Pilot test of Mn-Fe/Al2O3 catalytic ozonation in tertiary wastewater treatment

Abstract

Heterogeneous catalytic ozonation has received increasing popularity in wastewater treatment across China. However, some challenges, such as metal leaching from catalysts, still exist. Meanwhile, it is lesser known about its removal efficiency of dissolved organic carbon and impact on biological toxicity in pilot-scale applications. Here we synthesized an Al-based catalyst (Mn-Fe/Al2O3) for catalytic ozonation in pilot-scale. Results of characterization show that Mn and Fe were effectively supported on porous alumina and formed chemical bonds. The catalytic ozonation process could generate hydroxyl radical, superoxide radical and singlet oxygen for the deep degradation of dissolved organic carbon. Its chemical oxygen demand removal efficiency (average removal of 14.5 mg/L) could meet the requirement of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002) in China with acceptable metal leaching. The process also effectively removed dissolved organic carbon, especially the hydrophobic fractions (99 % removal). In toxicogenomics assay, the total transcriptional effect level index value for the effluent (1.40) was ≤ 1.50, indicating there was no obvious toxic effect for ecosystem. Based on economical estimation, the operational cost of the catalytic ozonation was 0.09 $/m3, much less than previous reported cases. This study provides convincing evidence for the effectiveness of Mn-Fe/Al2O3 catalytic ozonation in future wastewater treatment.