Comparison of Particle Behavior in Sewage Treatment Facilities

The behavior of particles was investigated in SBR and A2O systems, which are representative wastewater treatment methods. The SBR reactor was designed with a capacity of 8 L, the influent flow rate was 12 L/day, and the operating cycle was set to 4.0 hr/cycle. The influent characteristics were as follows: MLSS 1,700 mg/L, TOC 78.8 mg/L, SS 180.0 mg/L, T-N 44.394 mg/L, and T-P 4.666 mg/L. Particle behavior was analyzed by size (≥1.2 μm, 0.2-1.2 μm, ≤0.2 μm) and ionic metal substances. The results showed that all metal nanoparticles were adsorbed into the sludge and subsequently treated. ZnO was likely to be discharged into the river in ionic form under operating condition 1 (anoxic 90 min/cycle; oxic 210 min/cycle) and was shown to be effective in enhancing sludge treatment in the >1.2 μm size fraction by reducing the aeration time. The A2O reactor was operated in 4 cycles, with an effective volume of 73.4 L, an HRT (V/Q) of 18 h, and a treatment capacity of 97.87 L/day. The SRT was set to 15 days, and the influent flow rate was 67.96 mL/min. MLSS was operated at 3,795 mg/L, achieving removal efficiencies of 96.09% for Ti and 95.88% for Ce. In laboratory-scale experiments, removal efficiencies reached 99.17% for Ti and 99.76% for Ce under conditions of MLSS 2,560 mg/L, HRT 18 h, and SRT 15 days.