DSpace Repository

Welcome to the NWU Repository, the open access Institutional Repository of the North-West University (NWU-IR). This is a digital archive that collects, preserves and distributes research material created by members of NWU. The aim of the NWU-IR is to increase the visibility, availability and impact of the research output of the North-West University through Open Access, search engine indexing and harvesting by several initiatives.

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Valorisation of e-waste by means of direct liquefaction
(North-West University, 2024) Swanepoel, D; Venter, RJ; Waanders, FB; Marx, S
Global E-waste generation has increased rapidly in recent decades owing to a decrease in the lifespan of electronic equipment and an exponential increase in supply and demand. Due to inadequate treatment and disposal practices, the majority of e-waste is landfilled, polluting the air, soil, and water. E-waste can be a valuable source of secondary materials, with most end processing methods aimed at recovering the valuable metals. However, many of these procedures are not feasible without government support and cause secondary pollution in the form of pollutants released by emissions and effluents. Furthermore, the presence of organic components and low metal concentrations in end-products impedes economic viability. As a result, there is a need to investigate novel end-processing routes that can overcome the drawbacks of present technologies and lead to a more environmentally friendly and economically viable treatment method for e-waste. One such novel route is the thermochemical depolymerisation process known as hydrothermal liquefaction or direct liquefaction. The potential depolymerisation and conversion of organic fractions into other valuable organics, as well as the potential immobilisation of metals through co-processing with lignocellulosic biomass, could result in liquefaction becoming a promising option for e-waste valorisation and end-stage treatment. This study aimed to determine the suitability of direct liquefaction as a treatment method for locally obtained printed circuit board (PCB) e-waste co-processed with lignosulphonate biomass. The aim was achieved by studying the effect of hydrothermal liquefaction process conditions while co-processing PCB e-waste with lignosulphonate biomass in an SS-316 batch reactor. The effect of liquefaction temperature (250-330°C), residence time (20-80 min), and waste loading (0-100 wt.% of feed) was studied by analysing the recovery of metals and formation of organic compounds in the residues, and aqueous phases obtained from processing. The intertwining effect of residence time and temperature on the product yields was determined through calculated severity factors. The formation of organics was established by elemental analysis, proximate analysis, total phenolic analysis, Fourier-transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), and Gas Chromatography-Mass Spectrometry (GC-MS). Metal recovery was determined through the digestion of reactor products, followed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) to determine the concentration of metals and mineral elements. This study found low yields of bio-oils at all process conditions, however, the oils mostly consisted of phenolic compounds. Residue products consisted of inorganics, such as ceramics and metals, as well as unreacted epoxy resin and heavy carbon molecules. Temperature influenced the yields and composition of products more than residence time. Generally, longer residence times mostly affected the products by allowing HTL reactions to progress, whereas temperature heavily influenced the rate of these reactions. Both the bio-oil yield and the phenolic content increase with increasing temperature and reached a turning point as the rate of cracking reactions overtook the recombination. At 250°C, longer residence times increased the bio-oil and residue yields, however at 330°C a dynamic equilibrium between decomposition and repolymerisation reactions was reached. Furthermore, at lower temperatures, longer residence times increased the phenolic content of bio-oils. The optimum conditions for bio-oil production were determined as 300°C for 80 min. Nearly all of the metals remained in a stable state within the residues, with only small concentrations detected in the bio-oils and aqueous phases after HTL. It was concluded that the migration from the residues was in relation to the initial concentration of each metal in the feedstock. Both temperature and residence time produced mostly inconsistent trends. At both short and long residence times, several metals (Au, Cu, Fe, Ni, Sn and Zn) showed high concentrations in the residues at 250°C, as a result of the slow decomposition rate of the waste PCBs. However, as the temperature increased, an initial decrease in concentration was noted as more metals were released, after which the concentrations slightly increased, possibly due to the adsorption from the biochar structures. Longer residence times at 250°C decreased most of the metal concentrations, however, no conclusive trends were seen at other temperatures. It was observed that increasing the waste loading increased both the bio-oil and residue yields. The carbon content of the residues decreased from 49 wt.% at 0 wt.% PCB loading to 5 wt.% at a 100 wt.% PCB loading, confirming that almost all of the organic epoxy resin was depolymerised by HTL. Furthermore, the phenolic content of the bio-oils increased from 6 to 93 area%, confirming that the epoxy resin was primarily depolymerised and recombined into useful phenolic compounds. Increasing the waste loadings resulted in a non-linear increase for most metal concentrations, with the metal concentrations in the residues at 90 and 100 wt.% waste loadings being significantly higher than the original feedstock concentrations, with less than 6 wt.% carbon. This study revealed that hydrothermal liquefaction is an effective treatment approach for waste PCBs by confirming the organics in waste PCBs transform to valuable phenolic compounds while the majority of metals remain stable during processing, resulting in the production of metal-rich residues.
