Triclosan facilitates the recovery of volatile fatty acids from waste activated sludge

Highlights: • 200 mg/kg TSS of triclosan doubled acid recovery from 7284 to 15,083 mg COD/L. • Triclosan facilitates cell breakage and extracellular polymeric substances disruption. • Triclosan promotes all fermentation stages by enhancing enzyme activity. • Sludge containing triclosan is more suitable for acid recovery than methane. The emergence of triclosan (TCS) in the environment has caused extensive concern, but its role in waste activated sludge (WAS) anaerobic fermentation (AF) is still uncertain. This work investigated the impact of TCS on volatile fatty acids (VFAs) recycling from WAS. The results showed that TCS of 200 mg/kg TSS increased the maximum VFA accumulation from 7284 to 15,083 mg COD/L. The increase in total VFA production is attributed to the massive increase in acetic acid. Mechanism exploration showed that TCS promotes WAS solubilization by facilitating cell breakage and extracellular polymeric substances disruption, and stimulates AF by enhancing the activity of key enzymes among all stages. TCS promotes acidification stronger than methanogenesis, which makes VFA production faster than consumption, leading to increased VFA accumulation. These findings provide novel insights for revealing the role of TCS in WAS resource recovery, and offer thoughts for the selective production of final recycling products of TCS-containing WAS.