No abstract

Globally, water hyacinth is a known invasive species that predominantly threatens the pillars of sustainability. The cost of controlling these invasive plants is high and many Southern African countries are barely equipped for this liability as the process has to be performed over time. Despite this challenge, there is valuable resource recovery from water hyacinth which can be used to make financial and environmental returns. The visible differences between the control and utilisation methods lie in the definition, recognition, and matching of costs and benefits. Using a rapid appraisal of existing literature, which was analysed using meta-analysis, the current paper is an attempt to discuss the beneficial use of water hyacinth. It is argued in the paper that the economic feasibility of control methods which, on one hand, are used to calculate the economic value of water hyacinth, mainly relies on assumptions whose reliability and sustainability are questionable, thus implying limitations on using this kind of control methods. On the other hand, the costs and benefits of utilising water hyacinth can be quantifiable, making them susceptible to changes associated with time value and sensitivity analysis of possible fluctuations in cashflows. In the context of these annotations, other scholars have argued for the consideration of other utilisation alternatives, among which is included biogas which has been identified as the most viable option because of its potential in diversifying the energy mix, reducing greenhouse gas emissions, and contributing to improved water quality. Given these observations, this paper aims to contribute to policy and research discussions on the fiscal understandings of the material recovery from water hyacinth to promote the adoption of biogas technology. These views are discussed within the broader discourse of the sustainable development goals (SDGs).

It is well recognized globally that the footwear industry contributes to a large waste stream throughout its life cycle. This article reviews the literature pertaining to the life cycle of footwear products and their End-of-Life (EoL) management strategies. The review discusses critical aspects of the footwear industry, commencing with a background on the growth and consumption of footwear products across the globe. The review provides an overview of the environmental impacts of different footwear materials across their life cycles. In this regard, leather materials are given intense focus due to their poor environmental performance. The review further examines proactive and reactive approaches to footwear waste management, whilst additionally exploring the challenges facing EoL footwear recovery. Finally, pyrolysis is examined as a thermochemical treatment process with value due to its potential to recover materials from post-consumer footwear. The significant findings in this review paper are as follows: (a) leather footwear materials have the most detrimental environmental impacts across their life cycle; (b) there is limited scientific literature on thermochemical processes (particularly pyrolysis) as waste recovery options for post-consumer footwear; and (c) several challenges face the recovery of post-consumer footwear products, including inefficient reverse logistics, mixed product recycling and difficulties establishing a value recovery chain. This review paper recommends further research on pyrolysis as a potential post-consumer footwear recovery option. Exploring the viability of new avenues for footwear waste recovery is significant due to its potential to divert this waste stream from landfills and allow a progression toward a more circular economy.

The prioritization and improvement of rural road networks is important in developing countries in order to uplift the socioeconomic conditions experienced by communities. So far, limited information exists on the conditions of unpaved or gravels roads, particularly in rural areas and the associated implications to rural economies. The present study therefore used visual observations and field-based measurements to assess the physical, environmental and anthropogenic factors affecting Minor roads (R3), Collector roads (R4) and Local roads (R5) in four rural communities in the KwaZulu-Natal Province, South Africa. The function of these road classes is to provide access from homesteads to main roads that connect rural areas to towns. In this study, two classification methods were used to rate the severity and extent of each surface distress on each road class. Results indicate that there was more than one surface distresses identified and assessed on each road class within the selected communities. It was noted that all the road classes had moderate to severe surface distress, except for the R3 road class in Emazabekweni community, reflecting problems associated with poor drainage systems and maintenance. Visual observation and field-based methods are useful tools that can aid in identifying and assessing the physical conditions of unpaved roads, as well as possible environmental, physical and anthropogenic factors at interplay, especially in resource limited regions. This study recommended that road authorities should ensure that proper drainage systems should be well designed; constructed and maintained on all gravel roads in order to reduce surface deterioration associated with runoff.

Anaerobic digestion has been identified as a feasible fragment of a bioeconomy, yet numerous factors hinder the adoption of the technology in South Africa. Apart from its energy recovery, other nonmarket advantages support the technology. Though it may be challenging to have a price tag, they provide clear added worth for such investments. With a growing energy demand and global energy transitions, there is a need to sustainably commercialise the biogas industry in South Africa. Most studies are at laboratory scale and under specific conditions, which invariably create gaps in using their data for commercialising the biogas technology. The key to recognising these gaps depends on knowing the crucial technical phases that have the utmost outcome on the economics of biogas production. This study is a meta-analysis of the optimisation of anaerobic digestion through methodological approaches aimed at enhancing the production of biogas. This review, therefore, argues that regulating the fundamental operational parameters, understanding the microbial community’s interactions, and modelling the anaerobic processes are vital indicators for improving the process stability and methane yield for the commercialisation of the technology. It further argues that South Africa can exploit water hyacinth as a substrate for a self-sufficient biogas production system in a bid to mitigate the invasive alien plants.