Development of an IP cryptographic function for the HF radio environment
(North-West University, 2024) Streicher, D. E; Helberg, ASJ; Ferreira, M
Provisioning Internet Protocol (IP) services over military High Frequency (HF) radio networks has been of interest from at least as early as 1999. Historically, this has only been achieved with limited success for User Datagram Protocol (UDP) based IP services due to the high latency and low bandwidth of HF channels. However, emerging Wideband High Frequency (WBHF) technology holds promise as a key enabler for this application domain, creating a renewed drive to develop a workable IP over HF system. An aspect to consider in this system design is that of network security. While Annex E of the North Atlantic Treaty Organization (NATO) Standardization Agreement (STANAG) 5070 mandates the provisioning of security at the IP layer, little else is disclosed in the public domain. This presents a unique opportunity to develop an IP cryptographic function for the HF radio environment. This is approached by firstly investigating related subject matter on topics such as the HF transmission medium in general, traditional data transmission over an HF channel, the history of IP data communication over HF, traditional security mechanisms in the HF military environment, and security in traditional IP networks. A design and implementation of an IP cryptographic function, or IP crypto for short, is presented in the context of an envisioned IP over HF system. The design draws on information obtained in the literature study and from existing HF industry standards, and when necessary, compliance with HF industry standards is given preference when making design decisions. The implementation is done using the Linux Transform (XFRM) framework. It is suitable for the evaluation purposes of this research study and is not intended to be a fully developed IP crypto product ready for commercial use in the HF military environment. This IP crypto is evaluated using an IP over WBHF capable test bench consisting of Commercial Off-The-Shelf (COTS) equipment, including WBHF modems and an HF channel simulator. This process consists of developing throughput- and latency tests by modifying the open source IPERF3 network performance evaluation tool, using these tests to establish a performance baseline of the test bench, viz. without the IP crypto included in the system, repeating the tests with the IP crypto included in the system, and lastly, comparing the IP crypto results to the baseline test results. This comparative analysis quantifies the extent of the IP crypto's impact on the IP over WBHF test bench system's performance, and finds that this is more pronounced for the throughput rate than for the latency characteristics of the system. Additionally, while the presence of the IP crypto may influence the viability of some IP services over HF, it in no way renders the system completely unusable for IP services.
The realisation of the right to mental health care of children and adolescents with clinical depression
(North-West University (South Africa), 2026) Valentine, Larochelle; Serfontein, Erika M.
Due to its significant influence on socio-economic output, educational attainment, and human development, mental health has taken centre stage in discussions surrounding global health. The importance of the healthy development of children and adolescents for overall societal welfare and shaping a country's future as upcoming leaders, employees, and parents cannot be ignored. An international legal framework consisting of an all-inclusive set of yardsticks and systems for protecting the human rights of individuals globally recognises the right of access to health care as a fundamental right. The international legal framework for children's rights, concomitantly, recognises children as individuals having access to human rights. In noticing the detrimental consequences of mental illnesses such as clinical depression on the youth, this study aims to explore the extent to which South Africa is complying with international standards regarding the realisation of the right to health care for children and adolescents diagnosed with clinical depression. Regarding the right to healthcare for children and adolescents, including those with mental health disorders, South Africa has a strong legal and regulatory framework that de jure complies with international norms such as section 27 and 28 of the Constitution. The de facto implementation of the access to healthcare for children and adolescents with clinical depression in South Africa faces substantial obstacles, such as a lack of child and adolescent psychologists and psychiatrists, despite the country's robust legislative and administrative framework. The objectives of the study are: to analyse the right of children and adolescents to mental health care services, discuss the current position in international law regarding the duty to realise children and adolescent's right to mental health care, explore the legal duty of the South African State to realise children and adolescent's rights to mental health care and, lastly recommend ways in which the State can effectively comply with its legal duty. Data was generated through a thorough review of existing literature. This enabled the researcher to consolidate and analyse existing knowledge in the field of International Child Law with the aim of contributing to this field by offering guidance for enhancing current practices in South Africa to give effect to the right of access to health care in ii future. International, regional and national law, as well as case law, were used as primary sources. As secondary sources, peer-reviewed journal articles and edited academic books were employed. Findings indicate that South African national legislation aligns with international law pertaining to the right of access to health care, which the State is obliged to ensure. However, South Africa continues to experience significant challenges to effectively realise children and adolescents' right of access to health care despite having a strong legal framework guaranteeing and protecting children and adolescents' rights. Barriers such as societal stigma, a lack of resources, inadequate funding, and poorly implemented policies continue to restrict access to mental health services. As such, it is recommended that South Africa needs to prioritise mental health through practical reforms, allocation of more funding to the health sector, and establishment of inclusive, community-based care to which equal access is ensured if it is to fully realise this right. The effective implementation of legislation requires a political will to invest in community-based mental health services, run awareness campaigns, and integrate mental health into primary health care.
