Grey2Green
A Circular Approach to Greywater Reuse and Nutrient Recovery
PLENTY is a Centre for a Symbiotic and Circular Food Provisioning based at KTH, which aims to transform the food system by turning underutilized side streams and waste into valuable resources for food production. By integrating technological innovation, systemic analysis, and societal perspectives, the project promotes a resilient, circular, and resource-efficient food system that enhances sustainability, competitiveness, and preparedness.
As part of this effort, the Grey2Green project explores the potential of greywater as a resource for nutrient and water recovery. Greywater, a relatively underutilized household wastewater stream, is generated from activities such as showering, washing, and cooking. This means that it contains organic matter and essential nutrients like nitrogen and phosphorus, making it a promising candidate for circular reuse. Thus, in this project, greywater will be collected directly from the KTH Live-In Lab, providing a real-life urban sample for experimental work. The work includes comprehensive characterization of the collected greywater (e.g., physicochemical properties, nutrients, contaminants, and microorganisms), followed by the investigation of innovative pathways for resource recovery, both from a process design and experimental validation perspective. These include the production of solid fertilizers (e.g., struvite), liquid nutrient solutions, and reusable irrigation water.
By linking real-world greywater streams to advanced recovery technologies, the project aims to demonstrate how urban water systems can be integrated into circular food production. Ultimately, Grey2Green contributes to PLENTY’s vision by closing nutrient and water loops, reducing environmental impacts, and unlocking new sustainable resource pathways within cities.
