Understanding and regulating the impact of tetracycline to the anaerobic fermentation of waste activated sludge

Tetracycline (TC), a widely used antibiotic, was enriched in waste activated sludge (WAS) at significant levels. However, the TC impact on WAS anaerobic fermentation are still poorly understood. This work aims to analyze the effect of TC to the WAS anaerobic fermentation by investigating the differences of sludge properties, short-chain fatty acids (SCFAs) production and microbial community abundance. The results showed that the environmental level of TC had no effect on the SCFAs production, but with the further increase of the content of TC to 60 mg/kg TSS, the maximum SCFAs yield decreased from 125.1 ± 3.2 to 90.8 ± 1.7 mg COD/g VSS. Mechanism exploration indicated that TC had no significant effect on solubilization, hydrolysis and homoacetogenesis processes, but severely inhibited acidogenesis, acetogenesis and methanogenesis processes. Microbial analysis showed that the presence of TC reduced the diversity of microbial communities and the abundance of functional microorganisms relevant to SCFAs production and complex organic degradation, such as Proteiniclasticun and Novosphingobium . This negative effect was persistent because only a small amount of TC can be degraded in the anaerobic fermentation process. Hence, CaO 2 was proposed and studied as a regulation strategy that can reduce the toxicity of TC on anaerobic fermentation. • When the TC level were 5, 30 and 60 mg/kg TSS, the SCFAs production decreased by 11.0%, 18.2%, and 27.4%, respectively. • TC severely inhibited acidogenesis, acetogenesis and methanogenesis processes. • The most of TC was stuck after anaerobic fermentation of WAS. • CaO 2 improved the SCFAs production by degrading TC and disintegrating sludge.