Amoxicillin enzymatic decomposition via H[formula omitted]O[formula omitted]-stimulation of catalase-positive bacteria in a sequential batch reactor

Abstract

The concentration of amoxicillin, one of the most prescribed antibiotics, has increased in water sources. This investigation aimed to explore the enzymatic biodegradation of amoxicillin (AMX) from wastewater through H2O2 stimulation of catalase-positive bacteria in a 5-liter sequential batch reactor (SBR). The bacterial consortium was first adapted by slowly increasing the concentration of amoxicillin for 12 days. The results showed that the biomass was well acclimatized for enzymatic degradation of AMX in wastewater. Real wastewater with TDS and COD concentrations of 20,000 mg/L and 300 mg/L, respectively, and a nutrient solution with a C/N/P ratio of 1/10/100 was provided as a feed of the SBR. After 22 h of reaction, the AMX removal rate increased to 98.9% and finally reached 99.6% on the 25th day of operation. When the AMX content was suddenly increased to 700 mg/L, the AMX decomposition efficiency was decreased to 90.3%, and in the next operation cycle, the removal efficiency reached 98.1%. The key bacterial species involved in the system were Pseudomonas spp., Bacillus spp., and Klebsiella oxytoca. The sludge volume index and total solid of the produced sludge in the SBR were analyzed to be 71 mL/g and 10.2 g/L, respectively. According to the findings, enzymatic biodegradation is one of the best systems for the removal of high-content AMX wastewater.