From estate planning to estate administration legal challenges posed by digital assets
(North-West University (South Africa), 2026) Roestorff, Charlize; Gildenhuys, Anél
The rapid digitisation of wealth has introduced a novel asset class, namely digital assets, into the realm of succession law. From cryptocurrencies and non-fungible tokens to social media accounts and cloud storage, these intangible assets present unique challenges regarding identification, access and transfer upon death. South African legislation, specifically the Administration of Estates Act 66 of 1965 and the Wills Act 7 of 1953, was drafted in a pre-digital era and currently lacks explicit provisions for digital estate administration. This dissertation investigates the legal nature of digital assets, analysing whether they constitute "property" capable of inheritance, particularly in light of the Western Cape High Court's decision in Bester v Mirror Trading International 2023 3 All SA 101 (WCC), which classified cryptocurrency as intangible movable property in terms of the Insolvency Act 24 of 1936. It further critiques the contractual impediments imposed by Service Providers' Terms of Service, which often extinguish rights upon death, thereby conflicting with the principle of freedom of testation. Through a comparative analysis of the United States' Revised Uniform Fiduciary Access to Digital Assets Act of 2015 and Canada's Uniform Access to Digital Assets by Fiduciaries Act of 2016, this study proposes legislative reform for South Africa. It recommends the adoption of a "Digital Assets Access Act" to clarify fiduciary authority and advocates for practical estate planning measures, such as the use of sealed memoranda for security credentials, to prevent the permanent loss of digital wealth.
Exploring the role of the public sector in revitalising rail transport in South Africa
(North-West University (South Africa), 2026) Malimagovha, Portia Mpho; Mutambara, Emmanuel
The rail system in South Africa has been around for hundreds of years. It played a major role in the development of the economy. Today, it is in systemic decline where the infrastructure hardly works. The system is marred with unreliable operation. Additionally, there is a significant diversion of market share from rail freight to road freight. The decrease has significant economic costs, said to be about R1 billion each day, and worsen social and spatial disparities. Although the public sector is supposed to spearhead the revitalisation, its effectiveness is seriously hampered by widespread governance failures and a serious lack of credible and usable data. The study will explore and critically examine the public sector's role in the revitalisation of rail transport in South Africa with specific reference to the challenges of governance and data issues. Based on a realist research paradigm, the study used a convergent parallel mixed methods design. A purposively chosen sample of 30 rail sector experts drawn from public entities, government departments and the private sector were used to gather the data via a single survey instrument. The analysis of the quantitative data for Likert-scale questions was done through descriptive statistics. Thematic analyses were done for the qualitative data of open-ended ones. It was integrated during interpretation. Outcomes indicate that the area is in an institutional crisis. Quantitative results indicate the severity of political interference (GOV1 mean=4.43) and no data available for strategic decisions (DATA1 mean=2.40). The qualitative themes shed light on these numbers to reveal a pathology of governance failure. More specifically, there is a political capture of technical decisions and a culture of impunity. There is also a "black hole" of data that exists. Lastly, this culture of governance failure propels a high-cost reactive maintenance culture and prevents investment. The research demonstrates that the lack of data is not a minor technical problem. Rather, it is a manifestation of a governance system that actively blocks transparency, accountability, and evidence-based management. The study concluded that dual-track strategy governance and data need to be addressed for effective revitalisation. The public sector must primarily act as a strategic enabler and not a direct operator by promoting an independent rail regulator, data transparency on a radical scale, and public-private partnerships. Foundation governance reforms should be prioritized first, followed by selective investments and digitization initiatives in a phased v manner. The study contributes to theory by drawing support for institutional theory in a developing world SOE context and extends the resource-based view by framing reliable data as a strategic resource. In practical terms, it provides a diagnostically informed roadmap for essential reforms in the country's rail sector for policymakers and industry leaders.