Enhanced neonicotinoid removal in constructed wetlands using Fungus-Fe/Mn biochar

Area of Science:

• Environmental Science
• Environmental Chemistry
• Biotechnology

Background:

• Neonicotinoid pesticides like imidacloprid (IMI) and thiamethoxam (THX) persist in the environment, posing risks to aquatic ecosystems.
• Conventional constructed wetlands (CWs) show limited efficiency in removing these persistent pollutants.

Purpose of the Study:

• To evaluate the efficacy of a novel Fungus-Fe/Mn biochar substrate in enhancing the removal of IMI and THX from agricultural wastewater using CWs.
• To elucidate the mechanisms behind the enhanced pesticide removal in the modified CWs.

Main Methods:

• Constructed wetlands were amended with Fungus-Fe/Mn biochar, Fe/Mn biochar, or operated as a control.
• Pesticide removal efficiencies were measured using simulated agricultural wastewater.
• Mechanistic investigations included adsorption, microbial degradation, metagenomic analysis, and analysis of redox-active species.

Main Results:

• CWs with Fungus-Fe/Mn biochar achieved significantly higher removal rates: 73.3% for IMI and 66.7% for THX.
• Removal was attributed to combined substrate adsorption (32.3-37.5%) and microbial degradation (32.4-35.1%).
• Metagenomic analysis revealed increased microbial diversity and enrichment of key pesticide degradation genes (e.g., p450, mnp) in amended systems.

Conclusions:

• Fungus-Fe/Mn biochar synergistically enhances pesticide removal in CWs through improved adsorption and microbial activity.
• This novel substrate offers a scalable and sustainable solution for remediating neonicotinoid contamination in aquatic environments.
• The study identified key microbial players and genes involved in pesticide degradation, paving the way for targeted bioremediation strategies.