A Comparative Study on Performance of an Intermittent Aeration SBR and a Traditional SBR for Treatment of Digested Piggery Wastewater

Abstract

An intermittently aerated sequencing batch reactor (IASBR) and a traditional sequencing batch reactor (SBR) were respectively used for treating digested piggery wastewater, and the pollutant removal performance was studied at different ratios of chemical oxygen demand (COD) to total nitrogen (TN) in the influent and different loading rates. The results showed that the pollutant removal rates in the IASBR were much higher than those in the SBR. Under influent COD/TN of about 2.2 and NH4+-N loading of (0.12±0.04) kg·(m3·d)-1, the removal rates of NH4+-N, TN and TOC in the IASBR were 97.2%±4.4%, 81.5%±7.5% and 88.5%±2.4%, respectively, higher than the corresponding rates of 78.3%±19.6%, 79.8%±4.9% and 86.6%±3.2% in the SBR. As the NH4+-N loading was increased to (0.18±0.02) kg·(m3·d)-1, the removal rates of NH4+-N, TN and TOC in the IASBR were slightly decreased to 92.4%±7.3%, 77.5%±5.3% and 86.4%±2.2%, but still higher than the corresponding values of 78.1%±15.4%, 61.8%±11.2% and 81.8%±5.6% in the SBR. As the NH4+-N loading was remained at (0.20±0.01) kg·(m3·d)-1, but the influent COD/TN ratio was increased to about 3.0, the pollutant removal rates in both IASBR and SBR were increased, compared to those at influent COD/TN ratio of 2.2.The removal rates of NH4+-N, TN and TOC in the IASBR were 99.6%±0.2%, 91.5%±2.9% and 92.0%±0.9%, respectively, higher than the corresponding rates of 90.2%±1.4%, 83.0%±1.9% and 90.2%±0.5% in the SBR. Based on the above, the IASBR was more efficient in TN and ammonium removal and more shocking load resistant, and therefore was more feasible than SBR for treating low COD/TN ratio wastewaters such as the digested piggery wastewater.