Sequencing Batch Reactors (SBR's) offer many advantages and few disadvantages to the wastewater treatment process selection. Due to the relatively recent surge of interest in SBR's, few plants have been on-line long enough for Engineers to have developed a thorough understanding of all design aspects and considerations. The author has been involved directly in the design, equipment supply, start-up and operation of almost 60 SBR's of all sizes. About two thirds of the installations are municipal and one-third of these installations are industrial sites involving wastes from food processors, dairies, distilleries, petro-chemical manufacturers, landfill leachate, tanneries, Government munition plants and pharmaceutical manufacturers. The control of filamentous bulking has also been excellent with SBR's.
This paper will consider the mechanical, process and control aspects for design of an SBR. The mechanical aspects will include HRT and basin sizing, selection of aeration equipment and effluent decanters. The process parameters discussed will include loading rates and F:M considerations, MLSS concentration, oxygen requirements and D.O. uptake rate, flow proportional aeration, the benefits of an anoxic fill cycle, and finally, nutrient removal. Control considerations are briefly discussed.