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MPhil in Engineering for Sustainable Development

global challenges, engineering solutions

Studying at Cambridge

Daniel Clayton

Water and the Circular Economy
Population growth, urbanisation, industrialisation, intensifying food production and climate change are contributing to the depletion and degradation of water supplies, other finite metal and mineral reserves, ecosystem services and human health. The process of ‘take, make, dispose’ associated with our economy is unsustainable, and so a circular alternative has been proposed.
The concept of a circular economy has been written about extensively, but its application to water is relatively new. This project explores the implications of the circular economy on the water sector. First, the concept itself is reviewed, including where it came from, what it means, and what its main criticisms are. It is stressed that – despite its popularity – this is a concept without a singular definition, and certainly without universal support.
Second, its suitability for adoption by the water industry is explored. It is argued that the salient opportunity for application is to the fluxional (rather than sunk) resource flows through the sector. To this end, three of the most important of these resource flows – water, energy and phosphorus – are considered. For each, an extensive analysis is set out, including how these resource flows are currently being managed within the sector, what their management would look like through the lens of a circular economy, and what the major barriers would be to getting there. It is argued that the future of water resource flows within a circular economy is one of high-grade reuse and extensive demand reduction. The future of energy resource flows is one of full decarbonisation, or energy neutrality. The future of phosphorus resource flows is commercial recovery, which means enhanced biological separation, followed by chemical precipitation as struvite.
These analyses are then used to inform a backcasting exercise, broadly following the methodology developed in the 1970s by Amory Lovin. This focuses explicitly on the water sector in the UK. The exercise begins with an assessment of the water sector of today, before setting out a vision of a 2050 water sector, in the image of a circular economy. This is a sector wherein bulk water is supplied fit for general use, and treated to drinking standards at destination. Asset managers are fully exploiting data analytics, resulting in marked reductions in leakage. As a result of widespread efficiencies and high-grade water reuse, demand across all sectors is significantly reduced. Storm water and contaminants have been eliminated from the sewer system. Wastewater treatment is primarily anaerobic, and supports wholesale commercial recovery of nutrients. The industry has achieved energy neutrality, thanks in large part to developments in biogas generation. Asset recovery hubs have been established, allowing for mechanical and electrical kit to be more effectively reused.
Each aspect of this vision is then scrutinised, yielding a set of actions aimed at achieving the transition from the water sector of today to that of the 2050 vision. Actions are categorised by type (technological, political, legislative and so on), and an attempt is made to assign ownership to each category, and to put a broad timescale to them.
Amongst many others, it is argued that actions which will enable, or disable, the transition include the implementation of a shadow price for water, the development of a regulatory environment which incentives water managers to overcome the impasse associated with so-called sunk infrastructure and to pursue innovations, the implementation of mandated emissions targets for the sector, and the development of a market for organic phosphorus which enables investors to achieve cost recovery.
The actions identified are not intended to delineate a hard-and-fast transition. It is highlighted that water management is an intrinsically local activity, and that different utilities’ action plans must reflect this.  It is hoped that this report, and the actions set out within it, contribute to the conversation over what these plans might look like.