Aerobic granulation in a sequencing batch airlift reactor

• Published in: Water research (Oxford) 2002-02, Vol.36 (3), p.702-712
• Main Authors: Beun, J.J., van Loosdrecht, M.C.M., Heijnen, J.J.
• Format: Article
• Language: English
• Subjects: Activated Sludge; Aerobic granules; Air Movements; Airlift reactor; Applied sciences; Bacteria, Aerobic - physiology; Biofilms; Biological and medical sciences; Biological treatment of waters; Biomass; Bioreactors; Biotechnology; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Particle Size; Pollution; Population Dynamics; Sequencing batch reactor; Sewage; Waste Disposal, Fluid - methods; Wastewaters; Water Movements; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(01)00250-0

Aerobic granular sludge was cultivated in an intensely mixed sequencing batch airlift reactor (SBAR). A COD loading of 2.5 kg Acetate-COD/(m 3 d) was applied. Granules developed in the reactor within one week after inoculation with suspended activated sludge from a conventional wastewater treatment plant. Selection of the dense granules from the biomass mixture occurs because of the differences in settling velocities between granules (fast settling biomass), and filaments and flocs (slow settling biomass). At ‘steady state’ the granules had an average diameter of 2.5 mm, a biomass density of 60 g VSS/l of granules, and a settling rate of >10 m/h. The biomass consisted of both heterotrophic and nitrifying bacteria. The reactor was operated over a long period during which the granular sludge proved to remain stable. The performance of the intermittently fed SBAR was compared to that of the continuously fed biofilm airlift suspension reactor (BASR). The most importance difference was that the density of the granules in the SBAR was much higher than the density of the biofilms in the BASR. It is discussed that this could be due to the fact that the SBAR is intermittently fed, while the BASR is continuously fed.