Assessing the levels of heavy metals and mineral salts contamination of community water sources along the Kiteezi landfill catchment, near Kampala

Abstract

World over, especially in the developing nations, landfills are still the main alternative to containing large volumes of municipal wastes. However, the reducing urban space and increasing volumes of municipal solid waste (MSW) is making this approach unsustainable. This study investigated the contamination of public water sources around Kiteezi landfill, Nangabo-Wakiso district with heavy metals and mineral salts. Eighty households living close to the landfill were interviewed to investigate their water sources and knowledge of risks posed by the landfill. Key informant interviews were conducted with stakeholders from Kampala Capital Authority, NEMA and landfill management to generate information on waste management processes. Leachate samples were collected from different locations within the landfill while forty water samples were collected from the leachate stream, community water sources such as streams, spring, water wells and bore holes. Control samples were collected upstream of Kiteezi landfill. All samples collected were analysed using ICP-MS. Kiteezi landfill leachate samples exhibited a wide range of heavy metal and mineral salts with elemental concentration (µg/L) ranging from Al (39.0-239) V (0.23-96.6), Cr (03.10-119.7), Mn (161-1778), Fe (112-2436), Co (2.26-69.93), Ni (3.77-142.1), Cu (8.68-245.7), Zn (20.5-478.6), As (0.49-2915), K (0.610-38.60). Mineral salts were in the range (mg /l) of Na (65.3-55.1), Mg (9.61-62.2), P (0.04-21.1), K (45.0-3824), Ca (33.1-77.96) and S (6.73-103.2). Over 70% of the public water sources sampled were highly contaminated with both heavy metal and mineral salts. The pH, EC, Na, K, Mn and Fe in 70% of the water samples were found to have exceeded the thresholds for international WHO standards of drinking water thus making water unfit for human consumption. It can be concluded that Kiteezi landfill is generating leachate with high concentrations of heavy metals, salts which are contaminating public water sources within the catchment. To minimise leachate contamination to public water sources, there is need for establishment of a new landfill with an integrated system of management to safeguard the environment.