Biochar-amended biofiltration system for stormwater nutrient removal

Overview

This solution addresses the growing challenge of nutrient pollution in stormwater runoff by integrating biochar into biofiltration systems. Total nitrogen and phosphorus—primarily in the form of ammonia and phosphate ions—are major contributors to water quality degradation in receiving water bodies. Biochar, a carbon-rich material produced from biomass pyrolysis, offers high surface area and sorption capacity for these nutrients. When incorporated into biofiltration media, biochar captures ammonia and phosphate ions on its surface and creates favorable conditions for microbial communities to further degrade them. The result is a passive, low-energy treatment approach suitable for urban stormwater infrastructure, parking lot drainage, and green infrastructure projects.

Technical specifications

Core mechanism:

• Biochar acts as a high-capacity sorbent for ammonia and phosphate ions due to its porous structure and surface chemistry
• Adsorbed nutrients are degraded by native microbial communities that colonize the biochar surface within the biofiltration system
• Biochar amendment is dosed at variable rates to optimize performance based on influent nutrient concentrations

System configuration:

• Lab-scale biofiltration columns amended with different biochar loadings
• Simulated and field-collected stormwater applied at varying event intervals
• Operational stability achieved over 2–3 month continuous runs
• Monitoring of effluent water quality and internal microbial community composition
• Field-scale validation using two existing biofiltration systems retrofitted with calculated biochar doses from lab data

Key features:

• Passive operation with no chemical inputs or energy requirements
• Scalable from laboratory columns to field-scale installations
• Compatible with existing green infrastructure and stormwater best management practices

Technology readiness level

The technology is currently at an early-to-mid stage of development. Laboratory-scale biofiltration systems have been designed to evaluate biochar performance under controlled stormwater conditions, with plans for 2–3 month operational runs to establish stable performance. Following laboratory validation, two field-scale biofiltration systems will be retrofitted with biochar to demonstrate real-world effectiveness. Further validation steps include monitoring nutrient removal efficiency and characterizing microbial community dynamics in both lab and field settings. The technology is positioned for pilot-scale demonstration and field deployment, with opportunities for collaboration on optimization, scale-up, and integration into existing stormwater treatment infrastructure.