The Effect of Wet Coffee Processing Plant Effluent on Physicochemical and Bacteriological Quality of Receiving Rivers Used by Local Community: Case of Aroresa District, Sidama, Ethiopia

Freshwater bodies such as lakes, rivers, and their biodiversity are being threatened with water pollution from industrial effluents and household sewages. The main objective of this study is to assess the effects of wet coffee processing plants effluent on the physicochemical and bacteriological properties of receiving rivers. Four rivers and 4 sampling points of the selected rivers were included in the study. Focus group discussion and interview were employed to gather primary data. The result showed that parameters of water quality for downstream of the rivers were significant, particularly in the dry season with BODs ranging from 45 ± 1 to 782.6 ± 97 g/ml, COD ranges from 71 ± 21 to 1072 ± 183 g/ml, Conductivity ranges from 75.5 ± 6.6 to 943 ± 56.3, Turbidity ranges from 7 ± 0.43 to 105 ± 6.2, TDS ranges from 62 ± 6.4 to 1059.6 ± 121 g/ml, temperature ranges from 20.1 to 33 ± 1, T. coli form ranges from 77 ± 1.1 to 493 ± 66 and E. coli ranges from 28 ± 1 to 213 ± 41 were significantly higher and DO ranges from 2.6 ± 0.15 to 6.1 ± 0.78 g/ml, NH(4) ranges from 1.85 ± 0.4 to 3.3 ± 0.5 g/ml, and pH ranges from 3.6 ± 0.2 to 7.3 ± 0.45 were significantly lower. Most of the samples taken from wastewater and downstream parts of the river showed high level of water contaminants that are significantly greater than the EEPA discharge limits for surface water. Moreover, the qualitative data indicated that the community was affected by bad smell and color change on rivers, skin irritation, malarial case in human due to coffee processing plant effluents. Therefore, coffee processing plants should treat their effluents before they discharge it into the rivers. Responsible government bodies should authorize activities of coffee processing plants in line with the regulations set for environmental safety.