Chapter 9 - Wastewater treatment by Sequencing Batch Reactor (SBR) without releasing excess sludge

Abstract

Operation of a Sequencing Batch Reactor (SBR) at zero discharged sludge could eliminate the sludge treatment cost. However, under this operational condition, the sludge would be accumulated in the reactor, resulting in a reduction in the working volume of reactor. Therefore, the volume of treated wastewater would be decreased. In this study, the SBR system was operated under different conditions, either oxic or anoxic. A volume of 5L of domestic wastewater was fed into the SBR. During operation, no excess sludge was discharged. As a result, the MLSS level was increased from 900mg/L to more than 8200mg/L. At such a high level of MLSS, the COD removal efficiency was in the range of 94%–98%. The nitrogen and phosphorus removal varied largely between these conditions. The removal of nitrogen and phosphorus by SBR depended on whether the reactor was operated under anaerobic or aerobic conditions. A TN removal efficiency of over 95% could be achieved at an MLSS concentration of 8200mg/L, while the TP removal efficiency could be found stable at 96%. In conclusion, the SBR could be operated without sludge discharge. The SBR system operated without sludge discharge could reduce the sludge treatment cost. This could be an alternative solution to treating domestic wastewater by the SBR system.