# Simultaneous Removal of Organic Pollutants and Pathogens from Stormwater by an Enhanced Ecological Gabion

## TL;DR

An enhanced ecological gabion system improves stormwater purification by removing pollutants and pathogens more effectively than traditional methods.

## Contribution

The study introduces an ecological gabion with functional fillers and vegetation for simultaneous removal of organic pollutants and pathogens.

## Key findings

- The enhanced gabion achieved 2.48 to 3.68 times higher removal efficiency for COD, NH4+–N, and TN compared to traditional gabions.
- It showed 329% and 137% higher removal of POC and DOC, respectively.
- Fluorescence and particle size analyses confirmed effective removal of DOM components and fine particulates.

## Abstract

Stormwater runoff represents a significant vector for the transport of organic pollutants and pathogens into aquatic ecosystems, posing serious environmental and public health risks. Although extensively employed for bank stabilization, traditional gabion structures demonstrate constrained efficacy in pollutant removal. In this study, an enhanced ecological gabion (EG) system was developed by integrating a stratified configuration of functional fillers (ceramsite, maifanite, and biochar) with vegetation (Iris germanica). This design leverages synergistic effects to enhance the concurrent removal of dissolved organic matter (DOM), particulate organic matter (POM), and fecal indicator bacteria (FIB) from simulated stormwater. The system was evaluated in continuous flow experiments through comparison with a traditional gravel gabion (TG). Results showed that, compared with the TG, the EG exhibited markedly enhanced removal performance, with chemical oxygen demand (COD), NH4+–N, and TN removal efficiencies being approximately 2.48, 3.68, and 3.56 times those of the TG, respectively. In addition, the EG exhibited significantly higher removal efficiencies for both particulate organic carbon (POC) and dissolved organic carbon (DOC) than the TG, with increases of 329% and 137%, respectively. Fluorescence spectroscopy and particle size distribution analyses revealed that the EG effectively transformed and removed diverse DOM components and fine particulates. The stratified filler media synergistically enhanced pollutant retention, with biochar serving as the primary agent for nutrient and pathogen adsorption. These findings demonstrate the viability of the EG as an integrated, eco-friendly solution for enhanced stormwater purification in riparian zones, providing a compact and multifunctional alternative to conventional end-of-pipe systems.