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Item Treating high nitrate groundwater using surfactant modified zeolite in fixed bed column(Taylor and Francis, 2011-05-02) Masukume, Mike; Eskandarpour, Akbar; Onyango, Maurice S.; Ochieng, Aoyi; Otieno, Fredrick Alfred O.High levels of nitrate in South African groundwater used for drinking purposes are a cause of concern due to the possible human health risks associated with consuming nitrate contaminated water. In this study, nitrate removal using surfactant modified zeolite (SMZ) in fixed bed column is explored. The performance of SMZ is studied as a function of bed height, initial concentration, flow rate, and bed diameter. The number of bed volumes processed and capacity of the bed at breakthrough point are used as performance indicators. The bed performance improves with a decrease in bed height while column diameter has no influence on bed performance. Within the studied flow rate range, the highest number of bed volumes processed and bed capacity are observed at a flow rate of 5 mL/min. In an adsorption-desorption process, the performance of SMZ is found to be poor in the subsequent cycle suggesting that the media is suited for single-use only.Item A process-based model for fluidized bed in sand filled reservoirs(ASCE: American Society of Civil Engineers, 2011) Olufayo, O. A.; Ochieng, George M.; Ndambuki, Julius M.; Otieno, Fredrick Alfred O.Arid and semi-arid regions are prone to severe water inadequacies. They are characterized by little rainfall resulting in several seasonal rivers. Seasonal riverbeds provide opportunity for water to be stored in river’s sand-beds while their surfaces may appear dry. It is an important source of water in most rural areas under arid conditions. Several numerical models have been developed for solving sediment problems in alluvial rivers. However, rarely if ever were a model applied for sand filled reservoirs. This study presents a model to understand interacting factors through which physical water storage potential can be increased in sand filled reservoirs. Finite different method (FDM) has been applied to numerically solve mass balance continuity equation in sand filled reservoir. There were reasonable agreements between estimated results and experimental measurements from a laboratory setup. The study could provide economic and suitability data for increasing water supplies to a small community.Item One-dimensional finite difference approach for sedimentation process in sand filled reservoirs(Academic Journals, 2011-04-04) Olufayo, O. A.; Ochieng, George M.; Ndambuki, Julius M.; Otieno, Fredrick Alfred O.There have been continuing efforts to decrease silt deposits due to interstitial blockage in sand-filled reservoirs. However, estimating weir height to allow for deposition of required grain sizes is difficult. This paper presents a numerical process-imitating model aimed at improving water storage potential in sand filled reservoirs. The technique uses a finite difference (FD) numerical model to numerically solve mass balance continuity equation built upon the conservative laws of solid-fluid mixture hydrodynamics. Present investigation shows that barrier height used in sand-filled reservoirs determines the grade quality of deposited sands. The predictions of the model compared with laboratory measurements show agreement between computational and experimental results. The study could provide economic and suitability data for increasing water supplies to a small community through determination of appropriate weir height that will increase subsurface water storage potential.Item Sand water storage : unconventional methods to freshwater augmentation in isolated rural communities of South Africa(Academic Journals, 2010-10-20) Otieno, Fredrick Alfred O.; Olufayo, O. A.; Ochieng, George M.South Africa water resources are scarce in global terms with mean annual rainfall of about half world average of 860 mm a year. On the other hand, current economy development with resulting contamination of available water resources will further reduce water availability, if present patterns of water use continue unchanged. The conventional water resources (largely surface water) in the country have been fully exploited with little opportunity for further expansion. So therefore, new approaches are necessary by accessing alluvial aquifers of non-perennial rivers in forming additional water resources in this part of semi-arid region. High evaporative losses from surface storage, increasing costs of large dams and aridity conditions have hindered development of conventional water resources with increasing interest in using groundwater for rural water supply. Many South Africa rivers are non-perennial, therefore, development of unconventional sand water storage is appealing for freshwater augmentation in isolated rural communities. This paper presents overviews of South Africa water resources highlighting sand water storage options for potential application in rural water supply for isolated communities where groundwater potential is low.