A recent study published in the Journal of Hazardous Materials explores the potential of potassium hydroxide (KOH)-modified biochar to improve the nitrogen metabolism of anammox bacteria in chloroquine phosphate (CQ)-contaminated wastewater. CQ, a common non-antibiotic drug, is a significant micropollutant due to its toxic effects on biological wastewater treatment systems, particularly the anammox process.

Anammox, a cost-effective and eco-friendly nitrogen removal process, faces challenges in CQ-contaminated environments. CQ disrupts the nitrogen cycle and hinders the growth of anammox bacteria by causing oxidative damage and enzyme inhibition. To address this, researchers investigated how KOH modification enhances biochar’s detoxification properties and electron exchange capacity (EEC).

The study found that KOH-modified biochar increased EEC by 70%, improving nitrogen removal efficiency by 55.6% compared to CQ-affected systems without biochar. The modification boosted biochar’s ability to bind CQ through hydrogen bonding and π-π interactions, reducing its toxicity. Additionally, biochar enhanced extracellular polymeric substances (EPS) production, which protected anammox bacteria and promoted sludge granulation.

Metagenomic analysis revealed that modified biochar stimulated key metabolic pathways, such as the Wood-Ljungdahl pathway, and increased the relative abundance of anammox bacteria by 86.8%. This work demonstrates that tailored biochar could mitigate micropollutant stress and support sustainable wastewater treatment solutions.

The findings highlight the potential for integrating high-EEC biochar into anammox systems, providing a promising approach for managing pharmaceutical-contaminated wastewater.