Non-conventional water reuse in agriculture: A circular water economy

Due to the growing and diverse demands on water supply, exploitation of non-conventional sources of water has received much attention. Since water consumption for irrigation is the major contributor to to-tal water withdrawal, the utilization of non-conventional sources of water for the purpose of irrigation is critical to assuring the sustainability of water resources. Although numerous studies have been conducted to evaluate and manage non-conventional water sources, little research has reviewed the suitability of available water technologies for improving water quality, so that water reclaimed from non-conventional supplies could be an alternative water resource for irrigation. This article provides a systematic overview of all aspects of regulation, technology and management to enable the innovative technology, thereby promoting and facilitating the reuse of non-conventional water. The study first reviews the requirements for water quantity and quality (i.e., physical, chemical, and biological parameters) for agricultural irriga-tion. Five candidate sources of non-conventional water were evaluated in terms of quantity and qual-ity, namely rainfall/stormwater runoff, industrial cooling water, hydraulic fracturing wastewater, process wastewater, and domestic sewage. Water quality issues, such as suspended solids, biochemical/chemical oxygen demand, total dissolved solids, total nitrogen, bacteria, and emerging contaminates, were assessed. Available technologies for improving the quality of non-conventional water were comprehensively investi-gated. The potential risks to plants, human health, and the environment posed by non-conventional water reuse for irrigation are also discussed. Lastly, three priority research directions, including efficient collec-tion of non-conventional water, design of fit-for-purpose treatment, and deployment of energy-efficient processes, were proposed to provide guidance on the potential for future research. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This article focuses on evaluating and managing non-conventional water sources to improve water quality and discuss the importance of sustainability for irrigation water resources. The study identifies five non-conventional water sources and discusses water quality issues and technologies for improving water quality. Finally, potential future research directions are proposed.