Sequencing batch reactors for biological wastewater treatment

The Sequencing Batch Reactor (SBR) is one of several periodically operated, suspended‐growth activated sludge systems. This periodic process accomplishes (in time) in one tank the same unit operations and processes that a conventional continuous‐flow system carries out in separate tanks. This paper discusses the history of periodic process development as well as the relationship of the SBR to other periodic processes and continuous flow‐systems. Bench‐and full‐scale performance of the SBR are described for synthetic substrates, municipal and industrial waste waters, and organics in Ieachates from hazardous waste disposal sites. Examples are given for the removal of biodegradable organics and nutrients (both nitrogen and phosphorus) and for the control of filamentous organisms. A brief discussion of the organism selection features of the SBR is presented as well as a comparison with genetic engineering approaches. The paper closes with two design examples, one dedicated to the treatment of industrial or hazardous wastes and the other to a 100,000 m³/d domestic wastewater treatment plant.