Abstract
Urban water managers around the world are adopting decentralized water supply systems, often in combination with centralized systems. While increasing demand for water arising from population growth is one of the primary reasons for this increased adoption of alternative technologies, factors such as climate change, increased frequency of extreme weather events and rapid urbanization also contribute to an increased rate of adoption of these technologies. This combination of centralized-decentralized water systems approach is referred to as “hybrid water supply systems” and is based on the premise that the provision of alternative water sources at local scales can both extend the capacity of existing centralized water supply infrastructures, and improve resilience to variable climatic conditions. It is important to understand, however, that decentralized water production and reuse may change the flow and composition of wastewater and stormwater, thereby potentially also having negative impacts on its effectiveness and performance. This paper describes a framework to assess the interactions between decentralized water supply systems and existing centralized water servicing approaches using several analytical tools, including water balance modelling, contaminant balance modelling and multi-criteria decision analysis. The framework enables the evaluation of impacts due to change in quantity and quality of wastewater and stormwater on the existing centralized system arising from the implementation of hybrid water supply systems. The framework consists of two parts: (1) Physical system analysis for various potential scenarios and (2) Ranking of Scenarios. This paper includes the demonstration of the first part of the framework for an area of Melbourne, Australia by comparing centralized water supply scenario with a combination of centralized water supply and reuse of treated waste water supply scenario.
Highlights
In most cities around the world, water services systems are mainly centralized
These results show that when population increases, contaminant concentration in of Tables A2 and A4 climate change has no significant effects on the contaminant concentration the wastewater increases in the centralized system
This study presents an evaluation framework coupled with water and contaminant balance modelling, future scenario analysis and multi-criteria decision analysis to assess the interaction between centralized and decentralized water systems
Summary
In most cities around the world, water services systems are mainly centralized. This is partly due to historical reasons, and in part due to the maturity of the technology and the opportunities for economics of scale. In the last 20 years, many alternative (non-traditional) water supply options like rainwater, stormwater and recycled water have emerged The combination of such decentralized water supply options with centralized system which is defined as hybrid water supply systems by Sapkota, et al [4], have displayed potential to meet the increasing water demand [11,12]. To ensure the smooth and effective implementation of hybrid water supply systems, it is necessary to evaluate their impacts on the existing wastewater and stormwater system. There is a need of comprehensive methodology for assessing conjointly the full range of technological alternatives the existing frameworks evaluate the environmental impacts of hybrid systems, they do available. The inanalysis is study together with an expanded description of the evaluation of hybrid water supply systems and based on analytical approaches to assist in understanding the interaction between centralized and some modifications of the methodology.
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