Sequencing Batch Reactors in Municipal Used Water Purification

Sequencing batch reactors employ a type of activated sludge process with a fill-and-draw operation in which the entire biological treatment procedure and clarification take place in a single reactor. The main steps of the SBR process consist of filling, mixing, aeration, settling, decanting, and idling, which are carried out in a predefined, timed sequence. There are a variety of SBR process options, and through the application of differing filling, mixing, and aeration strategies it is possible to achieve a range of nutrient removal objectives, which makes SBR both extremely efficient and flexible. Decanters represent important components in SBR plants and have to meet high standards of functionality, flexibility, and reliability. On the basis of long-term experience in the design of SBR plants, WABAG has optimized this technology and as a special feature has designed an advanced motor-driven decanter, which is presented in this chapter. A type of configuration matrix with a fixed, time-oriented sequence for the filling, reacting, settling, and decanting phases is often employed for the control of the SBR process. However, with the help of modern equipment, it is possible to increase the efficiency of standard SBR reactors and thus save costs by adapting the cycle time and optimizing the duration of the individual treatment steps. The latest development of the SBR system involves the application of granular activated sludge like that from the Nereda process, which offers several advantages over the conventional SBR such as reductions in both the space and power requirement, lower chemical consumption, and improved toxic and shock load tolerance. WABAG is a cooperation partner of Royal Haskoning DHV and has already built several Nereda® SBR plants.