Effect of ciprofloxacin on methane production and anaerobic microbial community.

This study investigated the effects and fate of CIP on anaerobic sludge over a wide range of concentrations (0.05-50 mg/L), and 0.5-50 mg/L significantly inhibited organic removal and methanogenic activity, increased volatile fatty acids accumulation and low molecular weight soluble microbial products (SMPs), including p-cresol and nitrogen-containing compounds. Although microbial communities exposed to CIP did not differ significantly from the control in species diversity indices, Syntrophobacter and Methanothrix associated with acetogenesis and acetoclastic methanogenesis, respectively, were underrepresented in the CIP-exposed communities. Our study advances understanding of how environmentally relevant concentrations of CIP disrupts anaerobic digestion, which has important implications for anaerobic engineered systems treating CIP-bearing waste streams.

Post-treatment of anaerobic membrane bioreactor (AnMBR) effluent using activated carbon.

Anaerobic membrane bioreactors (AnMBR) are very effective for wastewater treatment, however, with the antibiotic ciprofloxacin (CIP) (0-4.7 mg CIP/L) in the feed their performance decreases, the characteristics of the effluent changes, and further treatment is needed to recycle or discharge the treated effluent. Batch experiments using six activated carbons to treat AnMBR effluents resulting from the treatment of a synthetic wastewater containing ciprofloxacin were carried out at 35 °C. 22-82% COD was removed at a dose of 1 g activated carbon/L, while size characterization showed the 13.4 kDa and <1 kDa fractions were the most difficult to adsorb, while CIP was often removed with high efficiencies of mainly 100%. Significant removal of VFAs also occurred, up to 100%, and this contributed greatly to COD removal. Nitrogen containing compounds and phenols showed the highest removal (∼100%), whereas other groups such as esters, alkanes, and alkenes showed lower removal efficiency.