The SND process in two granular sequencing batch reactors with different mean granule sizes: a case study.

Conventional Activated Sludge plants (CASP) for wastewater treatment have several limitations related to high excess sludge production, large surface area demand and low flexibility. In addition, their upgrading generally involves the use of multiple tanks with the recycling of mixed liquor to obtain high concentrations of microorganisms, nitrates and degradable organics in the anoxic or anaerobic reactors. It also requires additional space that may not be available near the existing treatment plants and, in cases where the space is available, large capital investments are needed in crowded metropolitan areas. For this reason, in recent years the scientific community has been attracted by other innovative systems for wastewater treatment. Among these, the Sequencing Batch Reactor (SBR) with aerobic granular sludge represents a good alternative (Beun et al., 2001 and 2002).