Assessment of Surface Water Quality in River Rwizi
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Date
2023-03
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Kampala International University; School of Engineering and Applied Sciences
Abstract
Water is a crucial necessity for the sustenance of human, animal, and plant life. In Uganda, the River Rwizi is one of the major water sources for domestic, agricultural, and industrial use. However, the river is facing pollution challenges from domestic and industrial wastewater discharge, as well as surface water runoff from urban and agricultural areas. This has resulted in a high prevalence of water-borne diseases, making the water unsafe for use. A study was conducted to assess the seasonal changes in the physicochemical and biological parameters of the river between April and August 2022, representing the wet and dry seasons. The results indicated that the river's pH varied significantly during the wet season, with the highest average pH of 5.65 recorded at Ndiaja and the lowest average pH of 6.43 recorded at Kyani/Kakiika. Additionally, the river's electrical conductivity (EC) increased significantly during the dry season compared to the wet season, with the highest average EC of 135.00 (µS/cm) recorded at Kyani/Kakiika. The TDS levels in the river Rwizi were highest in the Kyani/Kakiika region during the dry season, with an average of 68.00 (mg/L), while the lowest levels were recorded in Ndiaja at 46.00 (mg/L). During the wet season, the average TDS levels were 59.00 (mg/L) in Kyani/Kakiika and 26.33 (mg/L) in Ndiaja, indicating that the river was more turbid during the wet season. The turbidity levels also showed a significant difference of -60.90 (NTU) between the dry and wet seasons, with the river being more turbid in the wet season. The concentration of BOD and COD were slightly higher during the dry season than in the wet season. Unfortunately, the levels of E-coli in all the sites exceeded the permissible limit of the National Standards for untreated river water set at 0 (CFU/100mL), with the highest concentration of 144.00 recorded in Ndiaja. The findings suggest that the river Rwizi is becoming increasingly polluted with E-coli, COD, and turbidity, which could pose a threat to the aquatic life. This problem is exacerbated during the rainy season when waste material such as feces and surface runoff from farmlands are discharged into the river. Therefore, it is essential to regularly monitor the quality of the river water and the effluents discharged by the nearby treatment plant to address this issue. To prevent contamination in Mbarara, which is expected to experience a population boom following its new city status, it is crucial that industries, markets, and urban areas adhere strictly to the NEMA wastewater management guidelines. Additionally, educating the community on the importance of proper waste disposal and its potential hazards can foster a sense of intrinsic motivation to keep the city clean.