Microplastic-Filtering Living Facades for Urban Stormwater and Air Bioremediation

Abstract

Urban environments face escalating air and stormwater contamination, requiring decentralized and multifunctional remediation solutions. This study investigates an integrated microplastic-filtering and air bioremediating living facade prototype that simultaneously treats polluted urban air (PM2.5, CO₂, VOCs) and rainfall-driven runoff containing microplastics, heavy metals, and toxic chemicals. The specific objectives were to quantify microplastic interception, evaluate facade-enabled air purification under extreme gas loads, and assess microclimate and ecological co-benefits. The methods include layered physical filtration with adsorption media (mesh screens, electrospun nanofiber membranes, biochar, and hydrophobic polymer traps), facade phytoremediation synergized with rhizosphere microbial degradation, microscopy-based contaminant quantification, hydrological monitoring, and thermal gradient assessment. Results confirm 96% microplastic removal in stormwater, leaving 25 particles per sample unit from the untreated baseline. Mixed contaminant mass (heavy metals, toxic chemicals, and microplastics) was reduced by 82%, yielding a 34% residual pollutant load. Air purification trials under extreme contamination stress (>281% above safe limits) achieved a 34% reduction in pollutant gases, with upward release of oxygen-enriched air as ecological feedback. The facade exhibited a 7 °C surface cooling gain (from 32 °C to 25 °C) and an overall 10 °C urban-to-facade microclimate differential. The system satisfies pollutant-reduction objectives while delivering measurable cooling and vertical habitat enhancement, demonstrating feasibility of building-integrated vegetation biofilters as decentralized green infrastructure for cleaner, cooler, and ecologically enriched cities.