Leachate characterization of active and closed dump sites in Port Harcourt metropolis, Nigeria
Leachates are said to have the capacity of polluting environmental media such as air, soil, surface and ground water. The knowledge of the composition of leachates is important to determine the dump sites that require immediate remediation attention and their effective treatment approach. This study characterizes the leachate quality of both active and closed dump sites in Port Harcourt City. Leachates were sampled from the base of the dum psites and analysed, pH, dissolved oxygen (DO), electrical conductivity and total dissolved solids were determined on the samples in-situ. While chloride, sulphate, phosphate, chemical oxygen demand (COD), biochemical oxygen demand (BOD), lead, zinc, iron, chromium, copper, cadmium and nickel were analyzed in the laboratory. The sample locations were Nkpolu Junction along East-West Road (LS1), Chindah Borrow Pit, off Chindah Road, Mile 4(LS2) and Rumuepirikom Community, off Iwofe Road (LS3). Locations 1 & 3 are closed dump sites, while location 2 is an active dump site. The mean pollution indices for Locations 1, 2 & 3 include; pH (7.96, 6.55 & 7.43), BOD (mg/l) (1.24, 5.95 & 2.94), COD (mg/l) (3.10, 14.87 & 7.35) and DO (mg/l) (2.3, 0.85 & 0.56). Heavy metals analyses reveals Iron (mg/l) having the highest concentration (0.176, 0.461 & 0.253 for LS1, LS2 & LS3 respectively) which exceeds the maximum contaminant levels of 0.05 mg/l prescribed by the Federal Ministry of Environment, which is a regulatory body in Nigeria. The ratio of BOD5/ COD was less than 0.5 for leachates from all sample locations, an indication of dump site stabilization while the pH values indicated that all sample locations in terms of age of the dump site vary partially from being young to mature in age. The study recommends continuous monitoring of leachates for the active dump site, as the concentration of individual parameters that make up the leachate is quite variable.
Keywords: Leachate quality, dump sites, remediation, BOD5/COD ratio.
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