An estimate of construction and demolition waste quantities and composition expected in South Africa

Construction and demolition (C&D) waste is generated from the construction, renovation, repair and demolition of the built environment. It is one of the largest waste streams and is generally not well documented or understood. Various methods for estimating C&D waste are reviewed, and the development of two methods for estimating C&D waste quantities and composition generated in South Africa is discussed. The lifetime method is based on current production quantities of key construction materials and their typical stock life. This is contrasted with the scale-up of a pocket of reasonably good statistics for Cape Town’s C&D waste on a per-capita basis to determine totals for South Africa. The lifetime method yielded a result of 20.2 Mt of potential C&D waste generated in South Africa in 2017, while the per-capita method suggests that 10.8 Mt of C&D waste reached disposal sites. These quantities are much higher than the 4.48 Mt reported in official national statistics for 2017. It is important to understand and accurately quantify C&D waste in South Africa so that effective waste management can be implemented. Specifically, the reuse of C&D waste needs to be understood, as this takes precedence over recycling or downcycling according to circular economy principles. Overall, this research highlights that C&D waste quantities in South Africa appear to be considerably underreported, undermining attempts to introduce more sustainable waste management practices.Significance:• The results of both methods used in this study were significantly higher than reported in official South African statistics, indicating considerable underreporting in national databases as in most waste statistics worldwide.• The informal sector is plausibly an intensive reuser of discarded building materials and demolition products from the formal sector. The omission of these informal waste management practices is a likely contributor to the difference between the official statistics and both estimates.• It is important to accurately quantify this waste stream as this can contribute to increasing materials circularity in South Africa and lower environmental impact through the achievement of circular economy goals

What material flow analysis and life cycle assessment reveal about plastic polymer production and recycling in South Africa

Global production and consumption of plastics have increased significantly in recent years. The environmental impacts associated with this trend have received growing attention internationally with single-use plastic packaging responsible for most plastic pollution. Locally, the SA Plastics Pact, the Industry Master Plan, and the National Waste Management Strategy all aim to transform the current linear sector model into a circular system by setting targets for increased collection and recycling rates and recycled content. However, the associated impacts of implementing such circular interventions have not yet been assessed across the plastics life cycle. Industrial ecology tools, material flow analysis and life cycle assessment, are used to generate mass-based indicators as well as indicators of climate damage in the form of the global warming potential. The carbon footprint of the South African plastics value chain from cradle to grave was estimated at 17.9 Mt CO2eq emissions in 2018, with 52% of these due to the local coal-based monomer production process. The end-of-life stage lacks proper waste collection for a third of the population, but contributes only 2% to the total greenhouse gas emissions, with recycling having a minimal environmental impact. Future projections of plastics production, use, disposal, and recycling for 2025 show that increasing mechanical recycling rates to achieve stated targets would start to have a significant effect on virgin polymer demand (in the order of several billion rands of sales annually) but would also reduce waste disposal by 28% relative to baseline growth and 18% below values calculated for 2018.Significance:• Despite increased attention, the flows and resulting life cycle-based carbon footprint of the plastics sector have not been evaluated on a local scale.• The carbon footprint of the South African plastics industry is sizeable at almost 18 Mt CO2eq per annum with emissions strongly associated with the linear rather than the circular stages of the value chain.• The impacts of a key circular economy intervention, namely increased recycling rates to achieve set targets include demand reduction for virgin polymer to the tune of several billion rands

A review of assessments conducted on bio-ethanol as a transportation fuel from a net energy, greenhouse gas, and environmental life cycle perspective /

