This study systematically compared the performance of different composite magnetic materials in enhancing activated sludge treatment of municipal wastewater. A sequencing batch reactor (SBR) process was used as the model system. Four different composite magnetic materials were examined: Fe3O4 composite activated carbon, Fe3O4 composite diatomite, Fe3O4 composite composite kaolin, and Fe3O4 composite composite fly ash. Their performance in enhancing activated sludge treatment of municipal wastewater was evaluated in terms of pollutant removal, sludge physicochemical properties, and molecular biology analysis. Furthermore, the two best-performing composite magnetic materials were further investigated at different dosages to examine their pollutant removal performance and mechanisms. Furthermore, the two best-performing composite magnetic materials were further investigated at different dosages to examine their pollutant removal performance and mechanisms. The results showed that, compared with the control system (without material addition), the addition of four composite magnetic materials improved the average removal efficiencies as follows: for the Fe3O4 composite activated carbon, Fe3O4 composite diatomite, Fe3O4 composite kaolin, and Fe3O4 composite composite fly ash systems, COD removal increased by 2.55%, 2.77%, 1.67%, and 4.10%, respectively; TN removal increased by 1.71%, 3.33%, 4.82%, and 0.82%, respectively; and TP removal increased by 4.96%, 7.02%, 6.01%, and 5.76%, respectively. In the Fe3O4 composite diatomite system, the highest average removal efficiencies of COD, TN, and NH4+-N were achieved at a dosage of 50 mg/L, whereas the highest average TP removal efficiency was achieved at a dosage of 200 mg/L. In the Fe3O4 composite kaolin system, the highest average removal efficiencies of COD, TP, and NH4+-N were achieved at a dosage of 50 mg/L, while the highest average TN removal efficiency was achieved at a dosage of 200 mg/L. High-throughput sequencing indicated that the highest activity of denitrifying genera was observed in the Fe3O4 composite diatomite system at a dosage of 50 mg/L and in the Fe3O4 composite kaolin at a dosage of 200 mg/L, respectively. The addition of composite magnetic materials enhances the efficiency of municipal wastewater biological treatment. These findings provide theoretical and technical guidance for the selection of magnetic composite materials in municipal wastewater treatment.
Ai et al. (Thu,) studied this question.
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