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The impact of landfills on the environment has come under increasing scrutiny in recent years due to the confounding effects of climate change and water scarcity. There is an urgent need to reduce from landfills the greenhouse gas emissions that cause climate change, and to provide effective treatment solutions for waste, thereby diverting it from landfills. With an estimated 80 million tonnes of plastic waste entering the world's oceans annually, the accumulation of marine plastic has become a global crisis. Plastic pollution threatens food safety and quality, human health and coastal tourism, and contributes to climate change. For these reasons, there is an urgent need to explore a bioplastic biorefinery process. This review paper examines the potential of organic waste as an alternative carbon source in the efficient and feasible microbial production of polyhydroxyalkanoate (PHA) and polyhydroxybutyrate (PHB), which are precursors for bioplastic. More specifically, this paper presents a concept for a bioplastic biorefinery from a technological perspective, based on data from previous studies. Biofuel production processes are also assessed with the aim of integrating these processes to construct a bioplastic waste biorefinery. Garden refuse and food waste have been shown to be feasible feedstocks for the production of PHA and PHB in singular processes. Diverting these wastes away from landfills will significantly ease the environmental impacts currently associated with their disposal. [ABSTRACT FROM AUTHOR]

The transition towards a circular economy is becoming a priority in many countries globally. However, the circular bioeconomy has received relatively less attention. In South Africa, the valorisation of organic waste is a priority area as demonstrated by national goals to divert organic waste from landfill. To support the growth of the organic waste value chain it is important to gain an understanding of the different value chain actors and their activities. Through a series of semi-structured interviews across the industry, this paper unpacks the organic waste value chain including the roles of different actors and the interlinkages amongst them. Interviewed actors were those involved in the waste treatment sector, including consultants, composters and technology providers and installers. The value chain is characterised by a number of partnerships, including sub-contracting and outsourcing, which enable value chain actors to offer services that they do not necessarily have the in-house skills or capacity to deliver on their own. The majority of actors were not directly engaged in activities related to the treatment of waste, with many of them engaging in support activities to facilitate the treatment of waste. This finding may be attributed to the fact that support activities have relatively lower barriers to entry. This has the potential to create a bottleneck, in which there will be limited capacity for waste treatment as new entrants opt for engaging in support activities. Greater investment is needed from both private and public sources in the waste treatment sector, including support for new entrants. This investment will help enable the country to meet its goals for organic waste diversion whilst contributing to job creation. [ABSTRACT FROM AUTHOR]