Nitrogen Effluence Separation and Treatment (NEST)

A Scalable System for Mitigating Eutrophication from Farmlands in the Midwest

Abstract

Nitrogen runoff from agricultural lands has emerged as a critical environmental and public health issue, contributing to widespread eutrophication, hypoxic zones, and contaminated drinking water. The Midwestern United States—home to extensive corn and soybean production—relies heavily on nitrogen-based fertilizers, yet over half of the applied nitrogen is lost to runoff. Addressing this challenge, we present the Nitrogen Effluence Separation and Treatment (NEST) system: a modular, dual-phase filtration technology designed for retrofitting into existing tile drainage infrastructure. NEST first employs a density-based separation unit to isolate particulate-bound nitrogen and sediment, followed by a biochar-based absorption chamber that targets dissolved nitrogen species through electrostatic and microbial interactions. Across 30 lab-simulated trials, NEST achieved an average nitrogen removal efficiency of 91.2%, with Phase 1 (physical separation) and Phase 2 (biochar filtration) independently recording efficiencies of 92% and 94%, respectively. The system’s design emphasizes scalability, low cost, and environmental neutrality, leveraging renewable biochar and eliminating the need for synthetic chemical inputs. Compared to traditional methods such as constructed wetlands or nitrification inhibitors, NEST demonstrates superior efficiency, adaptability, and ease of implementation. This proof-of-concept establishes a promising path forward in sustainable nitrogen management, offering a viable, farmer-friendly solution to reduce agricultural runoff and restore ecological balance in vulnerable watersheds.