Zeolite/zvi stormwater nutrient treatment system

Overview

Stormwater runoff carries nitrogen species and phosphorus that degrade water quality in urban and receiving waters. This solution offers a passive, low-maintenance treatment system that combines two complementary media—granular zeolite and zero valent iron (ZVI)—housed within precast structures to capture and treat stormwater before discharge. The system targets ammonium, nitrate, and phosphorus through a combination of ion exchange and chemical/biological reduction, converting reactive nitrogen species into innocuous nitrogen gas.

The technology is designed for straightforward integration into existing stormwater infrastructure, making it attractive for municipalities, developers, and environmental remediation projects seeking cost-effective nutrient management.

Technical specifications

Treatment mechanism:

• Granular zeolite removes ammonium through surface absorption (ion exchange of cations)
• ZVI reacts with water to generate hydrogen, which drives abiotic reduction of nitrogen species
• The hydrogen byproduct also supports autotrophic bacteria naturally present in stormwater, enabling biological reduction of nitrogen species to nitrogen gas
• Phosphorus removal is achieved through surface absorption onto the media

System configuration:

• Two media types housed in separate compartments to prevent ZVI reaction precipitates from coating the zeolite
• ZVI blended with sand to prevent clogging and maintain hydraulic conductivity
• Media contained in porous nylon or cloth-type enclosures for easy handling and replacement
• Designed for a superficial velocity of 1 gpm per square foot (0.134 ft/min)

Prototype dimensions (drain insert configuration):

• A 5 gpm dry weather nuisance flow requires approximately 5 square feet of cross-sectional area
• Rectangular insert dimensions of approximately 2.24 ft × 2.4 ft
• Compatible with precast structures from standard infrastructure suppliers

Technology readiness level

The technology builds on demonstrated expertise in zeolite-based ammonium removal from mining processing water, including applications for an Alaskan gold mine and prior work on cesium and strontium removal. The research team also has extensive experience applying ZVI for reduction of nitrate, chromate, chloroform, and chlorate in water treatment contexts, along with a track record of using metal oxides and ion-exchange resins for selenium, perchlorate, arsenic, hexavalent chromium, and heavy metal removal.

The next phase of development involves field testing of the prototype in the metropolitan Las Vegas area to validate combined-media performance under real stormwater conditions. The system is at an early-to-mid stage of development, with strong foundational science and a clear path to prototype validation.