Veruscha Fester

Cape Peninsula University of Technology | CPUT · Faculty of Engineering

Hydrocolloids form gel-like structures when dispersed in water and have garnered significant attention for their diverse applications in food, pharmaceuticals, and other industries. The extraction of hydrocolloids from natural sources, such as seeds, presents an intriguing avenue due to the potential diversity in composition and functionality. Util...

ZnO nanoparticles were successfully synthesized using aqueous extracts of Doum palm tree (Hyphaene thebaica) fruits. The green-synthesized ZnO particles annealed at 400, 500 and 600 °C, alongside commercial ZnO, were structurally and optically characterized using SEM, TEM, XRD, FTIR, BET surface area analysis and Diffuse reflectance spectroscopy. S...

This study provides a comparison of the chloride and nitrate anions, water and alcohol solutions in the formation of cobalt complexes, and their effect on the cobalt hydroxide polymorph formed and the subsequent impact on the catalytic performance of the resulting cobalt oxide. The formation of α- and β-cobalt hydroxide polymorphs as precursors to...

A systematic investigation into the equivalence between two methods of tuning average particle hydrophobicity: varying the extent of chemical anchoring of alkyl chains onto the surface of a single particle (chemical method) and mixing particles of different hydrophobicity (mechanical method), in stabilization of highly concentrated water-in-oil emu...

The use of orifices in measuring and regulating the discharge of Newtonian liquids from tanks has been studied extensively. For non-Newtonian liquids, this is not the case mainly due to the complex rheological properties of such liquids. To date only circular orifices have been used to measure the flow of Power-Law liquids from a tank. In this work...

Orifices are commonly used to control and measure the discharge of Newtonian fluids from pipes, channels, reservoirs and tanks and are available in different types, shapes and sizes. The accuracy of non-Newtonian fluid flow rate measurements through orifices from tanks is not well understood with little research available on discharge of non-Newton...

Non-Newtonian fluids have complex viscous characteristics, which make it difficult to measure the flow rate during their processing and handling. Several researchers have conducted studies on the flow rate measurement of non-Newtonian fluids using orifices installed in horizontal pipes. However, the same cannot be said for the gravitational flow of...

Urbanisation is putting enormous pressure on wastewater treatment plant facilities. Optimising the liquid and sludge process streams in existing plants is one way of prolonging the life span of such installations. Many Wastewater treatment plants (WWTP) have sludge dewatering installations where treated wastewater sludge is dewatered using belt fil...

Advanced oxidation process (AOP) based on sulphate radical generated by peroxymonosulfate (PMS) activation is a promising area for environmental remediation. One of the biggest drawbacks of heterogeneous PMS activation is catalyst instability and metal ion leaching. In this study, a simple organic binder mediated route was explored to substitute Ti...

The control and optimization of belt filter presses in the wastewater treatment industry is still largely dependent on operator intervention. This is mainly due to the lack of predictive models for belt filter press performance. This paper presents correlations determined via a factorial trial for the determination of filtrate suspended solids and...

https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2018011727

To optimise the design and operational management of wastewater treatment plants (WWTP’s) there needs to be an understanding of the viscous properties of wastewater sludges, which at higher concentrations become non-Newtonian. Worldwide, there is more and more pressure to attain higher sludge concentrations which complicates mixing and pumping. Pip...

To optimise the design and operational management of wastewater treatment plants (WWTP’s) there needs to be an understanding of the viscous properties of wastewater sludges, which at higher concentrations become non-Newtonian. Worldwide, there is more and more pressure to attain higher sludge concentrations which complicates mixing and pumping. Pip...

This work investigated the prediction of transitional flow of non-Newtonian fluids in open channels. A number of empirical methods are available in the literature, which purport to predict the frictional losses associated with the transitional flow in open channels of different shapes, but with no conclusive guidelines. Therefore, a large experimen...

A simple solution based deposition process has been used to fabricate Zn doped Co3O4 electrode as an electrocatalyst for non-enzymatic oxidation of glucose. XRD, HRTEM, SEM, EELS, AFM, EIS was used to characterise the electrode. The addition of Zn as dopant on Co3O4 resulted in enhanced electrochemical performance of Zn:Co3O4 material compared to p...

