution and over-extraction threaten groundwater resources (World Bank, 2012).
In Sub-Saharan Africa, out of over a billion people, there are still 319 million people without access to improved drinking water sources.
For sanitation, the picture is even gloomier, as 695 million people do not have basic sanitation and not a single Sub-Saharan African country has met the MDGs target regarding sanitation (UNICEF/WHO, 2015).
Mining, oil and gas, logging, and manufacturing represent the main industries in the region. All of these produce wastewater, which is often released into the environment with minimal or no treatment. For example, in Nigeria, less than 10% of industries reportedly treat their effluents before discharging them into surface waters (Taiwo et al., 2012; Ebiare and Zejiao, 2010). Moreover, where stabilization ponds exist, pollutant concentrations observed in the effluent were sometimes five times greater than those observed in Europe (Li et al., 2011).
Agricultural runoff containing agro-chemicals and plant and livestock wastes are a contributing source of pollution to water bodies. For example,
a link has been established between the periodic eutrophication of the Oyun Reservoir in Offa, Kwara State, Nigeria, and the runoff of phosphate fertilizers from nearby farms and from cow dung washing from the watershed into the reservoir (Mustapha, 2008).
In most African cities, rain washes municipal solid wastes and other pollutants into
rudimentary drainage systems and subsequently, into nearby rivers (cf. Taiwo, 2011) and
groundwater. The situation is further aggravated by the weak enforcement of, and
non-compliance with, town planning principles and regulations (Osibanjo and Majolagbe, 2012).
While agricultural and industrial wastewaters are recognized pollution sources in the region, the focus of this chapter is mainly on urban wastewater, as the latter is central to the new opportunities that could arise from improved management, in the context of accelerated urban growth.
9.2 Critical challenges
9.2.1 Urban settlements
One of the main challenges related to wastewater in Africa is the overall lack of infrastructure for collection and treatment.
Combined with high organic loads, unregulated waste input, power outages, increasing
wastewater flow rates, high energy costs and lack of re-investments (Nikiema et al., 2013), this results in the pollution of already limited surface and groundwater resources.
In urban settings, sewer collection tends to be limited, and connections from houses and facilities to municipal sewerage are insufficient. Where infrastructure exists, improper operation, poor maintenance and lack of skilled professionals severely limit the effectiveness of the treatment process, leading to the high concentration of pollutants found in the environment.
This chapter examines the critical challenges of Africa’s rapidly growing urban settlements and the opportunities provided through wastewater use.
Rural population growth (annual %) Urban population growth (annual %)
-2 -1 0 1 2 3 4 5 6 7
East Asia and Pacific (developing only)
Europe and Central Asia (developing only)
Latin America and Caribbean (developing only)
Middle East and North Africa (developing only)
South Asia
Sub-Saharan Africa (developing only)
Source: Based on data from the World Bank (n.d.).
Figure 9.1 Urban and rural population (% annual growth), 2013
In existing waterworks, the lack of stable financial support impedes the maintenance and upgrade of treatment facilities and the purchase and use of adequate monitoring instruments (Wang et al., 2014; Nikiema et al., 2013). In Addis Ababa, for example, the Kaliti treatment plant, initially designed to serve 50,000 people, was serving less than 13,000, which was attributed to a lack of investment in connecting houses to the sewerage pipelines, resulting in a low connection rate.
It has been calculated that, in 2009, less than 3% of the wastewater produced by the town reached wastewater treatment facilities (Abiye et al., 2009).
Another challenge hampering the ability of African countries to manage wastewater is the insufficient capacity for effective monitoring of wastewater before and after treatment. In Nigeria, for example, a recent study (UNESCO, 2016a) indicates that only a few laboratories in the country are able to detect emerging pollutants.
9.2.2 Governance and data needs
Poor governance, including ineffective policies and institutions, lack of enforcement, corruption, insufficient infrastructure and
a shortage of investments in human capacity, contributes to ongoing water and wastewater quality problems (UNEP, 2010).
A critical issue, which limits the possibility of establishing adequate policies for water quality, is the lack of available data about wastewater. In Sub-Saharan Africa, little quantitative data are available about wastewater generation, treatment, use and quality. Comprehensive information is available only for Senegal, Seychelles and South Africa, with data from Seychelles and South Africa dating back to early 2000 (Sato et al., 2013).
