Urban Green Infrastructure for Safe Greywater Treatment and Reuse

Green4Grey är ett internationellt forskningsprojekt som syftar till att utveckla och implementera decentraliserade,
naturbaserade system för säker behandling och återanvändning av gråvatten i urbana miljöer. Gråvatten, det vill
säga vatten från dusch, disk och tvätt, utgör cirka 65 % av det totala hushållsavloppet och är en värdefull resurs
om det kan renas och återanvändas lokalt. Projektet svarar på utmaningar som vattenbrist, klimatförändringar,
ökande belastning på central infrastruktur och begränsningar i dagens regelverk.
Som testbäddar används fem pilotområden i vitt skilda klimat och stadsmiljöer: Haifa (Israel), Heraklion
(Grekland), Prag (Tjeckien), Valencia (Spanien) och Florianópolis (Brasilien). I varje pilot anpassas och
utvärderas olika tekniker – gröna tak, permeabla ytor, konstruerade våtmarker och lokala reningsenheter – för
att både rena och återcirkulera gråvatten och regnvatten i byggnader och stadslandskap.

The growing challenges of water scarcity, climate variability, and urbanization demand innovative approaches to urban water management.
Decentralized and nature-based solutions (NbS) are emerging as key strategies to enhance urban water circularity, leveraging untapped resources
such as greywater and rainwater. Despite the global potential for water reuse, its application in urban contexts remains limited due to regulatory,
technical, and societal barriers. Green4Grey aims to address these challenges by advancing decentralized NbS for greywater treatment and reuse,
promoting resilience and sustainability in urban environments.
The project follows two complementary approaches: a top-down framework to establish best practices for integrating decentralized systems with
centralized infrastructure, and a bottom-up, multi-actor approach to tailor these solutions to local needs and foster stakeholder buy-in. Central to
Green4Grey are four pilot projects in Haifa (IL), Heraklion (GR), Prague (CZ), Valencia (ES), and Florianópolis (BR), representing diverse climates,
urban infrastructures, and regulatory environments. These pilots will serve as real-world testbeds for NbS, providing valuable insights into their
adaptability and performance across various contexts.
The project is structured into five interconnected work packages. WP1 develops City Information Models (CIMs) to assess and map non-conventional
water resources, optimizing NbS placement for maximum impact. WP2 focuses on designing and testing NbS in pilot sites, while WP3 establishes a
comprehensive risk assessment framework to ensure environmental and health safety. WP4 implements IoT-based monitoring and control systems,
enabling real-time adjustments and enhancing system efficiency. WP5 emphasizes dissemination and stakeholder engagement, ensuring knowledge
transfer and promoting the widespread adoption of project outcomes.
By addressing both technical and societal challenges, Green4Grey will deliver scalable and replicable solutions for urban water circularity. The project
is expected to reduce freshwater withdrawals, improve water quality, and enhance urban resilience, offering a significant contribution to sustainable
urban water management globally. Additionally, its outcomes will inform policy frameworks, foster public acceptance of water reuse technologies, and
provide a foundation for future research and innovation.