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Faculty of Engineering and Built Environment

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    Geopolymer cement in pavement applications : bridging sustainability and performance
    (MDPI AG, 2024-06) Ikotun, Jacob O.; Aderinto, Gbenga E.; Madirisha, Makungu M.; Katte, Valentine Y.
    Sustainability and the quest for a more robust construction material cannot be divorced from each other. While Portland cement has revolutionized the construction sector, its environmental toll, particularly in greenhouse gas emissions and global warming, cannot be ignored. Addressing this dilemma requires embracing alternatives like geopolymer cement/geopolymer binder (GPC/GPB). Over the last few decades, considerable strides have been achieved in advancing GPC as a sustainable construction material, including its utilization in pavement construction. Despite these advances, gaps still exist in GPC optimal potential in pavement construction, as most studies have concentrated on specific attributes rather than on a comprehensive evaluation. To bridge this gap, this review adopts a novel, holistic approach by integrating environmental impacts with performance metrics. To set the stage, this review first delves into the geopolymer concept from a chemistry perspective, providing an essential broad overview for exploring GPC’s innovations and implications in pavement applications. The findings reveal that GPC not only significantly reduces greenhouse gas emissions and energy consumption compared to Portland cement but also enhances pavement performance. Further, GPC concrete pavement exhibits superior mechanical, durability, and thermal properties to ensure its long-term performance in pavement applications. However, challenges to GPC utilization as a pavement material include the variability of raw materials, the need for suitable hardeners, the lack of standardized codes and procedures, cost competitiveness, and limited field data. Despite these challenges, the process of geopolymerization presents GPC as a sustainable material for pavement construction, aligning with Sustainable Development Goals (SDGs) 3, 9, 11, and 12.
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    39th Johannesburg International Conference on “Chemical, Biological and Environmental Engineering” (JCBEE-23) Nov. 16-17, 2023 Johannesburg (South Africa)
    (International Institute of Chemical, Biological & Environmental Engineering (IICBEE), 2023-11-16) Chetty, Manimagalay; Rathilal, Sudesh; Tetteh, Emmanuel; Singh, Nikita
    Abstract—Recent energy demand and environmental concerns associated with fossil fuels makes algae biomass a desirable energy source. Algal biomass has a high organic content and a variety of metabolic properties that make it a promising resource for managing wastewater and sequestering CO₂, in addition to producing profitable biobased products. However, the operation and valorization of algae biomass on a large scale are accompanied by significant costs and setbacks. Therefore, the transition towards a biobased economy requires this study to examine emerging technologies that could utilize algae biomass as an industrialized feedstock from the wastewater settings. A comprehensive analysis of various green technologies of producing high-value products (lipids and hydrocarbons) from algae biomass was reviewed. The fundamental principles that limit the cultivation , extraction, and conversion of different types of algae biomasses for commercialization are discussed. Furthermore, the challenges, future research directions and potential opportunities of valorizing algae biomass was highlighted. It was noted that, exploring algae biomass towards sustainable waste management with resources recovery is viable for industrialization.
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    Assessing the feasibility and effectiveness of rooftop rainwater harvesting in Winnie Mandela Madikizela Local Municipality
    (2023-05) Nakin, Abongile Ongezwa; Walker, Mark; Ikegwuoha, DC
    South Africa's primary source of water is surface water. The potability of this water is doubtful especially in rural areas. Evaluation of rainwater quality from various roof materials is crucial. Additionally, there is a need to evaluate the quantity and the economic viability of Rooftop Rainwater Harvesting (RRWH). Winnie Madikizela Mandela Local Municipality (WMMLM) of Nomlacu currently has 73.6% municipal water supply backlog. With the current challenges, it is important not only to explore ways to save water but also to generate own sources of water. This makes RRWH systems as a viable water resource, an option for alleviating water scarcity. The study aims to assess the feasibility and effectiveness of RRWH for domestic use in WMMLM. The target is to determine the potential of rainwater harvesting as a potable water supply and conservation alternative. Hydrological data was obtained from the Weather SA to facilitate the calculation of the quantity of rainwater that can be harvested per household. Moreover, catchment areas were obtained through QGIS to determine size and materials of the roof types. Thus, to analyse the impact of roof materials on water quality for human consumption and irrigation. According to the results obtained in this study, Turbidity and E. coli produced noncompliant results of (0.8 – 2.8 NTU) and (0 - >2420 MPN /100mL) respectively. Although within limits, Aluminium, Colour, and Zinc concentrations present higher values on zinc metal roof compared to tiled roofing material. This is due to the high radiation and good heat conducting capacity of the metal. Results also showed higher pH levels on tiled roofs (7.05 – 7.39) compared to zinc roofs (6.27 – 7.19), which is in line with the nature of concrete. The most significant and immediate threat to health that roof collected water poses is bacterial contamination. Therefore, it is important to regularly clean the system, use disinfection solutions like chlorine tablets and boiling water before consumption. Overall, Nomlacu area receives relatively high amounts of rainfall which is greater than country’s annual rainfall. The study showed that RRWH can meet the annual demand of rainwater and have an overflow of roughly 7211L/year which is equivalent to an approximate potential annual harvest of 124% when utilized to its optimal potential and at worst case scenario can alleviate the pressure from the municipal water supply system by at least 81%. Results showed that optimal rainwater harvesting can be achieved by using more than two storage tanks per household. This then makes it possible for the system to alleviate pressure from the municipal water supply. On the economically aspect, installing a RRWH system is financially feasible, it would spare the municipalities approximately 48.8% of the municipal water supply spend to supply water to the municipality should this project be a government initiative.
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    Data pre-processing for process optimization at a drinking water treatment plant in Ugu District Municipality, South Africa
    (Business Perspectives, 2015) Magombo, James; Dzwairo, Bloodless; Moyo, Sibusiso; Dewa, Mendon
    When testing and recording water quality data from treatment plants, errors arise. The errors are in the form of re-cordings left blank (missing values), obvious errors in writing or typing, or they can be as a result of values being very small to detect and are therefore censored. The censored values are known to be below the limit of detection (LOD). In statistical analysis, the blank cells can be filled with a certain value. Censored values are often corrected by substituting with a constant value throughout. This value will be a fraction of the limit of detection and most commonly used frac-tions are, half the limit of detection, the limit of detection divided by the square root of 2, or multiplying the limit of detection by 0.75. The direct substitution method for handling missing and values below the limit of detection results in a uniform distribution for values below the limit of detection, and a true distribution for those above. As a result, treat-ment of the values below the limit of detection is dependent upon their percentage in the sample size. An alternative method used will mimic the characteristic of the distribution pattern of the values above the limit of detection to esti-mate the values below it. This can be done with an extrapolation technique or maximum likelihood estimation. In this study, data from the Umzinto Water Treatment Plant was used to develop a data pre-processing program using Visual Basics for Applications (VBA) and Microsoft Excel 2013. The procedure involved 4 stages: data preparation, data pre-processing for blanks and non-detects, data pre-processing for the censored values and finally the identifica-tion of the outliers. The developed program was then used to pre-process raw water quality data, which resulted in satisfactory process time and data conversion. The methodology used can be borrowed for the pre-processing of data driven environmental models and hence it has a great influence on sustainability of water treatment plants.
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    Towards greener infrastructure
    (IMESA, 2012-04) Saroop, Shian Hemraj; Allopi, Dhiren