Abstract

The Awash River, (AR) is used for different purposes such as drinking, industrial supply, hydropower, and agriculture. These uses of the water have resulted in the rapid deterioration of water quality. The performance of wastewater treatment plants (WWTPs) situated with the river catchment area have been assessed together with the impact on the surface water quality of the Awash River. The study has been completed using five years water quality data from 5 sampling stations and wastewater data from more than 30 industries and 2 flower farms. In addition, questionnaires, interviews, and wastewater sampling have been used to evaluate pollution causes. Most of the surveyed industries use partially operated treatment plants and accumulated high amounts of sludge. This is due to different reasons, including lack of facilities, poor management, limited capital, limited technical manpower, and, poor maintenance. All these have contributed to the inefficiency of wastewater treatment plant. Out of the 30 industries sampled, 23% of them did not have well-constructed treatment plant and 73% of industries discharged their untreated effluents directly into the river without treatment. Consequently, the wastewater samples analysis showed extremely high value of EC (14,000μS/cm), TDS (10,000 mg/L) and EC (12,030 μS/cm), TDS (8,060 mg/L) were seen in the first and second survey respectively. In line with these, the five years of spatial and temporal physico-chemical trend data also showed an increasing pollution in the river system. Based on this investigation, it is possible to conclude that the untreated industrial wastewater disposal and agricultural runoff strongly degraded the quality of the AR. Thus, it is time to make urgent improvements to deal with the poor performance of WWTPs and to limit the untreated waste being discharged into the river system.

Key Words:  Inefficient Treatment Plant, Untreated Waste Disposal, Effluents, Source of degradation