Physico-Chemical, Nutrients and Bacteriological Water Quality of Mbagathi River, Kajiado County, Kenya
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Date
2023-10
Authors
Koikai, Jane Nashilu
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Monitoring of water quality is important to determine the use of that water in different sectors. Water pollution negatively impacts on human health, through exposure to disease causing pathogens in water and chemical toxicants via the food chain. The broad objective of this study was the assessment of the physico-chemical, nutrients and bacteriological contamination of Mbagathi River. The specific objectives included: to determine the physico-chemical parameters of water quality, to determine the bacteriological contamination of Mbagathi River, and assessment of the land use changes and land cover impacts on water quality along the river. The design used was longitudinal. The parameters measured were temperature, pH, turbidity, total dissolved solids, biological oxygen demand, chemical oxygen demand, nitrates, phosphates; as well as total coliforms and fecal coliforms. Water samples were collected in three sampling sites along the river, once every month for a period of four months. Temperature, pH, turbidity and total dissolved solids (TDS), were measured on site using portable meters. Water samples for biological oxygen demand (BOD), chemical oxygen demand (COD), nitrates, phosphates; as well as total coliforms and fecal coliforms were analyzed in the Water Resources Authority Laboratory in Nairobi. Data collected was analyzed using one-way Analysis of Variance (ANOVA) to test for significant differences at p≤0.05 between the different sampling points. Where significant differences were found to exist, Post-Hoc Tukey’s test was used to separate means. The Pearson correlation was also employed to find the relationship among the water quality parameters at the different sampling sites. The land use changes were assessed for the forest area, water area, cultivated areas and built-up areas. Results showed that temperature (20.0±2.94 - 20.50±3.11), pH (7.27±0.11 - 7.53±0.05), TDS (423.00±8.16 mg/l - 487.0±8.29 mg/l), BOD (3.88±1.14 mg/l - 10.45±3.47mg/l) and nitrates (23.50±2.04 mg/l - 62.70±5.06 mg/l) were within the acceptable set standards for drinking by WHO. However, turbidity (2.72±1.09 NTUs - 105.33±4.68 NTUs), COD (15.90±4.04mg/l - 35.33±3.61mg/l) and phosphates (2.10±1.07 mg/l - 3.35± 1.63mg/l) were above the WHO recommended levels of drinking water. Both total coliforms and fecal coliforms were exceedingly higher and ranged from 2415±10.0 MPN/100ml to 184± 52.19 MPN/100ml and 2400± 10.0 MPN/100ml to 7.25± 5.06 MPN/100ml respectively. The land use results showed there was a reduction in the forest area and an increase in the built-up area. A decrease in the water areas also resulted to a decline in the cultivated area. The findings indicated that the water was not fit for human consumption. The county government of Kajiado together with other lead agencies such as National Environment Management Authority and the Ministry of Water, need to come up with measures of reducing the channeling of municipal waste into the river. It’s also recommended that the public be informed on ways and importance of protecting the river as it’s their immediate source of water.
Description
A Research Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Master of Environmental Science in the School of Agriculture and Environmental Sciences, Kenyatta University, October 2023.
Keywords
Physico-Chemical, Nutrients, Bacteriological Water, Mbagathi River, Kajiado County, Kenya