Hybrid combination of advanced oxidation and biological processes for the micropollutant removal of carbamazepine

Carbamazepine (CBZ) is a frequently-detected aqueous pharmaceutical due to its extensive use and persistence in the environment. CBZ could not be efficiently removed by biological processes which led to its disposal in natural water bodies. This study coupled the Fenton process as pretreatment with the activated sludge process for aqueous CBZ removal. Fenton degradation studies showed that the application of excessive reagents might cause a decrease in CBZ removal. Apparent CBZ degradation at neutral pH supported the use of the Fenton process as pretreatment for CBZ removal. Treated with the hybrid combination system, CBZ, COD, and TOC removal were enhanced. The EEM analysis evidenced the biodegradable intermediates formed during the hybrid process. CBZ degradation pathways were explored using LC-MS analytical results and literature studies. Given the low biodegradability of CBZ, using the Fenton process as a pretreatment before sequencing batch reactor-activated sludge (SBR-AS) is an alternative to improve the aqueous CBZ treatment.