Multilayered adsorbents for selective capture of dissolved nitrogen species in stormwater

Overview

This research develops a passive, multilayered adsorption system that combines polymeric ion exchange resins with activated carbon materials to selectively capture dissolved nitrogen species, including nitrate, nitrite, ammonia, and organic nitrogen, from stormwater runoff. The approach addresses the challenge of intermittent water flow by providing a stable treatment train that does not require continuous energy input. By layering complementary adsorbents rather than mixing them, the system aims to minimize competitive interactions between co-occurring species and achieve reliable abatement of total nitrogen below regulatory maximum concentration limits.

The technology is relevant to stormwater management, water quality compliance, and decentralized treatment of agricultural, urban, and industrial runoff. Industry partners in the construction materials, environmental infrastructure, and water treatment sectors can leverage this approach to enhance pollutant removal performance in passive treatment systems.

Technical specifications

Target contaminants:

• Inorganic nitrogen: nitrate, nitrite, and ammonia
• Organic nitrogen species commonly found in stormwater matrices

Core approach:

• Layered configuration of selective adsorbents rather than homogenized mixtures to reduce competition between species
• Anionic exchange resins for nitrate and nitrite removal, leveraging proven high-efficiency ionic exchange chemistry
• Cationic exchange resins for selective ammonia capture
• Activated carbon layers for adsorption of organic nitrogen species

Validation methodology:

• Rapid small scale column tests (RSSCTs) used to estimate full-scale system capacities and bed volumes
• Performance evaluation under continuous flow and intermittent dosing conditions to simulate real stormwater variability
• Testing in both synthetic complex water matrices and collected real runoff water

Research team expertise:

• Prior validated experience with adsorption systems for organic trace pollutants, including N-organic species
• Background in catalytic nitrate treatment technologies, enabling understanding of competitive and complementary treatment approaches

Technology readiness level

The technology is at an early-to-mid stage of development. Phase 1 will benchmark removal capabilities of commercially available resins and carbons for individual target nitrogen species using RSSCTs, followed by testing in complex water matrices. Phase 2 will compare the multilayered adsorption system against homogenized mixtures of the best-performing materials identified in Phase 1, evaluating performance under continuous and intermittent flow conditions with real runoff water. The research team has prior validated experience with the underlying adsorption and ion exchange mechanisms, providing a strong foundation for advancing toward pilot-scale demonstration and eventual commercial deployment.