In addition, existing laws and legislation for the water sector at all the tiers of government usually do not take wastewater into consideration. In Nigeria, for example, there is little to no mention of wastewater in most of the federal and state laws (Ajiboye et al., 2012; Irokalibe, 1999 and 2002; Goldface-Irokabile et al., 2001). Enforcement of regulation (i.e. for the industries connected to the sewerage) is almost non-existent in most countries, directly affecting water quality downstream.
87
A f r i c a
Source: World Bank (2012, Fig. 1, p. 5).
* Notes: Cities abbreviations: ABJ, Abidjan, Cote d’Ivoire; ABV, Abuja, Nigeria; ACC, Accra, Ghana; ADD, Addis Ababa, Ethiopia; BLZ, Blantyre, Malawi; BZV, Brazzaville, Congo; CKY, Conakry, Guinea; COO, Cotonou, Benin; CPT, Cape Town, South Africa; DAK, Dakar, Senegal;
DLA, Douala, Cameroon; DSM, Dar es Salaam, Tanzania; DUR, Durban, South Africa; HRE, Harare, Zimbabwe; IBA, Ibadan, Nigeria; JHB, Johannesburg, South Africa; KAN, Kano, Nigeria; KIN, Kinshasa, D.R. Congo; KMS, Kumasi, Ghana; KRT, Khartoum, Sudan; LLW, Lilongwe, Malawi; LAD, Luanda, Angola; LOS, Lagos, Nigeria; LUN, Lusaka, Zambia; MBU, Mbuji-Mayi, D.R. Congo; MPM, Maputo, Mozambique; NBO, Nairobi, Kenya; OUA, Ouagadougou, Burkina Faso; YAO, Yaounde, Cameroon.
** Note on methodology: This figure presents an index that categorizes cities in two dimensions: water-related challenges and institutional and economic capacities. For each dimension, a number of variables were identified, for which indicators were then selected. For the water-related challenges dimension, indicators were selected for the following variables: urbanization challenges, solid waste management, water supply services, sanitation services, flood hazards, and water resources availability. For the institutional and economic capacities dimension, indicators were selected for the following variables: country policies and institutions, economic strength, water-related institutions, and water utility governance. Indicators were normalized, thus units value vary from 0 to 1. Indicators were assigned equal weights and aggregated for each dimension.
Figure 9.2 Urban water management challenges versus institutional and economic capacities
1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10
0.00 0.20 0.30 0.40 0.50 0.60 0.70 0.80
ABJ HRE MBU CKY
DAK KMS
DSMKAM COO
LUN KRT ACCYAO MPM
DLA JHB
CPT DUR
BLZ LAD
ABV IBA KAN KIN BZV
OUA
NBO ADD
LOS LUM
LLW Index 0—1.00
CAPACITIES
CHALLENGES Higher-capacity cities facing lower
water-related challenges
Lower-capacity cities facing lower water-related challenges
Higher-capacity cities facing higher water-related challenges
Lower-capacity cities facing higher water-related challenges
BOX 9.1 WASTEWATER USE IN KUMASI AND ACCRA, GHANA Ghana provides a good example of urban and peri-urban agriculture developing through informal irrigation with untreated wastewater from streams and drains. In Kumasi and Accra, where the central wastewater treatment plants are barely functional, wastewater is regularly used to irrigate crops. This practice, common in urban centres in many countries of Africa, provides food for the population, offers employment and alleviates poverty for a number of Ghanaians, and also helps to preserve freshwater resources.
In Accra, farmers irrigate more than 15 kinds of vegetables with untreated wastewater. Urban plot sizes vary between 22 and 3,000 m2 per farmer.
Year-round irrigated vegetable farming can achieve average annual income levels of US$400–800 per farmer. The annual market value for production is estimated at US$14 million and around 200,000 urban dwellers from all classes benefit from this production. The cultivated land in Kumasi is estimated to cover 115 km2, which is twice the total area reported under formal irrigation in the whole country.
There are, however, public health concerns, in particular regarding microbial contamination of these agricultural products. Analysis of vegetables sold in the markets has shown the presence of faecal coliforms and helminth eggs (Keraita and Drechsel, 2004).
Source: Bahri et al. (2008).