New Insights into the Influence Mechanisms and Impacts of Chlortetracycline on Volatile Fatty Acid Generation during Thermophilic Anaerobic Sludge Fermentation
摘要
Antibiotic contamination hinders sludge resource utilization, yet the role of chlortetracycline (CTC) in thermophilic anaerobic systems and its impact on volatile fatty acid (VFA) production remain unclear. This study fills this gap by investigating CTC’s dose-dependent effects on thermophilic anaerobic sludge fermentation and underlying mechanisms. Results revealed a dual role of CTC: low concentrations (50–100 mg/kg) enhanced VFA yields, with the optimal 100 mg/kg increasing peak VFA by 26.3% (to 245.6 mg/g VSS) and acetate accounting for over 75%. This was driven by CTC-activated extracellular hydrolases, promoting dissolved organic matter release (soluble chemical oxygen demand peak 5915 mg/L) and acetate-dominant pathways. Conversely, high concentrations (≥ 150 mg/kg) reduced VFA by 25.3% and induced propionate accumulation (18.1%) via suppressed hydrolysis. Mechanistically, CTC regulated system stability by modulating EPS, low doses increased soluble/loosely bound EPS and reduced tightly bound EPS, enhancing hydrolase accessibility. This study innovatively clarifies CTC’s dose-dependent regulation in thermophilic fermentation, providing a theoretical framework for optimizing antibiotic-contaminated sludge resource utilization based on concentration thresholds.
Graphical Abstract