Waste in the construction industry is the loss produced by activities that generate direct or indirect costs but do not add any value. In recent years, waste in the construction industry has been the subject of several research studies around the world; however, it still continues to be a critical issue. Thus, the objective of this study was to develop an analytical hierarchical model for the implementation of lean techniques for the reduction of construction waste in real estate companies in Addis Ababa, Ethiopia. The study was conducted on seven private residential real estate companies which were actively involved in the construction sector at the time, by targeting decision-makers as respondents. Analytical hierarchical process-based questionnaires and face-to-face interviews were conducted for the collection of primary data. Thus, comparison-based surveys and data analyses were used to quantify the relative priorities for a given set of alternatives on a ratio scale based on the judgment of the construction professionals. According to the data analyses, poor material handling, poor site management, and frequent changes in the design were identified to be the three most dominant sources of construction waste. It was found that the real estate companies do not have any waste reduction strategies or practices. Furthermore, the concerned professionals have limited awareness of the lean techniques and their implementation. Based on the findings, the construction companies are recommended to give proper attention to construction waste minimization and a huge task is ahead of the policymakers for lean techniques implementation.
Urban water utilities in Ethiopia, including Debre Tabor Town, commonly suffer from an intermittent water supply, water quality issues, poor service delivery, and other problems. Thus, the main focus of this study was to evaluate the actual performance level of the water supply system of the town based on hydraulic efficiency, quality, cost recovery and customer satisfaction. The water distribution system status was measured by using reliability, resilience, and vulnerability as performance indicators. Weightage Arithmetic Water Quality Index (WAWQI) and household-based questionnaires were used to evaluate the water quality and customer satisfaction, respectively. Pressure and velocity-based sustainability index of 0.614 and 0.132 showed acceptable and unacceptable water supply status, respectively, and overall moderate sustainability. Results of the WAWQI revealed that more than half of the sampled tap waters were either poor or unfit for drinking purposes. The comparison of income collected from customers and the water production costs of the utility showed that only 34.31% of production cost is covered by customers. Generally, 62.6% of the society confirmed that they are unsatisfied with the existing water supply system. Thus, to improve the performance, it is recommended to address all the major social, economic, environmental and technical problems.
Water quality change due to industrial pollution is one of the major environmental concerns in developing countries. The majority of industries in Ethiopia release their wastewaters into the nearby water bodies with limited or without any forms of treatment. The main objective of this study was to assess the suitability of Modjo River for irrigation use based on the assessment of salinity, reduced water infiltration rate, specific ion toxicity, and miscellaneous chemicals as water quality-related problems in irrigated agriculture. Water samples were collected from six sampling stations along the river, and the relevant physicochemical parameters were determined in the laboratory by the standard procedures. Besides, the sodium adsorption ratio (SAR) and irrigation water quality index (IWQI) were determined to evaluate the suitability of the river water for irrigation. Cluster and principal component analyses of the data set were carried out. The results of this study showed that the river water in the vicinity of industries was saline and thus affects sensitive crops. The SAR value varied from 57.6 to 122.3. The concentration of chromium in the lower reaches of the river was also above the standard value of 0.1 mg/L. Among the miscellaneous chemicals, concentration of potassium, carbonate, and bicarbonate at all the sampling stations were above the standard values set by FAO for irrigation use. Based on the computed IWQI of 30.6, Modjo River is in the medium class of suitability for irrigation. Effluents from industrial establishments, namely, tannery, abattoir houses, and poultry farms and domestic waste dumping, were identified as the main sources of water pollution in the study area. Based on the findings of the study, Modjo River water is not suitable for irrigation use without some forms of physical and chemical treatment.
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