In this work we report on the good photocatalytic properties of β-FeOOH/TiO2 heterojunction material for the inactivation of E.coli. XRD, HRTEM, EELS, ELNEFS was used to characterise the as prepared material. 1 log reduction of the initial bacterial population was achieved after 45 minutes of irradiation in the presence of 0.1 mL of hydrogen peroxi...

Conflicting reports exist about the critical process conditions for continuous hydrothermal synthesis of metal oxide nanopowders and are often accredited to the inability to isolate the effect of various operating parameters and the complexity of particle formation. In this study, an investigation was conducted on the effect of process parameters a...

The scarcity of rapid and large scale synthesis of functional materials hinders the progress from the laboratory scale to commercial applications. In this study, we report a rapid and large scale synthesis of micron size (1.3 μm) Co3O4 octahedron particles enclosed by (111) facets. The octahedron particles were composed of ±25 nm rectangular/cube s...

In this contribution, we have shown that mining waste derived Fe3 + can be used to enhance the photocatalytic activity of TiO2. This will allow us to harness a waste product from the mines, and utilize it to enhance TiO2 photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO2 and...

The performance of a new ultrasound transducer, which can measure velocity profiles non-invasively through high-grade stainless steel pipes, was evaluated for the first time with secondary wastewater sludges. This work is a follow-up study on the feasibility work initially done by the same authors. In-line process control based on accurate rheologi...

The prediction of non-Newtonian transitional flow in open channels is even more complex than for pipe flow. Not much work has been done in the field. The application is in mine waste and sludge disposal where it is important to distinguish between laminar, transitional and turbulent flows. Transitional flow is often characterised by its unstable na...

Photocatalytic performance of β-FeOOH/TiO2 heterojunction structure, created from ultra-small β-FeOOH nanorods (2-6 nm dia.) and spherical anatase phase of TiO2 nanoparticles (~100 nm), is reported in this study. Three different β-FeOOH mol % of (2, 5 and 10%) β-FeOOH/TiO2 composite was prepared. 5%β-FeOOH/TiO2 composite material showed the highest...

In this paper, we report on the catalytic properties of ultra-small β-FeOOH nanorods in ozonation of 4-Chlorophenol (4-CP). XRD, TEM, EDS, SAED, FTIR and BET were used to characterize the prepared material. Interaction between O3 and β-FeOOH was evident from the FTIR spectra. The removal efficiency of 4-CP was significantly enhanced in the presence...

Large quantities of fly ash (FA) are generated annually in South Africa and most of it is disposed in landfills and ash dams. Previous studies indicated that FA can be used to treat acid mine drainage (AMD), another waste stream commonly found in the minerals industry. Moreover, encouraging results were obtained from the studies carried out on the...

The rheological characteristics of sludge affect transportation, treatment and the disposal processes involved in sludge system design and management operations such as dewatering, including flocculation and filtration. The concentration of solid matter in the sludge has an effect on rheological parameters such as yield stress and viscosity. These...

This paper describes the homogeneous precipitation of β-FeOOH nanorods (±5 nm dia.) in alcohol—water mixed solvents. Four alcohols, butanol (BuOH), propanol (PrOH), ethanol (EtOH) and methanol (MeOH), were mixed with water as the solvents to evaluate the effect of alcohols on the β-FeOOH particle characteristics under different hydrothermal process...

The Hydraulic Institute method, developed for predicting centrifugal pump performance of viscous Newtonian fluids, is used by some for non-Newtonian fluids. This requires an average value of viscosity representing the variable non-Newtonian viscosities. To determine such an average viscosity, two approaches exist in the literature: the use of a Bin...

Based on the proposition that a quantitative and qualitative relationship between alcohol surface tension and particle growth exists, the effect of four different organic solvents on the growth kinetics of β-FeOOH (akaganeite) nanorods have been evaluated in this study. Two-stage growth of akaganeite nanorods have been observed in the presence of b...

There is data available in the literature showing that more accurate flow measurement of air can be obtained using fractal-shaped orifice plates. Furthermore, energy losses over the fractal orifices were less than for circular orifices of the same area. The design of energy efficient systems is becoming increasingly important, therefore the testing...