Abstract Interest in producing ethanol from biomass in an attempt to make transportation ecologically sustainable continues to grow. In recent years, a large number of assessments have been conducted to assess the environmental merit of biofuels. Two detailed reviews present contrasting results: one is generally unfavourable, whilst the other is more favourable towards fuel bio-ethanol. However, most work that has been done so far, to assess the conversion of specific feedstocks to biofuels, specifically bio-ethanol, has not gone beyond energy and carbon assessments. This study draws on 47 published assessments that compare bio-ethanol systems to conventional fuel on a life cycle basis, or using life cycle assessment (LCA). A majority of these assessments focused on net energy and greenhouse gases, and despite differing assumptions and system boundaries, the following general lessons emerge: (i) make ethanol from sugar crops, in tropical countries, but approach expansion of agricultural land usage with extreme caution; (ii) consider hydrolysing and fermenting lignocellulosic residues to ethanol; and (iii) the LCA results on grasses as feedstock are insufficient to draw conclusions. It appears that technology choices in process residue handling and in fuel combustion are key, whilst site-specific environmental management tools should best handle biodiversity issues. Seven of the reviewed studies evaluated a wider range of environmental impacts, including resource depletion, global warming, ozone depletion, acidification, eutrophication, human and ecological health, smog formation, etc., but came up with divergent conclusions, possibly due to different approaches in scoping. These LCAs typically report that bio-ethanol results in reductions in resource use and global warming; however, impacts on acidification, human toxicity and ecological toxicity, occurring mainly during the growing and processing of biomass, were more often unfavourable than favourable. It is in this area that further work is needed. Published by Elsevier Ltd

A technological and economic exploration of phosphate recovery from centralised sewage treatment in a transitioning economy context

Phosphate is one of the substances which wastewater treatment works (WWTW) have to lower in order to meet the South African regulatory discharge standard of 1 mg/L. Wastewater is increasingly viewed as a ‘water-carried waste’, presenting opportunities for resource recovery. South Africa has commenced its transition to a low-carbon and resource-efficient economy, all whilst it struggles to provide universal access to basic needs and is faced with massive infrastructure maintenance as well as upgrading backlogs in the sanitation sector in particular. Although phosphate recovery methods exist, there is little evidence to indicate that these techniques would be economically viable or socially accepted in South Africa. This paper explores the potential for centralized recovery of nutrients, through the conceptual design and techno-economic pre-feasibility assessment of two phosphate recovery options, at the largest WWTW in the Western Cape, South Africa. This assessment revealed that the digestate stream at the 200 ML/d Cape Flats WWTW (CFWWTW) has the potential to produce ~470 kg/d of struvite fertilizer, whilst recovering 4–8% of the plant’s costs in 20 years. When contrasted with the more familiar, yet less sustainable, chemical precipitation process, low-grade and high-grade struvite production establishment costs are 10 and 25 times higher, respectively. Still, to reduce effluent phosphate loading to within regulated standards, the low-grade struvite production option at an estimated net present cost of R25.4 million over a 20-year lifetime is more affordable than chemical precipitation at a net present cost of R51.2 million. Low-grade struvite production is thus concluded to be technically feasible and the economically most affordable option from a lifecycle-costs perspective. Although it is a simple process, it is not cheap. Municipalities will need to consider the lower operating costs, as well as the environmental benefit of producing a useful phosphate fertilizer, over the immediate capital investment, if they decide to install such an operation.Keywords: nutrient recovery; struvite; techno-economic assessment; phosphate recovery; South Afric

Life cycle inventories to assess value chains in the South African biofuels industry

The South African government ratified a new biofuels industrial strategy at the end of 2007. The feasibility study that forms the basis of the strategy highlights the potential environmental implications of such a strategy. However, at present there is no structured approach to evaluate the environmental profile of the scenarios within the strategy. This paper introduces life cycle inventories whereby the environmental profiles of biofuel value chains may be evaluated meaningfully. The scope of the paper focuses on the seed extraction biodiesel production scenarios of the strategy. The inventory analysis shows that the inputs and outputs of the farming unit process are sensitive to the type of crop and region of produce. Water usage is a highly variable parameter, which emphasises the importance of rainfall and irrigation to the overall burden of the biodiesel system on water resources. Crop yields may differ by a factor of two, which is a significant difference in terms of land and non-renewable energy resources requirements. The oil and meal/cake content of the seed proves to be the most important parameter that influences the initial unit processes of the value chains; almost all the inputs and outputs of the farming unit processes, for all the crops, range in the order of a factor of two due to this parameter. The uncertainties associated with the logistic system in the value chain also have major implications. Further, should there be no market offset for the meal/cake co-products, the waste treatment requirements would be highly uncertain. Very little uncertainties were detected in the biodiesel production unit process, although the energy efficiency, and sustainability, of the overall production system remains questionable. The paper identifies a number of limitations with inventory sets that need to be addressed through further research efforts to improve the environmental evaluations of a biofuel value chain in South Africa for policy-making purposes

