This project explores the potential of a specific type of natural-based decentralised wastewater treatment solution in a fast-growing area: Campbelltown local government area (LGA), Sydney, with a focus on experimental design based on different densification scenarios and centralisation level of treatment scheme. The analysis and design are carried on for three scales: Greater Sydney area, Campbelltown LGA, and two samples sites in the city centre of Campbelltown LGA. for Greater Sydney area, the design is revealed as a long-term and all-rounded proposal; for the main city centre of Campbelltown LGA, the design focuses on the redevelopment and functional division of its main water bone Bowbowing Creek to serve as a treatment media. In order to experiment the schemes in detail, Leumeah centre and Campbelltown centre are designed with 6 scenarios (2 densification scenarios x 3 levels of treatment centrlisation) for each site.

The results are evaluated with the same criteria, which reveals the feasibility, pros and cons of each scenario while confirming the possibility of implementing decentralised wastewater treatment in this area although it does not bring out the same performance for all the scenarios. Further research can be carried out to simulate the long-term performance of the schemes and to test the performance with different technical components of DEWATS for the locations.

Different government bodies, from the European Union down to the Port of Rotterdam Authority have implemented the policy goal to become circular by 2050 to minimize demand and dependence on finite resources. However, a circular economy - an economic model in which materials circulate in closed loops and waste is viewed as a resource - is vastly different from the current linear system of extraction, consumption and waste. The plastics industry that is currently present in the port of Rotterdam is one such industry where large amounts of raw material is being used and large amounts of waste generated. It is still far from circular. Thus, transitions in the industry itself and in our interaction with products are necessary. The question that arises is: how can the transition to circular plastic manufacturing in the Rotterdam maritime region contribute to a more sustainable, resilient and just economy?

Theory on transition management and socio-technical systems, analyses of spatial use and networks of the plastics industry in South Holland, and research on the developments in plastic manufacturing, has led to the understanding of the current networks and flows in the plastics industry. A subsequent analysis of stakeholders, policies and design options has led to a vision and strategy for the South Holland region, on how to shape a new circular plastics economy.

In the proposed strategy of Plasticity, (1) the strength of a strategic location in the port of Rotterdam is used to expand the renewable cycle of the bioplastics industry, and (2) by actively engaging citizens in reusing and recycling plastic products on a local level in the whole region, a technical circular cycle is enhanced in the whole province. Plastic is used as an example to demonstrate the contemporary issues around dependency on fossil material in the South Holland context, but similar principles regarding integrating the biological and technical cycle, facilitating space for innovation and growth of circular models, and engaging the whole socio-technical system in the transition process can be applied to other sectors and places. This expands the applicability of this vision and strategy beyond plastic.