Faculty of Engineering and Built Environment

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Application of organic coagulants in water and wastewater treatment
(IntechOpen, 2019-04-03) Tetteh, Emmanuel Kweinor; Rathilal, Sudesh
Coagulation is an essential mechanism that occurs in most conventional water and wastewater treatment plants. This occurs in a physical purification unit involving transport processes and the addition of coagulants for chemical reactions, charge neutralization, and formation of smaller flocs to agglomerate into larger flocs. This enhances the effective removal of recalcitrant contaminants by downstream processes. However, poor treatment of wastewater might have a high negative impact on biodiversity and the environment in general. This chapter seeks to address the limitation of employing inorganic coagulants by evaluating the efficiency of organic coagulants and exploring the factors and mechanism governing coagulation in a physiochemical treatment process of water and wastewater resources. The effect of pH, coagulant type and dosage to ease the high sludge production and discharge of residual metals into the downstream waters is addressed. The emerging of organic coagulants and technology to mitigate the performance and recovery of mineral coagulants from wastewater treatment residual is been proposed.
Compressive strength and water absorption capacity of clay bricks in South Africa
(Springer Nature, 2023-04-24) Khuzwayo, Bonga Praisegod; Aigbavboa, Clinton; Thwala, Wellington Didibhuku; Aghimien, Douglas
Some masonry unit manufacturers and suppliers make available to the public the compressive strength and water absorption capacity of burnt clay masonry units, as designers frequently request them. For this study, the compressive strength and water absorption capacity of several commonly used burnt clay bricks in South Africa were determined. The clay brick samples came from all over South Africa, but predominantly Durban (KwaZulu Natal). There were 37 different types. Seventeen were solid and twenty were perforated bricks. An analysis of the relationship between the compressive strength and water absorption capacity of solid clay bricks revealed that compressive strength increases as water absorption capacity decreases. This finding corroborates prior research indicating that a decrease in compressive strength results in an increase in water absorption. Correlation analysis between the capacity of perforated clay bricks to absorb water and their compressive strength revealed no significant relationship between the two. This is unsurprising, given that the compressive strength of perforated bricks decreases proportionately to the reduction in solid cross-sectional area. The study discovered that the type of brick affects the water absorption capacity after examining the effect of size (perforated versus solid) possibly, because they were unmatched low or high porosity burnt clay masonry units.
A computational methodology to select the optimal material combination in laminated composite pressure vessels
(2012-12) Tabakov, Pavel Y.; Walker, Mark
A methodology to select the best material combination and optimally design laminated composite pres-sure vessels is described. The objective of the optimization is to maximize the critical internal pressure subject to cost constraints. Exact elasticity solutions are obtained using the stress function approach, where the stresses are determined taking into account the closed ends of the cylindrical shell. The approach used here allows us to analyze accurately multilayered pressure vessels with an arbitrary number of orthotropic layers of any thickness and a combination of different materials. The design optimization of the pressure vessel is accomplished using the Big Bang–Big Crunch algorithm,subject to the Tsai-Hill failure criterion.
Flexural bond strength analysis of dry vs. water saturated burnt clay brick prisms : pilot study
(Springer Nature Switzerland AG 2023, 2023-04-24) Khuzwayo, Bonga Praisegod; Aigbavboa, Clinton; Thwala, Wellington Didibhuku; Aghimien, Douglas
To improve the bond strength between burnt clay bricks and mortar, SANS 227 recommends moistening or wetting the clay bricks prior to construction or laying of mortar beds. One may argue that the informal construction sector generally fails to comply with this recommendation, as there are many uninformed and un-skilled building applicators and operators. The study examined the effect of substandard practices by contrasting dry versus water saturated burnt clay bricks. Between 2017 and 2020, 122 clay brick prisms were constructed. Prisms were constructed comprising six courses in stack bond fashion and were subject to two-point flexure load testing at 28 days in order to assess the flexural bond strength. This pilot study reports up to a 21-fold difference in flexural bond strength between dry and water-saturated bricks. The findings of the study affirm the importance of moisture on the flexural bond strength in clay masonry construction and flexure design and suggest further investigation on full-scale models to ascertain the ramifications of inadequate preparation work on masonry.
Fouling and cleaning in osmotically driven membranes
(InTechOpen, 2018-03-06) Chollom, Martha Noro; Rathilal, Sudesh
Fouling is a phenomenon that occurs in all membrane processes. It is a complex problem, which limits the full operation of this technology. Fouling in pressure-driven membranes (PDMs) has been studied extensively, and the occurrence is well understood in that methods of mitigation have been proposed; however, limitations still occur for their full implementation. The use of osmotically driven membranes (ODMs) for water treatment is an emerging technology, which has shown some advantages such as low hydraulic pressure operation, high solute rejection and high recovery over PDMs. However, like in PDMs, fouling still presents a challenge. This chapter is aimed at evaluating the impact of fouling on the ODM performance, exploring the factors and mechanisms governing the fouling behaviour, developing approaches for mitigating fouling, elucidating the effect of membrane fouling and providing mitigation strategies as well as the causes of fouling in ODMs.
Treatment of water and wastewater for reuse and energy generation-emerging technologies
(IntechOpen, 2019-04-25) Tetteh, Emmanuel Kweinor; Rathilal, Sudesh; Chetty, Maggie; Armah, Edward Kwaku; Asante-Sackey, Dennis
Fresh water quality and supply, particularly for domestic and industrial purposes, are deteriorating with contamination threats on water resources. Multiple technologies in the conventional wastewater treatment (WWT) settings have been adopted to purify water to a desirable quality. However, the design and selection of a suitable cost-effective treatment scheme for a catchment area are essential and have many considerations including land availability, energy, effluent quality and operational simplicity. Three emerging technologies are discussed, including anaerobic digestion, advanced oxidation processes (AOPs) and membrane technology, which holds great promise to provide integrational alternatives for manifold WWT process and distribution systems to mitigate contaminants and meet acceptable limitations. The main applications, basic principles, merits and demerits of the aforementioned technologies are addressed in relation to their current limitations and future research needs in terms of renewable energy. Hence, the advancement in manufacturing industry along with WWT blueprints will enhance the application of these technologies for the sustainable management and conservation of water