Fenton oxidation of municipal secondary effluent: comparison of Fe/Ce-RGO (reduced graphene oxide) and Fe2+ as catalysts

The advanced treatment of municipal secondary effluent by heterogeneous and homogeneous Fenton processes using Fe/Ce-RGO (reduced graphene oxide) and Fe 2+ as catalysts was studied and compared. Sulfamethazine (SMT) was spiked in the effluent to examine the effectiveness of the emerging contaminant removal. The Fe/Ce-RGO catalyst was characterized using a scanning electron microscope (SEM) and cycle voltammetry curves. The removal of dissolved organic carbon (DOC), soluble chemical oxygen demand (SCOD), SMT, and ultraviolet-visible spectroscopy in 254 nm (UV 254 ) of municipal secondary effluents was examined. The DOC removal efficiency of secondary effluent (without addition of SMT) was 36.30% and 11.74% using Fe/Ce-RGO and Fe 2+ as catalysts, respectively. The removal efficiency of DOC, SCOD, and SMT in heterogeneous Fenton process was higher than that in homogeneous Fenton process. The changes of three-dimensional excitation-emission matrix (3DEEM) fluorescence, soluble microbial products (SMPs), humic acids, and UV 254 were determined, and the results indicated that UV 254, aromatic proteins, and humic acids decreased rapidly in both processes; however, polysaccharides and protein-like substances were difficult to degrade. Although some toxic substances produced after Fenton-like treatment, the biodegradability of the treated effluent was enhanced.