Correlations predicting the pressure loss coefficient along with the laminar, transitional, and turbulent limiting Reynolds numbers with the β ratio are presented for short square-edged orifice plates. The knowledge of pressure losses across orifices is a very important industrial problem while predicting pressure losses in piping systems. Similarl...

A lack of experimental data and predictive models prompted the determination of loss characteristics of four sharp square-edged orifices for laminar to turbulent flow regime (1 ≤ Re ≤ 100000). Novel experimental data for β ratios of 0.36, 0.4, 0.5 and 0.7 obtained with Newtonian and non-Newtonian fluids and an empirical correlation for predicting p...

The focus of this chapter is to provide a review of the loss coefficient data for laminar flow of non-Newtonian fluids in pipe fittings. Since the total pressure change in a piping system generally consists of three components: (i) the frictional pressure loss in the pipe, (ii) the frictional pressure loss arising from flow through fittings and (ii...

A lack of experimental data and predictive models prompted the determination of loss characteristics of four sharp square-edged orifices for laminar to turbulent flow regime (1 ≤ Re ≤ 100,000). Novel experimental data for ˇ ratios of 0.36, 0.4, 0.5 and 0.7 obtained with Newtonian and non-Newtonian fluids and an empirical correlation for predicting...

When predicting pressure gradients for the flow of sludges in pipes, the rheology of the fluid plays an important role, especially with increasing concentration of the suspended matter in the sludge. The f-Re relationship is often applied when designing pipelines, but it depends on the rheological parameters of the fluid and what definition of non-...

In this project a non-Newtonian CMC model fluid was tested in two different complex geometries using Ultrasonic Velocity Profiling (UVP). Velocity profiles were measured at three different positions at the center (contraction) of a specially manufactured 50% open diaphragm valve. The complex geometry coordinates and velocity magnitudes were analyse...

Recent work on fully opened rubber-lined diaphragm valves showed that due to the lack of geometric similarity, dynamic similarity could not be established. The laminar flow loss coefficient constant therefore becomes diameter dependent as is the case of turbulent flow loss coefficients. The purpose of this work was to establish if this is the case...

Despite the extensive use of straight-through diaphragm valves in many diverse industrial applications, very few studies of frictional pressure loss for straight-through diaphragm valves have been reported in the open literature. The few that are available are for fully opened valves based on the tacit assumption that different sized diaphragm valv...

Abstract Self compacting concrete has been used on a very limited scale in South Africa. SCC is more sensitive to the variability of materials and water/cement ratio than standard concrete. The reproducibility of an SCC mix is of vital importance and was intensively studied by a pan-European group to provide typical test values for SCC in a report...

Previous experimental work in globe valves has mainly been conducted over a narrow range of laminar or turbulent flow. The work available in laminar flow has not been conducted in geometrically similar valves, hence dynamic similarity could not be established—a critical precursor to practical engineering hydraulic design.In this work various Newton...

There are very few experimental results available for flow of viscous fluids in sudden contractions. Furthermore, there are discrepancies between the few sets of experimental data published so far. The objective of this work is to provide a set of reliable experimental results that confirms and extends existing datasets for experimental and numeric...

A systematic study of the effects of alcohols of different chain length in the synthesis of iron oxide nano-rods was conducted because it was evident from previous work done that it plays a vital role in the formation of rods in addition to that of surfactant. It was found that rod-like particles were obtained and that the length of the particles w...

There is a world-wide emphasis on energy reducing technologies. Accounting accurately for the losses that arise from pipe fittings, such as valves, can result in cost and energy savings. Efficient designs, using (for example) correctly sized pumps, are only possible if reliable loss coefficient data are available. There are currently limited loss c...

The need to save water world-wide is forcing industry to reduce water consumption which in turn leads to increasing concentrations of the mineral tailings handled. Design criteria are shifting from turbulent flow to laminar flow. Although diaphragm valves are used extensively to control flow, there is very little experimental data available. The us...

Fly Ash (FA) from South African power stations was successfully used to treat Acid Mine Drainage (AMD) and the insoluble residual solids that were obtained as a result of the reaction between FA and AMD proved suitable as a backfill material for mine stabilization. Particle Size Distribution (PSD) of FA varies from time to time depending on the coa...