Cost-effective modified agricultural residue adsorbent for nitrogen removal from urban stormwater

Overview

Urban stormwater runoff is a major contributor of nitrogen pollution to receiving water bodies, creating downstream challenges for water quality, aquatic ecosystems, and regulatory compliance. This solution offers a cost-effective adsorption technology that leverages locally available agricultural residues — such as straw and hull byproducts — as a sustainable alternative to commercial adsorbents. By applying chemical and electrochemical modification methods, the team transforms low-value agricultural waste into high-performance adsorbents capable of capturing multiple nitrogen species found in stormwater, including ammonium (NH4-N) and oxidized nitrogen forms (NOx-N).

Technical specifications

Core technology:

• Modified agricultural residue particles (e.g., canola straw) engineered for nitrogen adsorption
• Chemical and electrochemical surface modification methods to introduce new functional groups that serve as adsorption sites
• Proven track record: canola straw modification increased arsenic adsorption capacity by 30 times

Key advantages over untreated residues:

• Significantly higher adsorption capacity for target pollutants
• Faster adsorption kinetics, reducing required contact time
• Improved mechanical stability compared to fragile untreated residues
• Reduced coloration issues during treatment

Validation approach:

• Identification of nitrogen species present in urban stormwater
• Characterization of native functional groups on selected agricultural waste
• Surface treatment to improve accessibility of adsorption sites
• Chemical or electrochemical modification to introduce new adsorption-active functional groups
• Performance testing under realistic conditions, including the presence of competing stormwater pollutants

Technology readiness level

The underlying modification methodology has been experimentally validated for arsenic removal, demonstrating substantial gains in both adsorption capacity and uptake speed. Current work is focused on extending the technology to nitrogen compounds specific to urban stormwater. The next stages involve screening candidate residues for relevant nitrogen-binding functional groups, optimizing modification protocols for nitrogen capture, and validating performance against multi-pollutant stormwater matrices. The solution is positioned for pilot-scale evaluation and partnership with municipalities, stormwater management programs, and environmental technology integrators seeking affordable nutrient removal options.