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Development of a granular sludge sequencing batch reactor (GSBR) (Zwart et al. 2006; Van de Poel and Zwart forthcoming)

One drawback of traditional biological wastewater treatment plants is their large space demand or footprint, which is caused by the use of separate settling tanks and the slow settling velocity of the sludge. In the aerobic GSBR technology both size increasing factors are addressed. By using high-density granules, the time needed for the sludge to sink to the bottom at the end of each cycle is substantially reduced. Subsequently, the shorter deposit time increases the throughput of the installation and reduces the footprint. Second, it is hoped that different ecological zones inside the granules will be able to take care for the entire treatment process in one reactor instead of several separate tanks

The GSBR technology has been developed at the Department of Biotechnology, Delft University of Technology, the Netherlands. After successful laboratory experiments, the Dutch Foundation for Applied Water Research (STOWA) was found willing to invest in the scaling-up of the three-liter laboratory reactor to an outdoor pilot plant of 1.5 m3. In parallel to the upscaling of the pilot plant, funds were acquired for a PhD-project (funding organization: Technology Foundation STW). Finally, an international engineering and consulting firm, with water management technology as one of its main domains, showed interest in the commercial exploration of the GSBR technology. This firm was in charge of the research at the pilot plant, operated by a local water board. The results of the pilot plant have been positive and the firm anticipates a large demand for GSBRs