Water Supply and Environmental Engineering
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Browsing Water Supply and Environmental Engineering by Author "Alemtsehay, Gebremeskel (PhD)"
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Item Assessment of Solid Waste Collection Capacity in Addis Ababa, Ethiopia(Addis Ababa University, 2019-06) Solyana, Aweke; Alemtsehay, Gebremeskel (PhD)Waste collection and transportation is one of the crucial functional elements of municipal solid waste management. Available information about this matter is therefore essential for successful municipal solid waste management. The main objective of this study is to assess the solid waste collection practice in Addis Ababa. For the purpose of the study, 250 pre collector groups were selected for field survey of the primary solid waste collection. Background information was gathered using semi structured interviews with the pre collector groups and the respective cleansing management agency officers. To examine the secondary solid waste collection, field observation on the trucks and interviews with truck drivers and with waste agency officers of the city was carried out. From the study, the productivity of primary and secondary waste collection was determined; the collection capacity of the city was estimated and factors influencing the system were identified. For primary collection, three different collection methods were identified: push cart method, pushcart–collector method and truck collection method with average productivity of 2.12 m 3 /hr respectively. For secondary waste collection, the trucks productivity were determined to be 6.29 m / worker/day and 2.81m 3 / worker/day and 4.2m 3 /hr for container truck, 18.29 m 3 3 /hr for compactor (40 m 3 3 ) and 39.7 m /hr for compactor (80 m 3 ). The solid waste collection capacity was determined to be 3,192,868.8 m /year for the primary collection and 2,579,183.22 m 3 /year for the secondary collection. The solid waste generation rate of the city is determined to be 4, 157469.12m3/year. This shows that, on average, only 76% of the waste generated in the city was collected by primary collectors, and 80% was collected by the secondary collectors. The result indicates that the current collection system doesn’t cope with the solid waste generation rate of the city. 3 The role of solid waste transfer station in solid waste management is great. This study includes the basis of design and conceptual layout for a new facility of a pilot service area. This design and operational plan details the features and operational procedures for a municipal solid waste transfer station to ensure a safe, operationally efficient facility that meets the waste needs of the given service area.Item nvestigating the Efficacy of the Indigenous Water Purification Method Using African Spear Plant Case: Konso Community(Addis Ababa University, 2018) Sokate, Aylate; Alemtsehay, Gebremeskel (PhD)Water supply and environmental engineering primary concern should be making potable water available to the community at large. Among the many topics addressed in the discipline, water purification method is of paramount issue to be addressed. Water purification can be undertaken in more sophisticated method and traditional way. An indigenous method used by Konso community to purify water using African spear plant was investigated in this research. Lab scale study was conducted to assess the efficacy of African spear plant to purify water in terms of water quality parameters such as PH, Turbidity and Bacteria presence. The study has used triangulation approach, means, qualitative and quantitative approach. The qualitative approach is used for the exploration of the method being used by the society by interviewing significant people in the community and observation of the practice in the society and to know the situation in which the community uses this traditional method. The quantitative method was used for measurement of African Spear plant efficacy in terms of water quality parameters such as PH, Turbidity and Bactria presence. The study found that, when the water is stirred with a crashed African Spear plant for about 1 minute and kept for about 10-15 minutes, African Spear plant has the capacity to reduce the turbidity of water, capacity to reduce the level of bacteria in the water and reduce the PH of the water but if it is kept for long time in the water, the African Spear plant makes the water media more favorable for bacteria and the color of the water is changed to the color of the plants. Wet African spear plant has much effect than dry plant in purifying water.Item Removal Efficiency of Chromium Using Coffee Husk Activated Carbon in Hawassa Industrial Park Waste Water Treatment(Addis Ababa University, 2021-02) Mihretabe, Negash; Alemtsehay, Gebremeskel (PhD)In this study, the potential of activated carbon coffee husk for removal of chromium were examined. The influence of contact time, PH, adsorbent dosage, initial concentration and adsorption equilibrium were studied at batch experiments at room temperature. The modification process was done by treating the coffee husk with different chemicals and activation. Maximum sorption was found to be at pH 2. The biosorption was rapid for the first 45 minutes of contact, removing more than 75% and equilibrium has attained in 120 minutes. Kinetic studies demonstrate good correlation coefficient (R2) for a pseudo second order kinetic model. The biosorption capacity was found to increase with higher initial Cr( VI) concentration and lower solution pH. Langmuir model fitted the equilibrium data better. The calculated biosorption free energies from the D-R isotherm model indicated that the biosorption process proceeds via chemisorptions. Optimization using response surface methodology (RSM) indicated an initial metal ion concentration, solution pH; biosorbent dose and contact time played an important role for the biosorption of Cr (VI). The study concluded that coffee husk activated carbon could be applied as a low cost alternative biosorbent to remove Cr (VI) from aqueous solution.Item Using Plastic Waste in Road Construction, An Eco-Friendly Way of Plastic Waste Friendly Way of Plastic Waste Disposal(Addis Ababa University, 2019-06) Gizalem, Derege; Alemtsehay, Gebremeskel (PhD)The rapid increase in the use of plastic materials in the recent years led to the accumulation of extreme amounts of plastic waste. Thermoplastics such as PET, PE, PP, PS and PVC as well as materials that derived from these are the type of plastic most used and consequently create environmental problems. Landfill, incineration and recycling remains the primary options for solid waste management. One critical determinant of the acceptability of these options is the different health risks associated with each. The plastic waste that burnt and dumped in landfill sites can be recycled and used for different purpose. This includes the use of waste plastic in construction of asphalt road. By recycling waste plastic, it is possible to protect the environment from contamination. Using waste plastic in asphalt road construction as an aggregate binder is one of the recent plastic waste approach. This will help us to avoid the environmental pollution from open-air burning and landfill of plastic waste. In this research the applicability of the waste plastic as a binder, together with Bitumen has investigated, for this purpose, the plastic (Polyethylene terephthalate ) and bitumen mix was checked for certain quality that needed to be a good binder. The natural bitumen had modified by adding Polyethylene Terephthalate (PET) in different percentage by weight of bitumen. The tests that conducted on the modified bitumen quality are Ductility, Penetration, and Softening point of the plastic modified bitumen mix. Also the load bearing capacity of the modified bitumen asphalt (aggregate with modified bitumen mix), had been tested. The research had conducted the two methods of asphalt road making using plastic waste. After doing the quality test, the research identified what percentage by weight of plastic that should be mixed with bitumen to give a good quality of modified bitumen, accordingly 8% by weight in wet process and around 16% by weight of Polyethylene Terephthalate(PET) in dry process were able to give good binding property. This can enable us to recycle around 52.4 tons of PET waste (per kilometer of road) that would have gone to landfill and/or to open air burning and Incineration.