Kaliti Wastewater Treatment Plant and Sanitary Sewer Trunk Mains

Morrison Hershfield

Addis Ababa, Ethiopia 


For years, Ethiopia’s capital city of Addis Ababa had only a small percentage of its area and population served with a piped sanitary sewer system. Rapid development and increased density resulted in numerous challenges, including increased risk for a major disease outbreak. Morrison Hershfield, in collaboration with its partner ARMA Engineering PLC and client Addis Ababa Water and Sewerage Authority, discussed various treatment options during the preliminary design stage and created a decision matrix that established goals and evaluation criteria. A new wastewater treatment plant was designed and constructed to meet the 100,000 m3/d maximum demand, and the existing trunk main was twinned, adding 18 km of new pipe. The wastewater treatment plant process consists of an up-flow anaerobic sludge blanket front end, trickling filters, secondary clarifiers, and chlorination/dechlorination for disinfection before disposal in the river. Morrison Hershfield provided innovative, cutting edge treatment technology and training, resulting in a new, client-managed and operated system that improves the treatment process and sewage collection system, and ultimately, the quality of life of over two million people. Jury members applauded the project, which raised the bar by transferring knowledge to a client who lacked the expertise and for developing skills that transformed the lives of millions of residents.

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