Determination of Heavy Metal Concentration in Bottom Ash in the Medical Waste Incinerators: The Case Study of Dar es Salaam City

Anicetus, Honest E. (2014) Determination of Heavy Metal Concentration in Bottom Ash in the Medical Waste Incinerators: The Case Study of Dar es Salaam City. Masters thesis, The Open University of Tanzania.

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Abstract

The use of medical waste incinerators appears to be rapidly expanding in developing countries including Tanzania. Nuisance arising from medical waste has received much attention but relatively less consideration has been given to bottom ash. This study focused on determination of heavy metal concentration in bottom ash in medical waste incinerators found in different medical hospitals in Temeke, Ilala and Kinondoni Municipalities, Dar es Salaam. Samples of bottom ash were collected and analyzed at the Government Chemist Laboratory Agency. Statistical analysis of the data was done in the SAS software. The results show that, three types of incinerators namely high tech pyloritic, low cost pyloritic and single chamber are used in the study areas. Meanwhile, the findings show that the mean concentration value for Hg, Cd and As was below detectable limits while highest mean concentration of Fe was (9484.806 mg kg-1), Pb was (67.413 mg kg-1), Cu was (28.873 mg kg-1), Cr was (743.750 mg kg-1), and that of Ni was (596.906 mg kg-1). The amount of Cr, Zn, and Ni were above MPL (above 1,100, 150 and 100 mg/Kg respectively) for some hospitals. However, the levels of Cu and Pb obtained in all tested bottom ash were within maximum permissible levels (MPL) to be discharged to the environment. The excess Cd, Cr, Zn and Ni when leaching may contaminate the environment and results into public health risks The study recommends designing of engineered treatment methods for safe disposal of medical waste incinerator bottom ash to reduce contamination of surface and ground water, and soil in general.

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