Energy Sensitive Urban Water Planning in Developing Countries: Unlocking the Potential of Distributed Recycled Water Systems to Reduce the Overall Energy Intensity for Urban Water Services

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Energy is a significant operational expense for most water utilities, particularly in developing countries. The current linear approach to water management will further increase the overall energy intensity (kWh/kL) for water services as rapidly growing cities move towards remote sources of water, desalination or deep groundwater abstraction, all of which are energy intensive. This thesis firstly investigates the potential for distributed recycled water systems (decentralised systems connected to centralised systems) to reduce the overall energy intensity of urban water and wastewater systems in a developing country context. The literature review revealed that the energy intensity of treatment plants decreases with the increase in capacity. It was found that in most cases, the existing recycled water schemes treat water to a higher level than required for a particular end-use, so the energy intensity could be further reduced if ‘fit for purpose’ water were produced. Using Bengaluru as a case study, a water mass balance was prepared under the Urban Metabolism Framework, which demonstrated that in 2016/17, the recycled water in Bengaluru had the potential to replace 90% of the extracted water from the Cauvery River (1323 MLD), which is pumped more than 100km. Using energy density mapping based on primary sourced data and following the water use cycle, the average energy intensity of centralised water and wastewater services across all the service zones was 2.1 kWh/kL and for water supply only was 1.8 kWh/kL. In the case study, distributed recycled water systems were demonstrated to offer a viable means for reducing the overall energy intensity for water services. The model analysis revealed that for a specific selected zone, the energy intensities varied from 0.83 to 1.64 kWh/kL for potable water supplies, and 0.38 to 1.10 kWh/kL for non-potable water supplies, depending on the size of the plant and the technology used – all of which have lower energy intensities than the energy intensity for the selected zone (2.03 kWh/kL) and also the average energy intensity of the centralised water services. These energy intensities were also found to be lower than the energy intensity for the proposed Indirect Potable Reuse Scheme and the new long distant water transfers. The second objective was to investigate how the challenges and barriers of distributed recycled water systems could be overcome using the One Water framework. From the case study findings based on semi-structured interviews, an institutional framework has been proposed that provides for both internal (e.g. strong leadership, knowledge, less political interference) and external reforms (e.g. regulators and policy, pricing reform, external engagement and collaboration) in a developing country context. The findings of this research demonstrates the potential of distributed recycled water systems to reduce the overall energy intensity for urban water services, thereby making urban water service systems potentially more cost efficient, sustainable and resilient.
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