The importance of system configuration for distributed direct potable water reuse

Abstract

Water and wastewater infrastructure worldwide faces unprecedented demand and supply conflicts that require unconventional solutions. In this study, we develop a novel modelling framework to assess the environmental and economic implications of a hybrid water supply system that supplements a centralized surface water supply with distributed direct potable reuse (DPR) of municipal wastewater, as a strategy to address such challenges. The model is tested with real water and wastewater systems data from the City of Houston, Texas. Results show that supplementing the conventional centralized water supply with distributed DPR would reduce water age in the drinking-water distribution network and hence improve water quality; properly designed system configurations attain system-wide net energy savings even with the high energy consumption of existing technologies used for advanced treatment of the wastewater. A target energy efficiency for future advanced treatment technologies is identified to achieve net energy saving with all hybrid system configurations. Furthermore, distributed DPR remains financially competitive compared with other unconventional water supply solutions. The modelling framework and associated databases developed in this study serve an important research need for quantitatively characterizing distributed and hybrid water systems, laying the necessary foundation for rational design of integrated urban water systems.

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Fig. 1: Schematic representation of the modelled water and wastewater system.
Fig. 2: Water age difference between no water reuse (Baseline) and full implementation (All open).
Fig. 3: Changes in electric energy consumption (mid case) from the Baseline over a 24 h simulation period.
Fig. 4: Percentage of distributed DPR system configurations that keep energy consumption lower than Baseline as a function of WWTP energy intensity.
Fig. 5: Changes in annual financial costs (US$20181 million) from the Baseline.
Fig. 6: Difference in electric energy consumption versus additional financial costs identified by reclaimed water percentage.

Data availability

The data that support the findings of this study are available from Houston Public Works, but restrictions apply to the availability of these data, which were used under license for the current study and so are not publicly available. Data are, however, available from the authors upon reasonable request and with permission of Houston Public Works.

Code availability

The software and custom-developed code for this study are available from the corresponding author upon request.

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Acknowledgements

We acknowledge funding from the National Science Foundation (award no. CBET-1707117), NSF Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (ERC-1449500) and the National Natural Science Foundation of China (no. 51761125013). Part of the data used in this study was shared by Houston Public Works. The authors thank M. Ramon, P. Pradhan and F. Rabbi from Houston Public Works for data support and valuable technical discussions.

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All authors contributed intellectual input to this study. L.L., L.D.-O., L.S. and Q.L. designed the study, L.L. performed all analyses and worked with E.L. in configuring the model. L.D.-O., L.S., E.L., Y.X., P.J.J.A. and Q.L. worked on revising the manuscript. All authors contributed to the discussion of the results.

Corresponding author

Correspondence to Qilin Li.

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Supplementary Figs. 1–14, Tables 1–8 and Notes 1–4.

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Liu, L., Lopez, E., Dueñas-Osorio, L. et al. The importance of system configuration for distributed direct potable water reuse. Nat Sustain 3, 548–555 (2020). https://doi.org/10.1038/s41893-020-0518-5

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