Simultaneous disinfection of urban wastewater and antibiotics degradation mediated by CuMgFe-B(OH)4 layered double hydroxide with different oxidizing agents

Abstract

The activation of peroxymonosulfate (PMS), peroxydisulfate (PDS) and hydrogen peroxide (H2O2) by CuMgFe-B(OH)4 layered double hydroxide (LDH) was investigated for the degradation of selected antibiotics (i.e., sulfamethoxazole, ciprofloxacin, cephalexin and amoxicillin) and for bacterial disinfection (Escherichia coli and Enterococcus faecalis) in secondary treated urban wastewater in dark condition. The catalyst synthesized behaved differently according to the oxidants used. H2O2 activated system was efficient for disinfection but not for antibiotics degradation due to the formation of complexes between LDH cations and H2O2. PDS activated system relied on a non-radical pathway mostly involving singlet oxygen and Cu(III) with antibiotics removal but with a disinfection capacity limited to E. coli. The comparison of the investigated systems for the removal of SMX in the secondary treated urban wastewater (STWW) showed 18% and 48% of SMX removal after 120 min of reaction with H2O2 and PDS, respectively. On the other hand, with PMS, SMX was below detection limit after 20 min of reaction, demonstrating the superior performance of LDH/PMS for the treatment of STWW. Furthermore, PMS activated with LDH provided > 90% removal of all antibiotics after 120 min and complete inactivation of the pathogens using 0.5 g L-1 of LDH and 4 mM of PMS.