Determination and Spatial Mapping of the Physicochemical and Biological Characteristics of Sewage of Feeding the Kaliti Wastewater Treatment Plant in Addis Ababa Ethiopia
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Date
2025-02
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Addis Ababa University
Abstract
Urban development in Addis Ababa usually exerts enormous pressure on the existing sewer network systems. The insufficiency in the performance of the sewer network has become one of the most critical issues in the sewer system sector that requires immediate action. Kaliti Catchment sewer system has problems related to sewer system coverage, manholes overflow, and capacity deficiency. The current study aims to evaluate the city’s main wastewater infrastructure's performance and identify factors affecting the treatment efficiency of the plant, particularly the illegal discharge of toxic industrial waste, from exploring the characteristic nature of sewage within the Kaliti catchment area. Based on laboratory testing, geographic information systems, and statistical software applications, this study maps the physicochemical and biological properties of sewage at various sites. The characteristics of sewage were determined by considering 12 parameters at 20 stations (i.e., a total of 480 tastes were obtained). The laboratory analyses of the sewage samples were performed to determine the pH, temperature, electrical conductivity, total dissolved solids, chemical oxygen demand, biochemical oxygen demand, total coliforms and the concentrations of specific pollutants like phosphorus and nitrogen as well.as the heavy metals. The findings were shows that municipal wastewater is organic in nature, having values of BOD of 505.30±184.26 mg/l, COD of 1221.96±401.97 mg/l, dissolved solids of 697±155.95 mg/l, Electrical conductivity 1206.9±326.44 μs/cm, Temperature 21.88±1.67 °C, PH 7.72±0.17, Total Nitrogen 69.97±19.58 mg/l, Total phosphorus 14.08±3.69 mg/l, Total coliform 24.68x106 ±2.99x106 (per 100ml), Null Chromium mg/l,0.39 ±0.22 mg/l Manganese and0.01±0.02 mg/l Zinc. The spatial mapping was applied for detecting pollution hotspots and illegal sewer connections that could have compromised the city’s main wastewater treatment system's efficiency. It is believed that such findings will inform the Addis Ababa Water and Sewerage Authority (AAWSA), which is mandated to both water supply and sanitation of the city, and other stakeholders about the current state of sewage characteristics, thereby facilitating the implementation of targeted mitigation measures.
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Keywords
Characteristics of Wastewater, Kaliti, Spatial Mapping, Pollution, Sewage