Mitigation of\nPharmaceutical Wastewater Toxicity in\nAnaerobic Reactors Using Metal-Modified Biochar

Anaerobic\nsequencing batch reactors (ASBRs) treating\nwastewater\nrich in ciprofloxacin (CIP) were supplemented with an Fe/Zn@biochar\ncatalyst to improve their performance. ASBR4, with 100 mg Fe/Zn@biochar/g<sub>VS</sub>, showed substantial increased efficiencies in removing COD\nand CIP, reaching 86.9 ± 5.8 and 80.9 ± 8.6%, respectively,\ncompared to no biochar addition (25.2% and 51.1% higher, respectively).\nLikewise, biogas yield augmented from 0.17 ± 0.06 to 0.34 ±\n0.02 L/g COD<sub>removed</sub> owing to the boosted abundance of acetolactic\nmethanogens, i.e., Methanosaeta and Methanosarcina, which increased from 0.4 and 1.6%\nin the control ASBR1 to 1.6 and 2.2% in ASBR4, respectively. Microbial\nenzymatic activities, including dehydrogenase and extracellular polymeric\nsubstances (EPSs), highly increased by 38% and >100%, respectively,\naiding in biochar adsorption and microbial biodegradation synergy.\nFe/Zn@biochar contributed to both CIP adsorption and biodegradation\nwith percentages of 59.5 ± 4.9 and 34.7 ± 2.6%, respectively.\nThe synergistic effect between the biotic and abiotic impacts of Fe/Zn@biochar\nreached 94.2 ± 7.2%, suggesting that the addition of Fe/Zn@biochar\nis a promising approach to enhance the CIP-remediation process.