Characterisation of sewage wastewater and assessment of downstream pollution along Huluka River of Ambo, Ethiopia

This study was conducted to assess the downstream pollution profiles of Huluka River due to sewage water contamination, and to provide the data on the physico-chemical properties and nutrient content of Huluka River in Ethiopia. The water quality indices, viz. temperature, pH, electrical conductivity, carbon dioxide content, total dissolved solids (TDS), hardness, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), calcium, magnesium, chloride, nitrate, sulphate, and phosphate were determined. Results reveal a worsening trend in the variations of most of these parameters from upstream to downstream areas of the river, which indicates an introduction of pollution load from domestic sewage and agricultural activities. For example, TDS and DO values for some downstream water samples do not conform to the accepted standards, and these samples also have eight to ten times higher values of BOD and COD compared to those for the upstream samples. Progressing downstream, the majority of the measured ions also show an increasing trend. All of these findings indicate that the quality of the water of Huluka River is declining.