Comparison Between Sequencing Batch Reactors (SBR) and Stirred Tank Reactors (STR) in Handling Hydraulic Shock Loads

Abstract

The use of Stirred Tank Reactor (STR) in wastewater treatment requires a Clarifier in its operation so that Sequencing Batch Reactor (SBR) is an alternative solution. The clarifier is needed to recover some of the wasted microbes in the effluent stream. With SBR, the Clarifier function is replaced when the settle phase in the SBR operating cycle is executed. The four phases of SBR operation are carried out in stages and sequentially, namely, the fill, react, settle, and draw/decant phases. In this study, the performance of SBR and STR was compared in treating molasses-based wastewater. At an organic loading rate of 516 mg COD L-1 day-1 and 20 days HRT, these two types of reactors were capable to remove the COD content of wastewater with an efficiency of about 90%. At a hydraulic shock load of 10 days and the same organic loading rate, SBR showed its superiority. The organic compound removal efficiency of around 89% could still be maintained by SBR but the organic compound removal efficiency of only about 57% could be maintained by STR. The parameters of pH could be maintained by SBR in the pH range of 7.2 to 7.4, whereas the pH values in STR were in the pH range of 7.0 to 6.3.