Water circularity index: A novel approach for authorities and operators

Area of Science:

• Environmental Science
• Water Resource Management
• Circular Economy

Background:

• Conventional water use efficiency frameworks often overlook the interconnectedness of water quantity and quality.
• Optimizing water's added value and environmental protection requires a holistic approach to the water cycle.
• Existing metrics may not fully capture the complexities of water management in industrial and urban settings.

Purpose of the Study:

• To introduce an innovative metric, the Water Circularity Index (I_C), for assessing water quantity and quality balance.
• To evaluate the index's versatility across diverse industrial sectors and urban wastewater treatment plants.
• To demonstrate the index's utility in promoting best practices and evaluating environmental permit transitions.

Main Methods:

• Development of the Water Circularity Index (I_C) using Multi-Criteria Decision Analysis.
• Inclusion of eleven key factors: freshwater consumption, wastewater discharge, reuse, management practices, hazardous substances, microplastics, biodiversity, nutrient recovery, industrial symbiosis, sludge management, and incentive instruments.
• Application of the I_C to fourteen installations across seven countries, with a case study at a pulp mill.

Main Results:

• The Water Circularity Index (I_C) effectively categorizes water circularity into five levels: negative, no, low, medium, and high.
• The index demonstrated versatility across various industrial sectors and urban wastewater treatment plants.
• A pulp mill case study showed a significant improvement from negative to medium circularity after revising its environmental permit and adopting integrated water management.

Conclusions:

• The Water Circularity Index (I_C) provides a comprehensive tool for evaluating and enhancing water circularity in industrial and urban contexts.
• Integrated water management approaches, supported by metrics like I_C, are crucial for achieving circular economy goals.
• The study highlights the potential for substantial improvements in water management performance through strategic permit revisions and best practice implementation.