Deciphering the internal mechanisms of ciprofloxacin affected anaerobic digestion, its degradation and detoxification mechanism

• Published in: The Science of the total environment 2022-10, Vol.842, p.156718-156718, Article 156718
• Main Authors: Tang, Taotao, Liu, Min, Du, Ye, Chen, Ying
• Format: Article
• Language: English
• Subjects: Anaerobic digestion (AD); Ciprofloxacin (CIP); Intermediate metabolites; Microbial community; Toxicity
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.156718

Ciprofloxacin (CIP) is widely used in livestock farms, but the internal mechanism of the effect of residual CIP in actual livestock wastewater on anaerobic digestion (AD) performance remains unknown. This study examined the dose-specific effects of CIP (0.5–2 mg/L) on livestock wastewater AD by analyzing acidogenesis and methanogenesis. 0.5 mg/L CIP promoted methane production by facilitating acidogenesis and acetogenesis. Compared with the control, the cumulative methane production increased from 331.38 to 407.44 mL/g VS at a dose of 0.5 mg/L, an increase of 22.95 %. However, as the dose of CIP increased, the cumulative methane production gradually decreased to 217.64 mL/g VS (2 mg/L). Microbial community analysis revealed that CIP had the greatest impact on methane production by influencing the activity of acidogenic bacteria. Meanwhile, acidogenesis was critical for CIP degradation. In acidogenesis, hydroxylation, amination, defluorination, decarboxylation, and piperazine ring breaking not only degraded CIP but also reduced its toxicity. Therefore, a large number of intermediates could be continuously degraded by microorganisms. However, as the dosage of CIP increased, the ability of microorganisms to degrade intermediates decreased. [Display omitted] •The degradation and detoxification process of CIP mainly occurred in acidogenesis.•CIP mainly affected the production of methane by influencing the acidogenesis.•A large number of CIP intermediate metabolites could be degraded by microorganisms.