Studies to investigate the presence of heavy metals and other pollutants in the owabi raw water reservoir

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A study of the Owabi raw water reservoir and some tributaries in the catchment area was undertaken between March and June 1999 to investigate the presence of heavy metals and other pollutants (nutrients and faecal coliforms), to contribute to the establishing a baseline data for future studies Presence of heavy metals, nutrients and faecal coliforms pollution were studied in time and place. Six sampling sites one each from Stream Akos, Stream Esufo (both tributaries of Sukobri), Stream Sukobri, River Owabi and 2 sites on the reservoir at the intake (1m and 4m depth) and at Pipeline 2 (1m depth) were sampled 3 times for analysis. The final (drinking) water from the Owabi Water works was also sampled 3 times. Six sediment samples were also taken at these sites for heavy metal analysis. For the water samples, the streams were found to have faecal coliforms In the range of 3.0*104 to 20.0*104 cfu/l00ml. Nutrient levels were in the range of 0- 0.03mg/l for ammonium-nitrogen, 0 - 0.083mg/l for nitrite-nitrogen, 0.145mg/l 2.35mg/l for nitrate-nitrogen and 0-0.297mg/l for phosphate-phosphorus. The heavy metals, cadmium, iron, lead, manganese, aluminium and zinc were found to be present in the streams and the reservoir. No copper and chromium was detected in any of the water samples. No faecal coliforms were detected in the final (drinking) water from the Owabi Treatment Works. The levels of the heavy metals, cadmium, iron and lead - found in the final (drinking) water from the Owabi Treatment Works were above the WHO recommended Guideline values The bottom sediments of the streams feeding the reservoir were found to contain heavy metals. Stream Akos, and Stream Sukobri had the highest load of iron. Stream Esufo contained the highest load of Cadmium in the sediment. There is a build up of heavy metals in the bottom sediments a the intake (dam weir) eNmc}alhi zinc, iron., and mercury.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of the Degree of Master of Science in Water Supply and Environmental Sanitation, 1999