Stakeholder collaboration and learning during the concept design phase of an urban biogas project

Anaerobic digestion (AD) of organic matter to produce biogas is a waste management option for waste streams high in organic matter which are unsuitable for thermal treatment. In Africa, the implementation of this technology is slow compared to developed countries, more so in the urban areas in contrast with rural areas. An understanding of factors behind the low rate of implementation of this technology is needed. As a response to this challenge a research group at the University of Cape Town (UCT) set-up a multi-disciplinary team to implement a biogas digester on the UCT campus as a demonstration project. This paper aims at documenting notes on stakeholder collaboration and learning during the concept design phase to implement an urban biogas project. One of the findings of the project thus far is that a significant proportion of time needs to be dedicated to establishing key stakeholders and decision makers. Education, training and good relationship with stakeholders and the technology provider were also found to the important in the concept design of the project

Technologies for recovery of energy from wastewaters: Applicability and potential in South Africa

This study explored technologies for recovering energy from wastewater through production of biomass, combustion and gasification, generation of biogas, production of bioethanol, heat recovery and microbial fuel cells. A first order desktop analysis of the potential for applying these solutions to wastewaters in South Africa revealed that 3 200 to 9 000 MWth of energy has potential for recovery, equating to at most 7% of South Africa’s current electrical power supply. Formal and informal animal husbandry, fruit and beverage industries and domestic blackwater were identified as wastewaters with the greatest potential for energy recovery. Of the reviewed technologies, anaerobic digestion shows applicability to the widest range of feedstocks. Net energy generated, reduction in pollution, and water reclamation are identified as the main benefits, but additional benefits such as certified emission reductions, fertiliser production and the production of secondary products may dictate the economic feasibility

Technologies for recovery of energy from wastewaters: Applicability and potential in South Africa

This study explored technologies for recovering energy from wastewater through production of biomass, combustion and gasification, generation of biogas, production of bioethanol, heat recovery and microbial fuel cells. A first order desktop analysis of the potential for applying these solutions to wastewaters in South Africa revealed that 3 200 to 9 000 MWth of energy has potential for recovery, equating to at most 7% of South Africa’s current electrical power supply. Formal and informal animal husbandry, fruit and beverage industries and domestic blackwater were identified as wastewaters with the greatest potential for energy recovery. Of the reviewed technologies, anaerobic digestion shows applicability to the widest range of feedstocks. Net energy generated, reduction in pollution, and water reclamation are identified as the main benefits, but additional benefits such as certified emission reductions, fertiliser production and the production of secondary products may dictate the economic feasibility

Regional Mineral Beneficiation Policy Interventions in the SADC: Stakeholder Perspectives

The Importance of Mineral Beneficiation: Mining is a significant economic activity in most Southern African Development Community (SADC) countries, and mineral beneficiation has been identified and controversially discussed as one of the possibilities for industrialisation. The purpose of this article is to study mineral beneficiation policies and practices in the SADC countries with regard to the regional developmental agenda. Methodology and Interventions: With many member countries being economically too small to muster the human and financial resources, the recently adopted Regional Mining Vision (RMV) envisages interventions at a regional level. This study followed a qualitative approach with semi-structured interviews across the region mainly in English and seldom in French. Principal Results: Twenty-five semi-structured interviews were conducted with experts from SADC member countries during the 2019 Mining Indaba. Participants were divided on whether beneficiation should be carried out nationally or in the SADC region. While beneficiation could support value-keeping, key challenges named were infrastructure development (i.e. energy, water), scarce skills, access to technology and related cost, but also lack of free trade and movement. Conclusion: We submit that a more integrated beneficiation strategy for the SADC region, as was being developed through the RMV, would indeed be relevant in the future