Research Articles

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Now showing 1 - 5 of 12
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    Generalized storage-yield-reliability relationships for analysing shopping centre rainwater harvesting systems.
    (MDPI, 2017-10-10) Ndiritu, John; Moodley, Yashiren; Guliwe, Mondli
    The objective of this study was to develop guidelines for analysing rainwater harvesting (RWH) systems of shopping centres in South Africa. A model consisting of three dimensionless relationships relating rainwater supply and demand to storage capacity, yield and reliability was formulated. Data from daily simulation of potential RWHsystems of 19 shopping were used to obtain the relationships. The simulations revealed within-year storage behaviour with considerable variation of annual yield. By applying the Weibull plotting position formula, yield-reliability relationships were derived. The aim to maximize yield and reliability whilst minimizing storage identified Pareto-optimal combinations of the three variables and these combinations were used to develop two dimensionless relationships. An additional relationship based on the dependence of the slope of the yield-reliability plots on yield was formulated to enable analysis of hydrologically non-optimal systems. Verification tests using four RWH systems obtained results that matched those from simulation and the model could therefore be applied for RWH feasibility analysis and preliminary design. This study highlights the need to incorporate inter-annual variability in RWH analysis and shows how reliability can be used to quantify this. This study further demonstrates how reliability can be fully integrated into regression relationships for generalized RWH analysis.
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    Treated wastewater reuse in South Africa: Overview, potential and challenges.
    (Elsevier, 2010) Adewumi, J.R.; Ilemobade, A.A.; Van Zyl, J.E.
    Many communities in South Africa struggle to access reliable and adequate quantities of potable water for diverse water requirements. This is against the backdrop of decreasing freshwater availability and increasing water demands. Currently, interest in the reuse of wastewater for non-drinking water requirements is increasing. This paper therefore provides an overview of the South African water resources situation and wastewater 1 generation in order to put the need for wastewater reuse into perspective. Potential for broader implementation and parameters influencing wastewater reuse based on local attitudes and experience were discussed with recommendations to facilitate broader implementation of wastewater reuse. This paper concludes that significant potential exists for implementing wastewater reuse for large non-drinking applications (e.g. landscape irrigation and industrial processes) in arid areas of South Africa especially Western Cape Province. Parameters highlighted from local attitudes and experience to influence broader implementation in addition to aridity include distance from source, retrofitting versus new installations, quantity of reuse, tariffs, source quality, public health, willingness, public trust and knowledge, and regulations and guidelines for reuse. Prior to implementation, it is recommended that these parameters be addressed.
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    Undergraduate engineering training through institutional collaboration in the Southern African region.
    (Higher Education South Africa (HESA)., 2005) Ilemobade, A.A.; Ballim, Y.
    The University of the Witwatersrand (Wits) and The University of Namibia (UNAM) signed an Agreement of Co-operation (AOC) in 2000. This agreement, which formalised an existing informal collaboration, was primarily targeted at facilitating the transfer of potential Unam undergraduate engineering students to pursue engineering studies at the WITS Faculty of Engineering as well as improving staff collaboration in research and teaching. Students from UNAM's pre-engineering programme and science departments have been beneficiaries of this agreement. Four years later, an evaluation of the collaboration reveals critical issues vis-à-vis decreasing student enrolments, unimpressive student graduation rates, and financial and operational complexities affecting student mobility - all of which have institutional as well as regional implications. This paper presents highlights and pertinent lessons of the collaboration, and recommendations for similar collaboration in the Southern African region both at an institutional and regional level. As a whole, the paper uses the Wits experience to extrapolate principles and strategic issues facing institutions involved in academic collaboration and cross-border movement of students within the Southern Africa region.
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    Waste to wealth: A case study of the ondo state integrated wastes recycling and treatment project, Nigeria.
    (EuroJournals, Inc., 2009) Olanrewaju, O.O.; Ilemobade, A.A.
    The Ondo State Integrated Waste Recycling and Treatment Project, came into existence in June 2006 with the commissioning of the project office complex along Igbatoro Road, Akure by the Nigeria President, Chief Olusegun Obasanjo. The Project started operation in December 2006 with the aim of minimising solid waste in Akure and its environs. Since its inception, OSIWRTP has recorded huge successes in transforming the waste generated in Ondo State to wealth by the development of various valuable products using the basic concepts of sustainability: social progression, technical and technological improvements, environmental protection and economic development. Such waste is been generated from agricultural waste, nylon and plastic waste and foundry (metal) waste. Several techniques have been used to transform the waste into profitable products e.g. using anaerobic digestion (biogas) to produce energy and fertilizer; composting for soil conditioner; scrap iron for foundry products and other recycling techniques for solid wastes. The main output of OSIWRTP as at today are fertiliser, foundry materials and other recycled materials depending on the availability of wastes, and according to demands and need.
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    Application of a constrained non-linear hydraulic gradient design tool to water reticulation network upgrade.
    (Tayylor & Francis., 2006) Ilemobade, A.A.; Stephenson, D.
    Southern Africa has embarked on substantial expansion of its water supply network in order to ensure safe, reliable, convenient and sufficient water for everyone. To achieve this, new systems are being built and many existing systems are being upgraded. The upgrade of many existing systems is required for two reasons: some currently functional systems may run dry if subjected to additional demands as these systems were not initially designed to cater for such demand, and some systems are currently non- or sub-functional as they were ill-designed and/or ill-implemented from inception. Many of the systems that require upgrade are underdesigned due to a lack of skill, tools and/or knowledge of designers, or from other extraneous factors (e.g., illegal connections and sabotage). It is hardly surprising therefore that the failures of water projects in developing countries are recorded to be as high as 80%. Ill-designed systems increase operation and maintenance costs significantly. In especially Southern Africa, designers require simple, yet rigorously tested tools to facilitate sustainable, yet cost-effective network designs. Presented in this paper is a simple, yet robust constrained non-linear hydraulic gradient network reticulation design tool. The design tool is calibrated using the New York City water supply problem that has served as a benchmark problem for other models and then applied to the Selebi – Phikwe (SP) water reticulation network (WRN) in Botswana, which was designed based on engineering judgement. The optimization algorithm employed in the design tool is based on the concept that a hypothetical hydraulic gradient for a hydraulically balanced WRN exists that, when achieved iteratively, produces optimal pipe sizes and an optimal flow relation between each pipe. The unique problems and challenges of the SP WRN (pressure deficiencies in sections of the existing network and the proposed addition of three new residential developments) required determining the most appropriate peak and night flow operating scenarios, and optimal pipe sizes for the proposed expansion of the network. Optimization by trial and error had been previously employed in the design of the SP WRN—a common practice amongst water system designers, and the results are compared with those generated with the design tool. The design tool achieved a 62% reduction in total pipe cost from that obtained by trial and error for the SP WRN problem. At the same time, the design tool gives comparable pipe costs to those published in literature for the New York City water supply tunnels problem.