Determination of Biological, Physical and Chemical Pollutants in Mudi River, Blantyre, Malawi

Abstract

Contamination of river water by physical and chemical agents; and microbial pathogens has potential to affect the environment and health of people; and may lead to morbidity and mortality especially in vulnerable populations most at risk for water-related diseases. After observing the deteriorating state of Mudi River, the level of pollution was assessed to assist in designing control measures. The assessment was done during the rainy season a period during which the levels of pollution are at their lowest as the water in the river is diluted by rain so as to capture the minimum levels to which the Mudi River is subjected.

Samples of water were collected and analyzed using standard methods. Sampling was done at five different points depending on suspected pollution source. Sampling was done at source, three points as the river passes through industrial site and in the outskirts of the city. Water samples were collected by grab sampling technique. Total bacterial count ranged from 1433 to 1800+ colonies per 100ml. Except for the source which had 59,266 coliform colonies, all the other sampling points showed coliforms to be Numerous to Count (NC) colonies per 100ml. Biological Oxygen Demand (BOD) ranged from 29.20 to 89.20mg/l. The pH found in the river ranged from 7.02 to 8.23. Conductivity and Temperature ranged from 148.77 to 542.67Ns and 21.13 to 23.67 0C respectively.

Turbidity and Total Dissolved Solids (TDS) ranged from 28.93 to 130.37 NTU and 69.17 to 271.67 ppm respectively. Lead ranged from 0.21 to 0.93 mg/l, cadmium ranged from 0.00 to 0.02 mg/l, chromium ranged from 0.10 to 0.46 mg/l, zinc ranged from 0.05 to 0.18 mg/l, copper ranged from 0.04 to 0.12 mg/l and nitrates ranged from2.56 to 15.64 mg/l.

Most parameters were higher than European Commission Standards of 1994 for maintenance of aquatic life, irrigation and domestic use. Most parameters were lower at source as compared to other sampling points. There is need to trace possible sources of chemical, biological and physical pollutants which showed high levels.